In this study,a series of poly(ethylene succinate)-b-poly(butylene carbonate)(PES-b-PBC)multiblock copolymers were prepared through the chain-extension reaction of hydroxyl-terminated PES(PES-OH)and hydroxyl-terminate...In this study,a series of poly(ethylene succinate)-b-poly(butylene carbonate)(PES-b-PBC)multiblock copolymers were prepared through the chain-extension reaction of hydroxyl-terminated PES(PES-OH)and hydroxyl-terminated PBC(PBC-OH)prepolymers with 1,6-hexmethylene diisocyanate(HDI)as a chain extender.The effects of the prepolymer molecular weight and content on the structure and application properties of the PES-b-PBC copolymers were systematically investigated using various techniques.It was found that the compatibility of PES and PBC blocks in PES-b-PBC copolymers can be greatly enhanced by lowering the length of the prepolymers,and the amorphous phase of the PES and PBC chain segments in the PES-b-PBC copolymer would transform from immiscibility and partial miscibility to miscibility when the number-average molecular weight(M_(n))of the PES-OH and PBC-OH prepolymers is less than 2000 g/mol.Only the crystal structure of bare PES can be observed in the wide-angle X-ray diffraction(WAXD)spectrum of the PES-b-PBC copolymers,but their crystallinity degrees were found to decrease with increasing PBC fraction.The thermal behavior,crystallization performance,rheological properties,mechanical properties,and degradation properties of the PES-b-PBC multiblock copolymers can be easily modulated by altering the block length and composition of the prepolymers,offering potential applications in biodegradable materials.展开更多
The application of poly(butylene adipate-co-terephthalate)(PBAT)biodegradable plastics has long been constrained by insufficient light aging resistance.Hindered amine light stabilizers(HALSs),known as eco-friendly add...The application of poly(butylene adipate-co-terephthalate)(PBAT)biodegradable plastics has long been constrained by insufficient light aging resistance.Hindered amine light stabilizers(HALSs),known as eco-friendly additives,can scavenge free radicals to enhance polymer durability.However,rough choices have resulted in wastage of resources and environmental pressure.Based on the application of plastic films as the background for use,this study systematically evaluates application effects of five HALSs.The films underwent accelerated aging for various durations and were further investigated by a combination of experiments and molecular simulation.Results showed that all HALSs mitigated PBAT light aging,with Chimassorb-944(UV-944)and Tinuvin-770(UV-770)performing the best for real applications.Quantum chemical calculation results showed that UV-944 had stronger anti migration ability.After 300 h of aging,films with UV-944 and UV-770 retained superior tensile strength and elongation at break in the transverse direction compared to neat PBAT films.Polymeric HALSs provided better long-term stability than small-molecule ones.Further spectra analysis indicated that stronger C―O bonds in HALS/PBAT composites correlated with improved photostability.This study offers valuable insights into improving weather resistance of PBAT biodegradable films and optimizing the real application of HALSs.展开更多
Ocean-degradable polyesters incorporating hydrophilic and rapidly degradable glycolide(GL)units into the polymer chain are the most promising for addressing marine plastic pollution,however,it is challenging to obtain...Ocean-degradable polyesters incorporating hydrophilic and rapidly degradable glycolide(GL)units into the polymer chain are the most promising for addressing marine plastic pollution,however,it is challenging to obtain high-molecular-weight copolymers with narrow molecular weight distributions.Herein,we prepared a novel biodegradable material,poly(butylene succinate-co-glycolide)(PBSGL),through ring-opening copolymerization using glycolide,succinic anhydride,and 1,4-butanediol as raw materials,providing a new solution strategy for marine pollution.GL could be polymerized according to the pre-designed composition by 1H-nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)results,indicating controlled polymerization with the synthesized PBSGLs having a weight-average molecular weight of up to 12.30×10^(4) g/mol and a narrow molecular weight distribution(1.33–1.65).Differential scanning calorimeter(DSC)and thermogravimetric analysis(TGA)results showed that T_(g) of PBSGLs increased from−32.5°C to−26.5°C with the increase of GL content from 0%to 40%,while T_(m)(>76°C)was much lower than T_(d,5%)(>314°C),which indicated that PBSGLs had good thermal stability and expanded the processing window and application range of the original poly(butylene succinate)(PBS)materials.Under simulated difficult conditions,PBSGL copolyesters could degrade faster with increasing GL content,where PBSGL40 degraded by 22.6%in 12 days,showing good biodegradability.Currently,most biodegradable polyesters with good performance slowly degrade in seawater.In a 30-day artificial seawater degradation test,the amorphous PBSGL40 copolyester showed a about 15-fold(2.33%weight loss)improvement in degradation ability compared to pure PBS,demonstrating rapid seawater degradation capability.展开更多
Semicrystalline polymers usually undergo multilevel microstructural evolutions with annealing and stretching processes,which is es-sential to tailor the physical properties of the polymer.Here,poly(butylene carbonate)...Semicrystalline polymers usually undergo multilevel microstructural evolutions with annealing and stretching processes,which is es-sential to tailor the physical properties of the polymer.Here,poly(butylene carbonate)(PBC)sheets were prepared via isothermal annealing and unidirectional pre-stretching processes,then the changes of PBC in crystallinity,mechanical properties,thermal properties and microscopic changes before and after annealing and stretching were measured,as well as the relationship between microstructure and macroscopic proper-ties before and after stretching.The strengthening mechanism of PBC was also described.It was demonstrated that shish-kabab structure emerged under the pre-stretching process.With the increase of the tensile ratio,the crystallinity,structure and mechanical properties are in-creased differently.Among them,the crystallinity and tensile strength after annealing-stretching treatment increased to 24.45%and 104.5 MPa,respectively,which were about 1.55 times and 3.4 times of those-without any treatment.展开更多
The effects of crystallization temperature and blend ratio on the polymorphic crystal structures of poly（butylene adipate） （PBA） in poly（butylene succinate） （PBS）/poly（butylene adipate） （PBS/PBA） blends we...The effects of crystallization temperature and blend ratio on the polymorphic crystal structures of poly（butylene adipate） （PBA） in poly（butylene succinate） （PBS）/poly（butylene adipate） （PBS/PBA） blends were studied by means of differential scanning calorimetry （DSC）, wide-angle X-ray diffraction （XRD） and atomic force microscopy （AFM）. It was revealed that the polymorphism of PBA can be regulated by the blend ratio even in a non-isothermal crystallization process. The results demonstrate that high temperature favors fiat-on α crystals, while low temperature contributes to edge-on β crystals. It was also found that the effect of blend ratio on the crystallization mechanism of PBA is well coincident with that of the crystallization temperature. The increment of PBS content in the PBS/PBA blend gives rise to more β-form crystals of PBA. For those PBS/PBA blends with low PBA content, the interlamellar phase segregation of PBA makes its molecular chains so difficult to diffuse from one isolated microdomain to another that high crystallization temperature and sufficiently long crystallization time will be required if the PBA α-type crystals are targeted.展开更多
In order to improve the wettability and biocompatibility of the poly （butylene terephthalate） non-woven （PBTNW）, the method of surface modification is used to graft copolymerization of chitosan （CS） onto the PBT...In order to improve the wettability and biocompatibility of the poly （butylene terephthalate） non-woven （PBTNW）, the method of surface modification is used to graft copolymerization of chitosan （CS） onto the PBTNW under alkylpolyglycoside （APG） inducing. The product is thoroughly characterized with the Fourier transform infrared spectroscopy （FrIR）, the electron spectroscopy for chemical analysis （ESCA）, the thermogravimetric （TG） and the scanning electron microscopy （SEM）. It is found that chitosan is successfully grafted onto PBTNW. In addition, the water contact angles, hemolysis tests and cytotoxicity evaluation tests show an improvement in wettability and biocompatihility as a result of graft copolymerization of chitosan. So the CS-grafted PBTNW exhibits greater superiority than the original PBTNW. The CS-grafted PBTNW can be a candidate for blood filter materials and other medical applications.展开更多
A biodegradable blend foaming material of poly(butylene adipate-co-terephthalate)(PBAT)/poly(propylene carbonate)(PPC)was successfully prepared by chemical foaming agent and screw extrusion method.First,PBAT was modif...A biodegradable blend foaming material of poly(butylene adipate-co-terephthalate)(PBAT)/poly(propylene carbonate)(PPC)was successfully prepared by chemical foaming agent and screw extrusion method.First,PBAT was modified by bis(tert-butyl dioxy isopropyl)benzene(BIBP)for chain extension,and then the extended PBAT(E-PBAT)was foamed with PPC using a twin(single)screw extruder.By analyzing the properties of the blends,we found that Young’s modulus increased from 58.8 MPa of E-PBAT to 244.7 MPa of E-PBAT/PPC 50/50.The viscosity of the polymer has a critical influence on the formation of cells.Compared with neat PBAT(N-PBAT),the viscosity of E-PBAT increased by 3396 Pa·s and E-PBAT/PPC 50/50 increased by 8836 Pa·s.Meanwhile,the dynamic mechanical analysis(DMA)results showed that the storage modulus(E’)at room temperature increased from 538 MPa to 1650 MPa.The various phase morphologies(“sea-island”,“quasi-co-continuous”and“cocontinuous”)and crystallinity of the blends affected the spread velocity of gas and further affected the foaming morphology in E-PBAT/PPC foam.Therefore,through the analysis of phase morphology and foaming mechanism,we concluded that the E-PBAT/PPC 70/30 component has both excellent strength and the best foaming performance.展开更多
In recent years, poly(butylene adipate-co-terephthalate)(PBAT) has been widely used. However, PBAT-degrading bacteria have rarely been reported. PBAT-degrading bacteria were isolated from farmland soil and identified....In recent years, poly(butylene adipate-co-terephthalate)(PBAT) has been widely used. However, PBAT-degrading bacteria have rarely been reported. PBAT-degrading bacteria were isolated from farmland soil and identified. The effects of growth factors on the degradation of PBAT and the lipase activity of PBAT-degrading bacteria were assessed. The degradation mechanism was analyzed using scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, Xray diffraction, and liquid chromatography-mass spectrometry. The results showed that Stenotrophomonas sp. YCJ1 had a significant degrading effect on PBAT. Under certain conditions, the strain could secrete 10.53 U/m L of lipase activity and degrade 10.14 wt.% of PBAT films. The strain secreted lipase to catalyze the degradation of the ester bonds in PBAT, resulting in the production of degradation products such as terephthalic acid, 1,4-butanediol, and adipic acid. Furthermore, the degradation products could participate in the metabolism of YCJ1 as carbon sources to facilitate complete degradation of PBAT, indicating that the strain has potential value for the bioremediation of PBAT in the environment.展开更多
Poly（propylene carbonate） （PPC） was melt blended in a batch mixer with poly（butylene carbonate） （PBC） in an effort to improve the toughness of the PPC without compromising its biodegradability and biocompatibi...Poly（propylene carbonate） （PPC） was melt blended in a batch mixer with poly（butylene carbonate） （PBC） in an effort to improve the toughness of the PPC without compromising its biodegradability and biocompatibility. DMA results showed that the PPC/PBC blends were an immiscible two-phase system. With the increase in PBC content, the PPC/PBC blends showed decreased tensile strength, however, the elongation at break was increased to 230% for the 50/50 PPC/PBC blend. From the tensile strength experiments, the Pukanszky model gave credit to the modest interfacial adhesion between PPC and PBC, although PPC/PBC was immscible. The impact strength increased significantly which indicated the toughening effects of the PBC on PPC. SEM examination showed that cavitation and shear yielding were the major toughening mechanisms in the blends subjected the impact tests. TGA measurements showed that the thermal stability of PPC decreased with the incorporation of PBC. Rheological investigation demonstrated that the addition of PBC reduced the value of storage modulus, loss modulus and complex viscosity of the PPC/PBC blends to some extent. Moreover, the addition of PBC was found to increase the processability of PPC in extrusion. The introduction of PBC provided an efficient and novel toughened method to extend the application area of PPC.展开更多
Binary biodegradable polymers films, poly(butylene adipate-co-terephthalate)(PBAT) and poly(glycolic acid)(PGA), were prepared through batch melt mixing to obtain Film Ⅰ and Film Ⅱ under two different processing con...Binary biodegradable polymers films, poly(butylene adipate-co-terephthalate)(PBAT) and poly(glycolic acid)(PGA), were prepared through batch melt mixing to obtain Film Ⅰ and Film Ⅱ under two different processing conditions. PGA crystals played a major role in enhancing the mechanical and barrier properties of the films. For Film Ⅰ, there were initial PGA crystals before the film blowing process, the PGA molecular chain further crystallized, forming the oriented crystallization of PGA. Moreover, the Xcand crystalline size in Film Ⅰ were higher than those in Film Ⅱ. Compared with the different processing methods, Film Ⅰ has excellent mechanical and oxygen barrier properties due to the crystallization and orientation. The tensile strength reached 45.0 MPa, and tear strength exceeded 138.2 kN/m, while the elongation at break was as high as 750% for PBAT/PGA 85/15 in Film Ⅰ. The WVTR, WVP coefficients, and OP coefficients of PBAT/PGA films were decreased obviously with increasing the PGA content both in Film Ⅰ and Film Ⅱ. Moreover, the barrier properties of oxygen in Film Ⅰ were better than that in Film Ⅱ. This work reveals a feasible processing technique by introducing of initial crystallization of PGA to blow PBAT/PGA films with excellent mechanical and barrier properties.展开更多
A series of branched poly（butylene succinate）（PBS） were synthesized with several branching agents namely trimethylol propane（TMP）, malic acid, trimesic acid, citric acid and glycerol propoxylate. The structure o...A series of branched poly（butylene succinate）（PBS） were synthesized with several branching agents namely trimethylol propane（TMP）, malic acid, trimesic acid, citric acid and glycerol propoxylate. The structure of the branched polymers was analyzed by SEC and ~1H-NMR. The effect of branching agent structure on crystallization was also investigated and played a significant role. Isothermal studies showed that glycerol propoxylate could act as a nucleating agent. By contrast high content of TMP disturbed the regularity of the chain and hindered the crystallization of PBS. From the non-isothermal kinetic study, it was found that glycerol propoxylate increased noticeably the crystallization rate due to the flexible structure of the branching agent. A secondary nucleation was observed with glycerol propoxylate attributed to the crystallization of amorphous fraction included between crystallites formed at the primary crystallization. Chain topology was obtained through rheological investigations and the synthesized polymers showed a typical behavior of a mixture of linear and randomly branched PBS. The incorporation of branches improved the processability of PBS for film blowing application and the modulus and the stress at break of the resulting film were significantly increased.展开更多
Differential scanning calorimetry（DSC） has been widely applied to study crystallization and melting of materials. However, for polymeric lamellar crystals, the melting thermogram during heating process usually exhib...Differential scanning calorimetry（DSC） has been widely applied to study crystallization and melting of materials. However, for polymeric lamellar crystals, the melting thermogram during heating process usually exhibits a broad endothermic peak or even multiple endotherms, which may result from changes of metastability via recrystallization process. Sometimes, the recrystallization exotherm cannot be observed due to its overlapping with the melting endotherm. In this work, we employed a step heating procedure consisting of successive heating and temperature holding stages to measure the metastability of isothermally crystallized poly（butylene succinate）（PBS） crystals. With this approach we could gain the fraction of crystals melted at different temperature ranges and quantitatively detect the melting-recrystallization behavior. The melting-recrystallization behavior depends on the polymer chain structure and the crystallization temperature. For instance, PBS block copolymer hardly shows recrystallization behavior while PBS oligomer and high molecular weight PBS homopolymer demonstrate remarkable melting-recrystallization phenomenon. High molecular weight PBS isothermally crystallized in the low temperature range shows multiple melting-recrystallization while those isothermally crystallized at elevated temperatures do not exhibit observable recrystallization behavior. Furthermore, the melting endotherms were fitted via the melting kinetics equations. The original isothermally crystallized lamellae demonstrate quite different melting kinetics from the recrystallized lamellar crystals that melt at the highest temperature range, which is attributed to the different degrees of stabilization. Finally, the mechanism of melting-recrystallization is briefly discussed. We propose that apparent meltrecrystallization phenomenon be observed when melting of preformed lamellar crystals and recrystallization of thicker lamellae have similar free energy barrier.展开更多
Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry...Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties （crystallinity as well as crystal morphology）. Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.展开更多
The effect of PBS on the morphological features of PVDF has been investigated by optical and atomic force microscopies under various conditions. It was found that neat PVDF forms large γform spherulites with extraord...The effect of PBS on the morphological features of PVDF has been investigated by optical and atomic force microscopies under various conditions. It was found that neat PVDF forms large γform spherulites with extraordinarily weak birefringence at 170℃. Adding 30% PBS makes PVDF exhibit intrigued flower-like spherulitic morphology. The growth mechanism was explained by the decrease of the supercooling and the materials dissipation. Increasing the PBS content to 70% favors the formation of ring banded spherulites. Temperature dependent experiments verify the α→γ phase transition occurs from the junction sites of the ot and y crystals, while starts from the centers of α spherulites in the blends. Ring banded structures could be observed in neat PVDF, 70/30 blend and 30/70 blend when crystallized at 155℃, without γ crystals. The band period of PVDF α spherulites increases with crystallization temperature as well as the amount of PBS content. At 140℃, spherulites in neat PVDF lose their ring banded feature, while coarse spherulites consisting of evident lamellar bundles could be found in 30/70 blend.展开更多
Development of home compostable materials based on bioavailable polymers is of high strategic interest as they ensure a significant reduction of the environmental footprint in many production sectors.In this work,the ...Development of home compostable materials based on bioavailable polymers is of high strategic interest as they ensure a significant reduction of the environmental footprint in many production sectors.In this work,the addition of thermoplastic starch to binary PLA/PBAT blends was studied.The compounds were obtained by a reactive extrusion process by means of a co-rotating twin screw extruder.Thermomechanical,physical and chemical characterization tests were carried out to highlight the effectiveness of the material design strategy.The compounds were subsequently reprocessed by cast extrusion and thermoforming in order to obtain products suitable for the storage of hot food.The extruded films and the thermoformed containers were further characterized to highlight their thermo-mechanical,physical and chemical properties.Thermo-rheological,mechanical and physical properties of the material and of the cast film were analyzed thoroughly using combined technique as capillary rheometer,MFI,DSC,VICAT/HDT,XRD,FTIR,UV-Vis,SEM,permeability and,lastly,running preliminary chemical inertness and biodegradation tests.Particular attention was also devoted to the evaluation of the thermo-mechanical resistance of the thermoformed containers,where the PLA/PBAT/TPS blends proved to be very effective,also presenting a high disintegration rate in ambient conditions.展开更多
Poly(butylene adipate-co-terephthalate)(PBAT)is a promising biodegradable flexible polymer but suffers from slow crystallization rate,making it less attractive for some applications like the injection-molded products ...Poly(butylene adipate-co-terephthalate)(PBAT)is a promising biodegradable flexible polymer but suffers from slow crystallization rate,making it less attractive for some applications like the injection-molded products in comparison with low-density polyethylene(LDPE).This work aimed to accelerate the crystallization of PBAT by adding a self-assembly nucleating agent octamethylenedicarboxylic dibenzoylhydrazide(OMBH).PBAT/OMBH composites with various OMBH contents(0 wt%,0.5 wt%,0.7 wt%,1 wt%,2 wt%,3 wt%and 5 wt%)were prepared through melt-mixing.The effect of OMBH on the crystallization behavior,morphologies and mechanical properties of PBAT was investigated.The highest nucleation efficiency value of 59.6%was achieved for PBAT with 0.7 wt%OMBH,much higher than that of 22.7%for PBAT with 0.7 wt%talc.Atomic force microscopy results showed that OMBH formed fine fibers and induced the formation of transcrystalline layers of PBAT.Fourier transform infrared spectroscopy(FTIR)combined with two-dimensional correlation spectra suggested that the intermolecular dipole-dipole N—H…O=C interactions but not hydrogen bond between OMBH and PBAT promoted the crystallization of PBAT in the initial period of crystallization.The presence of OMBH did not change the crystal form of PBAT but had positive contribution in enhancing its crystallinity and mechanical properties.This work is essential for preparing PBAT with high crystallization rate,enhancing its potential applications in injection-molded products.展开更多
Biodegradable poly（butylene succinate） （PBS） and layered double hydroxide （LDH） nanocomposites were prepared via melt blending in a twin-screw extruder. The morphology and dispersion of LDH nanoparticles within ...Biodegradable poly（butylene succinate） （PBS） and layered double hydroxide （LDH） nanocomposites were prepared via melt blending in a twin-screw extruder. The morphology and dispersion of LDH nanoparticles within PBS matrix were characterized by transmission electron microscopy （TEM）, which showed that LDH nanoparticles were found to be well distributed at the nanometer level. The nonisothermal crystallization behavior of nanocomposites was extensively studied using differential scanning calorimetry （DSC） technique at various cooling rates. The crystallization rate of PBS was accelerated by the addition of LDH due to its heterogeneous nucleation effect; however, the crystallization mechanism and crystal structure of PBS remained almost unchanged. In kinetics analysis of nonisothermal crystallization, the Ozawa approach failed to describe the crystallization behavior of PBS/LDH nanocomposites, whereas both the modified Avrami model and the Mo method well represented the crystallization behavior of nanocomposites. The effective activation energy was estimated as a function of the relative degree of crystallinity using the isoeonversional analysis. The subsequent melting behavior of PBS and PBS/LDH nanocomposites was observed to be dependent on the cooling rate. The POM showed that the small and less perfect crystals were formed in nanocomposites.展开更多
The degradation of thermoplastic starch blend in the presence of commerciala-amylase and unpurified amylase of microbial origin was investigated.The blends consisting of thermoplastic starch and poly(butylene succinat...The degradation of thermoplastic starch blend in the presence of commerciala-amylase and unpurified amylase of microbial origin was investigated.The blends consisting of thermoplastic starch and poly(butylene succinate)have potential use in packaging applications thus,it is essential to establish susceptibility to degradation.Molar mass loss,gravimetric weight loss,and molecular structure were evaluated.The changes in the surface were observed with scanning electron microscopy.It was confirmed that there was a significant difference in gravimetric weight loss between the blends degraded in two different solutions.Unpurified enzymes of microbial origin,produced by Rhizopus oryzae cultures decomposed analyzed materials more efficiently than purified commercial ones.Moreover,it was proved that in applied conditions,the molar mass of PBS fraction did not change significantly.展开更多
The correlation between ring-opening polymerization （ROP） of cyclic butylene terephthalate （CBT） and crystallization of polymerized CBT （pCBT） strongly affected the final properties of pCBT and its composites. T...The correlation between ring-opening polymerization （ROP） of cyclic butylene terephthalate （CBT） and crystallization of polymerized CBT （pCBT） strongly affected the final properties of pCBT and its composites. The major objective of this contribution is to pinpoint the threshold temperature between them and the interrelation is successfully disclosed. That is, crystallization during polymerization occurs below 204 ℃ and the crystallization properties of pCBT are determined by this isothermal ROP stage; polymerization and crystallization are gradually separated with the increase of temperature of ROP （Tp） from 204 ℃, and the crystallization properties of pCBT are dominated by cooling stage; only polymerization is performed above 212 ℃. Moreover, quantitative analysis suggests that uniform crystal size distributions and thicker lamellar crystals derive from the stage of crystallization during polymerization. On the contrary, the crystal size distributions become wider above 204 ℃ of Tp and lead to obvious double melting peaks during heating scan. These efforts provide a very useful guide for the related investigation and application of CBT.展开更多
The main aim of this research was to investigate the synergistic influence of additives and poly（butylene succinate）（PBS） in improving both the mechanical and flame retardant properties of polylactide（PLA） blend...The main aim of this research was to investigate the synergistic influence of additives and poly（butylene succinate）（PBS） in improving both the mechanical and flame retardant properties of polylactide（PLA） blends. Tricresyl phosphate（TCP） and montmorillonite（MMT） were the additives used to improve the mechanical characteristics and fire resistance of PLA. Differential scanning calorimetry（DSC） thermograms revealed that the addition of TCP and MMT significantly affected their thermal behaviors. The results of the mechanical and morphological characterizations were in agreement with the changes in thermal behavior. The impact strength and limiting oxygen index（LOI） value of PLA significantly increased with the presence of PBS. The failure mode of the blends as evidenced by scanning electron microscopy（SEM） changed from brittle to ductile. The addition of TCP and MMT produced excellent anti-dripping and self-extinguishing behaviors of the blends, achieving V-0 rating. For the PLA/PBS blends, the synergistic combination of PBS and additives led to an acceleration of cold crystallization, a significant increment of flexibility and impact toughness, and an improvement of flame retardancy.展开更多
基金financially supported by the Science and Technology Projects of Changji Prefecture(No.2023112258)Shihezi Coal Chemical Industry Common Technology Research Institute Project(No.MGJY0104)the Program for Young Innovative Talents of Shihezi University(No.CXFZ202302).
文摘In this study,a series of poly(ethylene succinate)-b-poly(butylene carbonate)(PES-b-PBC)multiblock copolymers were prepared through the chain-extension reaction of hydroxyl-terminated PES(PES-OH)and hydroxyl-terminated PBC(PBC-OH)prepolymers with 1,6-hexmethylene diisocyanate(HDI)as a chain extender.The effects of the prepolymer molecular weight and content on the structure and application properties of the PES-b-PBC copolymers were systematically investigated using various techniques.It was found that the compatibility of PES and PBC blocks in PES-b-PBC copolymers can be greatly enhanced by lowering the length of the prepolymers,and the amorphous phase of the PES and PBC chain segments in the PES-b-PBC copolymer would transform from immiscibility and partial miscibility to miscibility when the number-average molecular weight(M_(n))of the PES-OH and PBC-OH prepolymers is less than 2000 g/mol.Only the crystal structure of bare PES can be observed in the wide-angle X-ray diffraction(WAXD)spectrum of the PES-b-PBC copolymers,but their crystallinity degrees were found to decrease with increasing PBC fraction.The thermal behavior,crystallization performance,rheological properties,mechanical properties,and degradation properties of the PES-b-PBC multiblock copolymers can be easily modulated by altering the block length and composition of the prepolymers,offering potential applications in biodegradable materials.
基金supported by the Key Research and Development Task Project of Xinjiang Uygur Autonomous Region(No.2022B02033)the National Natural Science Foundation of China(Nos.42211530566 and 42311530066)+2 种基金the NSFC-FNRS Joint Program BIOAGRIFILM(No.FNRS PINT-BILATM 2022)the Science and Technology Project of Bijie Tobacco Company of Guizhou Province(No.2022520500240192)the Agricultural Science and Technology Innovation Program(ASTIP)。
文摘The application of poly(butylene adipate-co-terephthalate)(PBAT)biodegradable plastics has long been constrained by insufficient light aging resistance.Hindered amine light stabilizers(HALSs),known as eco-friendly additives,can scavenge free radicals to enhance polymer durability.However,rough choices have resulted in wastage of resources and environmental pressure.Based on the application of plastic films as the background for use,this study systematically evaluates application effects of five HALSs.The films underwent accelerated aging for various durations and were further investigated by a combination of experiments and molecular simulation.Results showed that all HALSs mitigated PBAT light aging,with Chimassorb-944(UV-944)and Tinuvin-770(UV-770)performing the best for real applications.Quantum chemical calculation results showed that UV-944 had stronger anti migration ability.After 300 h of aging,films with UV-944 and UV-770 retained superior tensile strength and elongation at break in the transverse direction compared to neat PBAT films.Polymeric HALSs provided better long-term stability than small-molecule ones.Further spectra analysis indicated that stronger C―O bonds in HALS/PBAT composites correlated with improved photostability.This study offers valuable insights into improving weather resistance of PBAT biodegradable films and optimizing the real application of HALSs.
基金financially supported by the National Natural Science Foundation of China (No. 52203012)Shanghai Rising-Star Program (No. 23QC1400900).
文摘Ocean-degradable polyesters incorporating hydrophilic and rapidly degradable glycolide(GL)units into the polymer chain are the most promising for addressing marine plastic pollution,however,it is challenging to obtain high-molecular-weight copolymers with narrow molecular weight distributions.Herein,we prepared a novel biodegradable material,poly(butylene succinate-co-glycolide)(PBSGL),through ring-opening copolymerization using glycolide,succinic anhydride,and 1,4-butanediol as raw materials,providing a new solution strategy for marine pollution.GL could be polymerized according to the pre-designed composition by 1H-nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)results,indicating controlled polymerization with the synthesized PBSGLs having a weight-average molecular weight of up to 12.30×10^(4) g/mol and a narrow molecular weight distribution(1.33–1.65).Differential scanning calorimeter(DSC)and thermogravimetric analysis(TGA)results showed that T_(g) of PBSGLs increased from−32.5°C to−26.5°C with the increase of GL content from 0%to 40%,while T_(m)(>76°C)was much lower than T_(d,5%)(>314°C),which indicated that PBSGLs had good thermal stability and expanded the processing window and application range of the original poly(butylene succinate)(PBS)materials.Under simulated difficult conditions,PBSGL copolyesters could degrade faster with increasing GL content,where PBSGL40 degraded by 22.6%in 12 days,showing good biodegradability.Currently,most biodegradable polyesters with good performance slowly degrade in seawater.In a 30-day artificial seawater degradation test,the amorphous PBSGL40 copolyester showed a about 15-fold(2.33%weight loss)improvement in degradation ability compared to pure PBS,demonstrating rapid seawater degradation capability.
基金supported by the Sichuan Provincial Regional Innovation Cooperation Project(No.2024YFHZ0159).
文摘Semicrystalline polymers usually undergo multilevel microstructural evolutions with annealing and stretching processes,which is es-sential to tailor the physical properties of the polymer.Here,poly(butylene carbonate)(PBC)sheets were prepared via isothermal annealing and unidirectional pre-stretching processes,then the changes of PBC in crystallinity,mechanical properties,thermal properties and microscopic changes before and after annealing and stretching were measured,as well as the relationship between microstructure and macroscopic proper-ties before and after stretching.The strengthening mechanism of PBC was also described.It was demonstrated that shish-kabab structure emerged under the pre-stretching process.With the increase of the tensile ratio,the crystallinity,structure and mechanical properties are in-creased differently.Among them,the crystallinity and tensile strength after annealing-stretching treatment increased to 24.45%and 104.5 MPa,respectively,which were about 1.55 times and 3.4 times of those-without any treatment.
基金financially supported by the National Natural Science Foundation of China(Nos.21204045 and 21276151)Natural Science Basic Research Plan in Shaanxi Province of China(No.2011JQ2004)Key Scientific Research Group of Shaanxi Province(No.2013KCT-08)
文摘The effects of crystallization temperature and blend ratio on the polymorphic crystal structures of poly（butylene adipate） （PBA） in poly（butylene succinate） （PBS）/poly（butylene adipate） （PBS/PBA） blends were studied by means of differential scanning calorimetry （DSC）, wide-angle X-ray diffraction （XRD） and atomic force microscopy （AFM）. It was revealed that the polymorphism of PBA can be regulated by the blend ratio even in a non-isothermal crystallization process. The results demonstrate that high temperature favors fiat-on α crystals, while low temperature contributes to edge-on β crystals. It was also found that the effect of blend ratio on the crystallization mechanism of PBA is well coincident with that of the crystallization temperature. The increment of PBS content in the PBS/PBA blend gives rise to more β-form crystals of PBA. For those PBS/PBA blends with low PBA content, the interlamellar phase segregation of PBA makes its molecular chains so difficult to diffuse from one isolated microdomain to another that high crystallization temperature and sufficiently long crystallization time will be required if the PBA α-type crystals are targeted.
文摘In order to improve the wettability and biocompatibility of the poly （butylene terephthalate） non-woven （PBTNW）, the method of surface modification is used to graft copolymerization of chitosan （CS） onto the PBTNW under alkylpolyglycoside （APG） inducing. The product is thoroughly characterized with the Fourier transform infrared spectroscopy （FrIR）, the electron spectroscopy for chemical analysis （ESCA）, the thermogravimetric （TG） and the scanning electron microscopy （SEM）. It is found that chitosan is successfully grafted onto PBTNW. In addition, the water contact angles, hemolysis tests and cytotoxicity evaluation tests show an improvement in wettability and biocompatihility as a result of graft copolymerization of chitosan. So the CS-grafted PBTNW exhibits greater superiority than the original PBTNW. The CS-grafted PBTNW can be a candidate for blood filter materials and other medical applications.
基金financially supported by the National Key Research and Development Program of China(No.2016YFC0501402)Science and Technology Services Network Program of Chinese Science Academy(STS Project)(No.KFJSTS-ZDTP-082)Chinese Academy of Sciences(Changchun Branch)(Nos.2020SYHZ0002 and No.2020SYHZ0047)。
文摘A biodegradable blend foaming material of poly(butylene adipate-co-terephthalate)(PBAT)/poly(propylene carbonate)(PPC)was successfully prepared by chemical foaming agent and screw extrusion method.First,PBAT was modified by bis(tert-butyl dioxy isopropyl)benzene(BIBP)for chain extension,and then the extended PBAT(E-PBAT)was foamed with PPC using a twin(single)screw extruder.By analyzing the properties of the blends,we found that Young’s modulus increased from 58.8 MPa of E-PBAT to 244.7 MPa of E-PBAT/PPC 50/50.The viscosity of the polymer has a critical influence on the formation of cells.Compared with neat PBAT(N-PBAT),the viscosity of E-PBAT increased by 3396 Pa·s and E-PBAT/PPC 50/50 increased by 8836 Pa·s.Meanwhile,the dynamic mechanical analysis(DMA)results showed that the storage modulus(E’)at room temperature increased from 538 MPa to 1650 MPa.The various phase morphologies(“sea-island”,“quasi-co-continuous”and“cocontinuous”)and crystallinity of the blends affected the spread velocity of gas and further affected the foaming morphology in E-PBAT/PPC foam.Therefore,through the analysis of phase morphology and foaming mechanism,we concluded that the E-PBAT/PPC 70/30 component has both excellent strength and the best foaming performance.
基金supported by the Research Fund at the Shaanxi Provincial Science and Technology Department of China (No. 2018SF-375)Beijing Key Laboratory of Plastics Health and Safety Quality Evaluation Technology, Beijing Technology and Business University (No. TQETJP2018 004)。
文摘In recent years, poly(butylene adipate-co-terephthalate)(PBAT) has been widely used. However, PBAT-degrading bacteria have rarely been reported. PBAT-degrading bacteria were isolated from farmland soil and identified. The effects of growth factors on the degradation of PBAT and the lipase activity of PBAT-degrading bacteria were assessed. The degradation mechanism was analyzed using scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, Xray diffraction, and liquid chromatography-mass spectrometry. The results showed that Stenotrophomonas sp. YCJ1 had a significant degrading effect on PBAT. Under certain conditions, the strain could secrete 10.53 U/m L of lipase activity and degrade 10.14 wt.% of PBAT films. The strain secreted lipase to catalyze the degradation of the ester bonds in PBAT, resulting in the production of degradation products such as terephthalic acid, 1,4-butanediol, and adipic acid. Furthermore, the degradation products could participate in the metabolism of YCJ1 as carbon sources to facilitate complete degradation of PBAT, indicating that the strain has potential value for the bioremediation of PBAT in the environment.
基金financially supported by the fund of Science&Technology Bureau of Jilin Province of China(No.20126023)the National High Technology Research and Development Program of China(863 Program)(No.2012AA062904)the National Natural Science Foundation of China(No.51021003)
文摘Poly（propylene carbonate） （PPC） was melt blended in a batch mixer with poly（butylene carbonate） （PBC） in an effort to improve the toughness of the PPC without compromising its biodegradability and biocompatibility. DMA results showed that the PPC/PBC blends were an immiscible two-phase system. With the increase in PBC content, the PPC/PBC blends showed decreased tensile strength, however, the elongation at break was increased to 230% for the 50/50 PPC/PBC blend. From the tensile strength experiments, the Pukanszky model gave credit to the modest interfacial adhesion between PPC and PBC, although PPC/PBC was immscible. The impact strength increased significantly which indicated the toughening effects of the PBC on PPC. SEM examination showed that cavitation and shear yielding were the major toughening mechanisms in the blends subjected the impact tests. TGA measurements showed that the thermal stability of PPC decreased with the incorporation of PBC. Rheological investigation demonstrated that the addition of PBC reduced the value of storage modulus, loss modulus and complex viscosity of the PPC/PBC blends to some extent. Moreover, the addition of PBC was found to increase the processability of PPC in extrusion. The introduction of PBC provided an efficient and novel toughened method to extend the application area of PPC.
基金supported by the Science and Technology Development Plan of Jilin Province(Nos.20210203199SF and 20210509017RQ)the Science and Technology Development Program of Yantai of China(No.2022ZDCX015)+2 种基金the Chinese Academy of Sciences(Changchun Branch)(Nos.2021SYHZ0044 and 2021SYHZ0042)Science and Technology Bureau of Changchun City of China(Nos.21SH13 and 21KY01)Development and Reform commission of Jilin Province of China(No.2021C039-2).
文摘Binary biodegradable polymers films, poly(butylene adipate-co-terephthalate)(PBAT) and poly(glycolic acid)(PGA), were prepared through batch melt mixing to obtain Film Ⅰ and Film Ⅱ under two different processing conditions. PGA crystals played a major role in enhancing the mechanical and barrier properties of the films. For Film Ⅰ, there were initial PGA crystals before the film blowing process, the PGA molecular chain further crystallized, forming the oriented crystallization of PGA. Moreover, the Xcand crystalline size in Film Ⅰ were higher than those in Film Ⅱ. Compared with the different processing methods, Film Ⅰ has excellent mechanical and oxygen barrier properties due to the crystallization and orientation. The tensile strength reached 45.0 MPa, and tear strength exceeded 138.2 kN/m, while the elongation at break was as high as 750% for PBAT/PGA 85/15 in Film Ⅰ. The WVTR, WVP coefficients, and OP coefficients of PBAT/PGA films were decreased obviously with increasing the PGA content both in Film Ⅰ and Film Ⅱ. Moreover, the barrier properties of oxygen in Film Ⅰ were better than that in Film Ⅱ. This work reveals a feasible processing technique by introducing of initial crystallization of PGA to blow PBAT/PGA films with excellent mechanical and barrier properties.
基金financially supported by the company MBD Texinov(France)the company Roquette Frères(France)+4 种基金the ANRTthe framework of the collaborative project Agroboost funded by BPI FranceRhone-Alpes RegionRhone-Alpes FEDERthe Basse Normandie Regional Council
文摘A series of branched poly（butylene succinate）（PBS） were synthesized with several branching agents namely trimethylol propane（TMP）, malic acid, trimesic acid, citric acid and glycerol propoxylate. The structure of the branched polymers was analyzed by SEC and ~1H-NMR. The effect of branching agent structure on crystallization was also investigated and played a significant role. Isothermal studies showed that glycerol propoxylate could act as a nucleating agent. By contrast high content of TMP disturbed the regularity of the chain and hindered the crystallization of PBS. From the non-isothermal kinetic study, it was found that glycerol propoxylate increased noticeably the crystallization rate due to the flexible structure of the branching agent. A secondary nucleation was observed with glycerol propoxylate attributed to the crystallization of amorphous fraction included between crystallites formed at the primary crystallization. Chain topology was obtained through rheological investigations and the synthesized polymers showed a typical behavior of a mixture of linear and randomly branched PBS. The incorporation of branches improved the processability of PBS for film blowing application and the modulus and the stress at break of the resulting film were significantly increased.
基金financially supported by the National Natural Science Foundation of China(No.21374054)the SinoGerman Center for Research Promotion and the National Basic Research Program of China(No.2014CB932202)
文摘Differential scanning calorimetry（DSC） has been widely applied to study crystallization and melting of materials. However, for polymeric lamellar crystals, the melting thermogram during heating process usually exhibits a broad endothermic peak or even multiple endotherms, which may result from changes of metastability via recrystallization process. Sometimes, the recrystallization exotherm cannot be observed due to its overlapping with the melting endotherm. In this work, we employed a step heating procedure consisting of successive heating and temperature holding stages to measure the metastability of isothermally crystallized poly（butylene succinate）（PBS） crystals. With this approach we could gain the fraction of crystals melted at different temperature ranges and quantitatively detect the melting-recrystallization behavior. The melting-recrystallization behavior depends on the polymer chain structure and the crystallization temperature. For instance, PBS block copolymer hardly shows recrystallization behavior while PBS oligomer and high molecular weight PBS homopolymer demonstrate remarkable melting-recrystallization phenomenon. High molecular weight PBS isothermally crystallized in the low temperature range shows multiple melting-recrystallization while those isothermally crystallized at elevated temperatures do not exhibit observable recrystallization behavior. Furthermore, the melting endotherms were fitted via the melting kinetics equations. The original isothermally crystallized lamellae demonstrate quite different melting kinetics from the recrystallized lamellar crystals that melt at the highest temperature range, which is attributed to the different degrees of stabilization. Finally, the mechanism of melting-recrystallization is briefly discussed. We propose that apparent meltrecrystallization phenomenon be observed when melting of preformed lamellar crystals and recrystallization of thicker lamellae have similar free energy barrier.
基金financially supported by the National Natural Science Foundation of China(No.51173112)
文摘Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties （crystallinity as well as crystal morphology）. Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.
基金financially supported by the National Natural Science Foundations of China(No.20974011)the program of Introducing Talents of Discipline to Universities(No.B08003)
文摘The effect of PBS on the morphological features of PVDF has been investigated by optical and atomic force microscopies under various conditions. It was found that neat PVDF forms large γform spherulites with extraordinarily weak birefringence at 170℃. Adding 30% PBS makes PVDF exhibit intrigued flower-like spherulitic morphology. The growth mechanism was explained by the decrease of the supercooling and the materials dissipation. Increasing the PBS content to 70% favors the formation of ring banded spherulites. Temperature dependent experiments verify the α→γ phase transition occurs from the junction sites of the ot and y crystals, while starts from the centers of α spherulites in the blends. Ring banded structures could be observed in neat PVDF, 70/30 blend and 30/70 blend when crystallized at 155℃, without γ crystals. The band period of PVDF α spherulites increases with crystallization temperature as well as the amount of PBS content. At 140℃, spherulites in neat PVDF lose their ring banded feature, while coarse spherulites consisting of evident lamellar bundles could be found in 30/70 blend.
文摘Development of home compostable materials based on bioavailable polymers is of high strategic interest as they ensure a significant reduction of the environmental footprint in many production sectors.In this work,the addition of thermoplastic starch to binary PLA/PBAT blends was studied.The compounds were obtained by a reactive extrusion process by means of a co-rotating twin screw extruder.Thermomechanical,physical and chemical characterization tests were carried out to highlight the effectiveness of the material design strategy.The compounds were subsequently reprocessed by cast extrusion and thermoforming in order to obtain products suitable for the storage of hot food.The extruded films and the thermoformed containers were further characterized to highlight their thermo-mechanical,physical and chemical properties.Thermo-rheological,mechanical and physical properties of the material and of the cast film were analyzed thoroughly using combined technique as capillary rheometer,MFI,DSC,VICAT/HDT,XRD,FTIR,UV-Vis,SEM,permeability and,lastly,running preliminary chemical inertness and biodegradation tests.Particular attention was also devoted to the evaluation of the thermo-mechanical resistance of the thermoformed containers,where the PLA/PBAT/TPS blends proved to be very effective,also presenting a high disintegration rate in ambient conditions.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52073261 and U1704162).
文摘Poly(butylene adipate-co-terephthalate)(PBAT)is a promising biodegradable flexible polymer but suffers from slow crystallization rate,making it less attractive for some applications like the injection-molded products in comparison with low-density polyethylene(LDPE).This work aimed to accelerate the crystallization of PBAT by adding a self-assembly nucleating agent octamethylenedicarboxylic dibenzoylhydrazide(OMBH).PBAT/OMBH composites with various OMBH contents(0 wt%,0.5 wt%,0.7 wt%,1 wt%,2 wt%,3 wt%and 5 wt%)were prepared through melt-mixing.The effect of OMBH on the crystallization behavior,morphologies and mechanical properties of PBAT was investigated.The highest nucleation efficiency value of 59.6%was achieved for PBAT with 0.7 wt%OMBH,much higher than that of 22.7%for PBAT with 0.7 wt%talc.Atomic force microscopy results showed that OMBH formed fine fibers and induced the formation of transcrystalline layers of PBAT.Fourier transform infrared spectroscopy(FTIR)combined with two-dimensional correlation spectra suggested that the intermolecular dipole-dipole N—H…O=C interactions but not hydrogen bond between OMBH and PBAT promoted the crystallization of PBAT in the initial period of crystallization.The presence of OMBH did not change the crystal form of PBAT but had positive contribution in enhancing its crystallinity and mechanical properties.This work is essential for preparing PBAT with high crystallization rate,enhancing its potential applications in injection-molded products.
基金supported by the National High Technology Research and Development Program of China (863 Program No. 2009AA03Z319)the National Natural Science Foundation of China (Nos. 30870633, 31000427)the Fundamental Research Funds for the Central Universities (DUT12JB09)
文摘Biodegradable poly（butylene succinate） （PBS） and layered double hydroxide （LDH） nanocomposites were prepared via melt blending in a twin-screw extruder. The morphology and dispersion of LDH nanoparticles within PBS matrix were characterized by transmission electron microscopy （TEM）, which showed that LDH nanoparticles were found to be well distributed at the nanometer level. The nonisothermal crystallization behavior of nanocomposites was extensively studied using differential scanning calorimetry （DSC） technique at various cooling rates. The crystallization rate of PBS was accelerated by the addition of LDH due to its heterogeneous nucleation effect; however, the crystallization mechanism and crystal structure of PBS remained almost unchanged. In kinetics analysis of nonisothermal crystallization, the Ozawa approach failed to describe the crystallization behavior of PBS/LDH nanocomposites, whereas both the modified Avrami model and the Mo method well represented the crystallization behavior of nanocomposites. The effective activation energy was estimated as a function of the relative degree of crystallinity using the isoeonversional analysis. The subsequent melting behavior of PBS and PBS/LDH nanocomposites was observed to be dependent on the cooling rate. The POM showed that the small and less perfect crystals were formed in nanocomposites.
文摘The degradation of thermoplastic starch blend in the presence of commerciala-amylase and unpurified amylase of microbial origin was investigated.The blends consisting of thermoplastic starch and poly(butylene succinate)have potential use in packaging applications thus,it is essential to establish susceptibility to degradation.Molar mass loss,gravimetric weight loss,and molecular structure were evaluated.The changes in the surface were observed with scanning electron microscopy.It was confirmed that there was a significant difference in gravimetric weight loss between the blends degraded in two different solutions.Unpurified enzymes of microbial origin,produced by Rhizopus oryzae cultures decomposed analyzed materials more efficiently than purified commercial ones.Moreover,it was proved that in applied conditions,the molar mass of PBS fraction did not change significantly.
基金financially supported by the National Natural Science Foundation of China(No.21364004)Gansu Province University Fundamental Research FundsDoctor Research Fund of Lanzhou University of Technology,China
文摘The correlation between ring-opening polymerization （ROP） of cyclic butylene terephthalate （CBT） and crystallization of polymerized CBT （pCBT） strongly affected the final properties of pCBT and its composites. The major objective of this contribution is to pinpoint the threshold temperature between them and the interrelation is successfully disclosed. That is, crystallization during polymerization occurs below 204 ℃ and the crystallization properties of pCBT are determined by this isothermal ROP stage; polymerization and crystallization are gradually separated with the increase of temperature of ROP （Tp） from 204 ℃, and the crystallization properties of pCBT are dominated by cooling stage; only polymerization is performed above 212 ℃. Moreover, quantitative analysis suggests that uniform crystal size distributions and thicker lamellar crystals derive from the stage of crystallization during polymerization. On the contrary, the crystal size distributions become wider above 204 ℃ of Tp and lead to obvious double melting peaks during heating scan. These efforts provide a very useful guide for the related investigation and application of CBT.
基金financially supported by Prince of Songkla University (No.SCI600593S)the Faculty of Science Research Fund,Prince of Songkla University (No.1-2558-02-006)Development and Promotion of Science and Technology Talents Project (DPST)
文摘The main aim of this research was to investigate the synergistic influence of additives and poly（butylene succinate）（PBS） in improving both the mechanical and flame retardant properties of polylactide（PLA） blends. Tricresyl phosphate（TCP） and montmorillonite（MMT） were the additives used to improve the mechanical characteristics and fire resistance of PLA. Differential scanning calorimetry（DSC） thermograms revealed that the addition of TCP and MMT significantly affected their thermal behaviors. The results of the mechanical and morphological characterizations were in agreement with the changes in thermal behavior. The impact strength and limiting oxygen index（LOI） value of PLA significantly increased with the presence of PBS. The failure mode of the blends as evidenced by scanning electron microscopy（SEM） changed from brittle to ductile. The addition of TCP and MMT produced excellent anti-dripping and self-extinguishing behaviors of the blends, achieving V-0 rating. For the PLA/PBS blends, the synergistic combination of PBS and additives led to an acceleration of cold crystallization, a significant increment of flexibility and impact toughness, and an improvement of flame retardancy.
