A series of blends of Acrylonitrile-Butadiene-Styrene (ABS) and Polycarbonate (PC) were prepared and some of their thermal and mechanical properties were determined. The Young’s modulus changed gradually and monotoni...A series of blends of Acrylonitrile-Butadiene-Styrene (ABS) and Polycarbonate (PC) were prepared and some of their thermal and mechanical properties were determined. The Young’s modulus changed gradually and monotonically with the polycarbonate content. This effect was tentatively explained as the antiplasticization of the PC which is ascribed to the chain mobility, which permits the PC chains to pack more tightly, to the secondary cross-linking between the PC chains, or to the secondary attachment of bulky side-chains to the PC, thus producing steric hindrance to the rotation of the PC main chains. The experimental values found for the impact strength were intermediate between those of the neat polymers, depending upon the dispersed rubber particles of butadiene in the matrix of SAN (Styrene-Acrylonitrile), and the dispersed PC particles which generally make the ABS more brittle. A maximum value of about 88 KJ/m2 for the impact strength was observed for the blend with 90% PC. This may be attributed to the strong polymer-polymer interactions for this particular composition. The variations in the heat deflection temperature HDT and the Vicat softening point with the blend composition were very similar, and allowed us to assume that the phase inversion between the matrices of the two polymers takes place at 50% PC. The morphology of the blends revealed by SEM observation, show a co-continuous structure.展开更多
The equilibrium dynamics and nonlinear rheology of unentangled polymer blends remain inadequately understood,especially regarding the influence of short-chain matrix length N_(S) on the structure and rheological behav...The equilibrium dynamics and nonlinear rheology of unentangled polymer blends remain inadequately understood,especially regarding the influence of short-chain matrix length N_(S) on the structure and rheological behavior of dispersed long chains.Using molecular dynamics simulations based on the Kremer-Grest model,we systematically explore the N_(S)-dependence of static conformations,equilibrium dynamics,and nonlinear shear responses in unentangled long-chain/short-chain polymer blends.Our results demonstrate a decoupling between the static and dynamic sensitivity to N_(S):while the static chain size,R_g,follows Flory theory with slight swelling at small N_(S) due to incomplete excluded volume screening,the diffusion coefficient,D,and the relaxation time,τ_(0),exhibit a strong,non-monotonic N_(S)-dependence,transitioning from monomeric friction dominance at small N_(S) to collective segmental rearrangement at large N_(S).Additionally,we observe partial decoupling between the viscous and normal stress responses:while the zero-shear viscosity,η,is strongly N_(S)-dependent,the first and second normal stress coefficients,Ψ_(1) and Ψ_(2),collapse onto universal curves when scaled by the dimensionless shear rate,γτ_(0),suggesting a common mechanism of orientation and stretching.Under shear,long chains compress in the vorticity direction λ_(z)~Wi^(-0.2),which reduces collision frequency and contributes to shear thinning,while the scaling of weaker orientation resistance m_(G)~Wi^(0.35)reflects hydrodynamic screening by the short-chain matrix.These findings highlight the limitations of single-chain models and emphasize the necessity of considering N_(S)-dependent matrix dynamics and flow-induced structural changes in understanding the rheology of unentangled polymer blends.展开更多
In this paper,morphological structure,thermodynamic compatibility and relationship be-tween porosities and blend ratios of the wet coagulated PU/PVA sheets were studied by meansof observation of scanning electronic mi...In this paper,morphological structure,thermodynamic compatibility and relationship be-tween porosities and blend ratios of the wet coagulated PU/PVA sheets were studied by meansof observation of scanning electronic micrographies,tests of dynamic mechanical properties,moisture regain and vapor permeability.Furthermore,the formation of microvoids at interfacesof separated phases was discussed and a microvoid formation mechanism at phase interfaces ofhydrophobic-hydrophilic blends was suggested and compared with that ofhydrophobic-hydrophobic blends.展开更多
The combustion behavior of two single coals and three coal blends in a 300 kW coal-fired furnace under variableoperating conditions was monitored by a flame monitoring system based on image processing and spectral ana...The combustion behavior of two single coals and three coal blends in a 300 kW coal-fired furnace under variableoperating conditions was monitored by a flame monitoring system based on image processing and spectral analysis. A similaritycoefficient was defined to analyze the similarity of combustion behavior between two different coal types. A total of 20 flamefeatures, extracted by the flame monitoring system, were ranked by weights of their importance estimated using ReliefF, a featureselection algorithm. The mean of the infrared signal was found to have by far the highest importance weight among the flamefeatures. Support vector machine （SVM） was used to identify the coal types. The number of flame features used to build the SVMmodel was reduced from 20 to 12 by combining the methods of ReliefF and SVM, and computational precision was guaranteedsimultaneously. A threshold was found for the relationship between the error rate and similarity coefficient, which were positivelycorrelated. The success rate decreased with increasing similarity coefficient. The results obtained demonstrate that the system canachieve the online＂ identification of coal blends in industry.展开更多
The mechanical and thermal properties of solution-cast blends of Polyvinyl chloride (PVC) and Epoxidized Liquid Natural Rubber having 30 mole % epoxidation (ELNR-30) have been examined using Zwick materials testing ma...The mechanical and thermal properties of solution-cast blends of Polyvinyl chloride (PVC) and Epoxidized Liquid Natural Rubber having 30 mole % epoxidation (ELNR-30) have been examined using Zwick materials testing machine and heating in air circulating oven (200°C) at different time intervals respectively. The ELNR was prepared by oxidative degradation of natural rubber latex using Phenylhydrazine/Oxygen system and subsequent epoxidation with formic acid and 30% H2O2. Tensile strength of unblended PVC was 26.5 ± 0.5 MPa. The blends had lower tensile strength which decreased with increase in blend ratio of ELNR-30. Experimental data revealed that there was greater homogeneity in the PVC/ELNR-30 (80/20) compared with PVC/ELNR-30 (90/10). The PVC/ELNR-30 (80/20) also showed superior elongation at maximum (%) than the unblended PVC and PVC/ELNR-30 (90/10) in that order. Thermal stability decreased in the order PVC, PVC/ELNR-30 (90/10), PVC/ELNR-30 (80/20).展开更多
The article reviews a brief literature on the rheological properties of polymer melts and blends. Experimental results on polymer blends are summarized. Technically, vital types of multi-phase polymers such as compoun...The article reviews a brief literature on the rheological properties of polymer melts and blends. Experimental results on polymer blends are summarized. Technically, vital types of multi-phase polymers such as compounds and blends are discussed. The importance of the rheological properties of polymer mixtures in the development of the phase structure is discussed. And the importance of considering the stress and/or strain history of a material sample in a rheological investigation is discussed. Finally, the outlook on the past, present and future developments in the field of polymer rheology are given. The review concludes with a brief discussion on the opportunities and challenges in the field of polymer blends and blend rheology.展开更多
Silver particulate thin films on softened polymer blends of Polystyrene (PS)/Poly(2-vinyl pyridine) (P2VP), PS/Poly(4-vinylpyridine) (P4VP), and Poly(vinylpyrollidone) (PVP)/P4VP at a rate of 0.4 nm/s held at a temper...Silver particulate thin films on softened polymer blends of Polystyrene (PS)/Poly(2-vinyl pyridine) (P2VP), PS/Poly(4-vinylpyridine) (P4VP), and Poly(vinylpyrollidone) (PVP)/P4VP at a rate of 0.4 nm/s held at a temperature of 457 K in vacuum of 8 × 10-6 Torr by evaporation are deposited. These silver films were characterized by their electrical behavior, optical properties and Scanning electron microscopy (SEM). Silver films deposited on softened PS, and PVP give rise to a very high room temperature resistance approaching that of the substrate resistance due to the formation of a highly agglomerated structure. On the other hand, silver films on softened P2VP and P4VP give rise to a room temperature resistance in the range of tens to a few hundred MΩ/ which is desirable for device applications. Silver films on the composites of PS/P2VP, PS/P4VP and PVP/P4VP show resistances at room temperature. The optical and plasmonic response of Ag nanoparticles onto thin layers of blends shows encapsulation of nanoparticles. The electrical properties and SEM of silver nanoparticles on the thin layers of polymer blends indicate the formation of much smaller, narrower dispersion and wide size distribution.展开更多
In this work,a unique model is proposed for predicting the tensile strength of binary polymer blends considering the effects of polymer/polymer interface and the morphological variation of the system.The modeling was ...In this work,a unique model is proposed for predicting the tensile strength of binary polymer blends considering the effects of polymer/polymer interface and the morphological variation of the system.The modeling was performed based on the combination of analytical and artificial neural network (ANN) modeling methods.For the analytical part,Kolarik’s model was developed in accordance with the system requirements and ANN was simultaneously involved in order to interpret some effective model parameters using the tensile test result of an actual sample (e.g.the yield strength and thickness of the interface,etc.).Furthermore,the model accuracy was evaluated by comparing the tensile test results of differently preparediPP/PA and PS/PMMA blend samples and also some other data from literature with the model predictions.It was revealed that the designed ANN perfectly elevates the capability of the analytical section in order to predict the tensile strength of binary polymer blends with different compositions (prediction error <10%).展开更多
PA6/PTFE blends with varying polytetrafluoroethylene content from 3% to 15%(mass fraction) were irradiated by 60Co gamma-ray with various doses(20,50 and 100 kGy) under ambient conditions.Moisture absorption test,U-no...PA6/PTFE blends with varying polytetrafluoroethylene content from 3% to 15%(mass fraction) were irradiated by 60Co gamma-ray with various doses(20,50 and 100 kGy) under ambient conditions.Moisture absorption test,U-notched Charpy impact test and quasi-static tension and bending were conducted to investigate the effect of irradiation on moisture absorption and mechanical properties of the blends.It is shown that the exposure of the blend to 60Co irradiation improves the tensile modulus,tensile strength and flexural modulus due to irradiation induced cross-linking in PA6 phase.However,the Charpy impact strength of the blends is much lower than that of the original PA6 and it decreases slightly with the increase of irradiation dose.Moreover,the flexural modulus increases to a maximum value and then decreases with further increasing the PTFE content,and the moisture absorption decreases with the increase of the PTFE content and irradiation dose.展开更多
The increasing use of petrodiesel-biodiesel fuel blends throughout the world requires fast, economic and efficient analytical techniques that can be used for the quality control of these fuels. In this work, we develo...The increasing use of petrodiesel-biodiesel fuel blends throughout the world requires fast, economic and efficient analytical techniques that can be used for the quality control of these fuels. In this work, we developed an analytical method for determining the concentration of African palm biodiesel in blends with petrodiesel;the method is based on infrared spectroscopy (FTIR-ATR). To build a prediction model, nineteen petrodiesel-biodiesel blends were prepared in triplicate with biodiesel concentrations for 0%-100% by weight. The blends were analyzed using Fourier transform infrared spectroscopy, the spectral fingerprint data were used to build a prediction model through PLS regression. The optimal number of principal components (PCs), the standard error of calibration (SEC), the standard validation error (SEV), the correlation coefficient of calibration (r Cal) and the validation correlation coefficient (r Val) were used to validate the predictive ability of the model. The results show that the model obtained in this work has a good ability for determining the concentration of African palm biodiesel in petrodiesel-biodiesel blends.展开更多
In order to clarify the mutual effect between bituminite and anthracite in blends during industrial combustion, the influence of particle size and heating rate as well as oxygen concentration in atmosphere was analyze...In order to clarify the mutual effect between bituminite and anthracite in blends during industrial combustion, the influence of particle size and heating rate as well as oxygen concentration in atmosphere was analyzed. The results of non-isothermal thermogravimetric analysis indicated that the combustion behavior of blends was of great difference though blends were prepared with the same volatile content of 20%. The catalysis of bituminite to anthracite changed with the thermal and kinetic condition of combustion reaction, and consequently, blends with different collocations were suitable for various combustion environments. Superior combustion properties of some blends were achieved at high heating rates, while others might react faster under high oxygen-enriched atmosphere. Simultaneously, the volume model and unreacted core model as well as random pore model were introduced to fit the experimental data. The kinetic calculation results showed that the combustion of blends at different heating rates all agreed better with that of random pore model in comparison with the other two models, while the apparent activation energy of samples all decreased with the increase in heating rate. The similarity of functional group structure between bituminite and anthracite is closely related to the accordance in com-bustion stage of bituminite and anthracite in blends.展开更多
The performance and morphology stability of polymer bulk heterojunetion solar cells based on poly（3-hexylthiophene） （P3HT） as the donor and indene-C6o bisadduct （ICBA） or methanofullerene [6,6]-phenyl C61-butyri...The performance and morphology stability of polymer bulk heterojunetion solar cells based on poly（3-hexylthiophene） （P3HT） as the donor and indene-C6o bisadduct （ICBA） or methanofullerene [6,6]-phenyl C61-butyric acid methyl ester （PCBM） as the aeceptor are compared. Effect of the different donor and aeeeptor weight ratios on photo- voltaic performance of the P3HT：ICBA device is studied. The optimal device achieved power conversion emeiency of 5.51~o with dso of l0.86mA/cm2, Voc of 0.83 V, and fill factor （FF） of 61.1 % under AM 1.5G （lOOmW/cm2） simulated solar illumination. However, the stability measurement shows that cells based on P3HT：ICBA are less stable than those of the device based on P3HT：PCBM. Atomic force microscope results reveal that the morphol- ogy of the P3HT：ICBA film changed considerably during the storage periods due to unstable interpenetrating D-A network. This observation can be explained by the fact that there is lack of intermolecular hydrogen bonds in the P3HT：ICBA system. However, in the P3HT：PCBM system the molecules in the blend film are firmly held together in the solid state by means of intermoleeular hydrogen bonds originating from C-H. ~. Os bonds （where Os comes from the singly-bonded 0 atom of PCBM）, forming a stable three-dimensional network. The measured PL decay lifetimes for P3HT：PCBM and P3HT：ICBA systems are 33.66 ns and 35.34 ns, respectively, indicating that the P3HT：ICBA system has a less efficient exciton separation eftleiency than that of P3HT：PCBM, which may result in the interracial photogenerated charges accumulated on the D： A interface. Such progressive phase segregation between P3HT and ICBA eventually leads to the degradation in performance and deteriorates the stability of the device. We also present an approach to enhance the stability of P3HT：ICBA systems by adding PCBM as the second acceptor. Our results show that by carefully tuning the contents of PCBM as the second acceptor, more stable polymer solar cells can be obtained.展开更多
In this work, rheological properties of poly (lactic acid) (PLA), low density polyethylene (LDPE) polymer blends were investigated in the molten state. The experiments were carried on a capillary rheometer. The effect...In this work, rheological properties of poly (lactic acid) (PLA), low density polyethylene (LDPE) polymer blends were investigated in the molten state. The experiments were carried on a capillary rheometer. The effect of shear stress, temperature and blending ratio on the flow activation energy at a constant shear stress and melt viscosity of the blends are described. The results showed that the PLA/LDPE polymer blends are pseudo plastic in nature, where there viscosity decreases with increasing shear stress. Also it was found the melt viscosity of the blends decreases with increasing PLA content in the blend.展开更多
The method for measuring the spherulite growth rate and studying the morphology of polypropylene - based blends by image processing technology is described. The main advantages of this method, as compared to existing ...The method for measuring the spherulite growth rate and studying the morphology of polypropylene - based blends by image processing technology is described. The main advantages of this method, as compared to existing techniques, are: better reliability; reproducibility; ease of manipulation. Such an approach provides a means of measuring the rate of spherulite growth. In this study, isotactic polypropylene (PP), polystyrene (PS)/PP, and polybutylene terephthalate (PBT)/PP have been studied. The results show that the technology of image analysis is very useful in the study of the kinetics of crystallization of polymer.展开更多
Stable porphyrin-oxygenated carbon nanomaterial dispersions were prepared by blending porphyrin solutions with hydroxyl groups modified multi-walled carbon nanotubes(MWNTs-OH)and graphene oxide(GO)dispersions,respecti...Stable porphyrin-oxygenated carbon nanomaterial dispersions were prepared by blending porphyrin solutions with hydroxyl groups modified multi-walled carbon nanotubes(MWNTs-OH)and graphene oxide(GO)dispersions,respectively.Optical nonlinearity and optical limiting(OL)property of these blends are investigated in nanosecond regime.Results show that the OL performance of the blends can be tuned by changing the concentrations ratio of porphyrin and oxygenated carbon nanomaterials.The high concentration of oxygenated carbon nanomaterial leads to the poor OL performance.However,with the moderate concentration,the blends exhibit the low threshold value of OL and the enhanced OL performance at high fluence region.The superior OL performance can be attributed to complementary mechanisms and possible photoinduced electron or energy transfer between porphyrin moiety and oxygenated carbon nanomaterials.展开更多
In this work, we developed an analytical method based on UV-visible spectroscopy to determine the concentration of biodiesel from African palm in blends of petrodiesel. Seventy-five samples with biodiesel concentratio...In this work, we developed an analytical method based on UV-visible spectroscopy to determine the concentration of biodiesel from African palm in blends of petrodiesel. Seventy-five samples with biodiesel concentrations between 0-100 wt% were prepared. The spectral fingerprints that were obtained from the analysis of the samples by UV-visible spectroscopy were used to build predictive model using PLS regression. The predictive ability of the models was evaluated through statistical parameters: the standard error of calibration (SEC), the standard error of validation (SEV), the correlation coefficient of calibration (r Cal) and validation (r Val), the ratio (SEC/SEV), the coefficient of determination R2, the paired data Student’s t-test, cross-validation and external validation. The results indicate that the PLS model predicts the concentration of biodiesel from African palm with high precision in mixtures with petrodiesel. The method developed in this study can be applied to determine the concentration of biodiesel African palm in mixtures of petrodiesel in a more rapid and economical way. Moreover, this method has less analytical errors and is more environmentally friendly than the conventional methods.展开更多
The nature of the crystalline phase of poly(vinylidene fluoride)(PVDF) in compatible blends with poly(ethyl methacrylate)(PEMA) was investigated by using X-ray diffraction(XRD), infrared microscopy(IR) and differentia...The nature of the crystalline phase of poly(vinylidene fluoride)(PVDF) in compatible blends with poly(ethyl methacrylate)(PEMA) was investigated by using X-ray diffraction(XRD), infrared microscopy(IR) and differential scanning calorimetry(DSC). The βphase of PVDF was observed after quenching from the melt and further annealing above the glass transition temperature over a composition range. The PVDF/PEMA blend with weight ratio of 3:2 has formed higher content of PVDF β crystals than others. By taking advantage of fast cooling rate of ultrafast differential scanning calorimeter(UFDSC), the quenching process of blends was modeled and tested simultaneously, and the melting behavior of β crystals in all blends was investigated. Three types of crystallization behavior of βphase PVDF in blends were found after quenching-annealing at different temperatures.展开更多
Polymer blends have been obtained in the form of dimensionally stable and free standing films and their properties were characterized by different techniques. FTIR analysis and Raman spectroscopic analysis cleared the...Polymer blends have been obtained in the form of dimensionally stable and free standing films and their properties were characterized by different techniques. FTIR analysis and Raman spectroscopic analysis cleared the hydrogen bonding intermolecular interaction between –CONH2 groups in Poly Acrylamide (PAM) and C-O-C and –CH2OH group in Poly Ethylene Oxide (PEO). From Differential Scanning Calorimeter (DSC) the study shows that crystallinity is increasing with PEO wt%. From polymer interaction parameter we also show that the polymer blend is miscible. Thermal stability of films is investigated by Thermo Gravimetric Analysis (TGA) and derivative Thermo Gravimetric Analysis (DrTG). From UV-Vis absorption spectra, absorption band edge, direct/ indirect band gap and optical activation energy have been calculated.展开更多
The mechanical properties of composites prepared from wood flour and thermoplastic blends were investigated. Thermoplastic mixtures of polypropylene (PP) and high-density polyethylene (HDPE) and polystyrene (PS), virg...The mechanical properties of composites prepared from wood flour and thermoplastic blends were investigated. Thermoplastic mixtures of polypropylene (PP) and high-density polyethylene (HDPE) and polystyrene (PS), virgin or recycled, were mixed with wood flour in a high speed blender and then extruded by a specially designed twin/single screw extruder system to form wood-flour/thermoplastic-blends composites (WTBCs). Comparative studies were made to evaluate the effectiveness of the two modification methods of the thermoplastic blends, the one of the addition of maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MAH) as compatibilizer and the other of blend grafting of maleic anhydride (MAH) using dicumyl peroxide (DCP) as initiator by reactive extrusion. The results showed that the impact properties of WTBCs using SEBS-g-MAH as compatilizer were better improved than that of the blend grafting. However, adverse results were observed on the tensile and flexural properties of the corresponding WTBCs. The mechanical properties of WTBCs prepared from recycled plastic blends were poorer to some extent than that from virgin plastic blends in general, especially in elongation break. The morphology of WTBCs breaking section was analyzed by scanning electron microscopy (SEM) and the results showed that a good interfacial adhesion between wood flour and polymer matrix was observed with both of the two modification methods. However, by blend grafting of adding DCP as initiator and MAH as monomer, a better interfacial bonding between wood and plastic matrix was obtained than that of the addition of SEBS-g-MAH. Blend grafting can be considered as a potential way of increasing the interfacial compatibility of different plastics and between plastic blends and wood.展开更多
Fuel injection properties,including the injection rate(temporal aspects)and spray behavior(spatial aspects),play a crucial role in the combustion efficiency and emissions of diesel engines.This study investigates the ...Fuel injection properties,including the injection rate(temporal aspects)and spray behavior(spatial aspects),play a crucial role in the combustion efficiency and emissions of diesel engines.This study investigates the effects of different ethanol-biodiesel-diesel(EBD)blends on the injection performance in diesel engines.Experimental tests are conducted to examine key injection parameters,such as spray penetration distance,spray cone angle,and droplet size,alongside an analysis of coupling leakage.The main findings are as follows:(1)The injection behavior of ethanol and diesel differs significantly.The addition of ethanol reduces the density,viscosity,and modulus of elasticity of the fuel mixture.While the injection advance angle,penetration distance,and Sauter mean diameter show minimal changes,the spray cone angle and coupling leakage increase notably.These alterations may disrupt the“fuelair-chamber”matching characteristics of the original engine,potentially affecting performance.(2)In contrast,the injection performance of biodiesel ismore similar to that of diesel.As biodiesel content increases,the density,viscosity,and modulus of elasticity of the blended fuel also grow.Though changes in injection timing,penetration distance,and spray cone angle remain minimal,the Sauter mean diameter experiences a slight increase.The“air-fuel chamber”compatibility of the original engine is largely unaffected,though fuel atomization slightly deteriorates.Blending up to 20%biodiesel and 30%ethanol with diesel effectively compensates for the shortcomings of using single fuels,maintaining favorable injection dynamics while enhancing lubrication and sealing performance of engine components.展开更多
文摘A series of blends of Acrylonitrile-Butadiene-Styrene (ABS) and Polycarbonate (PC) were prepared and some of their thermal and mechanical properties were determined. The Young’s modulus changed gradually and monotonically with the polycarbonate content. This effect was tentatively explained as the antiplasticization of the PC which is ascribed to the chain mobility, which permits the PC chains to pack more tightly, to the secondary cross-linking between the PC chains, or to the secondary attachment of bulky side-chains to the PC, thus producing steric hindrance to the rotation of the PC main chains. The experimental values found for the impact strength were intermediate between those of the neat polymers, depending upon the dispersed rubber particles of butadiene in the matrix of SAN (Styrene-Acrylonitrile), and the dispersed PC particles which generally make the ABS more brittle. A maximum value of about 88 KJ/m2 for the impact strength was observed for the blend with 90% PC. This may be attributed to the strong polymer-polymer interactions for this particular composition. The variations in the heat deflection temperature HDT and the Vicat softening point with the blend composition were very similar, and allowed us to assume that the phase inversion between the matrices of the two polymers takes place at 50% PC. The morphology of the blends revealed by SEM observation, show a co-continuous structure.
基金financially supported by the National Natural Science Foundation of China(Nos.22341304,22303100 and 12205270)the National Key R&D Program of China(Nos.2023YFA1008800 and 2020YFA0713601)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDC0180303)。
文摘The equilibrium dynamics and nonlinear rheology of unentangled polymer blends remain inadequately understood,especially regarding the influence of short-chain matrix length N_(S) on the structure and rheological behavior of dispersed long chains.Using molecular dynamics simulations based on the Kremer-Grest model,we systematically explore the N_(S)-dependence of static conformations,equilibrium dynamics,and nonlinear shear responses in unentangled long-chain/short-chain polymer blends.Our results demonstrate a decoupling between the static and dynamic sensitivity to N_(S):while the static chain size,R_g,follows Flory theory with slight swelling at small N_(S) due to incomplete excluded volume screening,the diffusion coefficient,D,and the relaxation time,τ_(0),exhibit a strong,non-monotonic N_(S)-dependence,transitioning from monomeric friction dominance at small N_(S) to collective segmental rearrangement at large N_(S).Additionally,we observe partial decoupling between the viscous and normal stress responses:while the zero-shear viscosity,η,is strongly N_(S)-dependent,the first and second normal stress coefficients,Ψ_(1) and Ψ_(2),collapse onto universal curves when scaled by the dimensionless shear rate,γτ_(0),suggesting a common mechanism of orientation and stretching.Under shear,long chains compress in the vorticity direction λ_(z)~Wi^(-0.2),which reduces collision frequency and contributes to shear thinning,while the scaling of weaker orientation resistance m_(G)~Wi^(0.35)reflects hydrodynamic screening by the short-chain matrix.These findings highlight the limitations of single-chain models and emphasize the necessity of considering N_(S)-dependent matrix dynamics and flow-induced structural changes in understanding the rheology of unentangled polymer blends.
文摘In this paper,morphological structure,thermodynamic compatibility and relationship be-tween porosities and blend ratios of the wet coagulated PU/PVA sheets were studied by meansof observation of scanning electronic micrographies,tests of dynamic mechanical properties,moisture regain and vapor permeability.Furthermore,the formation of microvoids at interfacesof separated phases was discussed and a microvoid formation mechanism at phase interfaces ofhydrophobic-hydrophilic blends was suggested and compared with that ofhydrophobic-hydrophobic blends.
基金supported by the National Basic Research Program(973 Program)of China(No.2015CB251501)
文摘The combustion behavior of two single coals and three coal blends in a 300 kW coal-fired furnace under variableoperating conditions was monitored by a flame monitoring system based on image processing and spectral analysis. A similaritycoefficient was defined to analyze the similarity of combustion behavior between two different coal types. A total of 20 flamefeatures, extracted by the flame monitoring system, were ranked by weights of their importance estimated using ReliefF, a featureselection algorithm. The mean of the infrared signal was found to have by far the highest importance weight among the flamefeatures. Support vector machine （SVM） was used to identify the coal types. The number of flame features used to build the SVMmodel was reduced from 20 to 12 by combining the methods of ReliefF and SVM, and computational precision was guaranteedsimultaneously. A threshold was found for the relationship between the error rate and similarity coefficient, which were positivelycorrelated. The success rate decreased with increasing similarity coefficient. The results obtained demonstrate that the system canachieve the online＂ identification of coal blends in industry.
文摘The mechanical and thermal properties of solution-cast blends of Polyvinyl chloride (PVC) and Epoxidized Liquid Natural Rubber having 30 mole % epoxidation (ELNR-30) have been examined using Zwick materials testing machine and heating in air circulating oven (200°C) at different time intervals respectively. The ELNR was prepared by oxidative degradation of natural rubber latex using Phenylhydrazine/Oxygen system and subsequent epoxidation with formic acid and 30% H2O2. Tensile strength of unblended PVC was 26.5 ± 0.5 MPa. The blends had lower tensile strength which decreased with increase in blend ratio of ELNR-30. Experimental data revealed that there was greater homogeneity in the PVC/ELNR-30 (80/20) compared with PVC/ELNR-30 (90/10). The PVC/ELNR-30 (80/20) also showed superior elongation at maximum (%) than the unblended PVC and PVC/ELNR-30 (90/10) in that order. Thermal stability decreased in the order PVC, PVC/ELNR-30 (90/10), PVC/ELNR-30 (80/20).
文摘The article reviews a brief literature on the rheological properties of polymer melts and blends. Experimental results on polymer blends are summarized. Technically, vital types of multi-phase polymers such as compounds and blends are discussed. The importance of the rheological properties of polymer mixtures in the development of the phase structure is discussed. And the importance of considering the stress and/or strain history of a material sample in a rheological investigation is discussed. Finally, the outlook on the past, present and future developments in the field of polymer rheology are given. The review concludes with a brief discussion on the opportunities and challenges in the field of polymer blends and blend rheology.
文摘Silver particulate thin films on softened polymer blends of Polystyrene (PS)/Poly(2-vinyl pyridine) (P2VP), PS/Poly(4-vinylpyridine) (P4VP), and Poly(vinylpyrollidone) (PVP)/P4VP at a rate of 0.4 nm/s held at a temperature of 457 K in vacuum of 8 × 10-6 Torr by evaporation are deposited. These silver films were characterized by their electrical behavior, optical properties and Scanning electron microscopy (SEM). Silver films deposited on softened PS, and PVP give rise to a very high room temperature resistance approaching that of the substrate resistance due to the formation of a highly agglomerated structure. On the other hand, silver films on softened P2VP and P4VP give rise to a room temperature resistance in the range of tens to a few hundred MΩ/ which is desirable for device applications. Silver films on the composites of PS/P2VP, PS/P4VP and PVP/P4VP show resistances at room temperature. The optical and plasmonic response of Ag nanoparticles onto thin layers of blends shows encapsulation of nanoparticles. The electrical properties and SEM of silver nanoparticles on the thin layers of polymer blends indicate the formation of much smaller, narrower dispersion and wide size distribution.
文摘In this work,a unique model is proposed for predicting the tensile strength of binary polymer blends considering the effects of polymer/polymer interface and the morphological variation of the system.The modeling was performed based on the combination of analytical and artificial neural network (ANN) modeling methods.For the analytical part,Kolarik’s model was developed in accordance with the system requirements and ANN was simultaneously involved in order to interpret some effective model parameters using the tensile test result of an actual sample (e.g.the yield strength and thickness of the interface,etc.).Furthermore,the model accuracy was evaluated by comparing the tensile test results of differently preparediPP/PA and PS/PMMA blend samples and also some other data from literature with the model predictions.It was revealed that the designed ANN perfectly elevates the capability of the analytical section in order to predict the tensile strength of binary polymer blends with different compositions (prediction error <10%).
基金Project(10772156) supported by the National Natural Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of China
文摘PA6/PTFE blends with varying polytetrafluoroethylene content from 3% to 15%(mass fraction) were irradiated by 60Co gamma-ray with various doses(20,50 and 100 kGy) under ambient conditions.Moisture absorption test,U-notched Charpy impact test and quasi-static tension and bending were conducted to investigate the effect of irradiation on moisture absorption and mechanical properties of the blends.It is shown that the exposure of the blend to 60Co irradiation improves the tensile modulus,tensile strength and flexural modulus due to irradiation induced cross-linking in PA6 phase.However,the Charpy impact strength of the blends is much lower than that of the original PA6 and it decreases slightly with the increase of irradiation dose.Moreover,the flexural modulus increases to a maximum value and then decreases with further increasing the PTFE content,and the moisture absorption decreases with the increase of the PTFE content and irradiation dose.
文摘The increasing use of petrodiesel-biodiesel fuel blends throughout the world requires fast, economic and efficient analytical techniques that can be used for the quality control of these fuels. In this work, we developed an analytical method for determining the concentration of African palm biodiesel in blends with petrodiesel;the method is based on infrared spectroscopy (FTIR-ATR). To build a prediction model, nineteen petrodiesel-biodiesel blends were prepared in triplicate with biodiesel concentrations for 0%-100% by weight. The blends were analyzed using Fourier transform infrared spectroscopy, the spectral fingerprint data were used to build a prediction model through PLS regression. The optimal number of principal components (PCs), the standard error of calibration (SEC), the standard validation error (SEV), the correlation coefficient of calibration (r Cal) and the validation correlation coefficient (r Val) were used to validate the predictive ability of the model. The results show that the model obtained in this work has a good ability for determining the concentration of African palm biodiesel in petrodiesel-biodiesel blends.
基金This work was financially supported by Natural Science and Foundation of Liaoning Province (No. 20170540455)National Natural Science Foundation of China (51504131, 51474124, 51647639).
文摘In order to clarify the mutual effect between bituminite and anthracite in blends during industrial combustion, the influence of particle size and heating rate as well as oxygen concentration in atmosphere was analyzed. The results of non-isothermal thermogravimetric analysis indicated that the combustion behavior of blends was of great difference though blends were prepared with the same volatile content of 20%. The catalysis of bituminite to anthracite changed with the thermal and kinetic condition of combustion reaction, and consequently, blends with different collocations were suitable for various combustion environments. Superior combustion properties of some blends were achieved at high heating rates, while others might react faster under high oxygen-enriched atmosphere. Simultaneously, the volume model and unreacted core model as well as random pore model were introduced to fit the experimental data. The kinetic calculation results showed that the combustion of blends at different heating rates all agreed better with that of random pore model in comparison with the other two models, while the apparent activation energy of samples all decreased with the increase in heating rate. The similarity of functional group structure between bituminite and anthracite is closely related to the accordance in com-bustion stage of bituminite and anthracite in blends.
基金Supported by the Tianjin Natural Science Foundation under Grant Nos 13JCYBJC18900 and 13JCZDJC26700the National High Technology Research and Development Program of China under Grant No 2013AA014201
文摘The performance and morphology stability of polymer bulk heterojunetion solar cells based on poly（3-hexylthiophene） （P3HT） as the donor and indene-C6o bisadduct （ICBA） or methanofullerene [6,6]-phenyl C61-butyric acid methyl ester （PCBM） as the aeceptor are compared. Effect of the different donor and aeeeptor weight ratios on photo- voltaic performance of the P3HT：ICBA device is studied. The optimal device achieved power conversion emeiency of 5.51~o with dso of l0.86mA/cm2, Voc of 0.83 V, and fill factor （FF） of 61.1 % under AM 1.5G （lOOmW/cm2） simulated solar illumination. However, the stability measurement shows that cells based on P3HT：ICBA are less stable than those of the device based on P3HT：PCBM. Atomic force microscope results reveal that the morphol- ogy of the P3HT：ICBA film changed considerably during the storage periods due to unstable interpenetrating D-A network. This observation can be explained by the fact that there is lack of intermolecular hydrogen bonds in the P3HT：ICBA system. However, in the P3HT：PCBM system the molecules in the blend film are firmly held together in the solid state by means of intermoleeular hydrogen bonds originating from C-H. ~. Os bonds （where Os comes from the singly-bonded 0 atom of PCBM）, forming a stable three-dimensional network. The measured PL decay lifetimes for P3HT：PCBM and P3HT：ICBA systems are 33.66 ns and 35.34 ns, respectively, indicating that the P3HT：ICBA system has a less efficient exciton separation eftleiency than that of P3HT：PCBM, which may result in the interracial photogenerated charges accumulated on the D： A interface. Such progressive phase segregation between P3HT and ICBA eventually leads to the degradation in performance and deteriorates the stability of the device. We also present an approach to enhance the stability of P3HT：ICBA systems by adding PCBM as the second acceptor. Our results show that by carefully tuning the contents of PCBM as the second acceptor, more stable polymer solar cells can be obtained.
文摘In this work, rheological properties of poly (lactic acid) (PLA), low density polyethylene (LDPE) polymer blends were investigated in the molten state. The experiments were carried on a capillary rheometer. The effect of shear stress, temperature and blending ratio on the flow activation energy at a constant shear stress and melt viscosity of the blends are described. The results showed that the PLA/LDPE polymer blends are pseudo plastic in nature, where there viscosity decreases with increasing shear stress. Also it was found the melt viscosity of the blends decreases with increasing PLA content in the blend.
基金This project was supported by China Doctoral Special Foundation
文摘The method for measuring the spherulite growth rate and studying the morphology of polypropylene - based blends by image processing technology is described. The main advantages of this method, as compared to existing techniques, are: better reliability; reproducibility; ease of manipulation. Such an approach provides a means of measuring the rate of spherulite growth. In this study, isotactic polypropylene (PP), polystyrene (PS)/PP, and polybutylene terephthalate (PBT)/PP have been studied. The results show that the technology of image analysis is very useful in the study of the kinetics of crystallization of polymer.
基金supported by the National Natural Science Foundation of China(No.61174010)the Shanxi International Cooperation Project(No.2012081043)+1 种基金the Shanxi Scholarship Council(No.2013-038)the Scientific Research Starting Foundation from Taiyuan University of Technology(No.tyut-rc201162a)
文摘Stable porphyrin-oxygenated carbon nanomaterial dispersions were prepared by blending porphyrin solutions with hydroxyl groups modified multi-walled carbon nanotubes(MWNTs-OH)and graphene oxide(GO)dispersions,respectively.Optical nonlinearity and optical limiting(OL)property of these blends are investigated in nanosecond regime.Results show that the OL performance of the blends can be tuned by changing the concentrations ratio of porphyrin and oxygenated carbon nanomaterials.The high concentration of oxygenated carbon nanomaterial leads to the poor OL performance.However,with the moderate concentration,the blends exhibit the low threshold value of OL and the enhanced OL performance at high fluence region.The superior OL performance can be attributed to complementary mechanisms and possible photoinduced electron or energy transfer between porphyrin moiety and oxygenated carbon nanomaterials.
文摘In this work, we developed an analytical method based on UV-visible spectroscopy to determine the concentration of biodiesel from African palm in blends of petrodiesel. Seventy-five samples with biodiesel concentrations between 0-100 wt% were prepared. The spectral fingerprints that were obtained from the analysis of the samples by UV-visible spectroscopy were used to build predictive model using PLS regression. The predictive ability of the models was evaluated through statistical parameters: the standard error of calibration (SEC), the standard error of validation (SEV), the correlation coefficient of calibration (r Cal) and validation (r Val), the ratio (SEC/SEV), the coefficient of determination R2, the paired data Student’s t-test, cross-validation and external validation. The results indicate that the PLS model predicts the concentration of biodiesel from African palm with high precision in mixtures with petrodiesel. The method developed in this study can be applied to determine the concentration of biodiesel African palm in mixtures of petrodiesel in a more rapid and economical way. Moreover, this method has less analytical errors and is more environmentally friendly than the conventional methods.
基金financially supported by the National Natural Science Foundation of China (Nos. 21474049, 51673094 and 21404055)Tianshan Scholars Program by Yili Normal Universitythe Shenzhen Science and Technology Innovation Committee (Nos. JCYJ20160608140827794, JCYJ20160531151102203 and JCYJ20170818110206085)
文摘The nature of the crystalline phase of poly(vinylidene fluoride)(PVDF) in compatible blends with poly(ethyl methacrylate)(PEMA) was investigated by using X-ray diffraction(XRD), infrared microscopy(IR) and differential scanning calorimetry(DSC). The βphase of PVDF was observed after quenching from the melt and further annealing above the glass transition temperature over a composition range. The PVDF/PEMA blend with weight ratio of 3:2 has formed higher content of PVDF β crystals than others. By taking advantage of fast cooling rate of ultrafast differential scanning calorimeter(UFDSC), the quenching process of blends was modeled and tested simultaneously, and the melting behavior of β crystals in all blends was investigated. Three types of crystallization behavior of βphase PVDF in blends were found after quenching-annealing at different temperatures.
文摘Polymer blends have been obtained in the form of dimensionally stable and free standing films and their properties were characterized by different techniques. FTIR analysis and Raman spectroscopic analysis cleared the hydrogen bonding intermolecular interaction between –CONH2 groups in Poly Acrylamide (PAM) and C-O-C and –CH2OH group in Poly Ethylene Oxide (PEO). From Differential Scanning Calorimeter (DSC) the study shows that crystallinity is increasing with PEO wt%. From polymer interaction parameter we also show that the polymer blend is miscible. Thermal stability of films is investigated by Thermo Gravimetric Analysis (TGA) and derivative Thermo Gravimetric Analysis (DrTG). From UV-Vis absorption spectra, absorption band edge, direct/ indirect band gap and optical activation energy have been calculated.
文摘The mechanical properties of composites prepared from wood flour and thermoplastic blends were investigated. Thermoplastic mixtures of polypropylene (PP) and high-density polyethylene (HDPE) and polystyrene (PS), virgin or recycled, were mixed with wood flour in a high speed blender and then extruded by a specially designed twin/single screw extruder system to form wood-flour/thermoplastic-blends composites (WTBCs). Comparative studies were made to evaluate the effectiveness of the two modification methods of the thermoplastic blends, the one of the addition of maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MAH) as compatibilizer and the other of blend grafting of maleic anhydride (MAH) using dicumyl peroxide (DCP) as initiator by reactive extrusion. The results showed that the impact properties of WTBCs using SEBS-g-MAH as compatilizer were better improved than that of the blend grafting. However, adverse results were observed on the tensile and flexural properties of the corresponding WTBCs. The mechanical properties of WTBCs prepared from recycled plastic blends were poorer to some extent than that from virgin plastic blends in general, especially in elongation break. The morphology of WTBCs breaking section was analyzed by scanning electron microscopy (SEM) and the results showed that a good interfacial adhesion between wood flour and polymer matrix was observed with both of the two modification methods. However, by blend grafting of adding DCP as initiator and MAH as monomer, a better interfacial bonding between wood and plastic matrix was obtained than that of the addition of SEBS-g-MAH. Blend grafting can be considered as a potential way of increasing the interfacial compatibility of different plastics and between plastic blends and wood.
基金supported by Innovation Research Project for the training of high-level scientific and technological talents(Technical expert talents)of the Armed Police Force ZZKY20222415“13th Five-Year Plan”military key colleges and key disciplines-Equipment Engineering(Power)-17.
文摘Fuel injection properties,including the injection rate(temporal aspects)and spray behavior(spatial aspects),play a crucial role in the combustion efficiency and emissions of diesel engines.This study investigates the effects of different ethanol-biodiesel-diesel(EBD)blends on the injection performance in diesel engines.Experimental tests are conducted to examine key injection parameters,such as spray penetration distance,spray cone angle,and droplet size,alongside an analysis of coupling leakage.The main findings are as follows:(1)The injection behavior of ethanol and diesel differs significantly.The addition of ethanol reduces the density,viscosity,and modulus of elasticity of the fuel mixture.While the injection advance angle,penetration distance,and Sauter mean diameter show minimal changes,the spray cone angle and coupling leakage increase notably.These alterations may disrupt the“fuelair-chamber”matching characteristics of the original engine,potentially affecting performance.(2)In contrast,the injection performance of biodiesel ismore similar to that of diesel.As biodiesel content increases,the density,viscosity,and modulus of elasticity of the blended fuel also grow.Though changes in injection timing,penetration distance,and spray cone angle remain minimal,the Sauter mean diameter experiences a slight increase.The“air-fuel chamber”compatibility of the original engine is largely unaffected,though fuel atomization slightly deteriorates.Blending up to 20%biodiesel and 30%ethanol with diesel effectively compensates for the shortcomings of using single fuels,maintaining favorable injection dynamics while enhancing lubrication and sealing performance of engine components.
