We reported here the simultaneous influence of surface acidity and pore size of M-substituted hexagonal mesoporous silicas （Al- doped plugs-containing SBA-15 and M-doped MCM-41） on polymerization of THE These materi...We reported here the simultaneous influence of surface acidity and pore size of M-substituted hexagonal mesoporous silicas （Al- doped plugs-containing SBA-15 and M-doped MCM-41） on polymerization of THE These materials were directly synthesized by introduced aluminum isopropoxide into reaction mixture including surfactant and siliceous precursor. Al-doped plugs-containing SBA-15 （denotes as PAS） samples not only possess typical two-step desorption isotherms, which implied PAS materials generated plugs in their mesochannel, but also exhibit larger pore size and thicker wall than that of Al-doped MCM-41 （denotes as ACM）, which implied PAS would have a great advantage on catalytic reaction involving large molecular （e.g. polymer of THF） in industrial point＇of view. To investigate catalytic activity of PAS and ACM with moderate acidic sites the polymerization of THF in the presence of acetic anhydride was carried out. The results showed PAS exhibiting good performance on polymerization of THF. Such result could be related to the large pore size and moderate acidic sites.展开更多
The particle size distribution of polymer always develops in emulsion polymerization systems,and certain key phenomena/mechanisms as well as properties of the final product are significantly affected by this distribut...The particle size distribution of polymer always develops in emulsion polymerization systems,and certain key phenomena/mechanisms as well as properties of the final product are significantly affected by this distribution.This review mainly focuses on the measurement methods of particle size distribution rather than average particle size during the emulsion polymerization process,including the existing off-line,on-line,and in-line measurement methods.Moreover,the principle,resolution,performance,advantages,and drawbacks of various methods for evaluating particle size distribution are contrasted and illustrated.Besides,several possible development directions or solutions of the in-line measurement technology are explored.展开更多
An acrylic size 8K is synthesized by emulsion polymeriza-tion,the properties of which depend on the monomersparticipating in copolymerization and reaction tech-niques.The structure of the size molecule is character-iz...An acrylic size 8K is synthesized by emulsion polymeriza-tion,the properties of which depend on the monomersparticipating in copolymerization and reaction tech-niques.The structure of the size molecule is character-ized by infrared spectrum.The hardness of the size filmis characterized by the glass transition temperature of thesynthesized copolymer which is a flexion point of DSCcurve.The micro state of the size adhering to yarns isshown by scanning electron microscopy.According tomeasurements,the acrylic size Size 8K has good adhesivepower and low water absorption,proper viscosity andhigh thermal stability,strong abrasion resistance andgood compatibility with other sizing agents.It aslo im-proves yarn breaking strength, yet has limited elongationloss.The acrylic size is a potential size to replace PVAand to apply to high speed looms.展开更多
On the basis of population balance a mathematical model is developed to describe the formation of polymer particle in styrene suspension polymerization. The characteristics of coalescence and breakage of droplets and ...On the basis of population balance a mathematical model is developed to describe the formation of polymer particle in styrene suspension polymerization. The characteristics of coalescence and breakage of droplets and the gel effect are analyzed in particular. Parameters of the models are estimated by experimental data on reaction conversion and particle size distribution. The results show that the model is suitable for predicting polymerization processes.展开更多
Submicron-sized peanut-shaped poly（methyl methacrylate）/polystyrene （PMMA/PS） particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed p...Submicron-sized peanut-shaped poly（methyl methacrylate）/polystyrene （PMMA/PS） particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed particles. The obtained peanut- shaped particles showed a novel internal morphology： PS phase formed one domain which linked to the other domain having PMMA core encased by PS shell.展开更多
A series of St/BA/MAA emulsion polymerizations was carried out. By using PCS (photon correlation spectroscopy), the particle size distribution (PSD) of the whole St/BA/MAA emulsion polymerization process was gotten e...A series of St/BA/MAA emulsion polymerizations was carried out. By using PCS (photon correlation spectroscopy), the particle size distribution (PSD) of the whole St/BA/MAA emulsion polymerization process was gotten easily and quickly. The effect of polymerization condition on PSD in St/BA/MAA emulsion process was discussed.展开更多
A series of poly （ 2-ethylhexyl acrylate-co-acrylic acid ） s （ P （2-EHA-co-AA） ）s with different mole contents of 2-ethylhexyl acrylate （ 2-EHA ） were synthesized through free radical copolymerization in ethan...A series of poly （ 2-ethylhexyl acrylate-co-acrylic acid ） s （ P （2-EHA-co-AA） ）s with different mole contents of 2-ethylhexyl acrylate （ 2-EHA ） were synthesized through free radical copolymerization in ethanol for investigating the influences of copolymer composition upon the performance such as apparent viscosity, film behaviors, and adhesion to fibers for warp sizing. The content of 2-EHA was varied from 80 % to 40 %. The adhesion was estimated by measuring tensile strength and work-to-break of impregnated roving. The film behaviors were evaluated in terms of breaking strength, breaking elongation, work-to-break, and flex- fatigue resistance. It was observed that the viscosity, adhesion, and film behaviors of the copolymers strongly depended on the content of 2-EHA. Excessively increasing or decreasing the content of 2-EHA units incorporated into the copolymeric chains reduces the serviceability of P（2-EHA-co-AA） in warp sizing. The adhesion and film behaviors of the copolymcr reach their maximal values at mole content of 50 % simultaneously. Therefore, the copolymer used as sizing agent should be synthesized under equal mole of 2-EHA and AA in monomer formulation.展开更多
Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and ...Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.展开更多
Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases an...Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases anddisappears at conversions greater than 30%. Scanning electron micrographs show that PVC grains are composed of looselycoalesced primary particles, especially for PVC resins prepared in the presence of poly(vinyl alcohol) dispersant. The size ofprimary particles increases and porosity decreases with the increase of conversion. In view of the particle features of PVCresin, a particle formation mechanism including the formation of primary particles and grains is proposed. The formationprocess of primary particles includes the formation of particle nuclei, coalescence of particle nuclei to form primary particles,and growth of primary particles. PVC grains are formed by the coagulation of primary particles. The loose coalescence ofprimary particles is caused by the colloidal stability of primary particles and the low swelling degree of vinyl chloride in the primary particles.展开更多
A general protocol was described for fabricating uniform molecularly imprinted polymer （MIP） particles via controlled living radical precipitation polymerization at ambient temperature. By adopting glutathione as mo...A general protocol was described for fabricating uniform molecularly imprinted polymer （MIP） particles via controlled living radical precipitation polymerization at ambient temperature. By adopting glutathione as model template, benzyl dithiocarbamate as iniferter agent, 4-vinylpyridine as monomer, and ethylene glycol dimethacrylate as cross-linker, it is demonstrated that the polymerization parameters including the iniferter concentration, monomer loading and molar ratio of cross-linker to functional monomer have profound effect on the final particle size and recognition property of the MIP particles. The batch static binding experiments were carried out to estimate the adsorption kinetics, adsorption isotherms and selective recognition of the MIP particles. The adsorption behavior followed the pseudo-second order kinetic model, revealing that the process was chemically carried out. Two adsorption isotherm models were applied to analyze equilibrium data, obtaining the best description by Langmuir isotherm model. In addition, the MIP particles also could selectively recognize glutathione over similar analogs, indicating the possibility for the separation and enrichment of the template from complicated matrices.展开更多
Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle s...Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.展开更多
The macroprocess of particle formation from suspension droplets of styrene in a pdymerizationsystem was investigated.Inorganic hydroxyapatite or its mixture with polyvinyl alcohol as thepolymerization system was used....The macroprocess of particle formation from suspension droplets of styrene in a pdymerizationsystem was investigated.Inorganic hydroxyapatite or its mixture with polyvinyl alcohol as thepolymerization system was used.Those items such as the effects of the Weight fraction of dispersed-phase,the amount of the inorganic stabilizer and the agitation speed on the breakup and coalescence of thetransient dispersed drops etc.Were examined.Results showd that the dynamic behavior of the transi-ent polymer droplets changed in the presence of the suspension stabilizer during the reaction.展开更多
The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, t...The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, the transmittance and the refractive index of the latex, and by measuring the particle size, the molecular weight and the glass transition temperature (T_g) of the polymers. The results show that compared to the batch feeding mode, the semi-continuous feeding mode is more favorable to form a PMMA microlatex with a higher transmittance, a smaller particle size, a higher molecular weight and a higher T_g. And the obtained PMMA microlatex has a 30%—40% (mass fraction) polymer content, a 0. 03 emulsifier/water weight ratio, a 0. 05 emulsifier/monomer weight ratio and a 17 nm average particle diameter, which is very important for the industrialization of the microemulsion polymerization technique.展开更多
Here we present the polymerization of n-butyl acrylate (BA), ethyl acrylate (EA) and methyl acrylate (MA) in tri-component microemulsions, using a cationic surfactant such as dodecyl trimetyl ammonium bromide in water...Here we present the polymerization of n-butyl acrylate (BA), ethyl acrylate (EA) and methyl acrylate (MA) in tri-component microemulsions, using a cationic surfactant such as dodecyl trimetyl ammonium bromide in water, as a function of temperature, initiator type and, monomer and initiator concentration. The final latexes are transparent and blue color, with particle size ranging between 20 and 60 nm determined by quasielastic light scattering (QLD) and SEC molar masses of the order of 106 g/mol. Reaction times are short and reaction rates are high with final conversions between 70 and 98% depending on the monomer and the reaction conditions.展开更多
This paper describes a study about the synthesis of self-fixed sizing agent and gives a detailed example about this kind of sizing agent’s practical operation. The study focuses on the condition of emulsion polymeriz...This paper describes a study about the synthesis of self-fixed sizing agent and gives a detailed example about this kind of sizing agent’s practical operation. The study focuses on the condition of emulsion polymerization and the proportions of monomer, which can make the product not only have a nice waterproof attribute but also have a better stability of emulsion. At the same time the use of the cation monomer enables the polymer to adhere to fiber easily.展开更多
Surface sizing is an effective way to increase paper’s water-resistance and printability.The purpose of this study was to study synthesis process to develop an efficient cationic styrene-acrylic acid ester emulsion(S...Surface sizing is an effective way to increase paper’s water-resistance and printability.The purpose of this study was to study synthesis process to develop an efficient cationic styrene-acrylic acid ester emulsion(SAE)for the surface sizing of paper.Dimethylaminoethyl methacrylate methyl chloride(DMC)was used as the cationic monomer,and cationic starch or native starch was used as the emulsion stabilizer to copolymerize with styrene and butyl acrylate.The results indicated that the SAE synthesized with cationic starch and DMC had a high cationic charge density and a high DMC conversion rate.Paper sized with the cationic SAE had higher surface strength and lower Cobb value than the paper sized with other surface sizing agents such as,anionic SAE,and cationic or oxidized starch.Scanning electron micrographs revealed that the paper sized with a combination of oxidized starch and cationic SAE had smoother surface morphology when compared to the paper sized with oxidized starch alone,or with oxidized starch and anionic SAE.展开更多
Nano-sized spherical polymer brushes （SPBs） consisting of both a polystyrene （PS） core and a brush shell of poly（acrylic acid） （PAA）, poly（N-acrylcysteamine） （PSH）, or poly（N-acrylcysteamine-co-acrylic a...Nano-sized spherical polymer brushes （SPBs） consisting of both a polystyrene （PS） core and a brush shell of poly（acrylic acid） （PAA）, poly（N-acrylcysteamine） （PSH）, or poly（N-acrylcysteamine-co-acrylic acid） （P（SH-co-AA））, were prepared by photo-emulsion polymerization. The core-shell structure was observed by dynamic light scattering and transmission electron microscopy. Due to the strengthened Donnan effect, the PAA brush can adsorb heavy metal ions. Effects of the contact time, thickness of PAA brush and pH value on the adsorption results were investigated. Due to the coordination between the mercapto groups and heavy metal ions as well as the electrostatic interactions, SPBs with mercapto groups are capable to remove heavy metal ions selectively from aqueous solutions. The order of adsorption capacity of the heavy metal ions by SPBs with mercapto groups is： Hg2＋ ≈ Au3＋ 〉 Pb2＋ 〉 CH2＋ 〉 Ni2＋. The adsorbed heavy metal ions can be eluted from SPB by aqueous HCI solution, and the SPBs can be recovered. After three regenerations the recovered SPBs still maintain their adsorption capacity.展开更多
Incorporating fluorophores into polymeric nanoparticles has been testified as a feasible way to improve the emitting property and bio-compatibility of nano-emitters, which can be applied as fluorescent probes in label...Incorporating fluorophores into polymeric nanoparticles has been testified as a feasible way to improve the emitting property and bio-compatibility of nano-emitters, which can be applied as fluorescent probes in labeling cells for imaging. Plenty of efforts have been made on the above direction. However, the size effect of nano-emitters has not been addressed yet mainly given the difficulties in controlling morphology and size of the assemblies. In our preceding study, we employed post-polymerization modification method for preparing amphiphilic copolymers, and obtained core-shell(the hydrophobic fluorophores are wrapped inside the nanoparticle to form the core) assemblies in aqueous solution. By this method, we are able to regulate the ratio of the hydrophilic/hydrophobic moieties, and thus alternate the size of the assemblies in a rather simple way. In this study, we synthesized a series of random copolymers by changing the ratio of poly(ethylene glycol) to tetraphenylethylene groups. Notably, the number of repeating units of the polymer was controlled constant for all the copolymers. The self-assembly of these copolymers resulted in different sizes of nanoparticles, and the size decreased with the decreasing fraction of poly(ethylene glycol). Interestingly, the emission of the nanoparticles showed size dependence, and smaller diameter corresponded to stronger emission. Being cultured with HeLa cells, either the large(diameter of ~300 nm) or the small(diameter of ~180 nm) nano-emitters allowed for very high cell viabilities up to 25 μg·mL-1. Both of them can be applied in cell imaging and provide high contrast fluorescent images.展开更多
Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins(PN)and polysaccharides(PS)in the sludge,the PN/PS ratio,the particle sizes,and their relationship wi...Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins(PN)and polysaccharides(PS)in the sludge,the PN/PS ratio,the particle sizes,and their relationship with sludge dewaterability(as determined by capillary suction time,CST).The sludge flocs were stratified through centrifugation-and ultrasound-based method into four fractions:(1)slime,(2)loosely bound extracellular polymeric substances(LB-EPS),(3)tightly bound EPS(TB-EPS),and(4)pellet.The results showed that PN was mainly partitioned in the pellet(80.7%)and TB-EPS(9.6%)fractions,while PS distributed evenly in the four fractions.During hydrolysis and acidification,PN was transferred from the pellet and TB-EPS fractions to the slime fraction,but PS had no significant transfer trends.The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification.The pH had a more significant influence on the dewaterability of sludge flocs than temperature.Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340-450 s under alkaline conditions.However,it was just slightly increased under acidic conditions.Further investigation suggested that CST was affected by soluble PN,soluble PN/PS,and particle sizes of sludge flocs,but was affected slightly by total PN,PS,or PN/PS in the whole sludge flocs and other fractions(except slime).展开更多
The objective of this paper is to model the size-dependent thermo-mechanical behaviors of a shape memory polymer (SMP) microbeam.Size-dependent constitutive equations,which can capture the size effect of the SMP,are p...The objective of this paper is to model the size-dependent thermo-mechanical behaviors of a shape memory polymer (SMP) microbeam.Size-dependent constitutive equations,which can capture the size effect of the SMP,are proposed based on the modified couple stress theory (MCST).The deformation energy expression of the SMP microbeam is obtained by employing the proposed size-dependent constitutive equation and Bernoulli-Euler beam theory.An SMP microbeam model,which includes the formulations of deflection,strain,curvature,stress and couple stress,is developed by using the principle of minimum potential energy and the separation of variables together.The sizedependent thermo-mechanical and shape memory behaviors of the SMP microbeam and the influence of the Poisson ratio are numerically investigated according to the developed SMP microbeam model.Results show that the size effects of the SMP microbeam are significant when the dimensionless height is small enough.However,they are too slight to be necessarily considered when the dimensionless height is large enough.The bending flexibility and stress level of the SMP microbeam rise with the increasing dimensionless height,while the couple stress level declines with the increasing dimensionless height.The larger the dimensionless height is,the more obvious the viscous property and shape memory effect of the SMP microbeam are.The Poisson ratio has obvious influence on the size-dependent behaviors of the SMP microbeam.The paper provides a theoretical basis and a quantitatively analyzing tool for the design and analysis of SMP micro-structures in the field of biological medicine,microelectronic devices and micro-electro-mechanical system (MEMS) self-assembling.展开更多
基金supported by Science Foundation of China(No.20573071)Key Scientific and Technological Projects of Shanxi Province(No.20090321059)
文摘We reported here the simultaneous influence of surface acidity and pore size of M-substituted hexagonal mesoporous silicas （Al- doped plugs-containing SBA-15 and M-doped MCM-41） on polymerization of THE These materials were directly synthesized by introduced aluminum isopropoxide into reaction mixture including surfactant and siliceous precursor. Al-doped plugs-containing SBA-15 （denotes as PAS） samples not only possess typical two-step desorption isotherms, which implied PAS materials generated plugs in their mesochannel, but also exhibit larger pore size and thicker wall than that of Al-doped MCM-41 （denotes as ACM）, which implied PAS would have a great advantage on catalytic reaction involving large molecular （e.g. polymer of THF） in industrial point＇of view. To investigate catalytic activity of PAS and ACM with moderate acidic sites the polymerization of THF in the presence of acetic anhydride was carried out. The results showed PAS exhibiting good performance on polymerization of THF. Such result could be related to the large pore size and moderate acidic sites.
基金The National Key Research and Development Program(2020YFA0906804)the National Natural Science Foundation of China(22078325,22035007,91934301)+1 种基金the NSFC-EU project(31961133018)the Special Project of Strategic Leading Science and Technology,CAS(XDC06010302)are gratefully acknowledged.
文摘The particle size distribution of polymer always develops in emulsion polymerization systems,and certain key phenomena/mechanisms as well as properties of the final product are significantly affected by this distribution.This review mainly focuses on the measurement methods of particle size distribution rather than average particle size during the emulsion polymerization process,including the existing off-line,on-line,and in-line measurement methods.Moreover,the principle,resolution,performance,advantages,and drawbacks of various methods for evaluating particle size distribution are contrasted and illustrated.Besides,several possible development directions or solutions of the in-line measurement technology are explored.
文摘An acrylic size 8K is synthesized by emulsion polymeriza-tion,the properties of which depend on the monomersparticipating in copolymerization and reaction tech-niques.The structure of the size molecule is character-ized by infrared spectrum.The hardness of the size filmis characterized by the glass transition temperature of thesynthesized copolymer which is a flexion point of DSCcurve.The micro state of the size adhering to yarns isshown by scanning electron microscopy.According tomeasurements,the acrylic size Size 8K has good adhesivepower and low water absorption,proper viscosity andhigh thermal stability,strong abrasion resistance andgood compatibility with other sizing agents.It aslo im-proves yarn breaking strength, yet has limited elongationloss.The acrylic size is a potential size to replace PVAand to apply to high speed looms.
文摘On the basis of population balance a mathematical model is developed to describe the formation of polymer particle in styrene suspension polymerization. The characteristics of coalescence and breakage of droplets and the gel effect are analyzed in particular. Parameters of the models are estimated by experimental data on reaction conversion and particle size distribution. The results show that the model is suitable for predicting polymerization processes.
基金supported by National Natural Science Foundation of China(No.50943028)Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘Submicron-sized peanut-shaped poly（methyl methacrylate）/polystyrene （PMMA/PS） particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed particles. The obtained peanut- shaped particles showed a novel internal morphology： PS phase formed one domain which linked to the other domain having PMMA core encased by PS shell.
基金the Natural Science Foundation of Hubei Province
文摘A series of St/BA/MAA emulsion polymerizations was carried out. By using PCS (photon correlation spectroscopy), the particle size distribution (PSD) of the whole St/BA/MAA emulsion polymerization process was gotten easily and quickly. The effect of polymerization condition on PSD in St/BA/MAA emulsion process was discussed.
基金Open Project Program of Key Laboratory of Eco-Textiles,Ministry of Education,China(No.KLET0617)
文摘A series of poly （ 2-ethylhexyl acrylate-co-acrylic acid ） s （ P （2-EHA-co-AA） ）s with different mole contents of 2-ethylhexyl acrylate （ 2-EHA ） were synthesized through free radical copolymerization in ethanol for investigating the influences of copolymer composition upon the performance such as apparent viscosity, film behaviors, and adhesion to fibers for warp sizing. The content of 2-EHA was varied from 80 % to 40 %. The adhesion was estimated by measuring tensile strength and work-to-break of impregnated roving. The film behaviors were evaluated in terms of breaking strength, breaking elongation, work-to-break, and flex- fatigue resistance. It was observed that the viscosity, adhesion, and film behaviors of the copolymers strongly depended on the content of 2-EHA. Excessively increasing or decreasing the content of 2-EHA units incorporated into the copolymeric chains reduces the serviceability of P（2-EHA-co-AA） in warp sizing. The adhesion and film behaviors of the copolymcr reach their maximal values at mole content of 50 % simultaneously. Therefore, the copolymer used as sizing agent should be synthesized under equal mole of 2-EHA and AA in monomer formulation.
基金Open Research Foundation of "Anhui Key Laboratory of Textile Materials",China(No.2006F2003)
文摘Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.
基金The project is supported by the National Natural Science Foundation of China (No. 29906009)
文摘Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases anddisappears at conversions greater than 30%. Scanning electron micrographs show that PVC grains are composed of looselycoalesced primary particles, especially for PVC resins prepared in the presence of poly(vinyl alcohol) dispersant. The size ofprimary particles increases and porosity decreases with the increase of conversion. In view of the particle features of PVCresin, a particle formation mechanism including the formation of primary particles and grains is proposed. The formationprocess of primary particles includes the formation of particle nuclei, coalescence of particle nuclei to form primary particles,and growth of primary particles. PVC grains are formed by the coagulation of primary particles. The loose coalescence ofprimary particles is caused by the colloidal stability of primary particles and the low swelling degree of vinyl chloride in the primary particles.
基金financially supported by the National Natural Science Foundation of China(No.21174111)Graduate Starting Seed Fund of Northwestern Polytechnical University(No.Z2013145)
文摘A general protocol was described for fabricating uniform molecularly imprinted polymer （MIP） particles via controlled living radical precipitation polymerization at ambient temperature. By adopting glutathione as model template, benzyl dithiocarbamate as iniferter agent, 4-vinylpyridine as monomer, and ethylene glycol dimethacrylate as cross-linker, it is demonstrated that the polymerization parameters including the iniferter concentration, monomer loading and molar ratio of cross-linker to functional monomer have profound effect on the final particle size and recognition property of the MIP particles. The batch static binding experiments were carried out to estimate the adsorption kinetics, adsorption isotherms and selective recognition of the MIP particles. The adsorption behavior followed the pseudo-second order kinetic model, revealing that the process was chemically carried out. Two adsorption isotherm models were applied to analyze equilibrium data, obtaining the best description by Langmuir isotherm model. In addition, the MIP particles also could selectively recognize glutathione over similar analogs, indicating the possibility for the separation and enrichment of the template from complicated matrices.
基金Supported by the National Natural Science Foundation of China (No. 29906009).
文摘Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.
文摘The macroprocess of particle formation from suspension droplets of styrene in a pdymerizationsystem was investigated.Inorganic hydroxyapatite or its mixture with polyvinyl alcohol as thepolymerization system was used.Those items such as the effects of the Weight fraction of dispersed-phase,the amount of the inorganic stabilizer and the agitation speed on the breakup and coalescence of thetransient dispersed drops etc.Were examined.Results showd that the dynamic behavior of the transi-ent polymer droplets changed in the presence of the suspension stabilizer during the reaction.
基金Supported by the National Natural Science Foundation of China(No. 29974021) and the Educational Ministry of China.
文摘The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, the transmittance and the refractive index of the latex, and by measuring the particle size, the molecular weight and the glass transition temperature (T_g) of the polymers. The results show that compared to the batch feeding mode, the semi-continuous feeding mode is more favorable to form a PMMA microlatex with a higher transmittance, a smaller particle size, a higher molecular weight and a higher T_g. And the obtained PMMA microlatex has a 30%—40% (mass fraction) polymer content, a 0. 03 emulsifier/water weight ratio, a 0. 05 emulsifier/monomer weight ratio and a 17 nm average particle diameter, which is very important for the industrialization of the microemulsion polymerization technique.
文摘Here we present the polymerization of n-butyl acrylate (BA), ethyl acrylate (EA) and methyl acrylate (MA) in tri-component microemulsions, using a cationic surfactant such as dodecyl trimetyl ammonium bromide in water, as a function of temperature, initiator type and, monomer and initiator concentration. The final latexes are transparent and blue color, with particle size ranging between 20 and 60 nm determined by quasielastic light scattering (QLD) and SEC molar masses of the order of 106 g/mol. Reaction times are short and reaction rates are high with final conversions between 70 and 98% depending on the monomer and the reaction conditions.
文摘This paper describes a study about the synthesis of self-fixed sizing agent and gives a detailed example about this kind of sizing agent’s practical operation. The study focuses on the condition of emulsion polymerization and the proportions of monomer, which can make the product not only have a nice waterproof attribute but also have a better stability of emulsion. At the same time the use of the cation monomer enables the polymer to adhere to fiber easily.
基金Financial support for this work was provided by the National Natural Science Foundation of China(No.31370583)Brand Specialty Construction First Stage Projects of Jiangsu Universities 2015.The article was partly presented at the 4^(th) International Conference on Pulping,Papermaking and Biotechnology on Nov.7-9,2012 at Nanjing China.The organizer agreed for the contents to be submitted to Journal of Bioresources and Bioproducts.
文摘Surface sizing is an effective way to increase paper’s water-resistance and printability.The purpose of this study was to study synthesis process to develop an efficient cationic styrene-acrylic acid ester emulsion(SAE)for the surface sizing of paper.Dimethylaminoethyl methacrylate methyl chloride(DMC)was used as the cationic monomer,and cationic starch or native starch was used as the emulsion stabilizer to copolymerize with styrene and butyl acrylate.The results indicated that the SAE synthesized with cationic starch and DMC had a high cationic charge density and a high DMC conversion rate.Paper sized with the cationic SAE had higher surface strength and lower Cobb value than the paper sized with other surface sizing agents such as,anionic SAE,and cationic or oxidized starch.Scanning electron micrographs revealed that the paper sized with a combination of oxidized starch and cationic SAE had smoother surface morphology when compared to the paper sized with oxidized starch alone,or with oxidized starch and anionic SAE.
基金financially by the National Natural Science Foundation of China(No.21004021)the Fundamental Research Funds for the Central Universitiesthe High School Specialized Research Fund for the Doctoral Program(No.20110074110003)
文摘Nano-sized spherical polymer brushes （SPBs） consisting of both a polystyrene （PS） core and a brush shell of poly（acrylic acid） （PAA）, poly（N-acrylcysteamine） （PSH）, or poly（N-acrylcysteamine-co-acrylic acid） （P（SH-co-AA））, were prepared by photo-emulsion polymerization. The core-shell structure was observed by dynamic light scattering and transmission electron microscopy. Due to the strengthened Donnan effect, the PAA brush can adsorb heavy metal ions. Effects of the contact time, thickness of PAA brush and pH value on the adsorption results were investigated. Due to the coordination between the mercapto groups and heavy metal ions as well as the electrostatic interactions, SPBs with mercapto groups are capable to remove heavy metal ions selectively from aqueous solutions. The order of adsorption capacity of the heavy metal ions by SPBs with mercapto groups is： Hg2＋ ≈ Au3＋ 〉 Pb2＋ 〉 CH2＋ 〉 Ni2＋. The adsorbed heavy metal ions can be eluted from SPB by aqueous HCI solution, and the SPBs can be recovered. After three regenerations the recovered SPBs still maintain their adsorption capacity.
基金financially supported by the National Natural Science Foundation of China (Nos. 21674075 and 21233003)the Natural Science Foundation of Jiangsu Province (No.BK20161211)+1 种基金Key University Science Research Project of Jiangsu Province (No. 17KJA150007)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Incorporating fluorophores into polymeric nanoparticles has been testified as a feasible way to improve the emitting property and bio-compatibility of nano-emitters, which can be applied as fluorescent probes in labeling cells for imaging. Plenty of efforts have been made on the above direction. However, the size effect of nano-emitters has not been addressed yet mainly given the difficulties in controlling morphology and size of the assemblies. In our preceding study, we employed post-polymerization modification method for preparing amphiphilic copolymers, and obtained core-shell(the hydrophobic fluorophores are wrapped inside the nanoparticle to form the core) assemblies in aqueous solution. By this method, we are able to regulate the ratio of the hydrophilic/hydrophobic moieties, and thus alternate the size of the assemblies in a rather simple way. In this study, we synthesized a series of random copolymers by changing the ratio of poly(ethylene glycol) to tetraphenylethylene groups. Notably, the number of repeating units of the polymer was controlled constant for all the copolymers. The self-assembly of these copolymers resulted in different sizes of nanoparticles, and the size decreased with the decreasing fraction of poly(ethylene glycol). Interestingly, the emission of the nanoparticles showed size dependence, and smaller diameter corresponded to stronger emission. Being cultured with HeLa cells, either the large(diameter of ~300 nm) or the small(diameter of ~180 nm) nano-emitters allowed for very high cell viabilities up to 25 μg·mL-1. Both of them can be applied in cell imaging and provide high contrast fluorescent images.
基金supported by the National Hi-Tech Research and Development Program(863)of China(No.2006AA06Z384).
文摘Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins(PN)and polysaccharides(PS)in the sludge,the PN/PS ratio,the particle sizes,and their relationship with sludge dewaterability(as determined by capillary suction time,CST).The sludge flocs were stratified through centrifugation-and ultrasound-based method into four fractions:(1)slime,(2)loosely bound extracellular polymeric substances(LB-EPS),(3)tightly bound EPS(TB-EPS),and(4)pellet.The results showed that PN was mainly partitioned in the pellet(80.7%)and TB-EPS(9.6%)fractions,while PS distributed evenly in the four fractions.During hydrolysis and acidification,PN was transferred from the pellet and TB-EPS fractions to the slime fraction,but PS had no significant transfer trends.The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification.The pH had a more significant influence on the dewaterability of sludge flocs than temperature.Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340-450 s under alkaline conditions.However,it was just slightly increased under acidic conditions.Further investigation suggested that CST was affected by soluble PN,soluble PN/PS,and particle sizes of sludge flocs,but was affected slightly by total PN,PS,or PN/PS in the whole sludge flocs and other fractions(except slime).
基金Project supported by the National Key Research and Development Program of China(No.2017YFC0307604)the Talent Foundation of China University of Petroleum(No.Y1215042)the Graduate Innovation Program of China University of Petroleum(East China)(No.YCX2019084)
文摘The objective of this paper is to model the size-dependent thermo-mechanical behaviors of a shape memory polymer (SMP) microbeam.Size-dependent constitutive equations,which can capture the size effect of the SMP,are proposed based on the modified couple stress theory (MCST).The deformation energy expression of the SMP microbeam is obtained by employing the proposed size-dependent constitutive equation and Bernoulli-Euler beam theory.An SMP microbeam model,which includes the formulations of deflection,strain,curvature,stress and couple stress,is developed by using the principle of minimum potential energy and the separation of variables together.The sizedependent thermo-mechanical and shape memory behaviors of the SMP microbeam and the influence of the Poisson ratio are numerically investigated according to the developed SMP microbeam model.Results show that the size effects of the SMP microbeam are significant when the dimensionless height is small enough.However,they are too slight to be necessarily considered when the dimensionless height is large enough.The bending flexibility and stress level of the SMP microbeam rise with the increasing dimensionless height,while the couple stress level declines with the increasing dimensionless height.The larger the dimensionless height is,the more obvious the viscous property and shape memory effect of the SMP microbeam are.The Poisson ratio has obvious influence on the size-dependent behaviors of the SMP microbeam.The paper provides a theoretical basis and a quantitatively analyzing tool for the design and analysis of SMP micro-structures in the field of biological medicine,microelectronic devices and micro-electro-mechanical system (MEMS) self-assembling.
