Influences of Copolymer Composition upon the Behaviors of Poly(vinyl acetate-co-acrylamide)Sizing Agents

A series of poly(vinyl acetate-co-acrylamide)copolymers with different mole ratios of vinyl acetate to acrylamide units were synthesized by emulsion polymerization for investigating the influences of copolymer composition upon the performance such as apparent viscosity,film behaviors,and adhesion capacity to fibers for warp sizing operation.The mole ratios of vinyl acetate to acrylamide were varied from 0 to 4.By using an impregnated roving method,the adhesion was evaluated in terms of the maximal strength and work to break of a slightly sized roving.The film behaviors included breaking strength,breaking elongation,solution time and hygroscopic capacity.It was found that the viscosity,adhesion capability,glass transition temperature and film behaviors of the copolymeric sizing agent strongly depended on the mole ratio.Excessively increasing the amounts of vinyl acetate or acrylamide units incorporated into the copolymeric chains damages much of the performance.A favorable mole ratio of vinyl acetate or acrylamide was found to be 45∶55.Based on this mole ratio,the adhesion capability and film behaviors of the sizing agent reach their maximal values simultaneously.This demonstrates that the sizing agent should be synthesized under this copolymer composition from the viewpoint of adhesion and film behaviors.

Comparative Case Study on Adhesion of Three Common Sizing Agents to Cotton and Polyester Yarns

The adhesion between warp sizing and fiber was systematically studied by using the roving method.Cotton roving and polyester roving were sized with various concentrations between 0.01%and 2.50%of acid-thinned starch,polyvinyl alcohol and water-soluble polyester sizing,respectively,and tensile property of the sized roving was tested accordingly.The break force of the sized roving was considered as the adhesion force of the sizing to the fiber in the roving method.The experimental results show that the effects of sizing film strength and fiber strength on the adhesive force can be weakened when the concentration 0.5%of size paste is used,instead of 1%in the roving method.The size morphology in the sized roving and on the surface was observed through scanning electron microscopy,in the form of penetration and coverage of the sizing in or on the roving.On the other hand,the Young-Dupréequation was used to calculate the adhesion work.The advantages and disadvantages of roving method and the adhesion work method were compared.The adhesion obtained by both two methods reflects the rule of chemical similarity between warp sizing and fiber.

Nanometer TiO_2 Modified Polyacrylic Copolymer Sizing Agent

A series of new-type nanometer TiO2 modified polyacrylic copolymer sizing agent were synthesized from acrylic acid, ethyl acrylate, nanometer TiO2, oleic acid etc. by orthogonal design method. Results of the studies show that the synthetic method used in this paper was a new way and had never been found in the synthesis of acrylate sizing agent, and that the properties of those new-type size-agent were be improved, which had potential for substituting PVA (polyvinyl alcohol) sizing agent. The technology for solving the problem of nano-scale powder agglomeration and dispersion were also studied. The transmission electron microscope (TEM) observation showed that nano-TiO2had good dispersion and stability in aqueous solution and in sizing agent solution.

Perylene-Based Fluorescent Sizing Agent for Precise Evaluation of Permeability and Coating Property of Sizing Paste

Warp sizing is considered as the most important process of weaving preparation in the textile field.The quality of sized warp yarns is directly determined by the permeation and coating of sizing paste into/on warp yarns.However,many significant flaws of the current method of permeability and coating property of sizing paste,such as low accuracy and narrow variety adaptability for sizing agents and warp yarns,have emerged in the evaluation process.In order to eliminate the inherent flaws in the current method,the investigation chose chitosan(CS)as a representative of common sizing agents,introduced various amounts of perylene units onto molecular chains of the CS,and prepared a new functional sizing agent-fluorescent CS with different labeling degrees of perylene.Furthermore,PVA-perylene was synthesized to evaluate the permeability and coating property of PVA sizing paste.Then,three indexes to indicate the permeability and coating property of sizing paste,i.e.permeation percentage,coating percentage and integrity percentage of sizing film,were evaluated using the CS-perylene and PVA-perylene derivatives prepared.Due to the fluorescence emitted by the perylene units,the three indexes can be determined accurately and conveniently depending on only fluorescent microscope and common image processing software.The investigation efficiently solves the difficult problem of evaluating permeation and coating property of the pastes of both bio-based and petroleum-based sizing agents with appropriate degrees of labeling and has a significant guiding function on accurate determination of the quality of sized yarns.

Effect of Starch Dodecenylsuccinylation on the Adhesion and Film Properties of Dodecenylsuccinylated Starch for Polyester Warp Sizing

A series of dodecenylsuccinylated starches( DSSs) with different degree of substitution( DS) were prepared via the esterification of dodencenylsuccinic anhydride with hydrolyzed cornstarch in aqueous dispersion for investigating the influences of starch dodecenylsuccinylation upon the performances such as apparent viscosity and surface tension of starch paste, film behaviors,and adhesion to fibers for warp sizing. It was found that the dodecenylsuccinylation was able to reduce the surface tension of cooked starch paste and enhance the adhesion of starch to polyester fibers. It was also capable of depressing the brittleness of native starch and improving the mechanical behaviours such as breaking elongation and work-to-break of starch film. Initial increase in DS level of dodecenylsuccinylation enhanced these positive effects,while excessively increasing the level resulted in marked reduction in tensile strength of starch film and significant decrement in reaction efficiency. X-ray diffraction patterns of starch films showed the dodecenylsuccinates derivatized onto the backbones of starch depressed the degree of crystallinity of starch film. Based on the paste behaviors, adhesion, and film properties, the dodecenylsuccinylation level is recommended in a range of 0. 015-0. 025 for sizing polyester warps.

Research on the Sizing Performance of Starch Grafted Poly-hydroxy Alkyl-acid Esters

Starch grafted poly-hydroxy alkyl-acid esters were prepared via graft polymerization.Different characteristics of grafted starches were tested such as viscosity,viscosity stability,adhesion as well as properties of sized yarns.Sizing performance was analyzed from the aspect of physical and chemical reactions between polymer molecules.It shows that starch grafted poly-hydroxy alkyl-acid esters have excellent sizing performance and could absolutely be used as sizes for polyester-cotton yarns.

Synthesis and Performances of Poly(2-ethylhexyl acrylate-co-acrylic acid) Used for Warp Sizing

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.

Heterogeneous Reactions between Starch and AKD under Solvent-free Conditions

Oxidized starch powder and cationic starch solution were reacted with alkyl ketene dimer(AKD) under heterogeneous conditions at 70℃ for 12 h.The AKD molecules reacted with starch hydroxyl groups to form β-keto ester linkages under the above conditions.The reaction products were separated into CHCl_3-soluble and CHCl_3-insoluble fractions.FT-IR spectroscopy,SEM,Xray diffraction,and TG-DTA analyses of the CHCl_3-insoluble fraction indicated that β-keto ester substituents were introduced to hydroxyl groups on the starch surfaces.The results indicated that hydrogen bonds between the starch molecules were disrupted under heterogeneous conditions upon heating.The activity and accessibility of hydroxyl groups were enhanced,as a result of which β-keto ester bonds were produced between AKD and starch.Based on these results,we speculate that the β-keto esters which existed in the sheets sized by AKD emulsions were generated by the reaction between AKD and starch.

Synthesis of cationic styrene-acrylic acid ester copolymer emulsion for paper sizing

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.

DNA condensation and size effects of DNA condensation agent

Based on the model of the strong correlation of counterions condensed on DNA molecule, by tailoring interaction potential, interduplex spacing and correlation spacing between condensed counterions on DNA molecule and interduplex spacing fluctuation strength, toroidal configuration, rod-like configuration and two-hole configurations are possible. The size effects of counterion structure on the toroidal structure can be detected by this model. The autocorrelation function of the tangent vectors is found as an effective way to detect the structure of toroidal conformations and the generic pathway of the process of DNA condensation. The generic pathway of all of the configurations involves an initial nucleation loop, and the next part of the DNA chain is folded on the top of the initial nucleation loop with different manners, in agreement with the recent experimental results.