| The defects of sizing film were improved by blending polyacrylate with starch in this paper. In order to improve mechanical properties of polyacrylate/starch blend sizing film and evaluate the relationship between microstructure and the mechanical properties of the blend film, the texture of the blend film were characterized by SEM, AFM, XRD, and FT-IR. The effects of molecular structure of polyacrylate, starch modification, and blend proportion of polyacrylate and starch, on the texture and mechanical properties of polyacrylate/starch blend film were evaluated in terms of tensile strength, breaking elongation, abrasion resistance, and flex-fatigue resistance. The biodegradability of polyacrylate sizes with different molecular structure was explored and average molecular weights of polyacrylate sizes before and after cultivation were evaluated.The influences of reaction mediums upon the adhesion to fibers, and the properties of sizing film of polyacrylate sizes were investigated. Polyacrylate sizes were prepared in methanol, ethanol, furanidine, dioxane, acetone and isopropanol. The result showed that the adhesion and the properties of sizing films strongly depended on the mediums.Effect of molecular structure of polyacrylate on the mechanical properties polyacrylate/starch sizing film was investigated. It was found that incorporating appropriate amount of polyacrylate into starch was an effective method to decrease the brittleness of starch film. A favorable polyacrylate for toughening blend film was the copolymer of butyl acrylate with acrylic acid at a molar ratio of 70:30. Excessively increasing molar content of acrylate unit reduced the tougheness of blend film. The?-methyl in acrylate unit did not favor the enhancement of toughness of blend film.The mechanical properties of polyacrylate/starch were improved by starch modification. The microstructures and mechanical properties of polyacrylate/acetylated starch, polyacrylate/phosphorylated starch, and polyacrylate/carboxymethyl starch blend films were investigated. The effects of blend proportion of modified starch to polyacrylate, modification extent of starch, carbon atom number of alkyl ester in acrylate constituent units of polyacrylate, and molar ratio of the acrylate units to acrylic acid ones on mechanical properties of polyacrylate/modified starch blend films were studied in terms of tensile strength, breaking elongation, abrasion resistance, and flex-fatigue resistance of the films. The texture of the films was characterized by SEM, XRD and AFM. It was found that the mechanical properties were strongly dependent on the polyacrylate content and acrylate units as well as the modification extent of starch. Increasing the esterification extent of starch enhanced the breaking extension and flex-fatigue resistance of polyacrylate/starch blend film. The breaking extension and flex-fatigue resistance of polyacrylate/carboxymethyl starch blend film reached the maximum when the degree of substitute (DS) of carboxymethyl starch was 0.026. When the polyacrylate content was 50%, it was highly favorable to improve the toughness of the blend film The maximal breaking extension and flex-fatigue resistance were achieved. The phase-separation extent of the two ingredients within the film increased greatly when the polyacrylate content was 70%. Starch-g-poly(butyl acrylate-co-acrylic acid) [starch-g-poly(BA-co-AA)] was used as compatbilizer to improve the mechanical properties of polyacrylate/starch blend film. The dependence of mechanical properties of the film on the structure of grafting branched-chain was revealed. It was found that the mechanical properties of the film were greatly improved using starch-g-poly(BA-co-AA) as compatilizer. A favorable compatilizer for enhancing the mechanical properties was starch-g-poly(BA80-co-AA20) and preferred content based on the blends should be 10 wt%.Structural effect of (meth)acrylate units in polyacrylate, including the carbon atom number of alkyl ester groups and the presence of?-methyl group, on the biodegradability of acrylate copolymer was investigated. The effect of molar content of acrylate units in polyacrylate was also considered. The biodegradability was evaluated in terms of BOD5/COD. It was found that the polyacrylate degraded during cultivation via the attack of aerobic microorganisms on the molecular chains and average molecular weight of the polyacrylate decreased. To produce biodegradable polyacrylate sizes, essential requirement was to choose suitable type and amount of acrylates with shorter alkyl esters and without?-methyl in monomer formulation for the copolymerization with hydrophilic monomers. Preferred molar content of acrylate monomers in the formulation should be in a range of 60% to 70%. |
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