Preparation Of Starch Grafted Poly-hydroxy Alkyl-acid Esters And The Sizing Performance

Textile size plays an important role in textile warp sizing.Commonly used textile size is mainly comprised of starch,polyethylene alcohol and acrylic size.Although PVA size has excellent properties,it causes serious pollution to the environment.Nowadays "Energy-saving & Environmental Protection Sizing" is widely being appealed at home and abroad.Substitutes for PVA size are widely being studied.Grafted starch receives more chances due to wide variety of sources,low price and good environmental performance of starch size.After several years' research,many grafted starch come out as size.It mainly uses chemical or physical trigger and monomer of olefine,bring reactive groups on macromolecular chains of starch.Copolymers of starch and biodegradable hydroxyl alkyl-acid or cyclic esters are biodegradable materials,being widely concerned in recent years.They are used as degradable plastics and biomedicines,but we never see their application in textile warp sizing.Graft polymerization plant were assembled,which involve reaction device,water bath device,mixing device,condensation equipment,vacuum equipment.Graft polymerization conditions involving reaction feed ratio,monomer ratio,reaction time,reaction temperature,concentration of catalytic agent were synthetically considered.Starch grafted poly-hydroxy alkyl-acid esters were prepared with DL-lactic acid andγ-butyrolactone(belongs to hydroxy carboxylic acid)as the grafting monomer,with stannous octoate as catalyst via ring-opening polymerization of ring esters.Starch grafted poly-hydroxy alkyl-acid esters was then centrifuged with the help of acetone. and grafted starch samples with different grafting yield from 21.54%to 35.07%were obtained. Fourier transform infrared spectroscopy spectra of grafted starch were analyzed and it was shown that poly-hydroxy alkyl-acid esters were successfully grafted onto starch molecules.Reaction mechanism of graft polymerization was researched and conclusion was drawned that DL-lactic acid generated lactide during polymerization,and DL-lactide andγ-butyrolactone were successfully grafted onto starch molecules via ring-opening polymerization.Grafted starch samples perform different properties via graft polymerization with different conditions.According to several evaluation indexes of sizing characteristics such as apparent viscosity,viscosity stability,adhesions,sizing percentage,tensile strength,elongation at break, abrasion resistance,regenerated hairiness were screened.Certain polymerization conditions were ascertained,in which sizing characteristics of this type of graft starch can be better developed.Graft polymerization was newly carried out.And reproducibility of sizing properties was demonstrated.A set of common size including acid hydrolysis starch size and mixture size of acid hydrolysis starch and PVA were chosen and were compared with graft starch regarding sizing properties.Sizing performance was analyzed based upon physical and chemical reactions between polymer molecules.It was shown that starch grafted poly-hydroxyl aikyl-acid esters can be put into use in the field of warp sizing,and grafted starch with excellent sizing performance for cotton yams and polyester-cotton yarns can be gotten via changing graft polymerization conditions. Sizing properties of this type of grafted starch are better than acid hydrolysis starch size and mixture size with little PVA size.It is poor than mixed size with large PVA size.