Effects of molecular structure of acrylates on sizing performance of allyl grafted starch

In order to improve the performance of allyl starch-g-poly(acrylic acid-co-acrylate) sizes, effect of molecular structure of the acrylate monomers grafted onto allyl starch has been studied. A series of acrylates including methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA) and 2-ethylhexyl acrylate (EHA) have been grafted onto allyl starch with the same degree of substitution through the initiation of Fe(NH4)2(SO4)2/H2O2 redox system respectively. Meanwhile, acrylic acid (AA) is also graft copolymerized to maintain good water-dispersibility of the grafted starch. Then the properties of the grafted allyl starch, such as the apparent viscosity, viscosity stability, and adhesion to polyester fibres and the mechanical properties of sizing film, have been studied. It is found that by grafting acrylates onto the molecular chains of starch, the sizing performance of the allyl starch is improved markedly. Under the same feed ratio of the acrylic monomers to allyl starch, allyl starch-g-poly(AA-co-MA) shows higher paste viscosity, viscosity stability, and film elongation than the other kinds of grafted allyl starch. Allyl starch-g-poly(AA-co-EA) also shows higher film strength than the other ones. Both of the allyl starches grafted with MA and EA show higher abrasion resistance of sizing film and better adhesion to polyester fibres.