乙烯基类单体与淀粉的接枝共聚反应Ⅱ—骨架淀粉结构与界面形态对接枝共聚反应的影响

Graft Copolymerization of Vinyl Monomers on to Starch(Ⅱ)——Effect of Structure and Interface Morphology of Starch on the Graft Copolymerization

本文以水作介质, Fenton’s 试剂(Fe^(2+)-H_2O_2)为引发剂,丙烯酸丁酯为接枝单体,研究了骨架淀粉的结构与界面形态,对丙烯酸丁酯与玉米淀粉按技共聚反虚的影响。发现骨架淀粉作为接枝共聚物的主干、母体,不仅对最终产物的性能有决定性意义,并对接枝反应的进行和接枝产物的结构与形态都具有直接的、关键性的影响。通常玉米淀粉呈微胞结构,其大分子聚集态结构由结晶区、取向区、无定形区三部分组成。反应活性为结晶区<取向区<无定形区。玉米淀粉经过氧化降解,除保持部分原有的活性—OH 以外,还引入了众多的活性—COOH,提高了接枝反应点数目.且众多的活性—CDOH 能将单体吸附到淀粉骨架附近,有利于接枝.另一方面,经过氧化降解,使淀粉分子量降低,粒度变细,比表面增大,活性端基充分暴露,因此反应活性得到提高。

In this paper,we report the effect of structure and interface morphology of starch on the graft copolymerization of Butyl Acrylate(BA) onto corn starch using Fenton′s reagent(Fe^(2+)-H?_2O_2) as initiator.Generally,corn starch is of microcell structure,and its state of aggragation consists of crystalline region,oriented region and amorphous region.When corn starch is treated by oxidication and gelatinaton,a lot of active-COOH are created on the backbones of starch,raise the number of graft site,and— COOH can absorb monomers,this is beneficial to grafting.On th other hand,cryatalline region of starch is destoryed,raise the interface compatib- ility between monomers and starch Thus,monomers are easier to disperse into starch.In addition,the crystallinity and orientation of starch are decreased greatly,amorphous easier to reaction is raised remarkably,the active end group is also outcropped,so that the reaction ability of starch is raised greatly,Thus,on the condition of same monomer concentration,the average molecular weight of branched chains are low,and its distribution is avoraging.Therefore,by chemical grafting,the critical surface tension of corn starch is decreased,and its wetting power to other matrixes is raised,