Studies On Fractionations For Chlorinated Polypropylene And Alkyd Resin

Polymer is made up of a series of macromolecules,which of molecular weight are different.It leads to the structural heterogeneity of polymer.Namely,fractionation for polymer is that separating it into some fractions according to the molecular weight, and its theory is that the solubility of polymer in Sol.depends on its molecular weight. The molecular weight distributions of fractions become more narrow or homogeneous than before by fractionating,and gain the precise structural information of macromolecules by virtue of other testing techniques,for example,GPC,"C-NMR, DSC and X-ray,and so on.Therefore,as an analytic and preparation technique, polymer fractionation is importance in the study on polymer structure.In this article,we chose two representatives from convertible coatings and non-convertible coatings in virtue of fractionation as a primary technique.Viewing chlorinated polypropylene(CPP) as the pattern of non-convertible coatings,mostly studies on the influence of difference of chlorinity on Mark-Houwink equation.It was detailedly studied that 30%chlorinity of CPP was an accelerating agent to printing ink on adhesive power.The emphases of this article is that the Mark-Houwink equation of 26%chlorinity of CPP,and the relation between 26% chlorinity of CPP and 30%chlorinity of CPP on Mark-Houwink equation.Fan's Mark-Houwink equation of 30%chlorinity of CPP is[η]=0.0174M_w^0.6919.In fact,it is applicable to molecular weight estimation of 26%-35%chlorinity of CPP.Viewing alkyd resin as the pattern of convertible coatings,mostly studies on the fractions of acid value,inherent viscosity and solubility parameter,and the law of performances on films coating made from fractions.In terms of literature survey,the study on fractionations of long oil alkyd resin is much more than others,but medium and short oil alkyd resins are few.This article aims at three types of domestic product, and compares them.In classic literatures,we can get Mark-Houwink equation because of the knowledge of specific formulation,but to the alkyd resin product,it is lack. This article finds a method to substitute for the former.Namely,Mark-Houwink equation can be fitted by virtue of acid value,instead of number-average molecular weight,and proves the reliability of acid value by direct ratio between solubility parameter and acid value.Therefore,acid value is an important parameter to alkyd resin,and compared with other parameters,it is easy to gain.Compared with other fractionations,gel permeation chromatography is excellent. But it is difficult to study on other performance because the weight of fractions is lesser.In this article,we use fractional precipitation to get fractions,prepare a series of films coating,and study their drying time,and so on.To alkyd resin,it is proved that drying time is due to the small molecular fractions.Therefore,alkyd resin belongs to convertible coatings,but compared to other resins,molecular weight distribution is still an importance parameter.