A Study Of The Linear And Non-linear Sub-Cluster Theory For Glass Transition Temperature On The Composition Of Copolymers

Copolymerization is one of the most important chemical techniques for modifying the property of materials . And the reaserch of the depandence of glass transition temperature (T_g) on the composition (X) of copolymers has been one of the most important items in the field of polymer science. From a vast amount of literatures concerned, it could be found that the existing equations derived from all kinds of theories could only fitted for some copolymer systems and thus did not own the universial applicability.Therefore, from a large amount of experiment facts ,the behavior of the glass transition temperature (T_g) of copolymers with their composition (X) could be summerized in eight types systematically. And on the basis of Sub—cluster theory , the Lin(?)ar and Non—linear Sub — cluster equations for the dependence of T_g on the composition of copolymers were derived. The fit provided by these equations to all kinds of T_g — Xcurves for copolymers , of which many were never studied , gave good accuracy. The formation and the distribution of the sub—clusters of the segments and the interaction among them in the copolymer systems could be reflected by the regular change of the linear and non — linear sub — cluster parameters which owned the explicit physical significance respectively. Thus the influence of the miero — structure factors of copolymers on their glass transition temperatures ,such as the sequence distribution, the relative polarity of monomers ,the shape and volume of the substitutive groups, the length of bloeks, crosslinking, and the morphology of copolymers , etc , could be characterized by above parameters.