THERMODYNAMIC EXPRESSIONS FOR MELTING OF TWO COMPONENT COPOLYMERS

As the representative theories on melting in copolymers composed of units of type A capable of crystallizing and other units B incapable of crystallizing, two theories proposed by P. J. Flory in 1949 and in 1955 are known well. However, there are not a few experimental results on melting in copolymers that can not be explained enough even with those theories. Above all, the causes of the discrepancy between numerical values of the heat of fusion derived from melting point depression in polymer A-diluent system and from melting point data in copolymer A-B has not been clarified strictly as yet.The purpose of this work is to investigate theoretically this problem by taking into consideration the conformational entropy of amorphous chains for copolymers composed of units of type A and other units B.Thus, some thermodynamic expressions were derived for melting in copolymer systems. The results obtained affords fair explanations for discrepancy between numerical values of the heat of fusion previously derived from melting point depression in polymer A-diluent system and from melting point data in copolymer A-B.