Study on the randomness of poly(ethylene naphthalate)/poly(ε-caprolactone) copolymer by melt blending

It is generally agreed that transesterification provides the,copolymer in the melt blending of poly(ethylene naphthalate) (PEN) and poly(epsilon-caprolactone) (PCL). Effects of the conditions of transesterification reaction and catalyst an the degree of randomness and average sequence length of PEN/PCL blends were investigated and results were used to interpret the biodegradability of PEN/PCL blends. It was found that degree of randomness values of obtained copolymer lied between 0 and 1, and it indicated that this blend consisted with physical blends of PEN/PCL and PEN/PCL block copolymers. The degree of randomness reached almost 1 which is the theoretical value of random copolymers and the average sequence length became shorter by the further transesterification reaction. In additions, it was found that the increase of copolymers, especially random copolymers reduced the biodegradability in PEN/PCL blends.