E0407

CRYSTAL STRUCTURE AND CRYSTAL TRANSITION OF POLY(TETRAMETHYLENE SUCCINATE) Y. Ichikawa, H. Kondo, K. Noguchi and K. Okuyama, Faculty of Technology, Tokyo University of Agriculture and Technology, Koganei Tokyo 184, Japan.

Recently, biodegradable polymers have been receiving special attention especially from the ecological viewpoint. It is well known that some of synthetic crystalline aliphatic polyesters, such as poly(tetramethylene succinate) (PTMS), poly(ethylene succinate) and their copolymers, show excellent biodegradability. Physical properties of crystalline polymers, in general, depend strongly on their crystal structure.

The molecular conformation and crystal structure of PTMS (a-form) was first investigated by Chatani and coworkers (Chatani, Y., Hasegawa, R., & Tadokoro, H., A Meet., Soc. Polym. Sci. (Japan), 1971, page 420). Recently, we found that a new crystal modification of PTMS (ß-form) was induced by strain (Ichikawa, Y., Suzuki, J., Washiyama, J., Moteki, Y., Noguchi, K., & Okuyama, K., Polymer, 1994, 35, 3338-3339). We have already reported that the thermodynamic first-order phase transition was the operative mechanism in the transition from a to ß-form(Ichikawa, Y., Washiyama, J., Moteki, Y., Noguchi, K., & Okuyama, K., Polym. J., 1995, 27, 1230-1238). In order to obtain a deep insight in the crystal transition mechanisms of PTMS, the two crystal structures have been investigated. The resulting structures of both crystal forms are summarized in the table.

Table. Crystal data of two crystal forms of PTMS

a-form ß-form

Crystal system monoclinic monoclinic

Space group P2₁/n P2₁/n

Cell dimensions a/Å 5.23(2) 5.84(5)

b/Å 9.12(3) 8.32(11)

c(fiber axis)/Å 10.90(5) 11.89(7)

ß/deg. 123.9(2) 131.6(5)

No. of chains per unit cell 2 2