Poly (lactic acid) was molded under four different kinds of condition to obtain samples with different microstructures. A single crystal was not observed in the specimen molded at 0°C. The size of spherulites became larger with increase of molding temperature. The density of spherulites increased with increase of molding time. Mode I fracture toughness, KIC, was measured at a static (1 mm/min) and an impact loading rate (1 m/s). KIC became lower with increase of degree of crystallization at the static loading rate. This is mainly due to suppression of craze formation in the vicinity of crack-tip. On the other hand, at the impact loading rate, KIC increased with increase of degree of crystallization. Thus, the results showed that crystallization has significant influence on KIC, and its effect on the static KIC was different from that on the impact one. Relationship between fracture toughness and fracture micromechanism was discussed on the basis of the results of fracture tests and microscopies.
|Number of pages||7|
|Journal||Nippon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A|
|Publication status||Published - Jan 2003|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering