Effect of molecular weight and crystallinity on poly(lactic acid) mechanical properties

✍ Scribed by Gabriele Perego; Gian Domenico Cella; Catia Bastioli

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 505 KB
• Volume: 59
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960103)59:1<37::aid-app6>3.0.co;2-n

✦ Synopsis

Several samples of poly(1actic acid) with different molecular weights and tacticity have been prepared, and some PLLA injection moulded specimens have been annealed to promote their crystallization. From the characterization data, poly(L-lactide) showed more interesting mechanical properties than poly(D,L-lactide), and its behavior significantly improves wit.h crystallization. In fact, annealed specimens possess higher values of tensional and flexural modulus of elasticity, Izod impact strength, and heat resistance. The plateau region of flexural strength as a function of molecular weights appears around Mu = 35,000 for PDLLA and amorphous PLLA and at higher molecular weight, around Mu = 55,000, for crystalline PLLA. The study of temperature effect shows that a t 56°C only crystalline PLLA still exhibits useful mechanical properties.