The effect of additives interaction on the miscibility and crystal structure of two immiscible biodegradable polymers

• Main Author: Ahmed Mohamed El-Hadi
• Format: Article
• Language: English
• Published: Associação Brasileira de Polímeros 2014-01-01
• Series: Polímeros
• Subjects: Biopolymers; poly(lactic acid) PLLA; poly(propylene carbonate) PPC; blends; plasticizer; compatibilizer; Poly((R)-3-hydroxybutyrate) PHB; Poly vinyl acetate PVAc; miscibility; morphology
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-14282014000100003&lng=en&tlng=en

Poly lactic acid (PLLA) is a promising biopolymer, obtained from polymerization of lactic acid that is derived from renewable resources through fermentation. The characteristic brittleness of PLLA is attributed to slow crystallization rates, which results in the formation of the large spherulites. Its glass temperature is relative high, above room temperature and close to 60 ºC, and therefore its applications are limited. The additives poly((R)-3-hydroxybutyrate) (PHB), poly(vinyl acetate) (PVAc) and tributyl citrate (TBC) were used as compatibilizers in the biodegradable polymer blend of (PLLA/PPC). Results from DSC and POM analysis indicated that the blends of PLLA and PPC are immiscible. However, the blends with additives are miscible. TBC as plasticizer was added to PLLA to reduce its Tg. PVAc was used as compatibilizer to improve the miscibility between PLLA and PPC. FT-IR showed about 7 cm-1 shift in the C=O peak in miscible blends due to physical interactions. POM experiments together with the results of DSC and WAXD showed that PHB enhances the crystallization behavior of PLLA by acting as bio nuclei and the crystallization process can occur more quickly. Consequently an increase was observed in the peak intensity in WAXD.