Preparation and characterization of compression-molded green composite sheets made of poly(3-hydroxybutyrate) reinforced with long pita fibers

Abstract

[EN] Novel green composites were successfully prepared from bacterial poly(3-hydroxybutyrate) (PHB) and pita fibers derived from the agave plant (Agave americana). Various weight contents (10, 20, 30, and 40 wt.-%) of pita fibers at different lengths (5, 15, and 20 mm) were successfully incorporated into PHB by compression molding. The newly prepared PHB/pita fibers composite sheets were characterized in terms of their mechanical and thermomechanical properties and then related to their morphology after fracture. Attained results indicated that the mechanical stiffness of PHB significantly improved with both the content and length of pita fibers, although ductile properties were reduced. In particular, the elastic modulus of the 40 wt.-% PHB composite sheets containing 20-mm-long pita fibers was approximately 55% higher than the unfilled PHB sheet. Shore D hardness also improved, achieving the shortest pita fibers the highest improvement. Pita fibers with lengths of 15 and 20 mm also increased the Vicat softening point and heat deflection temperature (HDT) by 38 and 21°C, respectively. Due to their optimal shape, it is concluded that pita fibers with lengths above 15 mm can potentially reinforce and improve the performance of PHB biopolymer. In addition, the compression-molding methodology described in this research work represents a cost-effective pathway to feasibly prepare long-fiber- reinforced thermoplastics (LFRTs) fully based on renewable raw materials. Resultant green composite sheets can be of interest for the development of sustainable parts in the automotive industry and other advanced applications in polymer technology.