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

Abstract

Novel green composites were successfully prepared from bacterial poly(3hydroxybutyrate) (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-fiberreinforced 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. K E Y W O R D S automotive parts, compression molding, green composites, pita fibers, polyhydroxyalkanoates F I G U R E 6 Thermomechanical properties of the poly(3-hydroxybutyrate) (PHB) composite sheets as function of the pita fiber content in weight (wt.-%) at different lengths in terms of (a) Vicat softening point; (b) heat deflection temperature (HDT)

Compatibilization of highly sustainable polylactide/almond shell flour composites by reactive extrusion with maleinized linseed oil

“…This supports a recent finding in which it was indicated that particle debonding was the main failure mechanism of cellulosic fillers in biopolymer matrices (Torres-Giner et al, 2017). This occurs due to the lack of adhesion or cohesion at the particle-matrix interface of the green composite.…”

“…The latter, i.e., the interfacial filler-matrix adhesion, is crucial since it is responsible for promoting a good stress transfer from the continuous phase to the dispersed fillers that must carry the load. Nevertheless, the high inherent hydrophilicity of cellulosic fillers does not habitually offer good adhesion with the hydrophobic or low hydrophilic polymers used as the composite matrix (Torres-Giner et al, 2017). Poor filler wetting causes a non-uniform distribution of fillers in the matrix, consequently aggregation and void formation is commonly observed during melt processing.…”

Tailoring the Properties of Thermo-Compressed Polylactide Films for Food Packaging Applications by Individual and Combined Additions of Lactic Acid Oligomer and Halloysite Nanotubes

“…The strands were cooled in air, granulated in pellets in an air-knife unit, and dried at 60 • C for 72 h to remove moisture. Thereafter, the pellets were thermo-compressed using a 10-Tn hydraulic press from Robima S.A. (Valencia, Spain) equipped with two hot aluminum plates and a temperature controller from Dupra S.A. (Castalla, Spain) [53]. For this, about 5 g of each composition was thermo-compressed at 180 • C with a pressure of 40 MPa tons for 3 min in a square frame of 10 cm × 10 cm by two hot plates and air cooled at room conditions.…”

On the use of acrylated epoxidized soybean oil as a reactive compatibilizer in injection‐molded compostable pieces consisting of polylactide filled with orange peel flour

“…The latest research performed on green composites shows that the use of lignocellulosic materials obtained from industrial by‐products and food or agroforestry wastes is increasing as cost‐effective fillers since they provide a sustainability enhancement and improve physical performance . Some recent examples include, for instance, wood flour, banana fibers, rice husk, peanut skin, wheat and soy fibers, pita fibers and Posidonia oceanica seaweed . In the study reported in the present paper, for the first time, orange peel flour (OPF) was used as a lignocellulosic filler to develop green composites of PLA.…”