The effects of cellulosic fillers on the mechanical, morphological, thermal, viscoelastic, and rheological properties of polyhydroxybutyrate biopolymers

Abstract

The aim of this study was to determine the effects of cellulosic fillers on the conventional and dynamic mechanical, thermal, morphological, and rheological properties of polyhydroxybutyrate (PHB) biopolymers. Polyhydroxybutyrate as a biopolymer matrix and cellulosic fillers including wood flour, microcrystalline cellulose, and cellulose nanofibrils (0.5 and 5 wt%) as reinforcing agents were used to produce the composite. According to the results obtained, the addition of 0.5 wt% cellulose nanofibrils improved both the flexural and tensile moduli of elasticity but other fillers and filler loading levels generally decreased the mechanical properties attributable to aggregations of fillers in the matrix. Thermal analysis results showed that the addition of cellulosic fillers did not influence the glass transition and crystallization temperature of the PHB whereas the crystallinity and melting temperature generally increased with the addition of the cellulosic fillers. Thermal stability of the composites generally improved with addition of the cellulosic fillers. The dynamic mechanical analysis results showed that both storage and loss moduli of all the samples generally decreased with increasing temperature. Elastic and viscous moduli of all the samples initially decreased with frequency but then generally increased according to the rheological analysis.

Effect of the Micronization of Pulp Fibers on the Properties of Green Composites

“…The neat polymeric matrices showed a degradation profile with one major weight loss at 236 • C and 281 • C for PHB P209E and PHB P226, respectively, and 336 • C and 364 • C for PLA 3D860 and PLA 3100HP, respectively. These main weight losses, credited to the degradation of the polymeric backbone, are in agreement with the maximum degradation temperatures of other PHB [62,63] and PLA [34,64] grades reported in the literature. Apart from PLA 3100HP, the other matrices showed a small degradation step at 338 • C, 395 • C, and 456 • C for PHB P209E, PHB P226, and PLA 3D860, respectively, which were likely due to the degradation of the additives.…”

Natural Fiber-Reinforced Polylactic Acid, Polylactic Acid Blends and Their Composites for Advanced Applications

“…The applicability of natural fibers such as hemp and flax as a reinforcement material was addressed by Loos et al [ 102 ], and the mechanical characteristics of flax and hemp employed in polymer reinforcement were studied. Previously, researchers showed that adding natural fibers to PLA bio composites improves their flexural, tensile, and impact strength [ 103 , 104 , 105 , 106 , 107 ].…”

In‐depth material characterization of polyhydroxybutyrate from a forest biorefinery

“…In contrast, viscoelastic properties such as the storage modulus, loss modulus and the damping properties (tan δ) are rarely reported. For applications of commercial PHB, detailed characterizations of PHB composites with cellulose fibers have been reported, 15,16 which can be used in food packaging. 17 PHB synthesized from glucose or vegetable oils have a high degree of crystallinity ranging from 60% to 80%.…”