Enhanced Mechanical and Water Absorption Properties of Rice Husk-Derived Nano-SiO2 Reinforced PHBV Composites

Abstract

Poly(3-hydroxybutyrate–co–3-hydroxyvalerate) (PHBV) is a biodegradable polymer and has several potential applications. Herein, we have used a rich biomass resource, rice husk, to obtain rice husk nano-SiO2 (RHNS) and prepared RHNS/PHBV composites by using hot-press molding. The results showed that the amorphous nature of spherical nano-SiO2 particles with an average diameter of 40–80 nm was obtained. The tensile strength and flexural strength of the RHNS/PHBV-3 composite reached up to 23.515 and 75.669 MPa, respectively, corresponding to an increase of 33.65% and 15.54% as compared to pure PHBV. The enhanced mechanical properties of the RHNS/PHBV composite can be attributed to the uniform dispersion and strong interfacial bonding of RHNS with the PHBV matrix. In addition, the water absorption rate of the RHNS/PHBV composite increased from 0.26% to 0.35% and the water swelling ratio followed the given order in different directions: thickness > width > length. Furthermore, the initial degradation temperature and residual rate of combustion at 700 °C of the composites increased with higher content of RHNS, which represents the enhanced thermal stability of RHNS/PHBV composites. In summary, RHNS served as an excellent reinforcement and RHNS/PHBV composites have shown promising properties for various potential applications.

Rice Husk Ash/Silicone Rubber-Based Binary Blended Geopolymer Coating Composite: Fire Retardant, Moisture Absorption, Optimize Composition, and Microstructural Analysis

“…Figure 13 e,f shows the S21 sample, which showed poor moisture absorption properties due to the crack development on the surface of the coating. As reported by Wang et al [ 63 ], cracks and holes formed due to non-uniform mixing during hot pressing consequently increased the moisture absorption rate. When a gap is filled with water, it flows into the adjacent matrix by a capillary action and forms fractured process zones.…”

Natural Biodegradable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Nanocomposites with Multifunctional Cellulose Nanocrystals/Graphene Oxide Hybrids for High-Performance Food Packaging

“…20,24,32 The shortest half-crystallization time (t 1/2 ) of the ternary PHBV/CNC-GO nanocomposites supported the above observations (Table 2). Besides, the n value of the neat PHBV was 2.50, which was assigned to the three-dimensional homogeneous nucleation and crystallization of the PHBV crystals, 5,11 while the binary PHBV/CNC nanocomposites exhibited higher n values from 2.52−2.62, and the binary PHBV/GO nanocomposites and the ternary nanocomposites exhibited lower n values from 2.21−2.47, indicating the heterogeneous nucleation of the PHBV crystals in these nanocomposites. 24,29 The spherulite morphologies of PHBV in various nanocomposites were investigated using a polarizing optical microscope (POM), as shown in Figure 6.…”

“…Well-dispersed CNCs with high rigidity can improve the mechanical strength and thermal stability of PHBV polymers due to hydrogen bonds between CNC surface groups and PHBV; 12 however, the toughness and new functional properties (e.g., antibacterial activity) could not be introduced by the addition of pristine CNCs. 11 Flexible GO with 2D nanostructure and excellent thermal conductivity 18 could enhance the mechanical properties and crystallization temperature of PHBV nanocomposites. 19−21 However, GO with few surface groups shows poor compatibility with PHBV matrix, so surface modification of GO was used to improve dispersion and compatibility of nanofillers within the PHBV matrix.…”

“…As environmental pollution from traditional packaging materials is becoming a major problem, the use of biodegradable nanocomposites with comparable properties in food packaging could replace petroleum-based plastic packaging materials . Biodegradable polymers, such as polyhydroxyalkanoates (PHAs) and polylactic acid (PLA), have received increasing attention as food packaging materials and in tissue engineering and biomedical fields due to good biocompatibility and enhanced properties. , Poly­(3-hydroxybutyrate) (PHB) and poly­(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) as main members in PHAs family are used to replace petroleum-based traditional packaging plastic due to their biodegradability, nontoxicity, friendly environmental effect, and biocompatibility. , Compared to high-crystallinity PHB with high melting temperature and brittleness, semicrystalline PHBV produced by adding a few (3HV) units into PHB shows larger toughness, lower melting temperature, and crystallinity; thus, PHBV is more suitable for the industrial packaging application. − These advantages make PHBV bioplastics an ideal choice as nanocomposite packaging materials for food products, especially the global bioplastics market with economical values of US $43.8 billion in 2020 at a compound annual growth rate of 28.8%. ,, However, PHBV polymer has some disadvantages such as its brittleness, narrow processing window, poor thermal and mechanical properties, no antibacterial activity, and low resistance to water vapor permeability. ,− These limitations can affect most packaging and biomedical applications. Besides, PHBV has a high price depending on the HV amount; , the used PHBV in this study contained a lower percentage of HV (2.57%) to reduce cost of the resulting nanocomposites.…”

“…Recently, a wide range of enhancement strategies has been reported to improve physical and biological properties of PHBV matrix . One of the enhancement approaches consists of adding organic or inorganic nanofillers as reinforcing agents, especially cellulose nanocrystals (CNCs), graphene oxide (GO), zinc oxide (ZnO), and so on. ,− Generally, CNC and GO are representative one-dimensional (1D) organic nanofillers and two-dimensional (2D) inorganic nanofillers, respectively, which could be used to enhance the property of PHBV matrix. Well-dispersed CNCs with high rigidity can improve the mechanical strength and thermal stability of PHBV polymers due to hydrogen bonds between CNC surface groups and PHBV; however, the toughness and new functional properties (e.g., antibacterial activity) could not be introduced by the addition of pristine CNCs .…”