Basalt/Wood Hybrid Composites Based on Polypropylene: Morphology, Processing Properties, and Mechanical and Thermal Expansion Performance

Abstract

The main aim of this study was to investigate the effect of basalt fiber (BF) reinforcement in wood–plastic composites (WPCs). Basalt/wood hybrid composites based on polypropylene (PP) were prepared with different percentages of the reinforcement (the total fiber content was 10 wt%, 15 wt%, and 20 wt%). The BCS17-6.4-KV16 chopped basalt fibers with nominal diameter of 17 μm, cutting length of 6.4 mm, and wood fibers—Lignocel C 120 with the particle size of 70–150 µm—were used as a reinforcement. Composites were produced by the injection molding method. The density of the produced composites and their processing properties such as Vicat softening point and shrinkage were determined. In addition, the thermal expansion behavior of filled plastic composites was investigated. Mechanical tests were subsequently performed to evaluate the tensile, flexural, and impact properties at various temperatures (i.e., at −24 °C, 23 °C, and 80 °C) and after soaking in water. Scanning electron microscopy images were acquired to assess the effects of reinforcement and homogenization of mixtures and to determine the characteristics of the microstructure. The results showed that the hybridization process improved the tensile and flexural properties of reinforced wood composites. Moreover, the incorporation of high-strength basalt fibers into the composite led to increased stiffness. Even a small addition of 10 wt% total fibers led to a significant decrease in shrinkage and coefficient of thermal expansion.

Hybrid Cellulose–Basalt Polypropylene Composites with Enhanced Compatibility: The Role of Coupling Agent

“…Increases in the strength and modulus of MCC-reinforced composites were recorded with the incorporation of basalt fibers due to the better mechanical properties of basalt fibers, as confirmed by other studies based on the hybridization of glass or basalt fibers in natural fiber composites [ 17 , 37 , 38 ], which had tensile and flexural properties that exhibited a similar trend. MCC/basalt (15/15) hybrid composites with compatibilized matrices showed tensile strength and modulus values that were increased by 45% and 284% in comparison with neat PP, respectively, and by 61% and 94% compared to composites reinforced with 30 wt.…”

Effect of Temperature and Strain Rate on the Flexural Behavior of Wood-Polypropylene Composites

“…This shows that the material does not yield and directly breaks, the maximum stress (flexural strength) is equal to the fracture flexural strength and the fracture is brittle. As a result, the addition of wood powder enhances the matrix’s resistance to misalignment and the lignin and wood fibers in wood powder provide high strength and stiffness to the composite while destroying the continuity of the matrix and reducing the toughness of the material, which corresponds to the previously reported results [34]. As the wood powder content increases, the failure mode of the composites is converted from ductile failure to brittle failure.…”

Investigation on impact performance and dimensional stability of polypropylene composites in cryogenic environment

“…More importantly, as the application in CT environments increases, the inconspicuous defects of PP composites at RT will be gradually exposed in CT environments. Among them, the 'thermal expansion and cold contraction' phenomenon of the raw materials will cause changes in the shape of the final composite product to some degree 9,10 . Therefore, the 'cold contraction' phenomenon of materials at CT environment will cause a certain degree of dimensional shrinkage of the composites product, 11,12 which may cause structural damage to some precision assembled devices.…”