Mechanical properties of reinforced polyvinyl chloride composites: Effect of filler form and content

Characterisation of Polypropylene Composite Reinforced with Chemi-Thermomechanical Pulp from Oil Palm Trunk via Injection Moulding Process

As the products made from wood-plastic composites (WPCs) become more sophisticated and required more detail profiles, the injection moulding processing method with wood pulp as the reinforcing material is the answer to cater to the rapid change and demands of composite products. The general objective of this study was to study the effects of the material formulation, as well as the injection moulding process parameters, on the properties of a polypropylene composite reinforced with chemi-thermomechanical pulp from oil palm trunks (PP/OPTP composite) via the injection moulding process. The PP/OPTP composite with a material formulation of 70% pulp/26% PP/4% Exxelor PO produced using injection moulding at 80 °C as the mould temperature and with 50 tonnes of injection pressure exhibited the highest physical and mechanical properties. The increment loading of pulp increased the water absorption capacity of the composite. Higher loading of the coupling agent effectively reduced the water absorption capacity and increased the flexural strength of the composite. The increase in mould temperature from unheated to 80 °C prevented excessive heat loss of the flowing material, which enabled the molten material to flow better and filled up all cavities in the mould. The increased injection pressure slightly improved the physical properties of the composite, but the effect on the mechanical properties was insignificant. For the future development of WPCs, further studies should be focused on the viscosity behaviour, as a greater understanding of the processing parameters' effects on the PP/OPTP's viscosity behaviour will lead to improved product design and enable great potential usage of WPCs.

Effect of Basalt Powder Surface Treatments on Mechanical and Processing Properties of Polylactide-Based Composites

Legislative restrictions and the needs of consumers have created a demand for sustainable materials. Polylactide (PLA) is a biodegradable polyester with advantageous mechanical properties, however, due to its low crystallization rate, it also has low thermomechanical stability. Its range of application temperatures can be widened using nucleating agents and fillers including basalt powder (BP), a waste product from the mining industry. This study analyzed the possibility of enhancing the properties of a PLA-BP composite by chemically treating the filler. Basalt powder was subjected to silanization with 3-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane and mixed with PLA at 5-20 wt%. The nucleating effect of a potassium salt of 3,5-bis(methoxycarbonyl) (LAK-301) in the silanized composite was also evaluated. The properties of the materials with silanized BP were compared with the unmodified basalt powder. The miscibility of the filler and the polymer was assessed by oscillatory rheometry. The structure of the composites was studied using scanning electron microscopy and their thermomechanical properties were analyzed using dynamic mechanical thermal analysis. Mechanical properties such as tensile strength, hardness and impact strength, and heat deflection temperature of the materials were also determined. It was concluded that BP-filled nucleated PLA composites presented satisfactory thermomechanical stability without silanization, but chemical treatment could improve the matrix-filler interactions.

Graphene oxide as a compatibilizer for polyvinyl chloride/rice straw composites

In this study, polyvinyl chloride (PVC)/rice straw (RS)/graphene oxide (GO) sustainable nanocomposite was prepared using the direct compounding method. Structural, morphological and mechanical properties of fabricated sustainable nanocomposites were compared with unfilled and RS-filled PVC compounds. Mechanical characteristics of PVC decreased with loading RS fibers. The main reason for the mechanical failure of PVC/RS composite is the incompatibility between PVC and RS fibers. GO nanosheets are used here to improve the compatibility between RS fibers and PVC macromolecules. Compared to the neat PVC, maximum strength of the RS/GO-loaded PVC composite increased up to 31%, with incorporating only 1 wt% of GO nanosheets. This enhancement in the mechanical characteristics of PVC/RS/GO nanocomposite can only be due to the role of GO nanosheets as a compatibilizer, as 1 wt% GO loading can only increase the mechanical strength of PVC compounds up to 9%. Fourier transform infrared spectroscopy results are used here to study the nature of these behaviors. It is suggested that the non-covalent and physical interactions between cellulose/hemicellulose portions of RS fibers and GO functional groups result in the enhancement of mechanical characteristics. Consequently, GO can be considered as a new compatibilizer for fabricating high performance PVC-based sustainable nanocomposites.