Effect of Surface Modification on the Properties of Buckwheat Husk—High-Density Polyethylene Biocomposites

Abstract

This study focuses on the production and characterization of biocomposites based on a thermoplastic polymer (high-density polyethylene, HDPE) and a biosourced filler (buckwheat husk, BHS) to develop more sustainable composites. Compounding was performed via twin-screw extrusion with three different types of BHS. In the first series, untreated BHS was directly mixed with the polymer matrix, while the second series used mercerized BHS and the third series used pretreated BHS with a coupling agent (polyethylene grafted with maleic anhydride, MAPE) in solution. The samples were prepared at different concentrations (10, 20, 30, 40 and 50 wt.% of BHS) to compare with the neat matrix (0%). All the samples were finally produced by compression molding and then cut to get the specimens for characterization. The latter included morphological (scanning electron microscopy), physical (density and hardness) and mechanical (tension, flexural and impact strength) properties. Based on the results obtained, it was observed that most of the mechanical and physical properties were improved, especially when the BHS was pretreated in solution before its introduction into the polymer matrix. The results showed that 30 wt.% of BHS in HDPE was the optimum for most of the properties investigated.

Modified Buckwheat Husk as a Filler for Urea–Formaldehyde Resin in Plywood Production

“…The aim of the first step, which was mercerization in NaOH solution, was to activate the surface and increase the availability of hydroxyl Polymers 2024, 16, 1350 4 of 13 groups. It was performed following the procedure described by Vázquez-Fletes et al [29]. For this purpose, 50 g of ground husk was soaked in 500 mL of 5% NaOH solution at room temperature for 10 min while stirring at 400 rpm.…”

“…Moreover, according to Kuznetsova et al [26], buckwheat husk is a source of flavonoids and phenolic acids, which, as shown by the outcomes of previous research on the use of phenolic-rich biomass, may be beneficial for the use as the UF resin filler. This type of husk was previously used as a filler for various polymeric materials, such as polyurethane-based composites [27], polypropylene-based composites [28], polyethylene-based composites [29] and poly(lactic acid)-based composites [30], and therefore, it can be an interesting choice for formaldehyde-based resin as well.…”