Preparation, Characterization and Tailoring Properties of Poly(Vinyl Chloride) Composites with the Addition of Functional Halloysite–Lignin Hybrid Materials

Abstract

In this article, halloysite–lignin hybrid materials (HL) were designed and obtained. The weak hydrogen bonds found between the components were determined based on Fourier transform infrared spectroscopy (FTIR), proving the achievement of class I hybrid systems. The HL systems were characterized by very good thermal stability and relatively good homogeneity, which increased as the proportion of the inorganic part increased. This was confirmed by analyzing scanning electron microscope (SEM) images and assessing particle size distributions and polydispersity indexes. Processing rigid poly(vinyl chloride) (PVC) with HL systems with a content of up to 10 wt% in a Brabender torque rheometer allowed us to obtain composites with a relatively homogeneous structure confirmed by SEM observations; simultaneously, a reduction in the fusion time was noted. An improvement in PVC thermal stability of approximately 40 °C for composites with HL with a ratio of 1:5 wt/wt was noted. Regardless of the concentration of the HL system, PVC composites exhibited inconsiderably higher Young’s modulus, but the incorporation of 2.5 wt% of fillers increased Charpy impact strength by 5–8 kJ/m2 and doubled elongation at break. This study demonstrated that favorable mechanical properties of PVC composites can be achieved, especially with an HL system with a ratio of 5:1 wt/wt.