Multifunctional and recyclable silane-grafted crosslinked poly(vinyl chloride) microspheres as modifiers for toughening and reinforcement of rigid PVC blends

Silane-grafted crosslinked PVC microspheres (P-K-M) was synthesized via the grafting copolymerization of MMA and KH-570. • P-K-M microsphere can significantly improve processibility and mechanical properties of rigid PVC. • P-K-M/PVC composites have good recovery efficiency for both the filler and the matrix. Enhancing the mechanical properties of polyvinyl chloride (PVC) is a crucial research direction for broader application and upgrading. Current chemical crosslinking strategies eg., peroxide and silane crosslinking are two industrially used techniques. However, these methods rely on crosslinking between molecular chains suffer from drawbacks such as poor controllability, high operational complexity, and elevated costs. Herein, a novel strategy to enhance the mechanical properties of PVC products by using silane-grafted crosslinked PVC microspheres (P-K-M) as functional fillers was developed. Briefly, crosslinked PVC microsphere was firstly synthesized via self-stable precipitation polymerization (2SP). Subsequently, the copolymer of γ-methacryloxypropyltrimethoxysilane and methyl methacrylate was grafted through radical copolymerization with the residual double bonds on the microsphere surface. Finally, PVC based blends were prepared by utilizing the P-K-M microsphere as multifunctional filler and using PVC as matrix. The impressive results showed that P-K-M microspheres can significantly reduce the plasticization time of rigid PVC, with the effect being particularly pronounced for P-K 15 -M microspheres. Adding 5 phr P-K 15 -M reduces the plasticization time from 38 to 20 s, while also lowering the material temperature from 186.2 °C to 183.1 °C. Additionally, the hydrolysis/condensation PVC blend with 7 phr P K 22.5 -M can achieve a high tensile strength about 63.0 MPa, which is increased 30.1% in comparison to that of the pure PVC (48.4 MPa). Meanwhile, the impact strength and vicat softening temperature were also increased by 29% and 41%, respectively. More notably, this technology by constructing a three-dimensional network through crosslinking between the P-K-M microspheres can endow the rigid PVC blend with highly efficient separation and recyclability, achieving separation yield of up to 95% for both the base PVC matrix and the crosslinked PVC microspheres. Download: Download high-res image (186KB) Download: Download full-size image