Microwave‐assisted alcoholysis of silicone rubber waste with geraniol for effective elastomer damping

Abstract

The first step in the mainstream end-of-life management of discarded siliconerubber-based composite insulators involves grinding and modification of them into fine silicone rubber powders (SRPs). However, significant knowledge gaps have prevented researchers from developing direct efficient surface treatments for SRPs that do not involve time-consuming and multi-step processes. Herein, we report a straightforward method for the efficient modification of discarded SRPs through a microwave-assisted alcoholysis process. Specifically, the siloxane moieties of the SRPs were cleaved using nucleophilic geraniol as a modifier, thereby facilitating the introduction of abundant alkoxysilyl groups on SRPs surface. During sulfur crosslinking, the intrachain vinyl functionalities of the modified SRPs co-crosslinked with the rubber matrix via sulfur bridges, thereby improving the dispersion state of the SRPs and the interfacial adhesion between the SRPs and the rubber matrix. Accordingly, even for a high SRP loading (200 phr, parts per hundreds of gum), the mechanical performance of the resulting systems, and in particular the tensile strength and extensibility were significantly higher than those of the rubber matrix. Moreover, the interfacial adhesion of the resulting systems was improved, and the resulting systems presented remarkable damping performance (tan δ ≥ 0.3) over a broad temperature range (≥80 C).

Controlled damping ethylene‐vinyl acetate copolymer/styrene ethylene butylene styrene foam in wide temperature range prepared by supercritical nitrogen

“…Mechanical energy is converted into internal energy via this segmental movement, leading to a decrease in storage modulus and an increase in loss factor (tanδ). Materials with high tanδ at or near use temperature have good damping performance and have been widely used in transportation, mechanical equipment, aerospace and other fields 3,4 …”

“…Materials with high tanδ at or near use temperature have good damping performance and have been widely used in transportation, mechanical equipment, aerospace and other fields. 3,4 From an engineering point of view, tanδ ≥0.3 is called effective damping, in which the temperature range is the effective damping temperature range (ΔT), 5,6 but the common single rubber varieties usually do not have both excellent damping and mechanical properties. The mechanism of blending to modify damping involves mixing two or more kinds of incompatible macromolecules to obtain a composite with microscopic phase separation characteristics.…”

Experimental and application of waste rubber low‐temperature green regeneration through ultrasound‐assisted method

“…Additionally, the production process of this method entails substantial environmental pollution. 12,18 To realize environmentally friendly waste rubber regeneration, several methods have been developed, including microbial, 19,20 microwave, [21][22][23] grinding, [24][25][26][27] twin-screw, 28,29 and supercritical 30,31 techniques. Unfortunately, these methods are difficult to popularize on a large scale due to their shortcomings such as low efficiency and high cost.…”

Highly Efficient Pyrolysis of Waste High-Temperature Vulcanized Silicone Rubber Assisted by Mechanochemical Milling

“…6,7 Zou et al used geraniol as a modifier to crack the siloxane part of SRP, which was conductive to promote the introduction of rich alkoxy groups on the surface of SRP, thus improving the dispersion state of SRP and the interfacial adhesion between SRP and the rubber matrix. 8 This method is widely used and has obvious economic benefits. 9 However, this mechanical recycling method cannot achieve the closed-loop recycling.…”

“…At present, the recycling of silicone rubber mainly focuses on mechanical recycling and chemical recycling. , Mechanical recycling means that silicone rubber is further ground into a fragmented product through specific processing equipment and then refined to obtain fine silicone rubber powder (SRP), which can be directly used as filler or used after modification (activation), such as polymer reinforcement, damping, and sound insulation. , Zou et al used geraniol as a modifier to crack the siloxane part of SRP, which was conductive to promote the introduction of rich alkoxy groups on the surface of SRP, thus improving the dispersion state of SRP and the interfacial adhesion between SRP and the rubber matrix . This method is widely used and has obvious economic benefits .…”