Chemical modification of neoprene rubber by grafting cardanol, a versatile renewable materials from cashew industry

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ORIGINAL PAPER

Chemical modification of neoprene rubber by grafting cardanol, a versatile renewable materials from cashew industry Wenzheng Zhang 1 & Tingting Zhang 1 & Ning Jiang 1 & Tinghao Zhang 1 Received: 14 November 2019 / Accepted: 16 April 2020 # The Polymer Society, Taipei 2020

Abstract In order to plasticize neoprene rubber (CR), a natural plasticizer,derived from Cashew Nut Shell Liquid (CNSL),was covalently bound to CR at room temperature via click chemistry. That is, the covalent attachment of the cardanol-based internal plasticizer to CR matrix, is descried for the first time. The chemical structure and properties of cardanol-based internal plasticizer and internally plasticized CR materials was characterized by FTIR, dynamic mechanical analysis (DMA), plasticizer migration tests, differential scanning calorimeter (DSC), and gel permeation chromatography (GPC). Results indicated when cardanol was grafted onto CR (CR-CPE), CR-CPE had a lower Tg compared with plain CR. Self-plasticization CR samples showed zero migration in petroleum ether, but 1. 58 mg·mL−1 of cardanol leached from CR/cardanol blend(CR-car) system into petroleum ether. The CRCPE materials were expected to be commercial application in producing food packing, toys, and medical devices with high requirements in migration resistance. Keywords Cardanol . Click chemistry . Internal plasticization . DSC;plasticizer

Introduction Plasticizers are the most consumable additives in polymer products, which can improve the mechanical and processing properties of polymers, and poly(vinyl chloride) (PVC) is the largest user of plasticizers. With the rapid development of polymeric industry and people’s increasing attention to environmental protection, people are starting to realize incontrovertible negative effects of plasticizers on mankind’s health and environmental impact [1–5], so the use of plasticizers, such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), have been limited in some fields, such as nursing bottle and child care products, and so on. So new type of natural plasticizers with competitive performance and cost need to be developed urgently [6–9]. Nowadays, more and more low toxicity natural plasticizers are constantly emerging, including epoxidized soybean oil, fatty acid esters and sunflower oil * Wenzheng Zhang [email protected] 1

Department of Materials Chemistry, School of Materials and Science Engineering, Shenyang Economic & Technology Development Zone, Shenyang University of Chemical Technology, Shenyang 110142, China

[10–12], but the problem of the migration of the plasticizers from polymeric products still exist, for the thermodynamic reasons still exist. Chemical and physical methods are two main methods for polymer plasticizing. Although plasticizers are easy to volatilize and migrate, and can also reduce the tensile strength and toughness of rubber products by physical plasicizing method [13–17], most producers still prefer to use these methods for plasticizing as it’s simpler than the former. The following me