نوع مقاله : تالیفی
نویسندگان
1 پژوهشگاه پلیمر و پتروشیمی ایران
2 عضو هیئت علمی / پژوهشگاه پلیمر و پتروشیمی ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
B ased on thermal behavior, polymers are divided into two main categories: thermoplastics and thermosets. Vitrimers are a new class of polymers that simultaneously have the desired mechanical/chemical properties of thermosets and the
reprocessability of thermoplastics. They are covalent networks that can change their topology through reversible bond exchange reactions. The viscoelastic behavior of vitrimers is described using two transition temperatures. The first one is the usual glass transition temperature, Tg, between the glassy and rubbery states of polymer networks. The second
transition temperature is derived from the cross-link exchange reactions of the network, where the transition from viscoelastic solid to viscoelastic liquid occurs at a temperature denoted as the topology freezing transition temperature. When vitrimers are heated above the topology freezing transition temperature, they can flow slightly like thermoplastics.
In this state, the total crosslink density remains constant, but the rate of bond exchange increases with temperature. This leads to a gradual decrease in viscosity with temperature, which differs from the relatively abrupt drop in viscosity associated at the melting transition of thermoplastic materials. Based on the their viscoelastic behavior, vitrimers are capable to provide unique properties such as repairing, reshaping, and recycling. However, these materials also experience limitations such as low scalability, high cost, and low mechanical properties. In this paper, after explaining the above-mentioned issues, two applications of vitrimers in the preparation of reversible adhesives and durable prepregs are investigated.
کلیدواژهها [English]
1790-1799, 2017.
2017.