Liquid Rubbers as Toughening Agents

Abstract

IntroductionToughness, the resistance of the materials to crack propagation, is one of the most important properties for materials intended for load-bearing applications. Thermoset materials such as epoxy and unsaturated polyester resins need to be modified with elastomeric materials to improve their properties. Blending thermosets resin with liquid rubber leads to a randomly dispersed rubber phase in the material and creates high dissipation energy for impact failures. Our focus is to discuss the use of liquid rubber from NR as a toughening agent in thermosets resin. The major advantage of natural rubber, which makes it dominant in many engineering applications, is its dynamic performance. NR has also properties which are attractive for toughening purposes such as low glass-transition temperature (T g ), high molecular weight, and high tear. Toughening of Thermoset ResinsMost of the thermoset resins developed over the past decade have been largely used as matrices in fiber-reinforced composites for aerospace industries. These resins are capable of withstanding elevated temperature applications via increasing rigidity and/or cross-link density of their networks. However, in almost every case, the same network that provides the high-temperature properties also inhibits molecular flow, thus rendering the material low in toughness [1,2]. Thus, it is necessary to enhance their fracture properties without sacrificing other mechanical properties.The commonly known approaches for toughening brittle thermosets include chemical modification of a given rigid thermoset backbone to a more flexible backbone structure, increasing thermoset molecular weight, lowering the crosslink density of the cured resin via use of low-functionality curing agents, and

Pengoptimuman Parameter untuk Penurunan Diimida Getah Asli Cecair dalam Sistem Hidrazin Hidrat/Hidrogen Peroksida Menggunakan Kaedah Rangsangan Permukaan (RSM)

“…LNR telah disediakan dengan menggunakan kaedah degradasi LNR bersama fotopemeka (Kargarzadeh et al 2014;Tahir et al 2017). 1 kg NR yang telah dipotong kepada saiz kecil direndam dalam pelarut toluena selama semalaman.…”

Comparison of thermoset soy protein resin toughening by natural rubber and epoxidized natural rubber

“…Natural rubber (NR) enjoys several advantages such as biodegradability and biocompatibility along with specific mechanical properties including high resilience, good tensile strength and tear resistance . The backbone of NR holds numerous noncollinear single covalent bonds about which rapid rotation is possible . NR also has properties which are attractive for toughening purposes such as low glass‐transition temperature ( T g ) of about −65 °C, high molecular weight and high tear strength .…”

“…The backbone of NR holds numerous noncollinear single covalent bonds about which rapid rotation is possible . NR also has properties which are attractive for toughening purposes such as low glass‐transition temperature ( T g ) of about −65 °C, high molecular weight and high tear strength . The flexible bonds and low T g make NR extremely flexible, even at room temperature.…”

“…Another disadvantage is its poor miscibility in various resins. Initially when NR is added to epoxy resin it is miscible with the resin . However, during the curing process, as the crosslinking reactions take place, NR phase separates in the resin .…”

“…Initially when NR is added to epoxy resin it is miscible with the resin . However, during the curing process, as the crosslinking reactions take place, NR phase separates in the resin . Adding rubber to the resin and uniformly dispersing it can improve the toughness of the resins.…”