Thermal and mechanical properties of nanostructured bio-based epoxies by amphiphilic copolymer determined at local scale

Beginning: January 2017

Abstract

In recent years, polymer materials derived from sustainable resources, usually called bio-based polymers have drawn more and more attention as environmental friendly alternatives to replace the petrochemical based feedstocks for sustainable development. Moreover, more and more drastic government regulations on toxicity force industries to explore ecofriendly substitutes to petroleum based resources. Especially, epoxies faces great challenge because of the classification of bisphenol A (the most important precursors of epoxies) as carcinogen, mutagen and reprotoxic (CMR) substance. This provides great opportunity to develop biobased epoxy resins. Mainly studies of bio-based epoxy resins has been done with vegetable oils because of its low price. The main drawback of these bio-resins to replace DGEBA is its glass transition temperature (T_g), lower than 0°C for high content. Therefore, mixture of vegetable oils and linear bio-epoxy to create interpenetrated polymers network (IPN) is a way to increase T_g and modulate the mechanical properties. The toughness of the epoxy can be improved by the incorporation of a second phase like block copolymers (BCP). Depending on the type of hardeners and curing conditions, micro and nanostructures will be observed in BCP modified epoxies resins. Amphiphilic block copolymer like PPO-PEO-PPO are a good toughening candidate.
No systematic studies has been done on the cure behavior, thermomechanical properties of the IPN-BCP. Moreover, differents AFM modes are now available to estimate local apparent Young modulus or T_g at nanoscale.
The main objectives of this study is to evaluate in one hand the curing conditions of micro-nanophase separations in a complex system composed of bio-epoxies mixtures cured with amines and BCP. On the other hand, the main is goal is to develop relationships between the network morphologies and thermo-mechanical properties of BCP-IPN network at nanoscale, focus on the different phases of the nanostructured network.