Cross-Linkable Epoxidized Maleinated Castor Oil: A Renewable Resin Alternative to Unsaturated Polyesters

Yeşim Müge Şahin,Sinan Şen,Emre Tekay,Gökhan Çaylı,Jesmi Çavuşoğlu

doi:10.1155/2016/5781035

Abstract

As an alternative resin to conventional synthetic unsaturated polyesters (UPEs), epoxidized maleinated castor oil (EMACO) was synthesized in two steps. For this purpose, castor oil was reacted with maleic anhydride at 70°C to obtain maleinated castor oil (MACO). Then, epoxidation of MACO was carried out by using a mixture of formic acid and hydrogen peroxide at 0–5°C. Then, the free carboxyl groups of the synthesized EMACO were further reacted with free epoxide groups of EMACO at 90°C. At the end of the reaction, an unsaturated polyester precursor-prepolymer was obtained (P-EMACO). FTIR and1H NMR spectroscopic techniques were used to characterize the monomers synthesized. The P-EMACO was then mixed with styrene and cross-linked in the presence of AIBN at 50°C. Thermal and mechanical properties of the final cross-linked product were investigated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) techniques. The degradation onset temperature of the material at which cross-linked X-EMACO loses 5% of its weight was found to be 209°C. Its dynamicTgand storage modulus at 25°C were determined as 72°C and 1.08 GPa, respectively. These results are higher than some of the different oil based polymers reported in the literature.

Highlights

Unsaturated polyesters (UPEs) are one of the most versatile and important liquid casting resins
In addition to undesired high energy requirement in the UPE synthesis, the abovementioned main components of these resins are almost derived from petroleum sources
Due to the depletion of petroleum reserves and environmental concerns, synthesis of alternative materials from renewable resources can be thought to be an alternative method to the synthetic one

Summary

Introduction

Unsaturated polyesters (UPEs) are one of the most versatile and important liquid casting resins. They are produced by the reaction between dibasic acids or anhydrides with glycols. For UPE production, phthalic and maleic anhydrides or their free acids are the mostly used anhydrides and ethylene glycol and propylene glycols are typically used glycols. During the production of UPEs, starting temperature is typically around 100∘C and the temperature is raised to 180–240∘C for 16–20 hours [1,2,3,4,5]. In addition to undesired high energy requirement in the UPE synthesis, the abovementioned main components of these resins are almost derived from petroleum sources. Due to the depletion of petroleum reserves and environmental concerns, synthesis of alternative materials from renewable resources can be thought to be an alternative method to the synthetic one

Methods

Results

Conclusion