Gel time prediction of polyester resin for lamination of polymer composites

C.O Ujah,A.P.I Popoola,I.C Ezema

doi:10.4314/bcse.v34i1.16

Abstract

Lamination of fibre reinforced plastics (FRP) and catalytic curing of unsaturated polyester (UP) resin were the major focus of this study. The polyester resin was cured at ambient temperature with methyl ethyl ketone peroxide (MEKP) catalyst, cobalt octoate accelerator and phenol inhibitor. This was used to generate model equations that can predict the gel time of polyester resin when curing additives are added. The gelation was obtained by stirring 20 g of catalysed UP resin weighed into a plastic container until the viscosity suddenly increased. Gel times obtained were subjected to regression analysis and analysis of variance (ANOVA) so as to obtain the best predictive model. The ANOVA result showed that the gel time (Ti) in terms of inhibitor concentration, Ti = 2820i – 6 was the best predictive equation of the gel time with a degree of accuracy of 98.89%; where i is the inhibitor concentration. In the model, catalyst and accelerator are at constant concentrations of 1% and 0.5%, respectively. The model was validated by laminating pilot components using hand lay-up technique. Thereafter, a laminating template was developed that would aid in reducing material wastes and lengthy down time during FRP lamination. This will be useful in increasing productivity and profitability in FRP small scale industry.  Bull. Chem. Soc. Ethiop. 2020, 34(1), 163-174. DOI: https://dx.doi.org/10.4314/bcse.v34i1.16

Highlights

Unsaturated polyester (UP) resin is a type of polymer referred to as thermoset that transforms from liquid to solid state when subjected to the right condition of curing [1]
Curing of polyester resin begun with gelling, which can be described as changing of the resin from liquid to semi solid or paste form
Lamination of fibre reinforced plastics (FRP) should be completed before gelling commences [1]

Summary

Introduction

Unsaturated polyester (UP) resin is a type of polymer referred to as thermoset that transforms from liquid to solid state when subjected to the right condition of curing [1]. This curing condition can either be by adding heat or curing additives. Styrene monomer is usually added to it to reduce its viscosity, improve its handle ability and facilitate its curability by cross-linking its molecular chains [2]. The styrene monomer gets attached to the reactive C* site

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