Comparative Study of Aromatic and Cycloaliphatic Isocyanate Effects on Physico-Chemical Properties of Bio-Based Polyurethane Acrylate Coatings.

Nurul Huda Mudri,Marwah Rayung,Min Min Aung,Dayang Radiah Awang Biak,Luqman Chuah Abdullah,Mek Zah Salleh

doi:10.3390/polym12071494

Nurul Huda Mudri, Marwah Rayung + Show 4 more

Open Access

https://doi.org/10.3390/polym12071494

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Journal: Polymers	Publication Date: Jul 3, 2020
Citations: 21	License type: CC BY 4.0

Affiliation: Universiti Putra Malaysia, Malaysian Nuclear Agency

Abstract

Crude jatropha oil (JO) was modified to form jatropha oil-based polyol (JOL) via two steps in a chemical reaction known as epoxidation and hydroxylation. JOL was then reacted with isocyanates to produce JO-based polyurethane resin. In this study, two types of isocyanates, 2,4-toluene diisocyanate (2,4-TDI) and isophorone diisocyanate (IPDI) were introduced to produce JPUA-TDI and JPUA-IPDI respectively. 2,4-TDI is categorised as an aromatic isocyanate whilst IPDI is known as a cycloaliphatic isocyanate. Both JPUA-TDI and JPUA-IPDI were then end-capped by the acrylate functional group of 2-hydroxyethyl methacrylate (HEMA). The effects of that isocyanate structure were investigated for their physico, chemical and thermal properties. The changes of the functional groups during each synthesis step were monitored by FTIR analysis. The appearance of urethane peaks was observed at 1532 cm−1, 1718 cm−1 and 3369 cm−1 while acrylate peaks were detected at 815 cm−1 and 1663 cm−1 indicating that JPUA was successfully synthesised. It was found that the molar mass of JPUA-TDI was doubled compared to JPUA-IPDI. Each resin showed a similar degradation pattern analysed by thermal gravimetric analysis (TGA). For the mechanical properties, the JPUA-IPDI-based coating formulation exhibited a higher hardness value but poor adhesion compared to the JPUA-TDI-based coating formulation. Both types of jatropha-based polyurethane acrylate may potentially be used in an ultraviolet (UV) curing system specifically for clear coat surface applications to replace dependency on petroleum-based chemicals.

Highlights

Polyurethane (PUR) is a versatile resin that can be used for various applications such as coatings, adhesives, sealants and elastomers
Two varieties of Jatropha oil-based polyurethane acrylate (JPUA) based on Toluene diisocyanates (TDI) and isophorone diisocyanate (IPDI) isocyanates have been successfully synthesised
JPUA-TDI had a higher viscosity and molar mass with a broad polydispersity index (PDI) value compared to JPUA-IPDI resin

Summary

Introduction

Polyurethane (PUR) is a versatile resin that can be used for various applications such as coatings, adhesives, sealants and elastomers. PUR is synthesised by reaction of polyols with isocyanates. Polymers 2020, 12, 1494 at a specific controlled temperature and reaction speed in a nitrogen purged system. Most of the polyols that are used in synthesising PUR are derived from petroleum and natural gas sources [1,2]. As non-renewable sources, petrochemical resins are facing issues with supply shortages and worldwide price fluctuations. The processing of these chemicals may release greenhouse gases that are harmful to the environment, leading to global warming. Usage of low toxic natural-based polymeric materials has been proposed to replace the dependency on petroleum-based chemicals in order to achieve sustainable development [3,4]

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