Environmentally friendly epoxy and alkyd coatings derived from natural rubber / Yong Ming Yee

Yong , Ming Yee (2022) Environmentally friendly epoxy and alkyd coatings derived from natural rubber / Yong Ming Yee. PhD thesis, Universiti Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (152Kb)
	PDF (Thesis PhD) Download (3930Kb)

Abstract

Environmentally friendly coatings are gaining more attention following the growing concern on the threat of environmental pollutions, as well as the depleting fossil resources that have been exploited to produce surface coating resins and additives for the coating industry. One of the approaches to produce environmentally friendly products is to reduce the dependency on petroleum-derived resources in the coating production. In this work, epoxidized natural rubber was utilised to produce epoxy coatings and alkyd coatings. The epoxidized natural rubber was subjected to UV treatment to reduce molecular weight and subsequently improve its solubility in a wide range of solvents. UV-degraded epoxidized natural rubber (UV-ENR25) was characterized with spectroscopies (FTIR and NMR) and gel permeation chromatography, GPC to confirm the reduction in molecular weight, while retaining its epoxide content. Rubber-based epoxy coatings were produced using two different types of hardeners. The first hardener was pentaerythritol tetra (3-mercaptopropionate) which is a common crosslinking agent used in epoxy coating. The second hardener utilised was naturally-sourced tannic acid. The film properties and thermal stability of both epoxy coatings were investigated using series of test methods comprising of physical, chemical, and thermal analyses. Both coatings, UV-ENR25/PETMP and UV-ENR25/tannic acid showed satisfactory coating properties, comparable to some of the reported petroleum derived epoxy coatings. One of the highlights is the focus on the biodegradability of UV-ENR25/tannic acid coating. Owing to the high natural content in UV-ENR25/tannic acid coatings, the coatings exhibited improved extent of biodegradation compared to the commercially available petroleum-derived epoxy coatings. Liquid epoxidized natural rubber was also utilized in alkyd resin synthesis. It served as a polyol in the synthesis and the effect of incorporating the rubber in alkyd synthesis was thoroughly evaluated. The liquid epoxidized rubber was introduced into the alkyd cook during the polyesterification step, for it to serve as polyol and react with polycarboxylic acid. The film properties and thermal stability of the resultant alkyd coatings were investigated using series of standard test methods, as well as chemical and thermal analyses. The results obtained suggest that the properties of alkyd coatings derived using rubber in the formulation was comparable to the control alkyd which was produced purely from the conventional polyol such as glycerol. The integration of rubber into the synthesis offered equivalent in majority and even improvement in some of the coating properties such as film hardness and film adhesion. In summary, natural rubber derivatives could be used as a sustainable raw material in the synthesis of surface coating resin, and the properties of the coatings could match those produced from petrochemical derivatives.

Actions (For repository staff only : Login required)