Accelerated Weathering and Water Absorption Behavior of Kenaf Fiber Reinforced Acrylic Based Polyester Composites

Muhamad Saifuddin Salim,Razaina Mat Taib,Zainal Arifin Mohd Ishak,Dody Ariawan,Mohd Zharif Ahmad Thirmizir,Mohd Fadli Ahmad Rasyid

doi:10.3389/fmats.2020.00026

Muhamad Saifuddin Salim, Razaina Mat Taib + Show 4 more

Open Access

https://doi.org/10.3389/fmats.2020.00026

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Abstract

Nonwoven kenaf (KF) mat reinforced acrylic-based polyester bio-resin composites that were prepared by an impregnation process followed by compression molding. They were exposed to the durability test of accelerated weathering and water absorption. Accelerated weathering test through UV irradiation caused modification in chemical, mechanical, surface appearance and color change of the composites. Two competing reactions occurred throughout the exposure period, i.e. post crosslinking and photo-oxidation process. FTIR analysis revealed that the former occurred at the early stage of exposure while the latter towards the end of the exposure, exhibited by an accentuated increase in carbonyl and vinyl index. The post-crosslinking process contributes to the improvement in flexural properties and thermal stability of the composites, whereas the oxidation process does not. SEM observation showed that the degradation by photo-oxidation resulted in the formation of voids and blisters on composite’s sample. Water uptake of all composites was found to follow Fickian behavior. Good recoveries (exceeding 79 %) of flexural properties were obtained upon re-drying. However, a significant reduction in flexural strength and modulus was obtained in the wet state condition. SEM observation revealed that full recovery was not possible because of the impairment of the -matrix interfacial region. Relatively higher flexural properties were exhibited by alkali-treated KF composites even after the durability test due to the improved strength and –matrix adhesion following the treatment.

Highlights

The increase in environmental awareness is the vital factor that motivates many researchers to explore and develop new alternatives capable of replacing traditional polymer composite materials
By definition, natural fiber that reinforces polymer composites (NFPC) can be called green composites because the reinforcing fibers come from renewable sources
The current study analyses the effects of accelerated weathering and water absorption test of kenaf fiber (KF) reinforced Acrylic-based polyester resin with the trade name of Acrodur R

Summary

Introduction

The increase in environmental awareness is the vital factor that motivates many researchers to explore and develop new alternatives capable of replacing traditional polymer composite materials. Green composites can be defined as materials composed of, in part or wholly, constituents which come from a renewable resource (Baillie and Jayasinghe, 2004) This definition applies to the matrix and reinforcement. Compared to inorganic-mineral like glass fiber, natural fibers are less abrasive toward processing machinery and tooling, less dangerous to the production employees in case of inhalation, and easy to be incinerated. They lead to final composites with lower specific weight per strength, as well as, exhibiting thermal and acoustic insulation properties (HerreraFranco and Valadez-González, 2004)

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