Wen Shyang Chow

Accelerated Weathering on Glass Fiber/ Epoxy/ Organo-Montmorillonite Nanocomposites

The glass fiber/epoxy composites with different loading of organo-montmorillonite (OMMT) were prepared using the hand lay-up technique. The effects of OMMT loading on the mechanical and morphological properties of glass fiber/epoxy/OMMT nanocomposites have been investigated. In this study, the effect of UV exposure on flexural properties and fracture toughness of glass fiber/ epoxy/OMMT nanocomposites has been studied using accelerated weathering test. The epoxy hybrid nanocomposites were subjected to UV radiation for 100 h. X-ray diffraction (XRD) and field emission scanning electron microscopy were performed to characterize the fractography of the glass fiber/epoxy/OMMT nanocomposites. The XRD analysis showed that glass fiber/epoxy/OMMT (1—3 wt%) exhibit exfoliated structures while glass fiber/epoxy/OMMT (4 wt%) showed intercalated structures. The retention-ability in flexural modulus and strength of epoxy hybrid nanocomposites after being subjected to accelerated weathering are considerably excellent. However, the fracture toughness of the glass fiber/epoxy/OMMT nanocomposites was reduced upon exposure to UV radiation.

Effect of Mixing Sequences on the Flexural and Morphological Properties of Epoxy/ Organo-Montmorillonite Nanocomposites

The epoxy nanocomposites were prepared by addition of Organo-montmorillonite (OMMT) varied from 0 to 10 wt%. In-situ polymerization method was used to prepare epoxy/OMMT nanocomposites by three different mixing sequence methods. Method 1 was performed by mixing OMMT with cycloaliphatic amine (curing agent) first, followed by addition of diglycidyl ether-bisphenol A (DGEBA). Method 2 was carried out by mixing the DGEBA with OMMT first, followed by addition of curing agent. In method 3, the DGEBA and curing agent were mixed first, followed by the addition of OMMT. The objective of the research is to study the effects of mixing sequences on the flexural properties and morphology of epoxy/OMMT nanocomposites. The flexural and morphological properties of epoxy/ OMMT nanocomposites were studied by flexural tests, Field Emission Scanning Electron Microscopy, and X-ray Diffraction (XRD). The flexural modulus of epoxy was improved significantly by the incorporation of OMMT. This is attributed to the reinforcement and exfoliation/intercalation of the OMMT. The flexural modulus and strength of epoxy/OMMT nanocomposites prepared by method 3 was relatively higher than that of the composites prepared by method 1 and 2. The XRD results showed the formation of exfoliated structure in the epoxy/OMMT nanocomposites. Sequence of mixing influenced the dispersion and intercalation/exfoliation of the OMMT in the epoxy matrix. Appropriate mixing sequence should be selected in order to achieve better exfoliation of OMMT and higher flexural modulus and strength of the epoxy nanaocomposites.

A study on the effects of organoclay content and compatibilizer addition on the properties of biodegradable poly(butylene succinate) nanocomposites under natural weathering

Biodegradable poly(butylene succinate)/organo-montmorillonite nanocomposites were prepared at different organo-montmorillonite loadings, using maleic anhydride-grafted poly(butylene succinate) as compatibilizer. Poly(butylene succinate) nanocomposites were exposed to outdoor natural weathering for 180 days. Weight loss and decrease in mechanical properties after weathering revealed the degradation of poly(butylene succinate). Natural weathering caused photo-oxidation on poly(butylene succinate), leading to the formation of degraded products, as manifested in Fourier transform infrared spectroscopy. Gel permeation chromatography showed a significant reduction in molecular weight after weathering. It was noted that poly(butylene succinate) nanocomposite exhibited lower degradability as compared to neat poly(butylene succinate), due to the enhanced barrier properties after the addition of organo-montmorillonite. However, the incorporation of maleic anhydride-grafted poly(butylene succinate) increased the degradability. Degree of crystallinity of poly(butylene succinate) reduced after weathering, as shown in differential scanning calorimetry. Scanning electron microscopy analysis revealed fungal and bacterial colonization on the sample surface. In addition, the isolation and identification of bacterial strain were also performed.