Accelerated weathering effects on mechanical, thermal and viscoelastic properties of kenaf/pineapple biocomposite laminates for load bearing structural applications

Abstract

Natural fibers are exceptional renewable resources to develop biocomposite materials for reducing the negative effects on the environment and producing economical and lightweight materials for load bearing semi‐structural applications. The present study is an attempt to develop kenaf/pineapple reinforced bio‐epoxy biocomposite and investigates thermo‐mechanical and viscoelastic properties under accelerated weathering conditions. The compression molding technique is used to develop biocomposite with four different arrangements of kenaf/pineapple laminates. To perform accelerated weathering, laminates are exposed to ultraviolet radiation and humidity conditions with extreme temperature in weathering tester machine. The tensile, flexural, impact, thermogravimetric analysis, thermal conductivity, viscoelastic properties, and water absorption tests are performed before and after accelerated weathering. The results revealed that the hybridization of kenaf/pineapple laminates showed better interfacial strength and stiffness while reducing the moisture sensitivity under accelerated weathering conditions. The morphology and fracture behavior of biocomposites are examined with scanning electron microscopy.

Simplified cooperative viscoplasticity theory based on overstress model for nanocomposites

“…Storage modulus initially showed a slight drop as the temperature increased, and then a rapid drop in the glass transition region. Similar behaviors and results are observed in studies in the literature 55–57 . While the storage modulus of pure epoxy at room temperature is 2.5 GPa, the storage modulus of nanocomposites with content 0.1 and 0.5% f‐GNF is 3.3 and 3.8 GPa, respectively.…”

“…For this purpose, first, the storage modulus of pure epoxy and 0.1 and 0.5 wt.% f‐GNF‐epoxy nanocomposite are determined experimentally and simulated with simplified C‐VBO. In DMA tests, the storage modulus (E') is a measure of the elastic response of polymer and GP nanocomposites and the material stiffness represented by the energy absorbed per cycle oscillation 55 . The storage modulus of graphene‐epoxy nanocomposites with different graphene contents were determined experimentally at a frequency of 1 Hz.…”

“…In DMA tests, the storage modulus (E') is a measure of the elastic response of polymer and GP nanocomposites and the material stiffness represented by the energy absorbed per cycle oscillation. 55 The storage modulus of graphene-epoxy nanocomposites with different graphene contents were determined experimentally at a frequency of 1 Hz. During the DMA test, a wide temperature range between 25 C and 250 C at a heating rate of 5 C min À1 and an oscillation strain of 0.05% was defined for the device and the samples were tested in these temperature ranges.…”

“…Similar behaviors and results are observed in studies in the literature. [55][56][57] While the storage modulus of pure epoxy at room temperature is 2.5 GPa, the storage modulus of nanocomposites with content 0.1 and 0.5% f-GNF is 3.3 and 3.8 GPa, respectively. By adding 0.1 and 0.5 wt.% f-GNF to pure epoxy, molecular mobilization of epoxy chains was prevented, a better resistance was created and an increase of 32% and 52%, respectively, was observed in the storage modulus.…”

Poly(phosphorus‐silicon‐alkyne): Widening the application potential in epoxy resin with excellent flame retardancy, mechanical property, and unimpaired thermal stability

“…43 Compared with pure EP, the viscoelastic properties of EP/PPSA are enhanced due to the higher strength and stiffness of PPSA, which would result in higher energy dissipation. [44][45][46][47] Tan δ is decided by the adhesion between EP and PPSA, which in turn depends on temperature. It can be found that the peak of tan δ decreases with increased ratio of PPSA, suggesting a reduction of T g induced by PPSA incorporation.…”