Polypropylene hybrid composites were made using silica and white rice husk ash (WRHA) fillers as reinforcing agents in the polypropylene (PP) matrix. Both fillers were used at the similar total filler loading i.e., 40% by weight of PP matrix. Results indicate that the increasing loading of WRHA in silica/WRHA weight ratio has increased the flexural modulus and tensile modulus but decrease the tensile strength, stress at yield, elongation at break, Eb and water absorption of PP/silica/WRHA hybrid composites. Degradation study shows that percentage loss of above properties increases with increasing the loading of WRHA in silica/WRHA weight ratio of composites. Scanning electron microscopy (SEM) of tensile fracture surfaces of composites indicates that silica has better adhesion with PP matrix compared to WRHA.
In this paper, we proposed an efficient method for manufacturing water-soluble polyimide (PI)sized carbon fiber (CF) reinforced poly (ether ether ketone) (PEEK) composites with excellent mechanical and thermal properties. The PI sizing agent used in this study was synthesized by thermal imidization of prepared poly (amic acid) salt solution. The PI-sized CFs were fabricated by an optimized process that included a sizing treatment and a spreading process using a specially customized equipment. Composites containing PI-sized CFs were characterized by interfacial shear strength and glass-transition temperature according to the PI concentration on the CF surfaces. Molecular dynamics simulations show that the presence of an appropriate amount of PI sizing agent on the CF surface significantly enhances the interface compatibility of the CF/PEEK polymer composites.
This study investigated differences in the thermo-mechanical properties of thermosetting polymer EPON 826 nanocomposites reinforced by modified nanofillers. Carbon nanotubes (CNTs) were modified by environmentally friendly plasma treatments. Composites containing various nitrogen doped CNTs were investigated by morphological and structural analysis, which confirmed that they provided better dispersion and stronger interfacial interaction with the epoxy matrix. In addition, the dynamic mechanical behavior and thermal conductivity were analyzed to understand the energy transfer mechanism in the nanocomposites. The thermal and mechanical properties of the Inductively coupled plasma treated CNTs (ICP-CNT) reinforced nanocomposites containing a high concentration of quaternary and pyridinic types were higher than that of mechanical shear force plasma treated CNTs (MSF-CNT). A molecular dynamics (MD) simulation was performed to support the experimental results and confirmed that controlling the type of nitrogen doping groups was important for improving the thermo-mechanical characteristics of CNT/epoxy nanocomposites.
The effects of partial replacement of silica by white rice husk ash (WRHA) and a compatibilizer, maleic anhydride-modified polypropylene (PP) on mechanical properties, water absorption and morphology of PP/silica/WRHA hybrid composites were studied. Results show that the increasing loading of WRHA in composites has increased the flexural modulus and tensile modulus but decrease the tensile strength, stress at yield, elongation at break and water absorption. At a similar filler loading, PP/silica/WRHA hybrid composites with a compatibilizer show better mechanical properties and lower water absorption. This observation was due to better filler-matrix adhesion as a result of the compatibilizer incorporation in the composites.
2015) Liquid crystal alignment behaviours on poly(methyl methacrylate) having polyhedral oligomeric silsesquioxane groups, Liquid Crystals, 42:1, 32-40, A series of poly(methyl methacrylate) derivatives containing polyhedral oligomeric silsesquioxane (POSS) groups (MCP#) were synthesised via free radical polymerisation (FRP) using methacryl isobutyl POSS (MA-POSS) and methyl methacrylate as monomers to investigate liquid crystal (LC) alignment property of these polymer films. The LC cells made from the films of the polymers having 100 mol% of MA-POSS units (MCP100) showed vertical LC alignment having a pretilt angle of about 90°. The vertical LC alignment behaviour on the MCP100 film was ascribed to the very hydrophobic MCP100 surface having the surface energy value smaller than about 23 mJ/m 2 generated by the nonpolar bulky POSS group. Good electro-optical characteristics, such as voltage holding ratio (VHR) and residual DC voltage (R-DC), were observed for the LC cells fabricated using MCP100 as a LC alignment layer.
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