Papers by Keyword: Polymer-Matrix Composites

Abstract: In recent years, polymer/ceramic composites with high thermal conductivity have been widely used in microelectronic devices, superconducting magnets and aviation, and further improving their thermal conductivity is a great challenge. In this work, spherical alumina nanoparticles were modified with 3-aminopropyltriethoxy-silane (APTES) successfully. Furthermore, the modified Al₂O₃(M-Al₂O₃)/Epoxy(EP) and Graphene(Gr)/M-Al₂O₃/EP composites were prepared and their properties were tested in the temperature range of 70 K-300 K. The results showed that the thermal conductivity of the composite with 1 wt% Gr and 60 wt% M-Al₂O₃ hybrid filler is 15 times higher than that of pure epoxy at 70 K, which indicates its application prospect in thermal interface materials.

Abstract: The photoelastic effect was used to visualize and quantify stresses at the end of fibers embedded in birefringent epoxy resin. A method was proposed allowing not to only quantify the differences in main principal stress for a single loading state, but to allow monitoring the evolution of local stress throughout the micro-mechanical experiment. It was found that the ends of fibers foster the formation of shear stresses which influence the principal stress distribution. Typically, star-shaped principal stress distributions were found at the ends of fibers. Finite Element simulations of the tests were in good agreement with the experimental evidence.

Abstract: Polyaniline-Zr(IV) tungstovanadate and Polyaniline-Zirconium oxide nanocomposite ion -exchangers were synthesized and physico-chemical characterization done by FT-IR-UV spectral studies, XRD, SEM and TGA. These composites are having high mechanical strength, good electrical conductivity and stability than their individual components. The organic polymeric component of the composites provides mechanical as well as chemical stability whereas the inorganic component supports the ion-exchange behavior and thermal stability. Both the inorganic and organic parts are jointly responsible for their improved electrical conductivity. They have more promising ion exchange capacity towards alkali metal halides and have selective adsorption towards Pb(II) ion and these can be used as powerful candidates for water softening

Abstract: The delamination and fibers pull out have been the main factors failure application of natural fibers in various engineering fields. To address these problems, particles reinforced composites are the promising candidate. The present paper investigates on vegetal particles (date palm seed particles/DPSp) and applies it as composites material reinforced unsaturated polyester (USP). The influence of alkali treatment on the surface morphology and structure of DPSp was investigated. They investigated by SEM and Energy Dispersive Spectroscopy (EDS) mapping. The water absorption results showed directly proportion with the particles loading as the relative increases were 0.645% and 7.345% for 10 wt% and 40 wt% of DPSp content, respectively. In addition, the water absorption ability of the composites showed low value comparing with many natural fibers. In addition, the fracture toughness of the composites was studied. Overall, addition of the proposed DPSp particles may be opens a new avenue to exploit the utilized natural cheap material to produce a green composite.

Abstract: 0-3 nanocomposites of PVDF with varying volume percents of strontium doped PZT have been synthesized using a combination of a modified solution casting process and the hot press technique. The nanocrystalline PZT used prepared from the sol gel route and was in the calcined state. An increase in the volume percent of PZT caused an increase in the dielectric constant, dielectric loss and piezoelectric charge coefficients. The experimental dielectric constants gave a perfect fit to the theoretical Furukawa model. However, no significant trend is perceived for the dielectric loss. SEM and XRD aided in determining the morphology and the crystalline phases in PVDF, PZT and PVDF/PZT composite. TG/DSC was done to confirm the percentage crystallinity of PVDF. A comparison with samples prepared from the conventional solution casting process has also been given. Composites prepared from the modified solution casting process using nanocrystalline strontium doped PZT give better piezoelectric properties as compared to earlier works.

Abstract: With the increased use of carbon fiber reinforced polymer (CFRP) composites in civil infrastructure, understanding the fire structural performance of these materials is an important safety issue. In this paper, the effect of temperature on the tensile strength of carbon fibers and carbon/epoxy composite sheets was experimentally determined from 20°C to 500°C. Meanwhile, in order to better understand the strength degradation of carbon fiber-polymer composites at elevated and high temperatures, the tension tests were also performed for pure epoxy resin and CFRP sheets by means of 10°C off-axis at the range of 20-80°C, respectively. The experimental results reveal that the strength decrease of carbon composites under tensile loading at elevated and high temperatures is dependent on both thermal softening of the epoxy polymer matrix and thermally-activated weakening of the fibers. The reduction in strength of carbon fiber is attributed to oxidation of the high strength grapheme layer at the near-surface fiber region.