Particulate polymer composites of Isophthalate based unsaturated polyester resin filled with different concentrations of lead monoxide were prepared. These composites were investigated for physical, thermal, mechanical, and gamma radiation shielding characteristics. The results of density evaluation, microscopic studies, and the radiation shielding properties for gamma rays of energy 0.662 MeV from Cs-137 point source have been presented in this article. The results show that, the density of the composites was observed to increase with filler loading. The morphological analysis of the composites made using the scanning electron microscope showed that, the lead monoxide particles were observed to disperse uniformly in the polymer matrix with an average inter particle distance of about 10 lm and an average size of about 5.36 lm. The linear attenuation coefficient of the composites was found to increase with increased filler content in the composites. The highest value of 0.206 cm
À1was found for 50 wt % of lead monoxide. These composites were observed to exhibit excellent % of heaviness and Half value layer in comparison with other conventional materials.
Particulate polymer composites of Isophthalate based unsaturated polyester resin filled with different concentrations of lead monoxide were prepared and investigated for physical, thermal, mechanical, and gamma radiation shielding characteristics. The results of thermomechanical studies have been discussed in this article. The composites were investigated to understand the effect of filler on glass transition temperature (T g ) and thermal expansion coefficients (a) at various temperatures under cyclic heating and cooling conditions. The results show that T g values of composites appear to decrease slightly with increasing filler content. The composites were observed to exhibit three phases of thermal expansion during first heating and cooling cycles where as they exhibit only two phases during second heating cycle. An anomalous expansion of the composites was observed in the temperature range from 60 C to 110 C only during first heating and it disappears in subsequent heating cycles. Further, all the composites were observed to exhibit a dimensional contraction only during first heating and cooling cycles. The cyclic heating and cooling technique using thermo-mechanical analyzer was observed to be very efficient in determining actual values of T g and also in determining the post curing temperatures of the polymer and its composites.
The influence of polypropylene fibers on the thermal degradation of epoxy composites was investigated with thermogravimetric analysis. Three composites with 5, 10, or 15 wt % polypropylene fibers were prepared with epoxy as a matrix material. The polypropylene fibers, used as reinforcing materials, retarded the thermal decomposition, and increasing the weight percentage of the fiber material increased the thermal stability to a certain extent. Of the three composites, the 10 wt % polypropylene fiber/epoxy resin composite showed very good thermal stability, which was indicated by the increase in the resin decomposition temperature from 2808C for the 5 wt % polypropylene fiber/ epoxy resin composite to 3758C for the 10 wt % polypropylene fiber/epoxy resin composite. The Horowitz-Metzger method was used to calculate the activation energies, and the results were tabulated. A morphological analysis was carried out with scanning electron microscopy to evaluate the dispersion of the fibers in the epoxy matrix.
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