In the present contribution, the tensile, flexural, vibration and damping properties of intraply aramid/carbon fiber reinforced epoxy composite with the effect of clay nanoparticles inclusion have been investigated. Seven clay nanoparticles contents of 0, 1, 2, 4, 6, 8, and 10 wt% were used to produce the composite laminates. The samples were produced and experimented in accordance with ASTM standards. The standards ASTM D 638, ASTM D 790, and ASTM E756 were used for tensile, flexural, and vibration tests, respectively. Vibration characteristics were calculated using experimental modal analysis. Half power band‐width method was applied to evaluate damping responses of first natural frequency modes of the composite samples. The results indicated that the high improvement of tensile and flexural strength was obtained at clay nanoparticle contents of 1 and 2 wt% with increment of 13.1% and 28.2%, respectively. The highest values of natural frequency, storage modulus, lost modulus were obtained at clay nanoparticle contents of 10, 1, and 2 wt% with increments of 23.4%, 20.7%, and 11.6%, respectively.

Polymer composites of Polyvinyl chloride (PVC) were loaded up with micro and nano PbO/CuO particles. The added percentage of each by mass was [10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.%] plus 40 wt.% of mixed composite (20 wt.% CuO+ 20 wt.% PbO). The mass and linear attenuation coefficients of the investigated composites were measured as a function of ?-ray energies going from 59.53 keV to 1408.01 keV utilizing standard radioactive point sources. To confirm the validity of these results the attenuation coefficients for bulk composites (PVC+PbO and PVC+CuO) were calculated by using XCOM software. The results were in good agreement with the values obtained from experimental work. On comparing the attenuation coefficients of the different composites it was found that those loaded with either nano PbO or CuO have higher values than those loaded with bulk sizes with the same percentage. Also, samples loaded with nano PbO have the highest attenuation coefficients even on comparing with (20 wt.% CuO+ 20 wt.% PbO), especially in the energy region below 1 MeV, but for greater energies, the values become very closed. The investigation of the mechanical properties of such composites due to the injection of bulk and nano metals reveals that tensile strength and Young?s modulus of PVC nanocomposite sheets were notably increased with the increasing concentration of CuO and PbO nanoparticles. CuO nanocomposite showed the highest values of flexural strength, toughness, and tensile strength among all the fabricated nanocomposite sheets.