This research consists of two parts: first; preparation of samples and after that exposure of these samples to some physical and mechanical properties tests. The tests are done at room temperature and then with the effect of immersion in three liquids (Tap water, NaOH (0.5N), and Benzene). Also we exposed some samples to sunlight to study the effect on some properties. First we prepared five kinds of specimens, PS resin was the matrix in all kinds using a casting technique; the samples were: (PS+EP) pure blend with a weight ratio of (80%PS+20%EP), PS pure resin filled with GP once and FS once again making a composite with a volume fraction of 15%GP and 15%FS respectively. Also we prepared composites from (80%PS+20%EP) blend filled with GP once and FS once again with a volume fraction of 15% to both; all samples were prepared at room temperature. Some mechanical and physical properties were investigated by performing tests such as: (impact strength (Charpy type), bending (3-point loading system), hardness (Shore D), thermal conductivity, and diffusion behavior); these tests carried on the samples in both normal conditions (without immersion) and after immersion for a period (2-10) weeks measured every (2) weeks. The results show that at room temperature, impact strength of (PS+EP) pure blend appears to have the highest value. Composite specimens filled with FS filler show the best results in the (thermal conductivity, hardness, and bending) tests. The immersion conditions indicated remarkable effect on all the examined physical and mechanical properties, compared to un immersed samples, also the exposure to sunlight has the same effect. In case of tap water immersion, the (PS+EP) blend that filled with FS has the highest diffusion coefficient value while (PS+EP) pure blend gives the lowest value. In case of NaOH immersion, (PS+EP) pure blend showed the highest value of diffusion coefficient while (PS+EP) filled with GP showed the lowest value. Benzene shows the strongest effect on examined physical and mechanical properties also diffusion behavior, since no weight gain in any sample was observed.