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Different composites were prepared from natural rubber/styrene butadiene rubber blends (50/50) using fixed 40 wt% content of silica, high-abrasion furnace carbon black, clay and titanium dioxide. The obtained composites were vulcanized using gamma irradiation up to 250 kilogray. The effect of fillers and irradiation dose on the mechanical properties such as tensile strength, tensile modulus at 100% elongation, elongation at break and hardness have been investigated. The %gel content and swelling number as physical properties, scanning electron microscope have been carried out as a function of absorbed dose for the blend and composites. The nature and particle size of filler and irradiation dose have a great effect on the mechanical properties. All studied properties of filled blend were enhanced; the reinforcing ability of the filler increased in the order of Hisil > high-abrasion furnace carbon black > clay > titanium dioxide. Scanning electron microscope studies of filled blend and unfilled blend have been carried out. The variation in properties was correlated with the morphology of the system.

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Chicken eggshell powder (ESP) as natural source of CaCO3 was incorporated as natural filler into High Density Polyethylene (HDPE).This natural source can be considered as an effective alternative for the commercial calcium carbonate (CC) filler. Characterization of ESP and CC was investigated by FTIR and XRD analysis. HDPE composites filled with 30 phr (ESP) and (CC) were prepared using internal mixer. 2 phr maleic anhydride (MA) was added as compatibilizing agent to HDPE/ESP composite. The prepared composites were vulcanized by using γ-radiation at doses from 50 to 150 kGy. Mechanical and flame retardancy properties of all composites were investigated; composites were thermally analyzed using TGA and DSC. The results showed that, the mechanical properties of HDPE decrease by incorporation of ESP or CC into it, as it was noticed that the mechanical properties of HDPE/ESP composite were better than the mechanical properties of HDPE/CC composite. Moreover, addition of MA led to improvement in mechanical properties of the HDPE/ESP composite. As well, the thermal stability and flame retardancy of the composites increased by adding ESP or CC to HDPE. The results were proved by scanning electron microscopy (SEM).

Composites from ethylene propylene diene monomer (EPDM) rubber filled with different concentrations 20, 40, and 60 parts per hundred rubber (phr) of aluminum oxide (Al2O3) were prepared. The samples were vulcanized by gamma irradiation at doses of 50, 100, 150, and 200 kGy. The effects of irradiation doses and Al2O3 contents on the mechanical properties (particularly tensile strength, elongation at break % and hardness), physical properties (volume fraction and crosslinking density) and thermal properties were studied by thermogravimetric analysis (TGA). The fire resistance was tested using Limiting Oxygen Index (LOI) and rate of burning methods of EPDM and its composites were studied. The results indicated that the improvement of mechanical as well as, physical properties occurred by increasing the concentration of Al2O3 (except the tensile strength values, where the highest values were obtained at concentration 20 phr Al2O3 in the composite irradiated at 100 kGy). The thermal stability and fire retardancy properties of the prepared composites were improved by increasing Al2O3 concentration. Generally, the addition of Al2O3 and gamma irradiation has improved the composite's performance. This method is suitable for preparing products of rubber serving in dynamic conditions, with longer expected service life.

Lichen Planus (LP) is a common T cell-mediated chronic inflammatory disease affecting skin & or mucous membranes. Also, T cellinduced autophagy is involved in the immunopathogenesis of the oral type of lichen planus (OLP). Beclin-1 is an autophagy marker with a critical role in the autophagic process. Heat shock proteins (HSP) synthesis increases in response to many stressors being the molecular chaperones. HSP has an important role in the Endoplasmic reticulum stress (ER stress) process. HSPs are assumed to be involved in the initiation and probably continuation of lichen planus through the autoimmune lymphocytic response. GRP78 (Glucose-regulated protein 78) is one of the HSPs that may play a substantial role in LP. ATF6 (activated transcription factor6) is one of ER stress pathway sensors that may link ER stress and autophagy. The study was conducted on 40 lichen planus patients and 20 healthy control subjects. GRP78, ATF6 and Beclin-1 gene expressions were estimated by real-time PCR. Patients with oral and cutaneous lichen planus showed a significant increase in GRP78, ATF6 and Beclin-1 compared to the normal control group. Conclusion; the results conduct an increase in autophagy and endoplasmic reticulum stress markers with lichen planus which may represent an inductive or protective mechanism for lichen planus.