High-temperature Thermo-oxidative Aging of Vulcanized Natural Rubber Nanocomposites:Evolution of Microstructure and Mechanical Properties

The aging of natural rubber(NR)at high temperatures will seriously affect its service lifetime in many key applications.In the present work,the changes in microstructure and mechanical properties of semi-efficient vulcanized NR/carbon black(CB)vulcanizates during thermooxidative aging at high temperatures(150-200℃)and a moderate temperature(95℃)were compared.At high temperatures,a two-stage aging behavior,which was characteristic of a first rapid decline and then a continuous rise in the crosslinking density(ve),was identified and was found to be closely related to the depletion behavior of antioxidants.The surface cracking behavior observed in the second stage of high-temperature aging was discussed in terms of the grafting reaction of macromolecular radicals on CB particles and thermal expansion.In contrast,the aging of NR at moderate temperatures was much mild,which featured a continuous increase in ve and an oxidation mechanism dominated by peroxy radicals attacking double bonds.In general,the mechanical properties of NR vulcanizates during high-temperature aging depended on the competition effects of structural evolution in the crosslinked network and oxidation-induced chain scission.

Study of Nanoskin ECM-Bacterial Cellulose Wound Healing/United Arab Emirates

Natural extracellular matrices (ECMs) perform the tasks necessary for tissue formation, maintenance, regulation and function, providing a powerful means of controlling the biological performance of regenerative materials. In addition, biomedical materials have claimed attention because of the increased interest in tissue engineering materials for wound care and regenerative medicine. Moreover, the nanostructure and morphological similarities with collagen make BC attractive for cell immobilization, cell support and Natural Extracellular Matrix (ECM) Scaffolds. In this work, we present the extracellular matrix (ECM) using the bacterial cellulose (Nanoskin®) which regulates cell behavior by influencing cell proliferation, survival, shape, migration and differentiation. Bacterial cellulose fermentation process is modified before the bacteria are inoculated for mimicking ECM to cells support and built new local material for wound healing. Chemical groups influences and thermal behavior in bacterial cellulose were analyzed using transmission infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. Besides, In vivo analysis was evaluated with clinical study at Sharjah Kuwait Hospital.

Special Nanoskin-ACT-Biological Membranes from Deep Wounds

Bacterial cellulose (BC) is established as a newest biomaterial, and it can be used for medical and odontology applications. In addition, it has called attention for uses such as membrane for wound care and tissue engineering. In this work, the bacterial cellulose fermentation process is modified by the addition of natural materials before the bacteria are inoculated. In vivo behavior using natural ECM for regenerative medicine is presented and completed wound healing process is 3 months.

Synergistic effect of chitin nanofibers and polyacrylamide on electrochemical performance of their ternary composite with polypyrrole

Development of simple methods for preparation of polymeric electrode materials with nanofibrous network structure is a perspective way toward cheap supercapacitors with high specific capacitance and energy density. In this work one-pot synthesis of electroactive ternary composite based on polypyrrole, polyacrylamide and chitin nanofibers with beneficial morphology was elaborated. Ternary system demonstrates better electrochemical performance in comparison with both polypyrrole–polyacrylamide and polypyrrole–chitin binary composites. Possible mechanism of synergistic effect of simultaneous influence of polyacrylamide and chitin nanofibers on the formation of composite＇s structure is discussed.The highest attained specific capacitance of electroactive polypyrrole in ternary composite reached 249 F/g at 0.5 A/g and 150 F/g at 32 A/g. Symmetrical supercapacitor was assembled using the elaborated electrode material. High specific capacitance 89 F/g and good cycling stability with capacitance retention of 90% after 3000 cycles at 2 A/g were measured.