Generally, polymers can be classified according to their thermal and mechanical properties into thermoplastics, thermosets and elastomers. Thermoplastics are amorphous or semicrystalline polymers that soft or melt during heating and solidify during cooling. The heating/cooling/heating process can be repeated without perceptible changes in thermal and mechanical properties of thermoplastics. The...

Humans are exposed to ethylenebisdithiocarbamates (EBDCs) from environmental sources. Exposure to EBDCs is chronic for workers in a variety of industries, where EBDCs are used for their properties as slimicides, vulcanization accelerators, antioxidants, and scavengers in waste-water treatment. EBDCs, and particularly the EBDC metabolite ethylenethiourea, have clearly defined, important toxic ef...

BACKGROUND Colour degradation is a major problem in maxillofacial silicone elastomers. Recent studies have focused on colour stability and the mechanical properties of the silicone elastomers. A colour match is also essential for the acceptance of the prosthesis by the patient. The aim of this study is to assess the colour degradation of the silicone elastomer after being moulded in different c...

in some special cases, rubber compounds with high amounts of unsaturated elastomer are recommended with organic sulfur donors instead of mineral sulfurs. in this condition, activated sulfur is produced in situ and curingprocess is facilitated without accelerators. organic sulfur donor compounds have low thermal stability and in the vulcanization temperature produce free and activated sulfurs. t...