As previous stated, silicone rubber has become one of the most important materials in the polymer family due to its thermal stability, environmental resistance, transparency, and biocompatibility. But sometimes, the inherent good properties of the silicone rubber are not enough, hence it is necessary that the material be filled with hard particulates or fibers, with silica being the most commonly used reinforcing filler. The reinforcement depends on several factors, such as particle size, structure, and filler content . The combination of a silicon rubber matrix and the filler results in an increase in properties, mainly mechanical, but additional synergies are created which affect the physical properties of the material. If the interaction between silicone rubber and filler is not well understood, some processing problems can occur, and changes in the behavior of the silicone rubber compound can seem like a mystery. It could be thought that conventional rubbers (based on carbon and hydrogen) and silicone rubber (based on silicon and oxygen) were completely different. However, a well-known phenomenon in the former can be also found in silicone rubber, and it is called bound rubber.
The rise of the medical and pharmaceutical industries, has led to the development of products designed to reduce human suffering and prolong life. Over several decades, materials such as metals, ceramics and polymers have been used to produce devices created to improve the health and quality of life. The biomaterials used are typically polymers, natural rubbers, polyurethanes, and silicone rubbers. Although the use of natural rubber can cause allergic reactions in some individuals, in general polymers can be “designed” according to the specific biomedical application and with special characteristics .
When injection molding Liquid Silicone Rubber certain problems can occur that directly affect the quality of the final product, in spite of the great planning that may have gone into material selection, machine, process, and the processing parameters. If these issues are not controlled promptly and properly, they could end up resulting in damage to the machine, mold, and finished product.
Since the introduction of Liquid Silicone Rubber (LSR) in the 1970’s, the optimization of processes and procedures has become increasingly important for achieving higher strength, hardness, flexibility, soft-feel, and durability properties in the end product; reducing lead times and costs.
Thermoplastics are a broad class of materials which are solid and brittle at room temperature but, when heated, become soft and pliable. Thermoplastics are generally separated into one of two categories: