High-performance polymers molding components

The ECN resins are multifunctional, solid polymers characterized by low ionic and hydrolyzable chlorine impurities, high chemical resistance, and good thermal performance. The ECN resins are widely used as base components in high-performance electronic and structural molding compounds, micro-chip encapsulation, high—temperature adhesives, structural molding powders, etc. 

Both spray-up and hand lay-up cannot achieve a high volume fraction of fibers. Therefore, these techniques are not suitable for high performance applications. They are most suited to large sheetlike components such as boat hulls and furniture. There is virtually no limit to the size of the part that can be made. The molds can be made of wood, metal, neat polymers, or polymer composites with glass fibers. Unlike other processes, they require little or no pressure. 

Details into the blow molding process have been recently smnmarized by Norman C. Lee [28] in which the engineering aspects of the process are primarily discussed. Ihis section will briefly. summarize the key components of the blow molding process, but will focus more on the polymer properties necessary for the blow molding process to provide high performance products. 

Impact modifiers are usually prepared by grafting methylmetacrylate and styrene on a styrene-butadiene rubber in an emulsion process (29,30). The preparation and properties of these polymers has been reviewed (31). Impact efficiency is achieved by controlling the rubber substrate particle size between 1000 and 3000 A in a narrow distribution range. The solubility-incompability balance determines the performance of impact modifiers. Typical opaque compound impact modifiers show high efficiency. High-efficiency impact modifiers are used in PVC conduit, injection molding components and calendered opaque films and sheets. Various types of impact modifiers are available (32,33). 

---