ABSTRACT
There are four commonly practiced processes for the production of impact-modified styrenics. These processes are bulk, bulk suspension, emulsion, and blending. During the polymerization, grafting occurs on the rubber backbone by either hydrogen abstraction of an allylic hydrogen or addition to a double bond. Emulsion polymerization is the primary process for the production of acrylonitrile-butadiene-styrene (ABS), with lesser amounts being produced by the bulk process. High-impact polystyrene is not produced by the emulsion process. In the emulsion process to produce ABS the rubber particles are first produced in a batch process, typically using a water-soluble initiator such as sodium peroxydisulfate, water, emulsifier, and butadiene. Toughened styrenics resins are used in a variety of applications and therefore must be capable of performing under a range of physical and environmental conditions. Many applications require the plastic to maintain its shape and physical properties for many years, often while being subjected to fatigue, chemical exposure, or oxidative attack.
