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Lowering Ejection Force During Injection Molding of Syndiotactic Polystyrene (SPS) Compounds

IP.com Disclosure Number: IPCOM000019870D
Publication Date: 2003-Oct-03

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The IP.com Prior Art Database

Related People

Inventors:
J. M. Warakomski A. P. Banks K. L. Nichols H. Fowler
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Abstract

QUESTRA* syndiotactic polystyrene (SPS) is a semi-crystalline polymer that is useful as an engineering plastic, especially when compounded with glass fiber reinforcement, and other additives, such as impact modifiers and flame retardants. With a melting point of 270ºC, SPS compounds have excellent properties such as heat resistance, solvent resistance, low dielectric constant, insensitivity to moisture, low specific gravity compared to other semi-crystalline polymers, and dimensional stability. During injecting molding operations, syndiotactic polystyrene compounds generally are ejected from the mold easily. In some cases, depending on the design and condition of the tool, improved demolding is desired. Ejection force can be deceased by up to 85% by adjusting molding conditions and adding mold release agents. We will describe a full factorial designed experiment from which we developed a predictive model for ejection force based on are mold temperature, hold pressure, and melt temperature. We will also describe the effect of internal and external mold release agents. *Trademark of The Dow Chemical Company