Molds release techniques

This paper will explore the effect of these attributes toward making the RIM process competitive with other plastic molding techniques. It will also Illustrate the Impact that pending developments 1n RIM technology, such as Internal mold releasing systems, will have 1n making PU-RIM even more economically viable. 

It would be desirable to make sample prototype tooling and analyze the flow effects on a product that is likely to present a flow problem. In addition to the usual physical testing of the product, the use of photo-stress analysis techniques plus the exposure to selected solvents to check for stress crack characteristics would lead to changes in the product to minimize the effects of the molding on the product performance. As an example there have been cases in the past where piano keys with frozen-in stresses have been released from perspiration, leaving open flow lines (Chapter 5, STRESS ANALYSIS). 

Alkaline phosphatase, an enzyme with a molecular weight of approximately 86,000, has been incorporated into a polyanhydride matrix using compression molded PCPP-SA 9 91. Five percent loaded wafers, 50 mg each, were perpared, and measured 1.4 cm in diameter, with a thickness of 0.5 mm. Release experiments were then conducted using techniques similar to those described for carmustine above. As can be seen in Pig. 13, the alkaline phosphatase was released in a well-controlled manner over a prolonged period of time, just over a month, from this polyanhydride. 

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