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1.1 This practice covers the preparation of compression-molded test sheets of Types I, II, III, and IV polyethylene plastics (Specification D 1248). This practice includes both branched and linear polyethylenes. Two of the procedures given provide for compression-molded sheets to be conditioned by first heating each material above its melting point for a period of time sufficient to erase its prior thermal history and then cooling it from the melt state at a controlled rate while maintaining the required dimensions of the sheet. The third procedure provides for molded test sheets to be prepared by cooling the platens of the compression press, and hence the molten polyethylene plastic, at a controlled rate. Three cooling schedules are provided for as follows:

1.1.1 Procedure A , in which the temperature of the initially molten plaque is lowered at a rate of 5 + 0.5

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