| 摘要 |
A method is provided for producing dimensionally stable rotationally mold ed parts from semi-crystalline materials. A test mold is constructed having dimensions closely approximating the desired dimensions of the final part. A test part is then molded in the test mold using conventional rotational molding techniques. After the test part has partially cooled, it is removed from the mold, allowed to cool to ambient temperature, measured and annealed in an oven. During annealing, the part is heated to the crystallization temperature, midway between the glass transiti on temperature and the crystalline melting temperature. After annealing, the pa rt is allowed to cool to ambient temperature and measured again. The post annealin g dimensions are then compared with the dimensions determined before annealing to determine the amount of shrinkage. A production mold is then constructed to take into account the amount of shrinkage calculated. Production parts may then b e molded in the production mold and annealed at the crystallization temperatur e to attain parts having a small dimensional tolerance and high tensile strength.
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