超音波によるプラスチックの結晶化度の測定

抄録

Presently, injection moldings of thermoplastics are widely used in many industries. When a crystalline or semi-crystalline thermoplastic is used, the crystallinity of the molded part can be directly related to its quality, that is, shrinkage, mechanical strength and so on. Many methods for measuring of the crystallinity have thus been proposed, although it is not very easy to measure the crystallinity.
In this paper, a new method of measuring the crystallinity of a molded part was developed. The crystallinity can be obtained in a nondestructive way by measuring the longitudinal sound velocity traveling through it because the sound velocity which is mainly related to the Young's modulus is different between amorphous and crystalline states. The measurement on a molded plate of high density polyethylene was carried out.