thixotropic hardening

例句：

1. 1.The material undergoes thixotropic hardening when it is heated.
   该材料在加热时会发生触变硬化。
2. 2.In the case of a polymer blend, thixotropic hardening can occur due to differences in molecular weight.
   在聚合物混合物中，由于分子量的不同，可能会出现触变硬化现象。
3. 3. The thixotropic hardening behavior of the composite was investigated using a rheometer.
   使用流变仪研究了复合材料的触变硬化行为。