He Hezhi

Performance of filled polymer systems under novel dynamic extrusion processing conditions

Abstract Dynamic extrusion processing experiments have been carried out on PP-CaCO3 and LDPE-CaCO3 blends using an electromagnetic dynamic plasticating extruder and the effects of vibration forcefield on the extrusion processing of lled polymer systems were studied. It is shown that a proper vibration force eld can reduce the extrusion pressure and the extrusion power with the result that the degree of mixing of lled polymer systems is effectively improved compared with a traditional extruder.

Preparation and properties of several Chinese herbal residue/polylactic acid composites

Disposal of Chinese herbal residues (CHRs) during Chinese herbal medicine production and processing has become a problem that requires attention. In this study, CHRs were pretreated by steam explosion or pulverization and composites were prepared by mixing pretreated CHRs with polylactic acid. The mechanical properties of composites of CHRs pretreated by two different methods were compared, the main compositions of CHRs were analyzed, and the morphology of various CHRs and brittle fracture surfaces of composites were observed by scanning electron microscopy. The results show that the mechanical properties of the composites are closely related to the herbal species and pretreatment methods. The mechanical properties of CHR composites pretreated by steam explosion are superior to those pretreated by pulverization. Choosing CHRs with large fiber cell wall–lumen ratio, high lignin and cellulose contents, low contents of hetero cells and hemicellulose are helpful in making composites with good comprehensive performance.