Composite characteristics compression molding techniques

N/inm. Composites reinforced with lyocell 6.7 and lyocell 15.0 multilayer webs reached values of 36 N/mm and 28 N/mm respectively. For the needle felt reinforced composites clear reinforcement effects were determined (lyocell 1.3-PLA = 63 N/ mm, lyocell 6.7-PLA = 61 N/mm and lyocell 15.0-PLA = 57 N/mm ). These results lead to the assumption that the kind of the semi-finished product has a clear influence on the mechanical characteristics of the composites produced by the compression molding technique CP-1. This effect could be attributed to a more homogeneous fiber distribution in the PLA matrix due to the additional needling process and the lower thickness of the needle felts compared to the multilayer webs. It is assumed that the lower thickness lead already in the pre-heating phase to a better heat conductivity and drying in the press. 

A clear improvement of the mechanical characteristics with regard to tensile and impact characteristics of multilayer web reiirforced PLA composites was achieved by using modified process parameters (compression moulding technique CP-2). In comparison to the processing technique CP-1 a pre-drying step was inserted (2 hr at 105°C) and the compression molding time in the hot press was reduced to 5 min. The cooling of the composites occurred in a cold press for 5 min at 25°C. 

---