ENHANCEMENT OF INTERNAL WELD LINE-STRENGTH IN THERMOTROPIC LIQUID-CRYSTAL POLYMER MOLDINGS

Shear Controlled Orientation in Injection Moulding (Scorim) has been a pplied to the moulding of a thermotropic liquid crystal polymer (TLCP) with the aim of eliminating the detrimental effects of internal weld lines. The Scorim technique induces macroscopic displacement of the mo lten material within the mould cavity. It has been found thar the init ial displacement of the melt, applied immediately after the cavity had been filled, was sufficient to virtually erase the weld line by re-or ientation of molecules and fibre filler. The tensile strength of the S corim modified weld was recorded to be up to 16 times that of the weld in conventionally moulded bars. Application of Scorim to a moulded ba r without internal weld lines results in a 90% improvement in strength .