FT‐IR photoacoustic and x‐ray diffraction study of orientation of an injection‐molded liquid‐crystalline poly(ester‐amide)

The orientation development that takes place during injection molding of liquid‐crystalline polymer (LCP) is analyzed by FT‐IR photoacoustic (PA) spectroscopy and X‐ray diffraction. The LCP used is the commercial Hoechst‐Celanese product Vectra B 900 prepared from 6‐hydroxy‐2‐naphthoïc acid, terephthalic acid and p‐acetoxyacetanilide. The analysis reveals the so‐called skin‐core morphology. The highly oriented skin layer is thought to originate in the advancing melt front where the “fountain flow” dominates. A less oriented transition layer due to the shear flow is located under the skin layer. The core is related to plug flow and has relatively poor orientation.