Development of <i>in situ</i> blends of poly(<i>p</i>‐oxybenzoate‐<i>co‐p</i>‐phenyleneisophthalate) with other thermotropic liquid crystalline polymers

Abstract

Abstract A new in situ polymerization method is discussed wherein monomers of the major component are polymerized in the presence of a preformed thermotropic liquid crystalline polymer (LCP). Poly( p ‐oxybenzoate‐ co‐p ‐phenyleneisophthalate) (HIQ) was chosen for this study. HIQ is well known to have a narrow process window and to be difficult to process reproducibly, both drawbacks for a commercial product. An in situ polymerization of the HIQ monomers in the presence of a fully polymerized LCP, such as poly(4‐oxybenzoate‐ co ‐6‐oxy‐2‐naphthoate) (CO) results in the “CO–HIQ” in situ blend. The in situ blend exhibited reduced biphasic morphology and was more homogeneous than was HIQ. The glass fiber‐filled CO–HIQ resin also featured improved melt flow and more reproducible mechanical properties than those of HIQ. The in situ blends were characterized by optical microscopy, 1 H‐NMR, and melt rheology. The effect of the LCP level on the morphology of the in situ blend is discussed. © 1994 John Wiley &amp; Sons, Inc.