ABSTRACT
Liquid crystalline polymers may be thermotropic or lyotropic [1,2]. A lyotropic material, small molecule or polymer, is one that forms an ordered solution when dissolved in an appropriate solvent. Thermotropic liquid crystalline polymers (TLCPs), featuring mesomorphic melts (anisotropic melts) within a defined temperature range, have attracted considerable attention in the past two decades [3,4]. For the most part, the interests in TLCPs lie in their excellent balance of mechanical performance and melt processability in the liquid crystalline state. When blended with a conventional thermoplastic resin, the melt processable TLCP phase not only can serve as a processing aid by lowering the melt viscosity of the material, but is also a prime candidate for improving the mechanical performance of the host thermoplastic matrix by forming fibrous reinforcements in situ, hence, the name in situ composites. The concept of generating TLCP reinforcing fibrils on an in situ base has a number of potentially attractive advantages over the use of the more commonly used glass-reinforced composites [5,6]. The potential advantages include a wider range of processing options, improved surface appearance, recyclability, and lower processing requirements. Most of these advantages, as well as their general processing conditions, have been discussed in many excellent reviews [3-8]. Recently, Handlos and Baird [5] reviewed overall processing conditions and associated properties of in situ composites.
