Page 288 - Engineering Plastics Handbook

250 Engineering Plastics

dimensional stability, and gas barrier properties. The melt blending of
an incompatible isotropic polymer and a thermotropic LCP produces a
composite in which fibrous LCP domains play a role of reinforcement in
the isotropic matrix polymer, because the molten LCP at the process-
ing temperature comes out as elongated reinforcing fibers with cooling.
Thus, the insitu formation of the reinforcing species during the fabri-
®
cation process leads to the term insitu composite. SIVERAS LC is a
®
blend of polycarbonate and Toray LCP SIVERAS by using micro com-
posite technologies. In addition to the good properties of polycarbonate
®
such as dimensional stability and electrical properties, SIVERAS LC
attains better flow even in thin parts and improves the dependence of
impact strength on thickness.
®
Features of SIVERAS LC
1. Excellent flowability for molding of thinner parts (Fig. 11.7)
2. Excellent vibration resistance
3. Higher impact strength in reduced thickness
4. High heat resistance
5. Excellent dimensional stability

Injection molding. Type II LCP can be molded with general-purpose
injection-molding machines. The points of injection molding of LCP are
shown below [18, 20, 21].

1. Preliminary drying. Although the water absorption of LCP is very
little, preliminary drying is required before injection molding to pre-
vent hydrolysis.
2. Injection molding machine. Because the principal application of LCP
is fine and precisely molded parts, the electromotive injection-molding

80
0.5 mmt
0.8 mmt
60
Flow length, mm 40

20

Figure 11.7 Flowability of
®
SIVERAS LC blend.
0
®
PC SIVERAS LC