Vectra® LCP resins

Thermotropic aromatic copolyester fibers are produced by melt spinning since the combination of an aromatic backbone and flexible segments results in an LCP which can be melt processed. Copolyesters, such as p-hydroxybenzoic add (PHBA) modified poly(ethylene terephthalate) (PET), 60/40 PHBA/PET (X7G) polymers, have been produced by the Tennessee Eastman Company [425-427]. Other melt processable nematic thermotropic LCPs (TLCP), based on combinations of 2,6-naphthalene dicarboxylic add (NDA), 2,6-dihydroxynaphthalene (DHN) and 6-hydroxy-2-naphthoic acid (HNA), and referred to as Vectra LCP resins, have been conunercialized (trademark by Hoechst Celanese Corporation [406]). 

Figure 6.76 Dynamic coefficient of friction for various Celanese Vectra LCP resins (P = 6 N, v = 60 cm/min) [19].

The largest volume applieations of thermotropic LCPs is injection-molded parts. For injection-molding resins, the addition of fillers or fiber reinforced elements into neat LCP resins is utilized to lower cost and improve performace. Two of the noajor families of mesotropic LCPs on the market are Vectra fi om... 

Specifically, Celanese has defined families of thermotropic polyesters derived from 2,6-naphthalene dicarboxylic acid (NOA), 2,6-dihydroxynaph-thalene (DHN) or 6-hydroxy-2-naphthoic acid (HNA). Indeed, the Vectra LCP engineering resins of Celanese Corporation are based on these monomers. 

Coil formers, which carry windings in inductors, motors and transformers, must be tough and able to withstand the temperatures experienced. Polymers used include Vectra LCP, PBT, PC, PA and phenolic resins. 

Entries 1-6 in Table I reveal an approximate constancy of volumetric CTE through the XYDAR 300, 400, and SRT-300 series resins. This result is not surprising, since the molecular structures of these materials are similar. However, the CTE values for a molded part reflect macroscopic structure (skin/core) as well as domain or molecular level morphology. The LCP molded part must therefore be regarded as a composite structure. These considerations as well as differences in basic molecular composition may explain the lower volumetric CTE for Vectra A-950 relative to the neat XYDAR resins, at least over the measured temperature range of 0-150 C. These factors may also be responsible for the lower anisotropy of the neat XYDAR 300 series resin. 

LCPs are finding use as replacement for epoxy and phenolic resins in electrical and electronic components, printed circuit boards (PCBs), and fiber optics. In these applications, the high mechanical properties, low coefficient of thermal expansion, inherent inflammability, good barrier properties, and ease of processing of LCPs (Vectra in particular) are important. 

Figure 11.18 shows commercial LCP tube made by Superex Polymer, Inc., from Vectra B-130, Zenite 6130, andXydar G-930 resins. Table 11.6 shows properties of the tubes. 

The materials used in this study were LCP (Vectra A950, Ticona) and PET (Eastapak PET 7352, Eastman Chemical Company). Both resins were in pellet form and were dried at 120°C in a vacuum oven for 24 h before use. 

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