Liquid crystal polymer
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| LCP | |
|---|---|
| Specific Gravity | 1.38 to 1.95 |
| Modulus (E) | 8530 to 17200 MPa |
| Tensile strength (σt) | 52.8 to 185 MPa |
| Tensile Elongation (%) | 0.26 to 6.2 |
| Notched Izod Impact | 21 to kJ/m2 |
Contents |
[edit] Background
Liquid crystal polymers (LCPs) are a unique class of wholly aromatic polyester polymers that provide previously unavailable high performance properties. A number of LCP resins were produced in the 1970s which displayed order in the melt phase analogous to that exhibited by non-polymeric liquid crystals. The structure of LCPs consists of densely packed fibrous polymer "chains" that provide self-reinforcement almost to the melting point. However, the commercial introduction of liquid crystal polymer resins did not occur until 1984, at which time LCPs could not be injection molded. Today, LCPs can be melt processed on conventional equipment at fast speeds with excellent replication of mold details.
A relatively unique class of partially crystalline aromatic polyesters based on p-hydroxybenzoic acid and related monomers. Liquid crystal polymers are capable of forming regions of highly ordered structure while in the liquid phase. However, the degree of order is somewhat less than that of a regular solid crystal. Typically LCPs have outstanding mechanical properties at high temperatures, excellent chemical resistance, inherent flame retardancy and good weatherability. Liquid crystal polymers come in a variety of forms from sinterable high temperature to injection moldable compounds.
LCPs are exceptionally inert. They resist stress cracking in the presence of most chemicals at elevated temperatures, including aromatic or halogenated hydrocarbons, strong acids, bases, ketones, and other aggressive industrial substances. Hydrolytic stability in boiling water is excellent. Environments that deteriorate the polymers are high-temperature steam, concentrated sulfuric acid, and boiling caustic materials.
[edit] Typical LCP applications
- Electrical/Electronic Applications (characterized up to 110 GHz for circuit operation)
- Automotive Applications
- Parts, Engineering
- Containers, Food
- Appliances
- Industrial Applications
- Connectors
- Optical Applications
- Parts, Thin-walled
[edit] Advantages of LCP
- High Heat Resistance
- Flame Retardant
- Chemical Resistance
- Dimensional Stability
- Moldability
- Heat Aging Resistance
- Adhesion
- Low Viscosity
- Weldable
- Low Cost
[edit] Disadvantages of LCP
- Form weak weld lines
- Highly anisotropic properties
- Drying required before processing
- High Z-axis thermal expansion coefficient
- Not hermetic*
