Polyarylates (PAR) are aromatic polyesters made from diphenols and aromatic dicarboxylic acids or from aromatic hydroxycarboxylic acids. Tere- as well as isophthalic acid and bisphenola A are built up on PAR. PET and PBT as well as PC and PEC are chemically similar to polyarylates. Therefore, many properties they possess are consistent, especially the electrical and chemical characteristics. The heat shape constancy increases with increasing proportion of aromatic benzene rings in the macromolecular series. According to their structure, PAR belong to the polycondensates.
Special properties of PAR
These aromatic polyesters denote amorphous thermoplastics of the average contrast. Sometimes the term polyarylate is also used as a collective term for aromatic polyesters (APE) and polyester carbonates. As aromatic polyesters, PAR are composed of one structural category, namely aromatic hydroxycarboxylic acids, or of two different structural categories, namely aromatic dicarboxylic acids and diphenols.
PAR are used at high temperatures. In terms of mechanical and thermal properties, PAR materials can be classified between polycarbonates and polysulfones. Resistance, rigidity and strength are significantly better than these properties of PC, especially at temperatures above 100 degrees Celsius. The hardness values are for the most part and down to -40 degrees Celsius quite high, but somewhat lower than the values of PC.
At times, polyarylates (PAR) can be used up to about 170 degrees Celsius. The heat expansion is in the medium range. Polyarylates are transparent and have a yellowish coloration. The electrical data are consistent with their polarity. Therefore, they are not suitable for use in the HF range.
The constancy to chemical liquids almost completely coincides with that of polyester carbonate. Just like polyester carbonates, polyarylates are sensitive to stress fracture. PAR are fairly weather resistant. However, without a UV absorber, they tend to yellow. They are difficult to ignite because they have high levels of aromatic groups.
Impact resistance is similar to ABS with medium impact strength. All electrical as well as dielectric properties remain unchanged up to 150 degrees Celsius. The dielectric properties are also independent of frequency. Molding materials made of polyarylates are durable to alcohol, oils, fats, acids, fruit juices, etc.
Processing and application examples
It is processed mainly by injection molding as well as extrusion. It must be completely dried before processing, as it tends to absorb moisture and is susceptible to hydrolysis at temperatures above 290 degrees Celsius. PAR give low preference injection molded parts to size. The material is suitable for outdoor applications as it is resistant to UV radiation.
In mechanical as well as automotive engineering, polyarylates can be used in gears, bearings, rollers, screws and sleeves. In electrical engineering, polyarylates are used in connectors, switching elements, coils, parts for power tools, molded parts for microwaves, control panels for ovens. Other examples of application are in reflectors for headlights and lamps, prostheses, hair dryer combs, insulating plates, control buttons, lamp covers, office machines, medicine bottles.
Polyarylates also find their application in membranes for small loudspeakers and microphones, printed circuit boards, solar glazing, fire helmets and shields, UV protective coatings, etc.
Polyarylates have no odor and taste, so they are not harmful to health.
On Muellerbestellung.de PAR finds its application in processing as a film and is marketed under the brand name "Aryphan". You can find more detailed information about our PAR here.