Normally in filtration acrylic refers to homopolymer acrylic which is essentially made from 100% of acrylonitrile. Occasionally less expensive lower performance copolymer acrylics are used.
The following illustrates the chemical difference:
HOMO POLYMER
HOMO POLYMER & CO POLYMER
The thermal performance of the homo polymer is significantly better, this image shows the two acrylic variants before and after exposure in air for 1 hour and 4 hours at 170°C showing the progressive darkening due to oxidation:
HOMO POLYMER
CO POLYMER
Typical applications for acrylic needlefelts are:
| Power Generation | Cement | Limestone |
| Incineration | Smelting | Asphalt |
The strength of acrylic is inherently quite low, and sometimes this is boosted by mixing the fibres with polyester and weaving the reinforcing scrim from acrylic and filament polyester yarns.
Even though acrylic doesn't hydrolyse, a number of applications use liquid repellent treatments to reduce the tendency of moist or oily cakes to adhere.
Being a synthetic fibre there can be a tendency in certain situations for the felts to develop a static electrical charge. With some dusts this can lead to a high explosion risk. The felts can be modified to dissipate this charge by the incorporation of either conductive fibres in the felt or by using a conductive scrim reinforcement. Steel is the preferred fibre here due to the conditions normally found with acrylic felts.
The major attributes of acrylic fibre are its excellent resistance to hydrolysis, its modest cost compared with the high performance fibres and reasonably high temperature resistance:
