PolyEthylene Coated Fabrics - Polyfabrics

Polyfabric generally consists of:-

1. woven HDPE tapes
2. low density PE coating
   both of which in themselves are very chemically resistant
3. additives - e.g. colour pigments and UV stabiliser in either or both of the tapes and coating; there are no plasticisers however.

Acids
Alkalis
Salts
Organic Solvents

However, it is not suitable for strong oxidising agents, some solvents, and most oils. This includes fuming sulphuric and fuming nitric acids, chlorosulphonic acid and carbon tetrachloride.

All oils attack polyfabrics to some extent; the greater being on the LDPE coating. Mineral oils have the greatest effect, dissolving LDPE at high temperatures and causing swelling, discoloration and disintegration of LDPE at lower temperatures. Vegetable and animal oils have less effect and short term contact at low temperatures may be acceptable.

Another problem with polyethelene is that surface active agents such as detergents and silicone oil can cause stress cracking, (as environmental stress cracking). thus a detergent in contact with a stressed polyfabric may cause cracking and subsequent breakdown of the fabric.

Effect on additives in the polyfabric :-

1. Colours - pigments -

   Can be stained or have the colour bleached out by various chemicals. They may be broken down by chemicals to give products which may attack UV stabilisers, although this would be rare.

2. UV Stabilisers

   The Hidered amine type is particularly sensitive to chemicals containing sulphur and/or halogens (F, Cl, Br, I) which will destroy the amines by acid attack. When this happens, UV protection is lost, and the combination of the acid attack, plus UV light is the most common example of the deleterious effect of chemicals on polyfabrics. It is particularly common with PE film or polyfabric hot house covers effected by horticultural spraying.