The polyester dominated world of textile polymers has started to witness the rise of the new polymer ‘polypropylene’. Due to its good balance in physical and chemical properties there is a significant growth in the use of polypropylene. The raw materials for making PP are olefins, which can be obtained from thermal cracking of selected hydrocarbon feedstock. Polypropylene can be classified as isotactic, syndiotactic and atactic. Among the three atactic PP is amorphous and rubbery whereas remaining two are crystalline. The isotactic form of polypropylene which can be manufactured using Ziegler – Natta catalyst is of commercial importance.
Though the physical properties are much dependent on molecular weight and molecular mass distribution of the polymer the general properties can be found as following.
General & electrical properties-
Thermal conductivity, Wm-1*C-1 0.209
Final M.P. 160-1700C (purified form: 176*C)
Specific gravity (ASTM D792-64T) 0.905
Since it has high crystallinity and absence of polar character PP is resistant to most aqueous & polar media. PP is soluble in xylene, chlorinated aromatic and aliphatic hydrocarbons etc. In solvents like esters, ethers, higher alcohols etc. it is soluble only at higher temperatures.
polypropylene finds growing applications in technical textiles as stated following
Polypropylene continuous multifilament yarns:
Artificial turf, Conveyor belts, Wrap fabrics & bags, Industrial sewing threads, Cords, ropes, Cigarette filter tips, Filament winding, Bristles etc.
Filter cloth, Coated & protective fabrics, Plastic reinforcement, Medical & surgica, Shoe fabrics and other canvass, Cement reinforcement, Carpet backing (non woven), etc