POLYPROPYLENE

With the present day consumer driving global markets, cost effective quality products with technological advancement and innovative breakthroughs is the only option to sustain. The current market is truly based on Darwin’s principle ‘survival of the fittest’.

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

PP 0.04%

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.

Applications

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.

Polylpropylene staple:

Filter cloth, Coated & protective fabrics, Plastic reinforcement, Medical & surgica, Shoe fabrics and other canvass, Cement reinforcement, Carpet backing (non woven), etc

Properties of Polyester

Physical Properties:
The moisture regain of polyester is 0.2 to 0.8 and specific gravity is 1.38 or 1.22 depending on the type of polyester fibres is moderate. The melting point of polyester is 250-300°C. A wide of polyester fibres properties is possible depending on the method of manufacture. Generally as the degree of stretch is increased, which yields higher crystallinity and greater molecular orientation, so are the properties e.g. tensile strength and initial Young’s modulus. Shrinkage of the fibres also varies with the mode of treatment. If relaxation of stress and stain in the oriented fibre occurs, shrinkage decreases but the initial modulus may be also reduced.
Miscellaneous Properties:
Polyester fibres exhibit good resistant to sunlight and it also resists abrasion very well. Soaps, synthetic detergents and other laundry aids do not damage it. One of the most serious faults with polyester is its oleophilic quality. It absorbs oily material easily and holds the oil tenacity.
Chemical Properties:
Effect of alkalies:
Polyester fibres have good resistance to weak alkalies high temperatures. It exhibits only moderate resistance to strong alkalies at room temperature and is degraded at elevated temperatures.
Effect of acids:
Weak acids, even at the boiling point, have no effect on polyester fibres unless the fibres are exposed for several days. Polyester fibres have good resistance to strong acids at room temperature. Prolonged exposure to boiling hydrochloric acid destroys the fibres, and 96% sulfuric acid and causes disintegration of the fibres.
Effect of solvents:
Polyester fibres are generally resistant to organic solvents. Chemicals used in cleaning and stain removal do not damage it, but hot m-cresol destroys the fibres, and certain mixtures of phenol with trichloromethane dissolve polyester fibres. Oxidizing agents and bleachers do not damage polyester fibres.
Polyester fibres have taken the major position in textiles all over the world although they have many drawbacks e.g.,

(a) low moisture regain (0.4%),

(b) the fibres has a tendency to accumulate static electricity,

(c) the cloth made up of polyester fibres picks up more soil during wear and it also difficult to clean during washing

(d) the polyester garments from pills and thus, the appearance of a garment is spoiled,

(e) the polyester fibres is flammable.

Thus, it has been suggested that surface modifications can have an effect on hand, thermal properties, permeability, and hydrophilicity.
Polyester fabrics have been widely accepted by consumers for their easy care properties, versatility and long life, In spite of such acceptance, complaints concerning their hand, thermal properties and moisture absorbency have been cited
Improved moisture absorbency of polyester fibres can be achieved by introducing hydrophilic block copolymers. However, this modification can lead to problems of longer drying time, excessive wrinkling and wet cling. In addition, penetration of water into the interior of the fibres has not been clearly shown to improve perceived comfort
Polyester fibres are susceptible to the action of bases depending on their ionic character. Ionizable bases like caustic soda, caustic potash and lime water only effect the outer surface of polyester filaments. Primary and secondary bases and ammonia, on the other hand, can diffuse into polyester fibre and attack in depth resulting in breaking of polyester chain molecules by amide formation.

Author : Bhushan Borse (Research Student) UICT, Mumbai, India

Online clothing

With the great revolution of internet, online shopping have been flourished in recent years. Though the electronic gadgets, books, games are some of the obvious choices of online customers, textile products also finds their place and its share is increasing at a rapid rate.
There are very wide options online for clothing line. The advantage of online clothes shopping is one can catch up the latest fashion pretty fast and also get to know what color or what fashion is currently in the news. The variety offered at online clothing is also great. There are lot of online clothing shops where you can find the clothes you need in no time.
The variety in terms of color, shade, garment type, clothes for girls, clothes for boys, T shirts, jeans, skirts along with clothing accessories like belts, purse, napkins, etc. is available just one click away.

Nylon Fibres

Nylon is a polyamide fiber, derived from a diamine and a dicarboxylic acid. There are very large numbers of polyamide materials available to produce nylon fibers, as a variety of diamines and dicarboxylic acids can be used as starting materials. It was the first truly synthetic fiber to be commercialized (1939). Nylon was developed in the 1930s by scientists at Du Pont, headed by an American chemist Wallace Hume Caruthers (1896-1937). The two most commonly used synthetic polyamides are nylon 66 (polyhexamethylene adiamide) and nylon 6 (Polycaprolactam, a cyclic nylon intermediate). The chemical reactions involved in the polymerization are as follows.