India Takes Pride of Place in Global Specialty Plastics Market

Dr Prakash Trivedi,
Polymer SBU, Gharda Chemicals Ltd
Specialty plastics market is an extremely niche sector; the global volume of production is just 225 KMTA. Dr Prakash Trivedi, Polymer SBU, Gharda Chemicals Ltd throws light on the intricacies involved in specialty plastics, right from its properties, production to its application and market size.

Specialty Thermoplastics are those which can withstand high temperatures, usually higher than 1700C for long periods. These usually have aromatic rings in chains, and therefore they have outstanding mechanical properties. Amorphous Polysulfone (PSU) with glass transition temperature (Tg) of 1790C is at their lower end and crystalline Polyether Ketone Ketone (PEKK) with melting point (Tm) of 3950C is at the highest end of specialty plastics.

Production
All specialty plastics are made using nucleaophilic or electrophilic substitution reactions on a single or two monomers at temperatures from ambient temperature to as high as 3200C in an aprotic solvent. Getting reactive end groups capped and getting rid of bye-products, usually salts and solvent are as challenging as controlling chain structures and molecular weights (MW). Importantly, for higher MW, the conversion of monomers needs to be higher than 99.7 percent.

While their overall production volume is low at about 225 KMTA, they make up with their higher prices starting at USD 6-10/Kg to USD 200/Kg and total business of USD 3.1 Billion. Major producers are Solvay, Ticona, Chevron Philips, BASF, Evonik, Arkema, Sumitomo and Gharda.

Having such high temperature Tg & Tm, it becomes necessary that they be further processed into any shape using injection or compression moulding or extrusion techniques at temperatures approaching 4000C or even higher. Thus, processing machines parts should be capable of such high temperatures besides being able to withstand corrosion. Specialty plastics thus can be extruded into pipe, rod, plate shapes, as also film, fibers and cable insulation. They can be moulded into a large variety of shapes or blown moulded into bottles and jars.

Properties
Specialty plastics are meant to be used only where other plastics fail. Being generally of lower specific gravity (1.2-1.5), they are also preferred for metal replacement, when weight saving is a norm as in auto or aerospace. The amorphous plastics also show transparency making them a good substitute for glass. Their chief usage lies in applications, where resistance to corrosive chemicals and higher mechanical load at higher temperatures is important. They score over common engineering plastics in all these aspects. For example, PEKK shows mechanical properties like tensile and flex strengths at 2500C, which are higher than those of polypropylene or ABS at room temperatures.

The real beauty of these specialty plastics is in the substantial increase in properties when carbon fibre or to a lesser extent glass fibre is compounded with them. As shown in figure 1, Polyehter Ketone (PEK) with 40 percent carbon fibre in its specific flex modulus equals to Aluminum and approaches to steel.

Applications
The applications for specialty plastics can be broadly divided into two basic categories; transparent like food trays, tapes, baby bottles, plumbing , etc and non-transparent with major engineering applications like seals, gaskets, bearings, cable sheathing and insulation and such others. Some of these plastics withstand high dosages of gamma ray making them most suitable for nuclear power plants and high temperatures up to 3000C, high pressures and chemicals (sour gas) making them useful in Oil/Gas exploration .

Few companies and countries produce specialty plastics and India takes pride of place among them with Gharda (PEK, PEKK & PBI), Solvay (PEEK, PES) and Ralies (PEKK) having their production plants in Ankleshwar, Panoli in Gujarat since late 1990s. While today their Indian market is small at less than 10 percent, it is a fond hope that in next 5-7 years, not only will they grow but India will also become an exporter of articles made from specialty plastics for real value additions.