Commodity Resins and Their Blends

Five large-volume polymeric groups belong to this category: polyethylenes, polypropylenes, styrenics, acrylics and vinyls. Their world market share remains relatively stable — the commodity resins represent 71% of all consumed plastics.

Table 1. World Market Share (MS) and Annual Growth Rate (AGR) by Resin Type (1995-2000)

Notes:
1-In chemistry, vinyl or ethenyl is the functional group ?CH=CH2, namely the ethylene molecule (H2C=CH2) minus one hydrogen atom. The name is also used for any compound containing that group, namely R?CH=CH2 where R is any other group of atoms.


2-Vinyl polymers:


3-Phenyl group or phenyl ring is a cyclic group of atoms with the formula C6H5. Phenyl groups are closely related to benzene. Phenyl groups have six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the remaining carbon bonded to a substituent.

Phenyl groups often have the general formula CnHn represented by the symbol Ph or, archaically, ?. Benzene is sometimes denoted as PhH.


Example 1: Polystyrene (PS)

Until the 1950’s, PS was produced in small quantities — the resin was
brittle, thermally unstable, with poor solvent and scratch resistance. The main use of styrene was in the manufacture of styrenics, viz. Buna-S, SBR, or ABS.
Common PS is atactic and amorphous. It has good optical clarity, low dielectric loss factor, modulus E = 3.2 GPa, strength ? = 45-65 MPa,
density ? = 1050 kg/m3, and CUT (Continuous use temperature) = 50-70°C.
Because of brittleness and low chemical resistance the demand for neat PS has decreased, and except for foaming, PS is rarely used.
PS can also be polymerized into crystalline forms: isotactic (iPS) or syndiotactic (sPS) with Tm = 230 or 272°C, respectively.
The high-impact PS, HIPS, has been known since 1911. In the USA,