D. D. Kale

Impact modification of polypropylene copolymer with a polyolefinic elastomer

Polypropylene copolymer (PP-cp) has a large number of applications and is preferred over the homopolymer due to its higher impact strength. These impact properties can be further improved by blending with polyolefinic elastomer (POE). Blends were prepared by using commercially available POE (Engage® EG 8150, Dupont–Dow Elastomers), by varying POE content up to 25%. The effect of processing conditions on the properties of the blends was studied. Although impact strength increased, flexural modulus decreased. Dicumyl peroxide caused chain scission of PP-cp rather than crosslinking of POE. The results seem to indicate that there may be optimum concentration of POE around 10% for the polymers used in the present work. The grade of PP-cp used in this work contained about 10–11% ethylene content (rubber phase around 17–18%). These results match with general observations that brittle–tough transition for PP occurs when total elastomer content is about 20–25%.

Lignin-filled polyolefins

Dry lignin powder was used as a filler in low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) up to 30% w/w. The tensile strength reduced for all polymers. Impact properties were almost unaffected for PP but reduced for the other two polymers, Use of five parts of ethylene acrylic acid copolymer (EAA) and 0.5 parts of titanate coupling agent improved mechanical properties considerably. The melt viscosity increased steadily with increasing amounts of lignin. Electrical properties showed improved electrical resistance. The color of the resulting compound could be evaluated only up to a 10% lignin level, beyond which the compounds became very dark. At lower concentrations, samples of HDPE showed a more reddish tinge, while at higher concentrations, all samples showed a green–blue tinge.

Effect of cashew nut shell liquid (CNSL) on properties of phenolic resins

Cashew nut shell liquid (CNSL) is a natural product, and because of its phenolic nature it undergoes reactions similar to those of phenol. The cost of CNSL is much less than phenol. The effect of replacement of phenol by CNSL on the properties of novolak and resole resins was experimentally investigated.