Vol 17, No.1, Page 13

a large thermoplastics structural foam case comprising a lid and base and 2) a small box enclosure made by injection moulding.

Plast. Rubb. Weekly, 1986, (Nov.~), 24

ANTISTATIC FOAMS Dow Chemical has developed antistatic foam for use in the pack- aging of electronic sub-assemblies and similar components, and for the cushion packaging of lightweight assembled electronic devices which need EM1 shielding protection. It uses similar technology to that already being applied in polyurethane foams which involves an evenly dispersed, non-migrating antistatic additive system that is not dependent on relative humidity.

Plast. Eng., 1986,.XLII, fAug.1, 76

GLASS BUBBLES IN Microcel Technology has developed a process for making glass STRUCTURAL COMPOSITES hollow spheres so precisely that they can be used to obtain FOR AUTOMOBILES specific engineering and processing properties in structural

composites. Bubble diameter and wall thickness can be main- tained within 10% and the dimensions can be controlled independently to provide specific combinations of strength and density. Hollow glass spheres have been used to date as resin replacing fillers but these close tolerance beads will broaden the application of load bearing structures. Another advantage of this uniformity is consistent pressure requirements for mould filling. Microcel is collaborating with General Motors and Ashland Chemical to develop composite systems for several structural applications in the truck market.

Plast World, 1986. 44, fNov.1, 67 -

REDUCING SCREW IN EXTRUDERS

WEAR Hoechst has developed a new wax which, used in masterbatch form, reduces the wear in extruder screws. When HDPE is processed on high speed equipment,the screw can be subject to such extreme wear that it must be replaced after only a few months. One method used to increase the life of these screws is to coat the plasticising unit with wear-resistant alloys but this is costly. Colour concentrates play an important role in bringing about this abrasive wear and although the embedment of pigment in pure HDPE minimisesthe abrasion, it is not possible to produce a high quality colour concentrate without the dispersion action of lower molecule weight auxiliaries. Hoechst developed a polythene wax it calls HOSTALUB H3 which has a high gelting point, but at the same time is extremely hard at 140 C. The melt is substantially less viscous than the low melting carrier waxes previously used, and good wetting of the pigment and good distribution of the finished masterbatch are ensured. The

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