Search results

THE self extinguising characteristics, chemical resistance and outstanding strength to weight ratio offered by ULTEM polyetherimide, from General Electric Plastics Europe (GEP), has given it an important role in aviation applications.

The milling properties of polybutadienes have been improved and scorch time decreased by the use of aluminium naphthenate, which can also be employed to ensure homogenous distribution of pigments in polyesters. Aluminium secbutoxide/naphthenic acid reaction products are useable in the preparation of cellular polyurethanes and mixtures of the material with polyethylene have been applied to textile fabrics. The naphthenate possesses rubber‐like properties to a certain extent and was in fact used as a rubber extender during the First World War. Mixtures of naphthenates and pentachlorophenol compounds have been utilised to preserve wood. Alum naphthenate has been used to produce poly (naphthenaluminophenyl siloxanes), polymers containing radicals f naphthenic acid chemically bound with aluminium atoms in the side chains. The product contains 9% silicon, 4.52% aluminium, approximate molecular weight 1600, and are easily soluble in benzene, toluol, carbon tert, and ether, giving stable film‐forming transparent solutions, whose films have an electrical volume resistency of 3.1 x 1015 ohms‐cm, a tongent of dielectric loss angle of 0.0082, an electric strength of 68.3 kv/mm and a dielectric constant of 2.9. Although the mechanical strength of these films is not high it can be increased by heating 10 hours at 120°C. When added to other silicon‐organic or organic polymers these products accelerate their drying gelatinization and hardening.

BIP of Oldbury in the West Midlands and part of T&N plc for over 30 years, celebrates its centenary this year. Now two sister companies, BIP Plastics and BIP Speciality Resins share the 11 hectare site straddling Tat Bank Road and bordered by Popes Lane and Rood End Road.

Although cure of paint coatings by radiation is no new phenomenon, there is considerable increased interest in development of industrial processes using radiation curing for a variety of reasons. Before studying the developments in detail, it is worth noting that radiated energy can basically be divided into two categories. In the first category we have ionising radiation which for our purposes includes electromagnetic radiation of wave lengths less than visible light and also accelerated electrons. In the second category is radiation, which is essentially thermal in its effect ranging from infra red through to microwave and radio frequency. The use of these longer wave length radiations, whose effect is essentially thermal, will not be discussed in detail since all coatings which can be cured in normal high temperature ovens are basically capable of cure with such methods. It is worth noting however, that improvement in the design of infra red lamps with peak radiation in the near infra red at around 1200 nanometers has led to speed up in infra red curing which has been particularly useful in cure of alkyd‐amino finishes on heat sensitive substrates such as wood. There is also developing interest in high frequency long wave length radiation, particularly in the area usually referred to as microwave. Here we have penetrative radiation which produces heat effects by what is sometimes referred to as molecular friction. The conversion of the microwave energy into heat depends on the loss factor of the material in question and so the process is most efficient with polar materials such as water. The most likely use of microwave heating is with water based coatings on substrates which will not themselves heat up rapidly, such as non‐polar plastic films.

New performance standards in dry classification below 10 microns at high feed rates are claimed for the new Majac Acu‐Cut classifier system, now being introduced on the European market. A patented high energy air concept is used to disperse thoroughly and then classify fine powders into coarse and fine fractions with cut size selectivity covering the entire sub‐sieve range from 0·5 to 50 microns. The manufacturers state that it is now possible to produce grit‐free powders below 5 microns in a dry process at production throughput rates or to pull out a specific size range anywhere within the particle size distribution range.

This review aims to present a speciality to the general documentationalist. It will contain too little chemistry for the chemist, and too little documentation for the documentalist. A reviewer cannot win!