April 199.3 Additives for Polymers

and household appliance markets. In particular the automotive industry is turning towards glass filled polypropylene components both to reduce weight and increase recyclability. One route by which the performance of glass-filled composites can be improved is by incorporating chemical coupling agents as described in this article. In addition development work with glass-filled polymer alloys is presented. (4 refs) Polymers & Polymer Composites, 1993, 1, (I), 4.5-51

thermogram (JIS K 7122). Test pieces made from neat resins and from reinforced resins with glass fibre or fused silica were evaluated in terms of thermal and mechanical properties, respectively. It was found that the heat resistance and the mechanical properties improved with increase of PHPMI or HPMI- St content in the hardener. (14 refs). Polymer International, 1993, 31, (3), 275- 282

HALS-phosphite polypropylene

stabilizers for

Antioxidants in polyolefins

A paper from the Institute of Chemical Physics in Moscow evaluates the effectiveness of antioxidants in polyolefins. Antioxidants added to a polymer take part not only in reactions leading to retardation of the polymer oxidation, but also in many other stages of the oxidation process, including direct interaction with oxygen. Their effectiveness in polyolefins can be evaluated by analysing the dependence of oxygen consumption rate on initial antioxidant concentration. (7 refs). Polymer Degradation & Stability, 1992, 39, (3), 305-306

Properties of epoxy resin cured by phenol novolac/4-hydroxy- phenyl-maleimide polymer blend hardeners

Organic phosphites combined with Hindered Amine Light Stabilizers (HALS) were used as stabilizers in the photo- and thermo-oxidation of polypropylene film. The efficiency of the mixture of HALS and phosphite was compared with the efficiency of the combination of HALS and phosphite in one molecule. A strong synergistic effect was observed for the molecule with HALS and phosphite moieties. Generally, the mixture of HALS and phosphite exhibited synergistic, antagonistic or additive effect. The efficiency of the mixture depends upon the chemical structure of the phosphite and HALS structural units as well as on the ratio of the components. (6 refs). Polymer Degradation & Stability, 1993, 39, (3), 367-371

Studies on polymer stabilizers-l

Phenol novolac/4-hydroxyphenylmaleimide homopolymer blends or phenol novolac/ HPMI-styrene copolymer blends were used as the hardener in epoxy resins in a study carried out at the Osaka Municipal Technical Research Institute in Japan. Curing behaviour of the above systems and thermal and mechanical properties of the cured epoxy resins were studied. It was not necessary to use a curing accelerator for this system because PHPMI or HPMI-St had an accelerating effect on the curing reaction. Curing behaviour was investigated by measurement of gelation time (JIS K 6910) and differential scanning calorimetry

These studies were undertaken by Sumitomo Chemical Co Ltd in Japan. The first dealt with the influences of structural factors on oxidative discoloration and the thermal stability of polymers. 2-ten-butyl-6-(3-ter- butyl-2-hydroxy-5-methylbenzyl)-4- methylphenyl acrylate (Sumitomo compound Sumilizer GM) is known as an effective thermal stabilizer which protects polymers against thermal degradation caused by heat or mechanical stress especially under oxygen- deficient conditions. Studies on the influences of structural factors of related phenols on oxidative discoloration and thermal stability

O1993 Elsevier Science Publishers Ltd 9