PLASTICISER Subject

Various types of additives are essential to give plastics new or enhanced properties. However, the safety of flame retardants, plasticisers and stabilisers, as regards potential health hazards, is attracting attention. Brome-based flame retardants have been the subject of safety disputes for several years and several substitutes have been developed. The shift to lead-free stabilisers is making further progress. 

The primary aldehyde product is reduced to the desired butanol, or it is subjected to a base-catalyzed aldol condensation and then hydrogenated to give 2-ethylhexanol. The phthalic ester of the latter is used as a plasticiser in PVC. The first process was based on a Co2(CO)s catalyst, a precursor of HCo(CO)4. The pressure is high, ca. 200-300 bar, in order to maintain the catalyst s stability. In the 60s Shell developed a process using phosphine ligands which allowed the use of lower pressures. The catalyst is less active but it directly produces alcohols with a somewhat higher linearity. 

PVC-P materials, subjected to ageing under model and climatic conditions, have been extensively tested. Properties are lost as a result of diffusion controlled desorption of the plasticiser and a mathematical description of the ageing process has been formulated to predict lifetime (277). Plasticiser loss on ageing has also been identified in the spectroscopic investigation of roof membranes in service for a varying number of years (240). 

Plasticised PVC was surface modified by nucleophilic substitution of the chlorine atoms of PVC by sulphide ions in aqueous media in the presence of a phase-transfer catalyst. The modified PVC was sterilised by steam autoclaving and gamma irradiation and subjected to plasticiser extraction. Surfaces were evaluated by contact angle measurements, SEM, cell culture studies, haemolysis assay and whole-blood clotting time measurements. Mechanical properties were examined. 31 refs. 

PVC is often used in food packaging and blood bags. This study concerns mass transfers between plasticised PVC, having been subjected to a treatment, and liquid food or food simulants. The treatment reduces the diffusion of the plasticiser and the influence of some factors of this processing were investigated. A mathematical model, able to simulate these mass transfers and to quantify treatment parameters, is proposed to quantify the diffusion rate in terms of an average diffusion coefficient. 16 refs. 

The primary aldehyde product is reduced to the desired butanol, or it is subjected to a base-catalysed aldol condensation and then hydrogenated to give 2-ethylhexanol. The phthalic ester of the latter is used as a plasticiser in PVC. The... 

A correct definition of dry has already been commented upon because even the most hydrophobic organic substances, e.g. polystyrene, absorb water vapour to some extent. Water has therefore been called Nature s ubiquitous plasticiser . Apart from this softening role, water, being itself a very reactive and versatile molecule, might also have other effects on amorphous solid substrates, some of them unexpected, and most of them deleterious. The role of low water contents (< 1 % w/w) in affecting the behaviour of solid solutions is a subject that deserves further investigation. 

Plastic pipe and fittings, particularly PVC-P and to some extent PE, are overwhelmingly being used in construction as a big competitor of metallics. APME s report [52] demonstrates that plastics use in gas, sewage and water piping has tripled in the EU. Health hazards in PVC-P pipes and fittings, are subject to emission of the plasticisers used. Polyacetals are also used for sanitary ware and plumbing. 

Although the scale of typical liquid-gas interfaces is large compared to the resolution of many modern characterisation techniques, they are difficult to observe because the surface of interest is situated beneath the drop of the liquid. The method presented here bypasses this difficulty by solidifying the drop and inspecting the surface directly. Slight shrinkage of the drop when it is subjected to the laser beam of the confocal microscope may cause a problem. Earlier works have used a plasticising drop where this is not a problem [15]. However, the benefit of the present method is that it uses a water-based system with a surface tension similar to that of water. 

Recent legislation issues in Europe have involved the end-of-life disposal of vehicles and electrical goods. Food contact legislation has been updated. Plasticisers, brominated flame retardants and biocides have also been the subject of EU legislation. The EU s proposals on the testing of chemicals are expected to create difficulties for the plastics and additives industries, although compensations may become apparent. 

Health effects of PVC itself and its additives (mainly plasticisers) have been the subject of a very intense debate for many years, beginning from the danger of release or extraction of the heavy metal based stabilisers and health implications of phthalate plasticisers and other additives to the danger of formation of dioxins and hydrogen chloride gas during accidental fires . For many years, there has been a never ending debate between different parties about PVC and its effect on health and on the environment, some are... 

Thermoplastics and paint systems that behave Uke thermoplastics are quite often soluble in organic solvents. Many adhesives contain small amounts of such solvents or plasticisers. The diffusion of these products towards the boundary layer can lead to a softening of this layer at the adhesive interface. If the joint is then subjected to stress, the adhesive bond may fail. Since the diffusion process takes place very slowly, months may elapse before the damage manifests itself. Additionally, the user should seek the adhesive manufacturer s advice on an appropriate method of surface preparation. 

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