Long-term heat stabilisation by (natural) polyols in heavy metal- and zinc-free poly(vinyl chloride) |
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Authors: | Johan Steenwijk Rik Langerock Jacco van Haveren Leonardus W Jenneskens |
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Institution: | a Agrotechnology & Food Innovations (A&F B.V.), Wageningen University and Research Centre, P.O. Box 17, NL-6700 AA Wageningen, The Netherlandsb Debye Institute, Organic Chemistry and Catalysis, Utrecht University, Padualaan 8, NL-3584 CH, Utrecht, The Netherlandsc Limburgse Vinyl Maatschappij NV (LVM), Industriepark Schoonhees, H. Hartlaan 2030, B-3980, Tessenderlo, Belgium |
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Abstract: | The long-term heat stabilisation efficiency of (natural) polyol additives in heavy metal- and zinc-free poly(vinyl chloride) (PVC) has been investigated. It is shown that polyols, such as sorbitol and xylitol, markedly reduce the dehydrochlorination rate and improve Congo Red values. Extraction experiments on unprocessed and ground-processed PVC-sorbitol (1.0 phr) mixtures after thermal degradation at 200 °C revealed that especially in the ground-processed PVC-sorbitol system, sorbitol is partly converted into its mono- and dianhydro-derivatives 1,4-sorbitan and isosorbide, respectively. Apparently, the HCl released during thermal degradation acts as the catalyst. Similar intramolecular cyclodehydration reactions also occur with the natural polyols, erythritol and xylitol, under these conditions. Scrutiny of the measured dehydrochlorination rates and the Congo Red values for ground-processed heavy metal- and zinc-free PVC-polyol mixtures show that in particular polyols containing primary hydroxyl groups exert long-term heat stabilisation and that they act as efficient HCl scavengers. |
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Keywords: | PVC Additives Thermal degradation Stabilisers Renewable resources Sorbitol 1 4-Sorbitan Isosorbide Intramolecular cyclodehydration |
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