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Towards the prediction of pinking of PVC profiles in mild climatic conditions
Author(s) -
Lemaire Jacques,
Siampiringue Narcisse,
Chaigneau Richard,
Delprat Patrick,
Parmeland Georges,
Dabin Philippe,
Spriet Christine
Publication year - 2000
Publication title -
journal of vinyl and additive technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.295
H-Index - 35
eISSN - 1548-0585
pISSN - 1083-5601
DOI - 10.1002/vnl.10227
Subject(s) - polyene , chemistry , oxygen , materials science , chemical engineering , environmental chemistry , organic chemistry , engineering
Pinking of TiO 2 ‐pigmented PVC can be observed for profiles exposed to the mild environmental conditions of Northern European countries. In this paper, the pinking phenomenon is accounted for at the molecular level by the formation of polyene sequences which are not completely photooxidatively bleached under conditions of oxygen starvation. Photoreduction of TiO 2 to give Ti(III) species accounts for greying which cannot be converted into pinking under mild thermooxidative conditions (65°C). The polyenic sequences which account for an initial greying after brief exposure in the SEPAP 12.24 apparatus can be converted into shorter, modified polyene sequences which explain the pinking. From the basic understanding gained, a predictive test has been designed and validated by comparison with results obtained under natural exposure conditions.