Thermo-oxidative degradation of polyethylene—III: The effect of titanium dioxide pigments on low-density polyethylene

✍ Scribed by Arne Holmström; Arne Andersson; Ealing M. Sörvik

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 317 KB
• Volume: 13
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(77)90130-6

✦ Synopsis

Low-density polyethylene (LDPE) free from additives and containing 0.1% phenolic antioxidant (4A'-thio bis (6-tert.butyl-3-methyl)phenol) was mixed with 40% by weight titanium dioxide pigment (TiO2) in a Brabender Plastograph under a nitrogen blanket. Eight different pigment qualities were used. The mixtures were heated in ultra-pure nitrogen at 315 and 355:. and in air at 150. Structural changes were studied by gel chromatography, differential scanning calorimetry and gravimetry. Uncoated TiO2 pigments caused a pronounced yellowing of the LDPE containing antioxidant during the mixing operation. No other structural changes were observed and subsequent heat treatments caused no further yellowing. During heating in ultrapure nitrogen above 300. the pigments exerted only minor influences on the degradation. In the thermo-oxidative degradation at 150 in air. uncoated rutile and anatase pigments promoted degradation while the coated qualities exerted a stabilizing action, increasing with the degree and complexity of the coating.