Abstract
Thermal oxidation of thin films of trilinoleoylglycerol (TLG) under air was investigated by termogravimetric analysis (TGA). Hydroperoxidative products of TLG film formed by thermal oxidation with TGA under air were converted to polymerization products quantitatively, during vacuum thermogravimetric analysis (VTGA).
The following results were obtained :
1) Weight percent of hydroperoxidative products of TLG film (17 μm : thickness of film) obtained by programed heating under air was 1.04 wt %/°C and 80°C to 128°C. For film thickness of 85 μm, this parameter was 0.88 wt %/°C at 60°C to 120°C and 0.49 wt %/°C at 120°C to 145°C.
2) The relationship between TLG film thickness (17 μ m to 310 μm) and hydroperoxidative products (wt %) for maximum TLG film weight achieved by programed heating under air could be expressed quantitatively as 0.056 wt %/ μm. For less than 17 μm of thin films of TLG, hydroperoxidative product amounts greatly increased.
3) The initial logarithmic rate of the thermal oxidation of TLG film was proportional to the reciprocal of absolute temperature of the reaction. From Arrhenius plots apparent activation en ergy (ΔE ) of the TLG film (17 μm) oxidation was 8 kcal/mol and ΔE of the TLG film (85μ m) oxidation, 6 kcal/mol.
4) Qualitative assignment of thermal oxidative polymerization products was made at 100 and 200°C for 4 min, using thermograms of VTGA. The first peak corresponded to the dimer and its oxidation products and the second and third peaks, to the trimer and its oxidation products.
