A study of parameters interfering in oxidative induction time (OIT) results obtained by differential scanning calorimetry in polyolefin

Sample preparation and test conditions are parameters recognised to influen ce Oxidative Induction Time (OIT) results obtained by Differential Scanning Calorimetry (DSC). Therefore, many laboratory practices have been written to prevent this interference. However, quantitative results on the variabil ity of OIT as a function of these parameters have not been presented system atically in the Literature. The following parameters were investigated using a two level factorial desi gn and High Density Polyethylene samples: (1) sample shape-pulverising and cutting pieces of sample; (2) amount of sample-2 and 8 mg; (3) heating rate s to reach the isotherm-fast and 10 degrees C/min; (4) oxygen flow-20 and 6 0 ml/min. Sample shape, amount of sample and heating rate were the parameters that sh owed significant variability. Higher order interactions were considered neg ligible. Finally, the variation of the parameters under assessment was desc ribed by a linear model obtained with the aide of the chemometric method of Yates' Algorithm. (C) 2000 Elsevier Science Ltd. All lights reserved.