Influence of sample preparation on thermal decomposition of wasted polyolefins-oil mixtures

Significant influence of sample preparation on thermal decomposition of polyolefin-technological oil mixtures was proved during tests. Samples of polymer-oil mixtures were prepared with two methods: reducing size and components mixing and soaking in temperature 170°C. Soaking causes decreasing thermal stability of the charge. This fact manifests itself in decreasing of thermal decomposition temperature in laboratory scale, as well as in change of characteristic decomposition temperatures during thermogravimetric analyses. Data analysis was performed with the use of classic method based on Arrhenius kinetic equation and three-parameter model. The influence of sample composition and preparation method on values of three-parameter equation coefficients was observed.     

Analysis of the thermal decomposition of azo-peroxyesters by Arrhenius-type and three-parameter equations

Thermogravimetric analysis of azo-peroxyesters revealed two decomposition stages on TG curves. Molecular nitrogen is released in the first stage and carbon dioxide in the second. Fitting the thermogravimetric data by means of the three-parameter model and a classic one based on an Arrhenius-type kinetic equation showed that the former approach satisfactorily describes the process within the wide range of the extent of decomposition. It was found that two coefficients of the three-parameter equation are related to the temperature of maximum reaction rate. One of the coefficients of the three-parameter equation is also related to the activation energy. The compounds investigated can be grouped with respect to their kinetic characteristics, structure and stage of decomposition.     

Examination of polyolefins-organic compounds interactions by inverse gas chromatography

The investigations of interactions between polyolefins and test solutes at temperatures 58–122°C were carried out in the work. The test solutes were intentionally selected as representatives of the most important groups of compounds occurring in technological oils, which may be used as additives in conditions of industrial decomposition of polyolefins in Poland. For this purpose both the Flory-Huggins theory and inverse gas chromatography (IGC) were used. On the basis of retention data the values of both interaction and solubility parameters of analyzed polymers were determined. Solubility parameter δ and interaction parameter χ are related to some heat quantities e.g. excess free energy of mixing. It was observed influence of molecular mass and existence of chain branches on the values of the parameters. The obtained values allowed determination of influence of composition change of typical technological oils on their interactions with polymers and, at the same time, on course of charge preparation in these processes.     

Analysis of relative rate of reaction/process

Kinetic or rather thermokinetic analysis of thermal decomposition with releasing gaseous products is a current subject of discussion in many works and still devotes much attention to the property and meaningfulness of the single kinetics triplet determination. Analysis of thermogravimetric data by the relative rate of reaction/process were used to examine the frequently studied process of thermal dissociation of calcium carbonate as a model compound and comparing with published data for chemically defined compounds (azo-peroxyesters) and complex polyolefins?Cliquid paraffin mixtures. Two methods of correlation between parameters of the model were observed: thermodynamic and analytical expression. It was shown that these relations depend on course of the process. For analyzed model substance, enthalpy of reaction can be deduced on the basis of relation between coefficients in three-parameter equation. For large values of coefficients it is not possible, but other type of correlation was proved. Also, the relative rate of CO₂ gasification (Boudouard reaction) of brown and bituminous coals was analyzed and compared to that of its pyrolysis.