The modication of local polymeric conformation of poly(acrylic) acid (PAA), induced by hydration and neutralization with triethanol amine (TEA), was investigated by IR and Raman spectroscopy. The eect of water is the perturbation of hydrogen bonds established between dierent polymeric chains and the modication of the local conformation of the polymer. The neutralization with TEA aects the carboxylic groups and modies the local conformation of the polymer. These modications are correlated with the shift and the modication of the characteristics of IR and Raman spectra.
The thermal degradation of some starch based materials was investigated using XRD method. The samples were obtained by thermal extrusion of mixtures of different proportions of starch, glycerol, and water. Such materials are suitable for the manufacturing of low pollutant packaging. Thermal degradation is one of the simplest ways to destroy such materials and this process is followed by structural modification of the local ordering of samples, water evaporation, crystallization, oxidation, or destruction of the chemical bonds. These modifications need to be studied in order to reduce to the minimum production of pollutant residues by burning process. XRD measurements show modification of the local ordering of the starch molecules depending on the temperature and initial composition of the samples. The molecular ordering perturbation is more pronounced in samples with low content of starch.
The concentration and temperature dependence of the viscosity is observed for some aqueous dispersions of Carbopol. The experimental data are analyzed with the power model, and reveal non-Newtonian behavior (shear thinning) of the samples.
Thermal degradation of commercial polystyrene was investigated by XRD and FT-IR metods. The samples were heated 30 minutes at temperatures 140ºC, 200ºC, 250ºC, 300ºC and 350ºC and then brought back to room temperature. XRD investigation denotes structural modification for samples heated above 200ºC. This modification is confirmed by FT-IR measurments. Some vibration bands are affected by thermal degradation at temperatures higher than 200ºC. Both FT-IR and XRD methods reveal modification of microscopic structure of the polystyrene submitted to thermal degradation.
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