The aim of this paper is to replace toxic coinitiators (tertiary amines) by non-toxic compounds such as glycerol and inositol (polyalcohol) in dimethacrylate resins. For this purpose, mid infrared spectroscopy (MIR) was used to calculate the monomers' degree of conversion (%DC); as well as simultaneous Thermogravimetric Analysis -Differential Thermal Analysis (TGA-DTA) and Differential Scanning Calorimetry (DSC) were conducted to evaluate thermal stability, degradation steps, and thermal events. The use of different initiator systems did not modify the thermal events or the thermal stability of each of the dimethacrylate resins. Results show a substitution of system 2 (toxicity) by system 3 (low toxicity), which had a good conversion velocity and total conversion in some monomers, is plausible.

The objectives of this study were to verify the viability of the photoinitiating system using curcumin as a photoinitiator and glycerol as a coinitiator, to analyze the thermal and morphological features of the polymers produced, and finally evaluate the possibility of removing toxic Ethyl-p-dimethylaminobenzoate from the photoinitiating system. Curcumin, an orange-yellow dye extracted from the rhizoids of the plant Curcuma longa, is known to be a common photosensitizer, and the type II photoinitiating system consisting of a dye and an amine is long known to be effective. In recent years, the production of biodiesel has increased, and consequently, so has the generation of its main by-product, glycerol. Thus, it becomes necessary to study ways to incorporate glycerol into products. Using thermoanalytical methods (Thermogravimetry, Differential Thermal Analysis, and Differential Scanning Calorimetry), Middle Infrared Spectroscopy, and Scanning Electronic Microscopy, it was possible to assess the thermal and morphological characteristics of the polymers produced, and compare whether the presence or lack of tertiary amine, as well as the addition of different molar ratios of glycerol, had any significant impact on these characteristics. Results suggested that neither the removal of tertiary amine nor the addition (in different proportions) of glycerol affected the thermal stability of the polymers. Also, removing the tertiary amine enhanced the total conversion degree of the polymers.

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O objetivo deste trabalho foi formar um novo co-cristal de ácido salicílico (AS) com ácido nicotínico (NCO) por moagem mecanoquímica e estudar seu comportamento térmico, espectroscópicos e difratograma de raio X. Para esta finalidade, o método de difração raio X (DRX) pelo método do pó foi utilizado para verificar a diferença de cristalinidade do AS, NCO e o cocristal. Os dados espectroscópicos (FTIR) foram usados para determinar os locais de interação nestas moléculas; bem como Análise Termogravimétrica-Análise Térmica Diferencial (TG-DTA) simultaneas e Calorimetria de Exploratória Diferencial (DSC) foram realizadas para avaliar a estabilidade térmica, etapa de degradação, e eventos térmicos como ponto de fusão e de cristalização. Todas estas técnicas foram utilizadas para verificar a formação do cocristal.