In this work, the optimization of extraction of polysaccharides from Citrullus colocynthis curd polysaccharides (CCPs) is investigated by using the analysis of variance. For this aim, a chemical extraction method has been developed in order to be able to isolate CCPs at high level of purity. The extraction was performed by using boiling water at different extraction times (30, 60 and 120 min), extraction temperatures (50, 75 and 100°C), and a material ratio (30, 60 and 100 g/ml), for maximum polysaccharide extraction. The 3-D response surface plot and the contour plot derived from the mathematical models are used to determine the optimal conditions. The optimum extraction conditions are as follows: extraction temperature 100°C, extraction time 120 min and the ratio of water 30 ml/g. Under these conditions, the experimental final mass is 210.6 mg which is very close to the predicted value (209.46 mg) with a regression coefficient of 94.01%. In addition, the existence of the polysaccharide has been confirmed by the characterization of the galactomannan obtained from C. colocynthisis obtained by Fourier transform infrared-attenuated total reflection, IR-Raman spectroscopy and X-ray diffraction.

The present research aims at studying the kinetics of non-isothermal crystallization of the polyamide 66 matrix and its composites with the presence of a glass fiber load. To achieve that goal, the non-isothermal crystallization of polyamide 66 has been studied by means of DSC. The ratio of tested reinforcement varies from 7% to 50% of glass fiber in mass. The modeling, by the theories of Jeziorny and those of Mo, has allowed us to study the influence of adding this reinforcement, as well as the variation of the rate of cooling, on the kinetics of crystallization of the composites in question, which has been manifested by a remarkable change in the nucleation mechanism of the polyamide 66 matrix. Regarding the reinforcement effect, the incorporation of the glass fibers load into the polyamide 66 matrix has caused the appearance of exothermic peaks in a higher temperature range and that for all the working materials. Finally, the results showed that the Mo model is the most suitable for the study of polyamide 66/glass fiber crystallization kinetics.

This study presents the effect of the addition of 0.4 wt.% carbon black (CB) to polyamide 66 (PA66) containing 30 wt.% short glass fibers (GFs) on the behavior of composite thermal crystallization. Composites were studied by differential scanning calorimetry analysis (DSC) at different cooling rates using wide-angle X-ray scattering (WAXS) and scanning electron microscopy (SEM). This thermal crystallization study highlights the nucleation effect of GFs that promote PA66 crystallization by significantly increasing crystallization kinetics and rates. The activation energies (Eas) calculated by model-free (FWO; KAS) and model-fitting (Kissinger method and C–R method) approaches showed that the combination of both GF and CB decreases the activation energy with respect to neat PA66, meaning that the presence of both additives facilitates crystallization. The Coats–Redfern and Criado methods showed that the crystallization of neat PA66 and related composites follows the second-order reaction, i.e., the decelerated reaction, evidencing compatibility between GFs and the matrix.