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Fatliquoring is one of the most important processes in leather making, in which the collagen fibers are split effectively, while the crust acquires a good softness and mechanical strength. The effectiveness of fatliquoring depends not only on the variety and dosage of fatliquoring agent but also on its distribution in hierarchical collagen fiber la...
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... Figure 2 shows DSC curves of the polyols (A) and the three PU formulations (B) studied. Castor oil is a unique vegetable oil with good low-temperature fluidity and no crystallization temperature (as observed in the DSC curve), different from other natural oils such as sunflower oil [30]. The T g of the CO (red line) and PE (black line) polyols is observed at − 67 °C and − 55 °C, respectively ( Fig. 2A). ...
The tuning of the viscosity of polyurethane (PU) during its polymerization enables its use in different applications including the liquid composite molding (LCM). In this work, the rheological behavior during polymerization of PU from castor oil (CO), polyether (PE), and a mixture of both polyols (COPE, 50/50 wt%) was investigated using oscillatory rheometry at different isotherms (40, 50, 60, 70, and 80 °C). Approaches based on artificial neural networks (ANNs) and response surface methodology (RSM) were used for data analysis and to obtain prediction tools related to the PU polymerization. This approach can contribute to experimentally estimate new formulations to obtain information that kinetic models based on conversion rates are unable to provide. The polymerized PU(CO), PU(COPE), and PU(PE) compositions showed flexible phase Tg of 15, − 13, and − 30 °C, respectively. Due to the greater reactivity of the PU(CO), its viscosity increased faster than that of PU(PE). The balance of properties obtained with the mixtures of polyols resulted in viscosity values of 300, 500, and 1000 mPa s, which are suitable for the LCM. This approach shows the combination of ANN and RSM can be advantageous to complement the kinetics analysis of PU resins with tunable properties for the LCM.
Highlights
Rheokinetics of PUs analyzed using oscillatory rheometry.
Experimental data examined with neural networks and response surface methodology.
Successful utilization of ANN and RSM for predicting PU polymerization.
Combined ANN and RSM enhance kinetics analysis of PU resins.
This approach reveals viscosity values suitable for composite liquid molding.
... It has been applied in the location of enzymes, [22][23][24] acrylic resin retanning agents, [25][26][27] amino resin retanning agents 28,29 and fatliquors. [30][31][32] The brief procedure for this technique is described below. Fluorescein was used to label these chemicals via covalent binding at first. ...
Dialdehyde polysaccharides possess a sustainable nature and good tanning performance. However, the lack of specific detectable groups in their molecular structure results in the difficulty in the determination of the location of dialdehyde polysaccharides in leather fiber networks. In this study, dialdehyde sodium alginate (DSA) tanning agent was fluorescent labeled by 5-(4,6-dichlorotriazinyl) aminofluorescein (DTAF). The purified DTAF-DSA showed high and stable fluorescent intensity at emission wavelength of 515.2 nm when the pH was over 6.0, and the temperature was in the range of 20°C to 50°C. DTAF-DSA was used in tanning and tracked using fluorescence microscopy. Its penetration in the fiber network could be clearly visualized, and its distribution in leather differed with the molecular weight of DSA. As a result, this fluorescence tracing technique could display the mass transfer behavior of dialdehyde polysaccharide tanning agents in leather matrix, which will provide underlying data for tanning mechanism exploration.
The traditional wet-finishing process for leather manufacturing is complicated and uses numerous chemical additives, limiting the leather industry's development in the direction of energy saving and emission reduction. Integrated with...
Fatliquors are very important chemicals (chemically modified products of animal and vegetable oil) used during the fatliquoring process, a unit operation in the leather making measure and helps to maintain the softness and flexibility of leather. A fatliquor is utilized to lubricate and reduce the friction between the leather fibres with different chemical compositions/structures (or ratios) for making leather. In this paper we examined the physicochemical properties of different types of fatliquors (viz., phospholipid, silicone, paraffin and synthetic oil-based, etc.) by different techniques (viz., conductometric, viscometric, DSC and TGA (thermal behaviours), microscopic, particle size (mean/average), the zeta potential, etc.). The present study will guide to make or formulate fatliquors which will help to improve the quality of the leather according to the market demands. The information in this work’s findings will assist in choosing a reasonable fatliquor for planning a fatliquoring manner for improving quality leather.
