On the Use of a Twin Screw Extruder for Continuous Solid Feeding and Dissolution for Continuous Flow Processes

Synthesis and application of multifunctional lignin-modified cationic waterborne polyurethane in textiles

Waterborne polyurethanes (WPUs) often have limitations like inadequate weathering resistance and thermal stability. To overcome these shortcomings, lignin has been selected as a modifier for its abundant availability, renewability, and biocompatibility. This study synthesized a cationic WPU using isophorone diisocyanate and polyethylene glycol as raw materials. Hydrophilicity was attained through the inclusion of dihydroxyethyl dodecylamine as a chain extender, while the introduction of epoxy monomers and lignin served to modify the polyurethane. Furthermore, a dye dispersion for cotton fabric dyeing was prepared by combining the synthesized polyurethane, chitosan, and dyes. The cationic nature of the polyurethane played a crucial role in facilitating dye adhesion and uptake on the fabric surface, resulting in improved dyeing performance. The incorporation of epoxy side chains and chitosan cross-linking contributed to the excellent color fastness of the dyed fabrics. Moreover, the incorporation of lignin and chitosan endowed the fabric with antibacterial properties. Simultaneously, it provided effective UV protection, characterized by a high UV protection factor value for the fabrics. This lignin-modified WPU exhibits tremendous potential in applications such as textile coatings, adhesives, and color fixation agents. It effectively addresses the limitations of traditional WPUs and offers notable advantages, including a renewable source, cost-effectiveness, and biocompatibility.

Investigation of dissolution rate kinetics of bulk pharmaceutical feed streams within a stirred tank vessel and a twin screw extruder

The introduction of continuous manufacturing of pharmaceuticals has highlighted the challenging area of continuous dissolution of solids for work ups to flow chemistry systems. In this study, the use of a 16 mm twin screw extruder (TSE) as a platform technology for solid feeds is investigated using four solid pharmaceutical ingredients (PI) in a mixture of water and IPA. In order for comparison, the same experiments were also carried out in a batch traditional stirred tank vessel (STV). The objectives of this work are to gain further scientific understanding on dissolution kinetics and to compare kinetics in both a batch and continuous system. The concentration of each PI during dissolution is monitored using an in-line UV-ATR probe, allowing the extraction of dissolution kinetics. Faster dissolution rates are achieved in the TSE than in the STV due to higher power dissipation generated by the aggressive shear mixing and thermal energy within the TSE. Complete dissolution of paracetamol is obtained within the residence time of the TSE; complete dissolution of benzoic acid and acetylsalicylic acid are achieved at higher barrel temperatures; however full dissolution of nicotinic acid is not achievable in the TSE under the experimental conditions.