Green Method for Production of Cellulose Multifilament from Cellulose Carbamate on a Pilot Scale

Abstract

In the cellulose industry, the viscose process is still occupying the leading position, although this process generates several environmentally hazardous byproducts. Here we report a novel method for the production of cellulose multifilament from cellulose carbamate (CC) on a pilot scale. In this method, CC was first prepared efficiently by microwave heating; it was then dissolved in NaOH/ZnO aqueous solutions through a freezing–thawing process. Wet spinning of the CC solution was performed on a pilot-scale machine. The cellulose multifilament displayed a dense circular microstructure and excellent physicochemical properties. The tensile strength and elongation at break of the multifilament in dry state were 2.58 cN/dtex and 12.1%, respectively. Moreover, the process could utilize most of the conventional equipment for the viscose method, which could have a great impact on the current cellulose industries.

Improved Synthesis of Cellulose Carbamates with Minimum Urea Based on an Easy Scale-up Method

“…As illustrated in Figure 10, the chemical shifts of C1 (105.2 ppm), C4 (87.8) ppm, C5 (75.0 ppm) and C6 (62.8 ppm) for the both parts are almost the same as those for regenerated cellulose fibers from CC-NaOH/ ZnO solution. 33,34 In a comparison of the dissolved part, the C4 peak of the insoluble was relatively weak. The previous studies revealed thermal treatment of cellulose would lead to decrease of bands associated with hydroxyl and glycosidic groups, especially in the C4 signal.…”

Structure and Properties of Regenerated Cellulose Filaments Prepared from Cellulose Carbamate–NaOH/ZnO Aqueous Solution

“…Moreover, there were neither organic transfer mediums (xylene) nor catalytic agents (sodium carbonate) used, and the energy savings was over 50% when compared to the conventional synthesis of CC. 31 Furthermore, the ZnO could be well recovered from the coagulation bath and washing water by adding CaO through the two-step precipitation method. 46 Therefore, the novel carbamate process demonstrated great potential for the production of high-quality cellulose multifilament in a much more environmentally friendly and economic way, in addition to potential for applications in the development of viscose-like products.…”

“…Most recently, it was determined that the solubility of CC could be significantly improved with the addition of a small amount of ZnO to the NaOH solution. 31 Moreover, green methods for the production of cellulose multifilament and membranes from CC have been reported. 31,32 The lower cost and lower toxicity of our novel carbamate method, and its relative ease for wet spinning, exhibited some good promises for the development of a more economic and environmently friendly process for regeneration of RC fibers.…”

Cellulose modification and shaping – a review

“…A process, which is analogous to the viscose process, is the carbamate process, where cellulose is reacted with urea to form cellulose carbamate [70]. Cellulose carbamate can then be processed in a similar manner as cellulose xanthate, but without the release of harmful compounds [71]. However, the process has not yet reached commercialization, most likely due to insufficient fiber properties.…”