Evolution of Physicochemical Structure of Waste Cotton Fiber (Hydrochar) During Hydrothermal Carbonation

To study the hydrothermal behavior of cotton fiber, the carbonization process and structural evolution of discarded or waste cotton fiber (WCF) under hydrothermal conditions were investigated using microcrystalline cellulose (MCC), and glucose was used as a model compound. Results showed that high temperature was beneficial for the hydrolysis of discarded cotton fiber, and the yield of sugar was 4.5%, which was lower than that of MCC (6.51%). WCF and MCC were carbonized at 240–~260°C and 220–~240°C, respectively, whereas the carbonization temperature of glucose was lower than 220°C. The C/O ratios of WCF and glucose hydrothermal products were 5.79 and 5.85, respectively. The three kinds of hydrothermal carbonization products had similar crystal structures and oxygen-containing functional groups. The carbonized products of WCF contained many irregular particles, while the main products of glucose carbonization were 0.5-mm-sized carbon microspheres (CMSs). Results showed that glucose was an important intermediate in WCF carbonization and that there were two main pathways of hydrothermal carbonization of cotton fibers: some cotton fibers were completely hydrolyzed into glucose accompanied by nucleation and then the growth of CMSs. For the other part, the glucose ring of the oligosaccharide, formed by the incomplete hydrolysis of cotton fibers under hydrothermal conditions of high temperature and pressure, breaks and then forms particulate matter.

Modal analysis of 3D needled waste cotton fiber/epoxy composites with experimental and numerical methods

The small-size microstructure models of the 3D needled waste cotton fiber/epoxy composites (3DNWCFCs) were brought out to predict their key vibration parameters (natural frequency and mode shapes) with the finite element analysis method. Six kinds of 3DNWCFCs with different parameters were prepared and tested by the experimental modal analysis method to verify the accuracy of the prediction of the natural frequencies and mode shapes with the finite element method. The effects of the fiber volume content and needling density of the composites on the modal behavior were investigated. The natural frequency of the cantilever beams of the composites increased with the increase of the fiber volume content and increased at first then decreased with the increasing needling density. The effect of needling density on the vibration properties of the composite depended on the degree of damage and entanglement of Z-direction fibers. The comparative analysis of the finite element analysis and the experimental results showed that the small-size microstructure models of the 3DNWCFCs were effective to predict their vibration parameters. Therefore, the small-size finite element models can be used to predict the modal properties of the staple fiber reinforced composites effectively with less time and lower economic costs.

Preparation and Characterization of Biodegradable Cotton Mulching Film

The extensive use of plastic film has caused serious environmental pollution. In this paper, the fully degradable cotton mulching film was produced from waste cotton fiber by wet papermaking process. The breaking strength, tearing strength, degradation rate, transparency, air and moisture permeability of the cotton film samples were tested and analyzed. The results show that the cotton mulching film has better mechanical properties, light transmittance, and excellent degradation characteristics.

Preparation and Analysis of Cotton Nonwoven Film Strengthened by Chitosan

The invention of plastic film has brought not only convenience but also environmental pollution to people. To use natural vegetable fiber is the mainly approach to solve the problem. In this paper, the waste cotton fiber was used as raw material and the cotton nonwoven sample was made through wet laying process, after strengthened by chitosan, degradable film was prepared. The performances of the film were characterized and analyzed by testing the strength, air permeability, moisture permeability and other indexes. The results showed that chitosan can be used as strengthening agent, the performances of the film strengthened were improved, and it was degradable.