Study On The Prepartion Of Dissolving Pulp And Waterproof Cellulose Film From Waste Cotton Textile

The output of waste fabrics in China has reached nearly 150 million tons,but the recycling rate is less than 10%.Nowadays,the recovery of waste cotton textiles is mainly physical recovery and chemical recovery,but physical recovery is difficult to realize multiple recycling like chemical recovery.It has great application potential to recycle waste cotton fabrics to prepare dissolving pulp,so as to prepare regenerated cellulose products.Regenerated cellulose film has many advantages and is widely used in packaging field.At present,most of the regenerated cellulose films on the market are cellophane produced by viscose method,and the production process has caused great pollution to the environment.However,with the rapid development of economy,the state has paid more and more attention to the ecological environment.It is of great significance for the sustainable development of chemical fiber industry to prepare Lyocell cellulose films by recycling waste cotton fabrics to prepare dissolving pulp.In this paper,the film module for preparing Lyocell cellulose film was redesigned based on our previous research.The Lyocell process for preparing cellulose film from waste cotton fabric recycled dissolving pulp was investigated.The structure and performance differences of Lyocell cellulose films prepared from waste cotton recycled dissolving pulp and domestic raw cotton pulp were compared.Moreover,waterproof cellulose films were prepared by modification to extend the application.The following results have been achieved:Lyocell cellulose films from raw cotton pulp and waste cotton pulp showed relative surface smoothness.With the increase of the winding rate,the tensile strength of the raw cotton pulp cellulose flat film increased to 218.1 MPa,and the tensile strength of the waste cotton pulp cellulose flat film increased to 140.6 MPa.The contact angle(CA)of the plasticized Lyocell film from raw cotton pulp is 10.5~o,while the CA of the contour part from waste cotton pulp is 20~o.After plasticizing,the mechanical properties of plain film of raw cotton pulp and waste cotton pulp decreased.The above research not only verified the feasibility of Lyocell device for cellulose flat film using waste cotton pulp as raw materials,but also showed that the process and film properties sill have more potentials to be optimized.Lyocell cellulose films from raw cotton pulp and waste cotton pulp showed limited surface smoothness.With the increase of winding rate,the crystallinity of the two kinds of films increased.The tensile strength of the raw cotton pulp Lyocell cellulose film increased to 99.9 MPa,and the tensile strength of the waste cotton pulp cellulose film increased to 86.2 MPa.The lowest contact angle of cellulose film of raw cotton pulp is 13.0~o,and the lowest contact angle of cellulose film of waste cotton pulp is 15.6~o;After plasticizing treatment,the tensile strength of the two cellulose films decreased,the elongation at break increases,and solves the problem of brittleness for refolding.The above research verifies the feasibility of Lyocell device for cellulose tubular film from waste cotton pulp.However,the process can be further optimized to improve the film properties.Finally,the modification process of waterproof of cellophane with KH550 and polylactide acid(PLA)was investigated.The performance characterization results showed that when cellophane,waste cotton pulp cellulose flat film and waste cotton pulp cellulose tubular film were treated with0.5 wt%KH550/ethanol,the tensile strength was improved,and the water contact angle was increased to 96.9~o,46.1~o and 65.3~o respectively.The waterproof time of treated cellophane is better,and the waterproof effect of waste cotton pulp tubular film is the worst.When the above films were treated with 0.6 wt%PLA/dichloromethane,the water contact angle and tensile strength of cellophane,waste cotton pulp cellulose flat film and waste cotton pulp cellulose tubular film changed.The waterproof effect of cellophane treated with 0.6 wt%PLA is the best;The waterproof effect of waste cotton pulp flat film and tubular film is slightly reduced.Moreover,PLA can effectively improve the heat-sealing performance of regenerated cellulose films,among which cellophane has the best heat-sealing performance.In this paper,a Lyocell process to prepare cellulose flat and tubular films from waste cotton pulp was investigated.Moreover,a waterproof modification method for the film was studied.It is expected to realize the industrialization of Lyocell cellulose film in the future,which is of great significance to the sustainable development of chemical fiber industry.