Preparation And Research Of Cellulose Packaging Film Based On Dissolution And Regeneration Process

Cellulose is one of the most common,widespread,and diverse natural polymer materials on the earth.It is not only safe,non-toxic,renewable,and degradable but also has excellent properties,so it is generally considered to be a substitute for petroleum-derived materials in the future.But at present,the cellulose films have some problems,such as harsh dissolution condition,complex preparation process,and poor comprehensive property.As a result,the paper used the commercial cellulose powder as raw material and LiCl/DMAc as solvent to dissolve the cellulose by a simple activation method.Using the prepared cellulose solution as the film-forming solution,the high-performance cellulose packaging films were prepared by optimizing the process and adding the reinforcing phase and the packaging properties of the films were tested and evaluated from various aspects.The research results are as follows:?1?Based on LiCl/DMAc solvent,the solubility,dissolution process,and rheological properties of cellulose were studied.The water-methanol-DMAc activation method and stirring speed above 1000r/min make cellulose have the most dissolution at the same time.4g of cellulose powder can be dissolved under high mixing speed at room temperature for 40min.The long fibers have blisterings and shreddings in the dissolution process.The viscosity of the cellulose solution increases exponentially with the concentration,increases slightly initially then decreases sharply with shear rate and oscillation frequency,which indicates the cellulose solution is a shear-thinning fluid.The viscoelastic property of the cellulose solution increases with oscillation frequency,and it is elastic in general.?2?Cellulose films?RCs?were prepared by dissolving,casting,gelling,regeneration and drying processes,and the effects of the cellulose particle size,solution concentration,and gel time on the mechanical properties,barrier properties,optical properties and thermal properties of RCs were investigated.Results of the orthogonal tests using tensile strength,elongation at break and oxygen permeability coefficient as the evaluation factors show that the solution concentration has the most significant effect on the tensile strength and the cellulose particle size has the most significant effect on the elongation at break,but all the factors and levels have no significant effect on the oxygen permeability coefficient.When the preparation conditions are the best,the tensile strength,elongation at break,and oxygen permeability coefficient of RCs are 111.1MPa,27.3%and 2.21×10^-17 cm³·cm·cm^-2·s^-1·Pa^-1.?3?TEMPO-oxidized cellulose nanofibers?TOCNs?were prepared by the method of the TEMPO/NaClO/NaClO₂ oxidation treatment combined with ultrasonic breaking treatment,and the effects of ultrasonic time on the physical properties of TOCNs were studied.With the increase of the ultrasonic time,the value of Zeta potential exceeds 30mV,the PDI is less than30%,and the lowest average particle size can reach 54.32nm,which all indicates that the stability of solution and uniformity of particle are significantly enhanced.All-cellulose composite films?ACCs?were prepared by using TOCNs as reinforcement based on the two-step method and the effects of TOCNs on ACCs were studied.When the TOCNs content is 1.0wt%,the comprehensive mechanical properties of ACCs are the best,tensile strength,younG's modulus,elongation at break and breaking energy is 134.3MPa,6.06GPa,21.6%and21.51MJ·m^-3 respectively.When the TOCNs content is 1.6wt%,the oxygen barrier property is the best,and the oxygen permeability coefficient is only 1.47×10^-17 cm³·cm·cm^-2·s^-1·Pa^-1,but the addition of TOCNs slightly reduces the transparency and thermal stability of ACCs.?4?Comparing the main packaging properties of regenerated cellulose-based films with the ordinary plastic films,the results show that the transparency of regenerated cellulose films is good,the tensile strength and oxygen barrier property are far superior to common plastic films,and the oxygen barrier property is even comparable to EVOH,but the tenacity and moisture resistance are poor.