Study Of Properties Degradation Of Recycled Plant Fibers In Physical Behavior

Recycling of waste paper is an important measure to reduce pollution and protect ecological balance. As the first process of making raw materials, pulping and refining are the key steps to use waste paper, and have an important impact on the effectiveness of waste paper utilization. Therefore, the research of refining and pulping process is an important issue to improve the effectiveness of waste paper utilization and reduce environmental pollution. In this study, feature of properties degradation of recycled plant fibers in pulping and refining process is researched, providing theoretical support to improve the effectiveness of waste paper utilization; and based on this theory, pulping and refining equipment is ameliorated, to delay the fiber degradation and improve fiber quality.The results show that the factors, such as pulping concentration, rotor speed, time, temperature, pH have impacts on fiber properties and sheet strength; hydrogen bond strength of fiber is changed in the pulping process, and affect the fiber crystallization conditions; In addition, the investigations on effect of pulping on average pore size and BET surface area had been done with low-temperature N2 adsorption-desorption method. The results indicated: pulping has a small impact on average pore size, but the cumulative pore volume increased 30.95%, BET increased 18.31% when pulping 20min.New pulping rotor was designed and optimized with advanced 3D design software Pro/Engineer, and study of working with pulp time 10min, the rotor speed 900rpm, pulp concentration 12%, pH 12, pulping temperature 40℃shows that, the new rotor broken paper faster and cyclostationary , achieving a high pulping concentration of more than 12%;Production capacity increased by 20% and power consumption per unit mass of slurry decreased 12.8%; fines contents increased 5.50%, fiber length decreased by 2.04% , the water retention value increased 5.35%, the two main strength index of tensile index and tear index increased by 4.77% and 5.76%; average pore size decreased of 4.72%, BET increased 17.59%. Compared with the old rotor, the new rotor has obvious advantages.The results show that, fines content increased over 10% by refining, refining with concentration 6% below has a certain degree of cutting function on the fiber, average length of the first and second recycled plant fibers decreased 8% and 8.16%; Refining can improve the quality of the recycled fiber, so tensile index of third recycled fiber increased 39.90%, 27.77%, 18.90%; Swelling properties of fiber was improved, WRV of the first and third recycled fiber increased 32.06%, 37.7%, But with the increase of recycled times, the effect of refining on improving the quality of secondary fiber gradually weakened; with the increase of the refining degree, crystallinity increased slightly and then decreased, cellulose hydrogen bonds increased firstly and then decreased; Average pore size, cumulative pore volume and BET increased with raise of refining degree .New refining grinding was designed and optimized with advanced 3D design software Pro/Engineer, and study of working with time of 10min, grinding concentration of 6%, gap of 0.3mm shows that: refining time of the new grinding shorten to 10min from 20min, production capacity increased 50%, power consumption per unit mass of slurry saved by 13.6%; fines content increased 5.18%, fiber length increased 4.54%, WRV increased 4.13%, tensile index and tear index increased by 7.01% and 6.88%; BET increased 2.61%, average pore size increased 9.35%,Cumulative pore volume increased 12.51%. Compared with the old grinding, refining effect of the new grinding has been greatly improved.