| Abstract:This research carried out three recycling processes for US old corrugated container (OCC) 12# and US OCC 13#, investigating the variations in the properties of regenerated fibers and the mechanical strength of paper as well as the correlation between them. The results show that 13# has larger physical dimensions, a higher content of fine fibers, and more severe damage compared to 12#. After three recycling cycles, the fiber length-weighted average decreased by 10.8% and 15.7%, while the splitting length increased by 11.2% and 2.3% for 12# and 13#, respectively. Twisted and bent fibers decreased, while broken fibers increased. The fine fiber content decreased in 13# and initially increased then decreased in 12#. During the third cycle, the tensile and burst indices of paper made from 12# dropped by 21.4% and 10.2%, respectively, while 13# decreased by 10.7% and 2.6%. However, the folding endurance of both materials improved by 25.6% and 3.2%, respectively. The tear index of 12# increased, while 13# decreased. Generally, 12# exhibited superior mechanical strength. Grey relational analysis showed that the proportions of short fibers, fine fibers, and twisted fibers are the key factors affecting paper strength, mainly acting on fiber bonding. |