| China is a agricultural country with abundant straw resources,however,the utilization of straw resources is not perfect.As an important straw resource in China,corn stover used for industry is only about 3%.In this paper,a new high-yield pulp was prepared with environmentally friendly hydrothermal pretreatment using corn stover as raw material.The fines and fiber fraction were obtained by sieving treatment,and the characteristics of fines in the pulp were studied.The focus was on the effects of fines content and morphological changes to recycled pulp and corn stover pulp.It was expected that fines will be rationally utilized to realize the high-value utilization of corn stover.First of all,the content of fines in corn stover high yield pulp is high,accounting for about 2/3.It is mainly composed of parenchyma cells,vessel elements and other miscellaneous cells,and its shape is mostly short and coarse.The high pressure homogenization treatment can change the shape of the fines,break the original rod-like structure,reduce the size and produce more filaments.The treated fines can be more uniformly filled between the fibers.It has been found that the effect of the high pressure homogeneous fines was more obvious when the high pressure homogenization treatment pressure was 50?60 MPa.Secondly,the high content of fines adversely affects the properties of the pulp,and removal of some fines contributes to the improvement of pulp properties.When the fines removal rate was 30.7%,the tensile strength,burst strength and ring crush strength were increased by 16.0%,25.3%and 2.7%,respectively,compared with unsieved pulp.When the addition amount of the fines was 20%to fiber fraction,the tensile index increased by 16.8%and the burst index increased by 13.2%.When the addition amount of the fines was 30%to fiber fraction,the ring crush index increased by 5.0%.At the same time,the high pressure homogeneous fines fraction was added to recycled pulp and corn stover high yield pulp.The results showed that the addition of fines can improve the pulp properties.When the high pressure homogeneous fines was used at 5%,the degree of beating was increased to 41°SR,the tensile index,burst index,ring crush index and Z-direction tensile index of recycled pulp increased by 15.9%,20.3%,33.5%and 43.5%.In addition,the effect of adding the fines to fiber fraction of corn stover pulp was studied.When the addition amount is 5%,the tensile index,burst index,ring crush index and folding resistance are close to or exceed the corresponding indexes of unsieved pulp,while the degree of beating is only 25 °SR.(the unsieved pulp was55 0 SR),the dewatering performance is greatly improved.When the addition amount was 25%,strength properties of the pulp were well,but its beating degree is as high as 70°SR.Thirdly,results showed that the binary retention system composed of CPAM and the fines can significantly increase the retention of fines in the pulp.Compared with the blank control without any additives,the system also improved the water filtration.And when the amount of the fines was 0.6%(related to the oven-dry pulp),the best retention rate was obtained and the physical properties of the pulp were improved.Finally,the effect of surface sizing on the corn stover high yield was investigated using starch as the surface sizing agent.When the concentration of starch was 6%,the paper properties made from fiber fraction of corn stover high yield pulp was improved significantly. |
PDF Full Text Request