Negin Ghahrani; Noraldin Nazrneghad; Omid Ramezani; Ghasem Asadpour
Abstract
One of the common applications of cellulose is dissolving pulp producing that requires high purity. Different cellulose sources are used to produce dissolving pulp. Due to Deforestation and lack of agricultural land and problems with cultivation, the use of wood and non-wood sources of cellulose is declining. ...
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One of the common applications of cellulose is dissolving pulp producing that requires high purity. Different cellulose sources are used to produce dissolving pulp. Due to Deforestation and lack of agricultural land and problems with cultivation, the use of wood and non-wood sources of cellulose is declining. Another source of cellulose is recycled pulp. Chlorine dioxide acts as a completely selective bleaching. Increasing kappa factors is very effective in removing lignin levels. In this research, dissolving pulp from recycled fibers is obtained during soda cooking and bleaching with chlorine dioxide. Then, the effect of changes in kappa factor of the second stage of chlorination on chemical composition (holocellulose and lignin), structural properties (degree of polymerization, alpha-cellulose and degree of brightness) and accessibility (water retention value) are investigated. The results showed that the degradation of holocellulose levels was not severe and did not cause cellulose damage and decreased alpha-cellulose levels as well as the degree of polymerization. The removal of lignin as a hydrophobic component and the presence of hemicellulose as a hydrophilic component increase accessibility (water retention) and decrease brightness degree.
Pulp and paper
Zohreh Taheri; Hamidreza Rodi; Hossein Jalali-Torshizi; Reza Shidpour
Abstract
DOR:98.1000/1735-0913.1398.34.112.66.1.1578.1610 Nowadays, the barrier property against water take up of different packaging papers which mostly prepared from recycled fibers is of highly significance for paper manufacturers. In current study, the effect of AKD sizing agent has been examined on the properties ...
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DOR:98.1000/1735-0913.1398.34.112.66.1.1578.1610 Nowadays, the barrier property against water take up of different packaging papers which mostly prepared from recycled fibers is of highly significance for paper manufacturers. In current study, the effect of AKD sizing agent has been examined on the properties of papers made from recycled fibers of Atrak pulp and paper industries. Sizing of pulp suspension using AKD was conducted at levels of 0, 0.5, 1 and 1.5 % based on oven dry (OD) pulp in neutral pH (7), according to the TAPPI standard methods. Then, by preparation of handsheets with basis weight of about 60±3 g/m2, their Cobb test (60 second) and different characteristics were evaluated. According to the statistical analysis of the results, up to 1 % AKD consumption amount based on OD pulp exhibited for optimum level in internal sizing of these recycled fibers. In such AKD level, water take up of size-free papers revealed 174±7.4 g/m2, decreased to the value of about 24±1.7 g/m2 in AKD-treated papers. Further, contact angle of water droplet with the paper surface increased from 35.2º to 109.1º. Applying 1 % of AKD, paper tensile index increased to 33.2±1.01 N.m/g by 2.4 unit compared to the base paper. Apparently, such phenomena can be attributed to the AKD potential in creating hydrogen bonds which concurrent to the development of paper water repellency, resulted in improving bonding-ability of paper network. Additionally, AKD treatment led to in meaningful increase of paper opacity. This can also be attributed to the increase in filler retention in fibers network, which influences the development of light scattering from the paper surface.
Pulp and paper
Fatemeh Naijian; Hossein Resalati; Hamid reza Rodi; Hossein Jalali-Torshizi; Kamal Pirmoradian
Abstract
Nowadays, recycled fibers are the main fiber source for manufacturing packaging papers. Sizing of such papers, based on the type of application, is of great importance. In this research, the effect of alum-cationic rosin consumption amount in pH of about 6.5 on the properties of papers made from white ...
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Nowadays, recycled fibers are the main fiber source for manufacturing packaging papers. Sizing of such papers, based on the type of application, is of great importance. In this research, the effect of alum-cationic rosin consumption amount in pH of about 6.5 on the properties of papers made from white sheets trimmings was examined. In order to optimize consumption extent, pulp suspension sizing with alum in six level of 0, 4, 5, 7, 8, and 10 %, and rosin with the ratio of 50 % of alum based on oven dry (OD) pulp was done according to the TAPPI standard methods. Then by preparation of handsheets with basis weight of about 65±5 g/m2, their Cobb test (45 second), structural and strength characteristics were investigated. Statistical analysis of the results have shown that alum and rosin consumption amount of about 7 and 3.5 % based on OD pulp is the best suitable level for internal sizing of white sheets trimmings fibers. In these alum-rosin level, Cobb value of papers decreased from 120±11.6 g/m2 the lowest value of about 64±9.7 g/m2. Contact angle of water droplet with the paper surface increased from 24.81º to 96.53º. Paper tensile index decreased up to 125±9.7 N.m/g by such sizing level and again increased with increasing alum-rosin level. Seemingly, such phenomena can be attributed to the alum role in charge neutralizing, cellulosic fines retention and improving bonding-ability of paper network. Meaningful decrease of paper surface roughness from 10.34±0.54 µm in control sample to 8.23±1.37 µm in sized papers in optimized level confirmed this assumption.
Pulp and paper
Hamid reza Rudi; Morteza Nazeryan
Abstract
In this study, the effect of using Layer-by-Layer (LbL) treated pulp as mixed with refined OCC recycled pulp was investigated on paper physical properties. The LbL treatments were conducted to build 7 consecutive cationic and anionic starch layers. Afterwards, at three levels of 10, 20 and 30 percent, ...
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In this study, the effect of using Layer-by-Layer (LbL) treated pulp as mixed with refined OCC recycled pulp was investigated on paper physical properties. The LbL treatments were conducted to build 7 consecutive cationic and anionic starch layers. Afterwards, at three levels of 10, 20 and 30 percent, LbL-treated pulp was added to the 10, 15 and 20 minutes refined pulp. From mixed pulp, handsheets with basis weight of 60 g/m2 were prepared and its physical properties including: thickness, density, roughness and formation was examined. The results of LbL treatment using AFM micrographs indicated that the surface of fibers was covered with starch polymer particles by means of Layer-by-Layer treatment. Also, SEM micrographs confirm starch impregnated fibers surface and formation of rough surfaces. Analysis mutual effect of independent variables revealed that addition of LbL-treated pulp to the refined recycled pulp had only significant effect on paper thickness and surface roughness, while variation of refining time had significant influence on all physical properties. In current research, considering the results of ANOVA test and the mutual effect of the content of LbL-treated pulp and different refining time levels on the paper physical properties using response surface methodology, adding of 10 % of LbL-treated pulp to the OCC pulp and applying the refining time of about 18.66 minutes was selected as optimum condition.
