جستجوی مقالات مرتبط با کلیدواژه « optical » در نشریات گروه « صنایع چوب و کاغذ »

In this study, the influences of nano-chitosan and poly-DADMAC on the optical and mechanical properties of chemi-mechanical pulp (CMP) were evaluated. For this purpose, some of the bleached CMP pulps of Mazandaran Wood and Paper Industries (MWPI) were randomly selected as a control sample. In addition, the poly-DADMAC were used as a white powder at 4 levels of ‎0, 0.3, 0.5, and 0.7%. The nano-chitosan was then added to the CMP pulps suspensions at 3 levels of 0, 1, and 2%, as well. Hand-sheets with a basis weight of 60 gr/m2 were prepared from the mentioned pulps. The optical and mechanical properties were measured and compared using TAPPI standard test methods. The results showed that by adding poly-DADMAC to the CMP pulps, brightness, a* factor, breaking length, tensile and burst strengths ‎increased, but yellowness, greenness and Cobb 60 decreased and opacity, tear strength and air resistance‎ not sensible changed. The results indicated that the brightness, a* factor, opacity, tear strength, burst strength and air resistance were increased and greenness and water absorption and were decreased by increasing nano-chitosan amount. In this condition, the suitable properties showed that in handsheets from adding nano-chitosan to CMP pulps. When poly-DADMAC and nano-chitosan were added simultaneously to CMP, the brightness, opacity, a* factor, tear strength, burst strength and air resistance were suitable increased, but yellowness, water absorption and greenness were decreased. Moreover, the findings showed that by simultaneous adding 2% nano-chitosan (separate) and 2% nano-chitosan with 0.5 and 0.7% poly-DADMAC to the CMP pulp, most of the paper properties were improved. Therefore, ‎it can also be introduced as the best treatment.

This study was aimed to investigate the effect of polyalumium chloride and ‎nano-chitosan on optical and mechanical properties of chemi-mechanical pulp. For this purpose, some of the bleached CMP pulp of Mazandaran Wood and Paper Industries (MWPI) were randomly selected as a control sample. In addition, the polyalumium chloride were used as a white powder at 4 levels of ‎0, 0.5, 1, and 1.5%. The nano-chitosan was then added to the CMP pulps suspensions at 3 levels of 0, 1, and 2%, as well. Hand-sheets with a basis weight of 60 gr/m2 were prepared from the mentioned pulps. The optical and mechanical properties were then measured and compared using TAPPI standard test methods. The results showed that by adding polyalumium chloride and nano- chitosan(separate) to the CMP pulps, brightness, opacity, greenness,tear, tensile, burst strengths, air resistance‎ ‎increased , but Cobb 60 and a* factor ‎decreased. On the other hand, with the addition of nano-chitosan and polyalumium chloride to CMP pulp, the brightness and greenness increased, but tensile, burst, tear strengths, air resistance, Cobb 60 and opacity low decreased and then suitable increased. Moreover, the findings showed that by simultaneous adding 1% polyalumium chloride and 2% nano-chitosan(separate) and 2% nano-chitosan with 1.5% polyalumium chloride to the CMP pulp, most of the paper properties were improved. Therefore, ‎it can also be introduced as the best treatment.

This study was aimed to investigate the effect of cellulose nano-fibers and ‎chitosan on optical and mechanical properties of chemi-mechanical pulp. For this purpose, some of the bleached CMP pulp of Mazandaran Wood and Paper Industries (MWPI) were randomly selected as a control sample. In addition, the cellulose nanofibers were used as a white gel at 3 levels of ‎0, 2, and 3%. The chitosan was then added to the CMP pulps suspensions at 5 levels of 0, ‎‎0.5, 1, 1.5, 2%, as well. Hand-sheets with a basis weight of 60 gr/m2 were prepared from the mentioned pulps. The optical and mechanical properties were then measured and compared using TAPPI standard test methods. The results showed that by adding chitosan, tear, tensile, burst and breaking length strengths, air resistance, ‎yellowness, and greenness ‎increased and brightness, Cobb 60 and a* factor ‎decreased. On the other hand, with the addition of chitosan and nano-‎cellulose to CMP pulp, the tensile, burst, breaking length strengths, air resistance, Cobb 60, yellowness and a* factor ‎increased and the tear, brightness, and opacity decreased. Moreover, the findings showed that by simultaneous adding 2% chitosan, 2% chitosan, and 3% cellulose nanofibers to the CMP pulp, most of the paper properties were improved. Therefore, ‎it can also be introduced as the best treatment.

To reuse recycled cellulosic fibers in paper production, contaminated particles and other impurities of the fibers can be greatly removed using a de-inking stage which is considered as a supplementary step in waste paper recycling technology. The effect of using ultrasonic pretreatment on the deinking of old newspapers was investigated utilizing the common conventional chemical method across this research work. Experimental design method was served to optimize the amount of ultrasonic bath temperature and sonication time. Therefore, 13 tests were designed using Response Surface Methodology (RSM) and Central Composite Design with Design Expert 7.0.0 Trial software. Ultrasonic bath temperature and sonication time at three different levels (1, 0 and 1+) and two axial points (α + and α-) were used as independent variables, and the optical and mechanical properties of handsheets were used as dependent variables. Response surfaces and contour plots were served to show the interaction between the independent variables and the response variable. ANOVA test showed that the quadratic model is the best model to explain the interaction among the studied variables. The predicted values of the obtained model had much conformity with the experimental results (R2=0.98). According to ANOVA results, it can be concluded that the effect of each of the variables on the optimal properties is significant and the ultrasonic time is the most effective factor on the response. According to the results, the proposed optimum conditions to achieve the highest amount of mechanical and optical properties (43.43) are the ultrasonic bath temperature 47 oC and the ultrasonic time of 31 min.

In recent years, environmental problems of irregular wood harvesting and shortages of raw materials made wood and paper Ind. & country to be faced serious crises. And some researchers and industry experts have led to fundamental and long-term solution for supplying raw materials to these industries. This present study aimed to determine the optimum conditions of pulping and bleaching for several hardwood forest species (as a separate cooking & Combining with 40% popular, 15% beech and hornbeam 45%) and paper evaluation. After preparing CMP in accordance with the terms of an 85% efficiency , Different cooking times (25-60 minutes, temperature of 170 °C, the ratio of L TO W & 7 TO 1 and Making hand sheet with standard 60 gram per square meter, Optical and mechanical properties of paper was evaluated. The results showed that, A species that was used in cooking, Poplar were better in terms of total properties with mechanical and optical properties. Also in Bleaching stage, the tensile strength index is decreased & Burst and tear strength index is improved. The maximum brightness is related to poplar species with mixing and without species and after bleaching the beech is the lowest ones. In both methods the rate of opacity and yellowness is decreased.

The objective of this research was accomplished on the effects of total chlorine free (TCF) and elemental chlorine free (ECF) bleaching on optical and mechanical properties of bagasse soda pulps. For this purpose, some unbleached bagasse soda pulps were randomly selected from Ahvaz Pars industry. Then these pulps were bleached with one, two and three P, OP, OPY, O(Ep)P, EHP and O(Ep)H bleaching stages by using oxygen(O) hydrogen peroxide(P), alkali extraction with hydrogen peroxide(Ep), sodium hypochlorite(H) and sodium dithionite(Y). The hand sheets with 70 gr/m2 were prepared from above-mentioned of pulps, and then the optical and mechanical properties were measured and compared according by using TAPPI standard test methods. The results showed that brightness, greenness, tear (except EHP stages), tensile, burst, breaking length strengths and folds were increased and opacity and a* factor were decreased by ECF and TCF bleaching stages. The effects of TCF bleaching stages were more sensible than ECF bleaching stages in improve of bagasse soda properties, too. In general, role of three OPY and O(Ep)H stages and two OP bleaching stages were better than EH(control) stage and unbleached bagasse soda pulps mill in improve of brightness and its paper strengths, too.

This study and it aim was accomplished on the effect of TCF bleaching on optical and mechanical properties of CMP pulp. For this purpose, some unbleached CMP pulps were randomly selected from Mazandaran Wood and Paper Industries (MWPI). Then these pulps were bleached with two and three OP, OPY, PY and O(Eo)P bleaching stages by using oxygen(O), alkali extraction with hydrogen peroxide(Eo), sodium dithionite(Y) . The hand sheets with 70 gr/m2 were prepared from above-mentioned of pulps, and then the optical and mechanical properties were measured and compared according by using TAPPI Standard test methods. The results showed that brightness, greenness, folds breaking length, tensile and tear strength were increased and opacity and a* factor were decreased. In general, role of three O(Eo)P stages and two OP and PY bleaching stages were better than P stage and unbleached CMP pulp mill in improve of brightness and its paper strength, too.

In this study, the possibility of using ash and orange bleached CMP pulp as replace in the full or part of CMP pulp of Mazandaran Wood and Paper Industries (MWPI) for making newsprint was investigated. For this purpose, first, ash and orange CMP pulps were prepared by using cooking conditions of MWPI with 101 gr/lit Na2O at the yield 85% in 75 minutes. Then some of the CMP pulps bleached with hydrogen peroxide, then its mixed samples with 15, 30, 45 and 60 percent to CMP pulp mill (control sample). From the mixed pulps provided hand sheets with 60 gr/m2 and these optical and mechanical properties measured and the data average were analyzed and compared. The results showed that newsprint from ash CMP pulp were more suitable than CMP pulp mill in all measured properties (except brightness) and orange CMP pulp (except opacity). Following bleaching with hydrogen peroxide, the brightness, tear, burst, tensile and breaking length strengths increased and opacity decreased. The results showed that ash and orange unbleached CMP pulps are not good properties for newsprint production and these pulps have to bleach with hydrogen peroxide. In generally, the best mixed pulps were includes 45-60 percent ash and orange bleached CMP pulps with 40-55 percent MWPI CMP pulp for newsprint production.

This study and it aim was accomplished on the effect of ECF bleaching on optical and mechanical properties of bagasse soda pulp. For this purpose, some soda unbleached pulps were randomly selected from Pars mill. Then these pulps were bleached with OD(Ep)P and OD(Ep)D stages by oxygen, chlorine dioxide and hydrogen peroxide. The hand sheets with 60 gr/m2 were prepared from soda unbleached and bleached from EH(control), OD(Ep)P and OD(Ep)D stages pulps, then the optical and mechanical properties were measured and compared according by using TAPPI Standard test methods. The results showed that residual lignin and kappa number decreased following above-mentioned of bleaching stages. The brightness, greenness and K/S ratio were increased in bagasse soda pulps by bleaching. In different treatments, the brightness, opacity, absorbance coefficient, burst, breaking length, tensile, tear strength sensible increased in OD(Ep)P and OD(Ep)D as compared with EH (control) mill bleaching stages. In general, first OD(Ep)P stage, then OD(Ep)D were better than EH (control) mill stage in more of were measured properties.

In this study the effects of oxidative bleaching and mechanical dispersion in different conditions on the optical and mechanical properties of deinked recycled pulp was investigated. Industrial deinked pulp was treated in the different conditions, including dispersion, combined oxidative bleaching during dispersion, and separate dispersion and then oxidative bleaching. Handsheet papers were made from obtained pulps and then scanned and taken photos were analyzed by Digimizer software, version 4.1.1.0 to analysis spot content. Optical and mechanical properties of obtained handsheets were determined and compared. Results indicated that mechanical dispersion decreased spot content and brightness and increased yellowing of the handsheets. Moreover, mechanical dispersion increased dry and wet tensile and burst strengths, water retention value (WRV), ash content and decreased tear strength of handsheet papers. This study revealed that combined dispersing and oxidative bleaching of de-inked pulp provided superior results in comparison to the separate dispersing and oxidative bleaching.

In the present research , the effect of utilizing a mixture of Birch with Hornbeam & Beech species (in the comparison with sample CMP( 75% Hornbeam 25% Beech) , on the mechanical and optical properties of papers produced within the domain of Freeness degree (CSF) of 300 ml and 85% yield has been reviewed . The CMP was prepared in accordance with 85% yield condition , different cooking times (30-120 min) , temperature of 170°C and white liquor ratio to chips in 7 to 1 & 20% Sulfide based on chips dry weight at 4 levels of 10, 20, 30 & 100% Birch mixed with Birch and Hornbeam species. After defibration and preparation of 60gm hand sheets, the optical and mechanical properties of that were assessed. The results indicated that by increasing the percentage rate of Birch , the quality of the manufactured paper was also increased and the best strength and optical properties were related to the 30 & 100% consumption rates of Birch in mixture with Beech and Hornbeam species.

This research and aim was using Bamboo and Reed CMP pulp for newsprint production. For this purpose, some chips of bamboo stem in the west of Mazandaran were randomly chosen. Then CMP Pulps were prepared at the yield 85%in 120 minutes(Bamboo) and 31 minutes(Reed), by using cooking conditions of Wood and Paper Industries of Mazandaran 60 gr/m2 newsprint handsheets were prepared from the Bamboo and Reed CMP and Mill(MWPI) CMP pulps, first in a separate and then mixed way with 25,50,75 percents. Then the optical and mechanical properties were measured and compared according by using TAPPI Standard test methods. The results showed that the most strength of the burst, breaking length, tensile, tear strength, yellowness and opacity were in the handsheets obtained from 100% the bamboo CMP pulp and the lowest strength (except brightness) was in Reed CMP pulp. The results also pointed out that the above-mentioned all strengths (except brightness) can be improved by using 25-100% of the bamboo CMP pulp, too. The results also indicated that 25-100% of the bamboo CMP pulp and 25% of the Reed CMP pulp can use for newsprint production.

In this study the effect of boiling water pretreatment on yield and optical, physical and mechanical properties of NSSC (Neutral Sulfite Semi Chemical) pulp of Golestan province wheat straw was investigated. Splinted wheat straw was pretreated with the boiling water (100 degrees) in the 10:1 ratio for 30 minutes. NSSC pulping carried out at constant condition including liquor to straw 10:1, maximum temperature 160ºC for 30 minutes. In order to study the effect of NaOH on strength properties of paper in some cases only Na2S03 were used. After pulping defibration was done by laboratory refiner to achieve 380±25ml (CSF). Hand sheets from each pulp with 60 gr/m² were made. The strength properties determined on the basis of TAPPI standard. Results show that pretreatment have a desirable effect on increasing the strength properties of papers such as and tensile, burst, breaking length, stiffness and density, except RCT strength other strengths of paper increase. Measuring the freeness of pulps showed that by increasing chemical contents specially NaOH freeness, yield, thichness and bulk decreased and density increased.