فهرست مطالب hossein jalali torshizi

In this study, the effect of alum- dispersed rosin sequence has been examined on different properties of papers made from recycled fibers. Therefore, reverse sizing recycled fibers with 0.5 consistency at pH6.5 was carried out by using 1 and 1.5 % alum, and 1, 1.5 and 2 % dispersed rosin, based on dry weight of pulp. Then, water absorption, optical and strength properties of papers with grammage (60±3 g/m2) were evaluated. Based on the results, to reduce the water absorption of papers, 1 % of both alum and dispersed rosin is required to achieve appropriate level of sizing. As a result, the water absorption of papers declined from 174±7.4 g/m2 to 36±0.4 g/m2, and the contact angle of water droplet with paper surface increased from 31.2 degree to 118.1 degree. Moreover, concurrent to the hydrophobicity of fibers surface formed by rosin molecules and its repellency impact of inter-fiber bonding, alum imparts an improvement of bonds in paper network owing to the neutralization of anionic trash and retention of cellulose fines. Paper opacity has been increased due to the development of filler retaining in fibrous web of paper.

Most of engineering applications require a series of properties which is not provided by a certain material. Therefore, composites production and utilization have extensively developed in various industries by materials combining. On the other hand, environmentally concerns compel environmentally friendly components in the composites manipulation. Then in this study, substitutability of imported synthesized Kevlar fiber by natural cellulosic fiber in epoxy resin matrix were investigated at presence and absence of nano bentonite. Dosages of 0.25 and 0.5 of fibers and 0.1 and 0.2 of nano bentonite were mixed into the epoxy resin and after bubble removal and complete curing, the composite panels were tested. The results showed that bubble removal and formation evenness mostly influenced the mechanical properties. So, tensile strength of 0.5% Kevlar composites was lower than its 0.25%. But opposite to the Kevlar, cellulose fiber increasing addition improved tensile strength and elasticity and rupture moduli properties, significantly. Consequently, 0.5% cellulosic fiber composite revealed higher the properties with lesser surface area demolished by the ballistic impact, which all attributed to shorter length of cellulosic fiber (1.8mm) compared to Kevlar (4.8mm), resulted in better composite formation. But Kevlar composite energy absorption (54 J) was higher than cellulosic composite (50 J). Individual incorporation of Kevlar and cellulose fiber into epoxy resin and their combinations with nano bentonite drastically reduced the demolished surface area (up to 10 cm2) and matrix cracks propagation with symmetrically pinned hole compared to the solely epoxy panels (10 cm2).

Providing some paradox properties of paper products at the same is of utmost challenging issues of papermakers, e.g., attaining proper strength together with high water absorbency in hygienic papers. Because higher bonding resulted in lesser accessibility to the hydrophilic functional group. Therefore, hydrogel as an ever-increasing material in bulk cellulosic diapers were surficial coated on paper and compared with distillated water saturated papers. The prepared chitosan-acrylic acid (AA) hydrogel converted into nanoparticles by ultrasonic homogenizer and the nano scaled particles approved by Dynamic Light scattering (DLS). SEM images and paper caliper revealed the nanohydrogel coating layer. All papers water uptake coated with 1, 1.5 and 2% nanohydrogel increased significantly up to 50% compared to the untreated sample. Burst and dry tensile strengths along with water uptake improved, with no toleration in tear strength. Increased fiber bonding due to plenty of carboxylic acid in AA together with hydroxyl and amine groups in chitosan, along with nanohydrogel film formation as a complementary assembly and constituent with the cellulosic substrate of paper were resulted in strength improvement. Wet tensile strength of paper revealed remarkable increment at 2% coating application, only; without enhancing effects at the lower dosages. Paper opacity, brightness and whiteness stayed almost stable, but due to chitosan yellowish nature, the paper yellowness increased. The coated paper stiffness enhanced compared to untreated paper, but revealed lesser stiffness than water saturated papers. Water treated papers revealed caliper, tensile and burst indices reduction and stiffness rising.

Application of chemical additives is an effective approach to improve the properties of recycled paper products and process, which new additives introduction are always under challenge and question. Recently, Cellulosic Nano Fibers (CNF) as a nano-bio-pmaterialarticle originated from the plant fibers received a great attention in different exareaploitations such as papermaking, which acquainted the performance assessments regarding to the various conditions of the different pfurnishesulp . With this respect, the effect of CNF (0.1, 0.15 & 0.2% OD pulp) on the well-known performance of cationic starch (CS) (0.5, 0.75 & 1% OD pulp), as the most famous polymer used in papermaking, were studied in the pulp recycled from packaging brown waste papers. The results showed that addition of CNF after starchpost ddition didn’ot improved pulp retention, but also declined starch role performance in the recycled pulp retention improvement boost, continuously and respectively corresponding to CNF usage increment. Also, the Rresults obtained from of dynamic drainage jar approved retention data, too; , and the least pulp loss was occurred at the lowest CNF addition. Individually addition of CNF decreased the pulp freeness (CSF) and the postits addition after starch didn’tno positively affected CSF, significantly; and often decreased it. The CNF addition to the starch contained pulp had no meaningfully effect on tensile and burst strengths of the recycled paper and diminished tear strength, too. Generally, unlike the traditional retention-drainage systems comprising cationic polymer/nanoparticles, the application of cationic starch/cellulose nanofibers revealed no positive effects on the properties of pulp and paper recycled from packaging brown papers.

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.

The aim of this study was to investigate the effect of using different fillers in the presence of cationic rosin sizing agent on the properties of pulp and paper made from CMP fibers. For this purpose, cationic rosin internal sizing agent at the levels of 0, 0.5, 1 and 1.5 % based on oven dry fibers, and fillers including grounded carbonate calcium (GCC), precipitated carbonate calcium (PCC), Talc and Zeolite in 25 % level based on oven dry paper accompanied with cationic polyacrylamide retention agent at the constant level of 0.3 % based on oven dry fibers were added to the CMP pulp suspension according to the TAPPI standard. In order to examine the effect of different fillers in the presence of cationic rosin, handsheets with basis weight of about 60±3 g/m2 were prepared from each experiment. Then, various pulp and paper characteristics were measured. Statistical analysis of the results revealed that type of filler has dissimilar behavior on the pulp and paper properties in the presence of cationic rosin. Drainage time of pulp suspension was lower when adding Zeolite and GCC fillers. Talc and PCC decreased more the paper strengths properties. Ultimately optical properties of papers improved more when Talc and PCC were added to the CMP pulp. Consequently, with respect to the priority of brightness and opacity for the copy and print papers made from CMP fibers, addition of Talc and PCC in the presence of cationic rosin sizing agent may be meet more the requirements compare to Zeolite and GCC fillers.

This research was targeted to compare the effect of Alkyl Ketene Dimer (AKD), cationic rosin and soap rosin sizing agents on the properties of papers containing Ground Calcium Carbonate (GCC) fillers. Therefore, treatment of ChemiMechanical Pulp (CMP) with 300±25 mL. CSF was firstly conducted by applying sizing agents AKD, cationic rosin and soap rosin at levels of 0, 0.5, 1 and 1.5 percent based on O.D. fiber weight. Afterwards, GCC mineral fillers and finally CPAM retention aid were added to the pulp suspension respectively at constant level of (25%) and (0.3%) based on OD weight of papers. Then, fabrication of standard hand sheets with 60±3 g/m2 basis weightand evaluation of its different properties including: water absorbency, strengths and optical characteristics was done according to the TAPPI standard methods. The results have shown that cationic rosin was more effective than other sizing agents in the presence of GCC filler. Since in roughly equal water absorbency and strengths, papers made from pulps treated with cationic rosin were detected meaningful higher optical properties than that of papers sized with AKD and soap rosin sizing agents.

Various kinds of chemicals are used in papermaking to enhance paper properties and to improve efficiency of the production process. In the presence of cationic starch as an anionic charge catcher, effects of Nano silica/cationic Polyacrylamide complex on retention, drainage time, water volume drained by Dynamic Drainage Jar and properties of paper recycled from old corrugated container were investigated. The results revealed that individual addition of CPAM is more efficient than the individual addition of anionic nano silica, regarding to the investigated properties, increase all characteristics compared to the situation without these addition. Higher volume of drained water (up to 6%) and lesser time needed for the sheet formation (up to 10%) combined with retention increment (> 2%) have been achieved by flocculation and consolidation of fines and fibers via bridging and network flocculation of pulp ingredients and contributing to charge neutralization of anionic surfaces, more and more, resulted in bigger flocs which could be retained by papermaking wire. The mentioned mechanism contributed to better bonding of paper network resulted in tensile and burst indicates improvement up to > 45% and >50%, respectively. Influence of silica anionic nanoparticle on strengthening of the flocs formed by CPAM, made higher energy requirements (> 12%) for paper tearing. In addition to higher yield of production, application of CPAM/nano silica complex resulted in a paper with higher value from quality and application point of view.

Alkali absorption method was used for reactivity measurement، in mechanical (ultrasonic) and oxidation (selective and non-selective and also by H2O2) treatments of alpha cellulose fibers made from cotton Linter. Evaluation of oxidation process and mechanical treatment of fibers by measuring of viscosity، cellulose molecular weight، carboxyl groups’ substitution in methylene blue methods and also fiber alkali absorption were shown that the mechanical treatment before chemical one was led to high accessibility and reactivity of fibers. Alkali absorption depends to fiber oxidation method and mechanical treatment before that. Results show that un-selective oxidized fiber with mechanical treatment compared to untreated samples increases reactivity and carboxyl groups’ substitution 2. 49% and 51. 45 mmol/kg، respectively.

Hemicellulose pre-extraction and recovering before pulping process is an approach for supplying the sugar feedstock used in production of fuels and chemicals. Wheat straw hot water pre-extraction for reaching to 10 % weight loss was carried out in the present study. Pre-extracted liquor from each stage was used as a media for subsequent extraction stage (three stages) in pre-extraction process. The results showed that soda-AQ pulping of pre-extracted straw is performed at less severe conditions i.e. shorter time and lower temperature as compared to non-pre-extracted straw. The pulping yield of pre-treated straw was higher than control pulp; however, the total pulp yield (based on oven dried weight of raw straw) was lower in the pre-extracted samples. Due to lack of hemicelluloses, pre-extracted pulps showed a weaker response to refining and the produced handsheets had lower tear index and air resistant than handsheets made of non pre-extracted pulp, while no significant difference was noticed in burst and tensile indices of handsheets produced from extracted and non-extracted pulp samples.