مجله تحقیقات علوم چوب و کاغذ ایران
سال بیست و هشتم شماره 3 (پیاپی 44، پاییز 1392)

Physical and mechanical properties of lightweight cement blocks made from lignocelluosic fibers and rice husk ash (RHA) were investigated. The cement blocks were made using three types of natural fibers including old corrugated container (OCC)، virgin kraft pulp and fiberboard fibers representing 25% of dry weight of the block. Rice husk ash varied at 0، 25 and 50 WT% combined with 5 WT% CaCl2. Density، water adsorption and compressive strengths of blocks were measured and compared using a factorial experiment with two factors at three levels. The results showed the significant effect of fiber type on the properties of blocks. OCC fibers provided the highest density and compressive strength and had the lowest water adsorption. The density of blocks reduced at higher dosage of RHA varied from 0 to 50%، and the lowest water adsorption and highest compressive strength was obtained at 25% RHA charge. The interactive effects of raw material on the properties of cement blocks were significant and the optimum properties were obtained with OCC fibers and RHA at 25%.

Considering the problems initiated by sodium silicate on reducing the life expectancy of processing equipments and paper strength، recycling of old newspaper using Poly (acrylic acid)، Sodium Salt Grafted to Poly (ethylene oxide) complex were investigated. The organic complex was used at 0. 3، 0. 5، 0. 7، 1، 2 and 3% levels (based on dry weight of waste paper) in deinking. The effect of various charges of the organic complex on the physical and optical properties of deinked pulp was studied and compared with the control (ONP deinked using 0. 5% sodium silicate). The results of physical properties measurements showed that the lowest paper caliper (143. 07 µm) and the highest density (0. 43 g/cm3) were obtained by increasing the complex charge up to 2%. Also، the highest and lowest freeness was observed applying 3% (426. 66 mL CFS) and 2% (350 mL CSF) organic complex respectively. These values were less than the freeness of the control sample. The results of optical properties analysis indicated that the brightness increased to 48. 01% ISO and the yellowness was reduced to 6. 23 % ISO by as the dosage of organic complex was increased up to 1%. The opacity of paper decreased as the organic complex charge increased. In general، the paper with higher density and brightness، lower yellowness and suitable opacity could be produced using 0. 7- 2% Poly Acrylic Acid-Sodium Salt grafted to Polyethylene Oxide complex in deinking of old newspaper.

The present study analyzed the effect of different enzymatic treatment times using endoglucanase and refining levels to improve the properties of OCC pulp. The OCC pulps were treated by endoglucanase enzyme at a constant dosage of 1u (on o. d. pulp) at different reaction times (0. 5، 1، 1. 5 and 2 hours) under constant process conditions. Based on the results، enzymatic treatment of OCC pulp at different time levels improved the physical and mechanical properties، compared with the control pulp، and the highest improvement level was observed at 0. 5 hour reaction time. Longer enzymatic reaction time (up to 2 hours) led to a significant decrease in the physical and mechanical properties of the pulp. Evaluation of different of enzymatic treatment times and different refining levels indicated that the papers produced from endoglucanse pre-treated pulp (for 0. 5 hour treatment time) showed better quality at different refining levels. However، increasing enzymatic treatment times up to 2 hours showed severe decrease both the physical and mechanical properties at higher refining levels. In general، refining enzyme pre-treated pulp and also the control pulp resulted in a higher strength property of the paper.

Two recycled polymers (rHTPE and rPP) combined with baggase fibers were used as the reinforcing material to improve the mechanical properties of wood plastic nanoclay composite. The amount of baggase fibers varied at three levels (25، 35 and، 45 percent). Two recycled polymers (rPP and rHDPE) were used as polymer matrix. Tensile، flexural and impact strength properties were measured according to ASTM standard tests. Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) was performed to interpret the results. The results were statistically analyzed using factorial experimental under completely randomized block design and the averages were compared using DMRT. The application of 35 percent bagasse fibers as compared with 25 and 45 percent increased the strength of wood plastics composites. However، higher impact strength was reached using 25% bagasse fibers as compared with either 35 or 45% bagasse fibers. rHDPE nano-clay composite showed higher tensile، flexural and impact properties compared with rPP. Imaging the morphology of nano-clay by X-Ray diffraction and scanning electron microscopy showed the distribution of nano-clay particles in polymer structure and intercalation was observed.

The objective of this research was to investigate the combined effect of polyaminoamide-epichlorohydrin (PAE) and carboxymethyl cellulose (CMC) on the mechanical properties of tissue paper made from virgin pulp. Three levels of CMC (0%، 0. 5%، 1%، and 1. 5%)، and three levels of PAE (0%، 0. 5%، and 1%) based on the dry weight of the fibers were used. A mixture of 60% short fiber and 40% long fiber pulps was formed by mixing bleached softwood and bleached hardwood pulps provided by Latif tissue making plant and the chemicals were added. Then 80 g/m2 laboratory hand sheets were prepared. All samples were placed in oven at 100±5 °C and also conditioned (23±1°C and 50±2% relative humidity) for 24 hours prior to testing. Strength properties (wet and dry tensile، wet and dry burst) of the hand sheets were measured. Results indicated that treating of pulps with both CMC and PAE as additives leads to enhancement of the mechanical properties of the paper sheets and higher dosages of CMC and PAE، improved all strength properties.

Investigation on the influence of the density reduction of the particleboard byThe impact of the addition of different amounts of canola straw to the composition of the hardwood particles for the production of particleboard was investigated. Four levels (0، 15، 30 and 45%) of Canola particles were added to hardwood particles and then particles were blended with 12% urea resin (based on the oven dry weight of the particles). Boards at three densities of 550، 600 and 650 kg/m3 were produced. The flexural and internal bonding strength and water absorption and thickness swelling after 2 and 24 hours immersion in water of the boards were determined using appropriate EN standard test methods. Addition of different amounts of canola particle to the hardwood particles did not change either modulus of rupture or modulus of elasticity of the boards، but the internal bonding of the boards was reduced. As the dosage of the canola particles increased، both water absorption and thickness swelling were reduced. Increasing the density of the boards increased both strength and dimensional stability.

The conversion of biomass into biofuels which is a blend of alcohols and phenolic compounds has received significant attention in most countries. The purpose of this study was to identify the chemical composition of the pyrolysis oil products from Oak، Poplar woods، and Bagasse produced in a fixed bed reactor at temperature of 573 oK. Identification of compounds in the extracted liquids was accomplished through making derivatives using GC - MS spectroscopy. Main compounds identified in our experiments comprised 1 - Phenanthrene carboxylic acid from oak wood، 1، 2 - benzene di carbocyclic acid base (2 – ethyl hexyl) ester from poplar wood، and Levoglucosan from bagasse at the levels of 42، 50 and 27 wt% of the reaction products، respectively.

Wet strength is one of the most important properties of tissue papers and presently the polyamideamine-epichlorohydrin (PAE) resin is widely applied to develop and conserve wet strength in paper products. In this study، the combined effect of PAE، retention aid (RTN) and carboxymethyl cellulose (CMC) on softness and wet and dry strength properties of tissue paper were investigated. The results showed that combined application of CMC، RTN and PAE significantly improved wet strength and softness of papers، as compared to single application of PAE. Application of 0. 2 % RTN with 1% PAE or 0. 4% CMC with 1% PAE enhanced wet tensile strength by 10% and 68%، respectively. The combined application of 0. 4% CMC، 0. 2 % RTA and 1% PAE improved wet tensile strength by 124%، compared to sheets treated with only the 1%PAE. The positive effect of combined application of CMC، RTA and PAE depends on the application ratio of the chemicals.

The physical and anatomical properties of old date palm wood (Phoenix dactylifera L.) and its drying behavior were studied. Four old date palm trees grown in Bam city (Kerman provenience) were felled. Then، boards with the dimension of 300 × 50 × 30 mm were cut at DBH of trees from pith to bark. After measuring the green moisture content and specific gravity the boards were dried in a semi-industrial kiln to reach the final moisture content of 8% using a mild wood drying schedule. Cross-sectional anatomical measurements were performed on the nearest boards to the bark and pith. Results showed that the green moisture content and specific gravity of date palm wood ranged between 150-260% and 0. 29–0. 39 and the moisture content was increased and the specific gravity decreased from pith to bark. Anatomical observations and statistical analysis revealed that there was no statistically significant difference between average number of vessel elements and vessel bundles between pith and bark، but the mean vessel area in pith was considerably greater than bark. Results also showed that the drying rate of date palm wood was high reaching to the final moisture content of 8% within 7 days. Drying rate of bark samples was higher than those of the pith and no deformation and surface crack was observed in the dried boards.

Mechanical properties of composite produced from recycled polymers (polyethylene and polypropylene) and paper mill sludge from two different sources (waste water sludge (s) and sludge on the DAF) were examined. Three levels of paper sludge (15، 30 and 45 wt %) were used to produce composites. Haake machine was used to blend materials and to produce standard samples، injection molding system was utilized. The mechanical properties including bending (strength and modulus) and impact strength were measured. Results showed that composites containing PP polymer and waste water sludge have higher mechanical properties than PE polymer and sludge on the DAF. The addition of both types of sludge as filler، results in enhancement of tensile properties compare to pure polymer. In the case، the higher content of sludge on the DAF was used، tensile strength of the composite decreased. Adding both types of sludge as filler، impact strength was lower than pure polymer. It was shown that composites containing sludge on the DAF have lower impact property than waste water sludge.

Plants are a rich sources of phenolic compounds as natural antioxidants. Antioxidants are the main factors in neutralizing free radicals and prevent the spread of diseases and destruction of many foods. These compounds are extractable from the bark of Eucalyptus camaldulensis and Pinus sylvestris trees. The purpose of this study was to evaluate the antioxidant properties and total phenolic and flavonoids of Eucalyptus and pine wood bark. After preparation of the bark، ethanol extracts were extracted using soxhlet extractor. First the amount of total phenol and flavonoids of the extract were measured. Then to evaluate antioxidant properties of the extracts، four methods including Diphenyl Picryl Hydrazyl، reducing power; nitric oxide and metal chelating activity were used. The results showed that total phenol and flavonoid content، in Eucalyptus bark was higher than pine. Test results to trap free radicals of diphenyl Pykryl Hydrazyl showed that 50% inhibitory concentration of ethanol extract of the Eucalypt and Pine bark values as 3. 02 and 15. 77 micrograms per milliliter، respectively. Also، in reducing power test، absorption rate for eucalyptus bark extract was higher than the pine. In nitric oxide trap test، 50% inhibitory concentration in ethanol extract of eucalypt bark was measured as 2. 41 and in pine extract was 22. 75 micrograms per milliliter. Furthermore، the results of Fe2+ chelating ability of ethanol extract of Eucalyptus and pine bark at a concentration of 100 micrograms per milliliter inhibited 37 and 97/18 percent respectively. Ethanol extracts of the eucalypt and pine bark in four case study tests، showed an acceptable antioxidant activity. Thus، these compounds can be regarded as good sources ofnatural antioxidants.

This research was carried out to compare the paper properties from rice straw applying sodium and potassium based Chemimechanical pulping processes. Cooking conditions in potassium based pulping were adjusted as; potassium sulfite 6، 8، 10 and 12%، potassium hydroxide 3، 4، 5، 6، 8 and 12% on oven dry weight of rice straw، impregnation time; 30 minutes، liquid to rice straw ratio of 7:1، cooking time 30 and 60 minutes and cooking temperature 130، 150، 160، 165 and 170 oC. In sodium- based pulping، cooking conditions were selected as; sodium sulfite 6 and 8%، sodium hydroxide 3 and 4 % on oven dry weight of rice straw، impregnation time 30 minutes، liquid to rice straw ratio of 7:1، cooking time 30 minutes and cooking temperature 130 and 150 oC. The selected treatment in potassium based pulping showed the average total yield of 65. 19 and reject of 4. 22% and in sodium based pulping showed the average total yield of 69. 75 and reject percent of 3. 68. After refining the selected pulp to reach the freeness of 300±25 ml CSF، 60 g/m2 hand sheets were made and physical، mechanical and optical properties were measured. Results showed that the tensile strength index، breaking length and apparent density of paper made from potassium based process was similar to paper made from sodium based process. The papers made from potassium based process had higher burst strength index and brightness compared to sodium based process and papers made from sodium based process had higher tear index and higher K/S values than potassium based paper.

The purpose of this study was to compare the chemical compositions and biometric features of stem and cone fibers (length, diameter, and wall thickness) and the derived coefficients of loblolly pine (Pinus taeda) in Astara district, Gilan province. Discs from stem and cone were randomly taken and the chemical compositions and biometric features were measured employing the TAPPI standard test methods and Franklin macerating technique, respectively. The biometric coefficients were estimated as well. Statistical analyses of the results indicated that the average cellulose content in stem and the cone were 54.83% and 27.57%, respectively. Lignin was estimated to be 32.57% in the stem and 34% in the cone. Furthermore, extractives soluble in ethanol, acetone and water from stem wood were measured as 92%, 1.97% and 7.04% respectively. The relevant values for pine cone were 1%, 2.45% and 7.28%, respectively. According to the results of statistical analysis, there was significant difference (α=5%) between the results measured from cones and the stem except for the slenderness ratio. Regarding the length, diameter, lumen diameter and flexibility factor, the P. taeda stem possesses a higher value compared with cone and the runkel ratio was higher in cones compared to stem.

This study was conducted to determine and compare the morphological characteristics and chemical components of Corn stalks (Zea mays: 704 & Oilseed varieties) cultivated in Astara area. Samples were prepared from both varieties، a part of stalks were selected for chemical components determination and the rest was used to examine the morphological features. The average of fiber length، fiber diameter، lumen diameter and fiber wall thickness for oilseed variety and 704 variety were measured as 0. 859 mm، 23. 63 µm، 16. 62 µm، 3. 51 µm and 0. 727 mm، 18. 77 µm، 11. 39 µm and 3. 7 µm respectively. Average percentage of cellulose، lignin، acetone extractives، alcohol extractives، hot water extractives and ash for oilseed variety was measured as 36. 99، 20. 5، 13. 85، 2. 02، 7. 53 and 6. 71، respectively. Relevant values for 704 varieties were 34. 33، 17. 5، 12. 35، 1. 35، 6. 30 and 5. 55 percent. Fiber dimensions and biometric coefficients between nodes and internodes، and between the varieties were compared and the results showed that there were significant differences between fiber length، fiber diameter، fiber lumen and biometric coefficients. The fiber dimensions and biometric coefficients between nodes and at the internododal sections of both varieties are compared and there was significant difference between all variables. The comparison of chemical components between stalk with and without bark for each variety showed that there were significant differences between the content of cellulose، lignin، hot water extractives and ash. However، there was no significant difference between lignin from 704 varieties. In comparison of chemical components between the two varieties in stalk with bark، there were significant differences between the content of cellulose، lignin، acetone extractives، hot water extractives and ash; whereas in the case of stalk without bark، these differences were significant only for the acetone extractives، hot water extractives and ash.

The main objective of the production of cement - wood products or mineral-bounded composite panels is to combine the mineral components of lignocellulosic materials such as wood and organic particles with inorganic binders such as cement، plaster، etc. Wood cement products which are presently produced in most countries possess desirable functional properties such as good weather ability، resistance to atmospheric، biological agents and fire and are lighter weight as compared with other building materials، and provides improved dimensional stability. The flat panels using conventional presses can be produced، and also other products such as concrete blocks، bricks and pieces of different forms can be produced using appropriate frames. Large wood cement- based panels are widely used in construction of residential and commercial buildings. In this research، with respect to the availability of lignocellulosic material (agricultural residues such as rice straw، wheat straw، cotton stalk) in various areas (Gilan، Mazandaran and Golestan Provinces)) and the additive material (as calcium chloride)، boards with similar structural was produced. Mechanical strength values including static bending strength، modulus of elasticity and elastic bending strength were measured. MSTATC based computer package was used to analyze the data. In terms of the maximum load strength، wood cement board made of poplar wood as the control boards (4. 4146 MPa) had the highest mechanical strength followed by cotton stalks (2. 463 MPa)، wheat straw (1. 6776 MPa) and rice straw (0. 8622 MPa)، respectively. In general، the study has indicated the suitability (given the appropriate ratio) of the agricultural residues in construction of wall and warehouse in farmlands.