مجله تحقیقات علوم چوب و کاغذ ایران
سال سی و دوم شماره 2 (پیاپی 59، تابستان 1396)

To study the tensile properties and impact strength in Wood Plastic Composites (WPC) polypropylene as a matrix and teada pine sawdust as reinforcement / filler is used. Ethylene / propylene / Diane / monomer (EPDM) as modified impact resistance with 10, 20 and 30 percent improved impact resistance and maleic anhydride grafted polypropylene (MAPP) at a rate of 3 percent as a fasteners to improve response and polymers and fillers were added to the composite. To evaluate the fracture surface of a structure scanning electron microscope (SEM) was used. The apply of 10 % elastomer and 3 % coupling agent cause to improved of tensile properties and the use of higher levels of elastomer (20 and 30 %) has shown a decreasing trend in these properties. The results showed that PP matrix by adding sawdust to a significant reduction in impact strength of composite than pure PP is observed. An EPDM additive used in all contents of composites PP / sawdust has improved impact strength. Simultaneous use of EPDM and MAPP used a positive effect in tensile properties and impact strength. The apply of EPDM (30%) and 3% (MAPP) has demonstrated the highest level of impact strength. SEM images show that the use of EPDM and MAPP composites will improve the connection of interface.

In this study effect of staple length (penetration length) and its number in connection, on withdrawal capacity in face and edge of laminated veneer lumber (LVL) out of poplar was investigated. In this investigation, the staple with 3 and 4 cm penetration length and staple with 3, 4 and 5 cm penetration length for withdrawal capacity in face and edge were used respectively. Number of staples at 4 levels (2, 3, 4 and 5) were chosen as a variable. Results have shown that withdrawal capacity in face significantly increases with increase of penetration length. Withdrawal capacity in edge increases drastically with increase of penetration length from 3 to 4 cm, but increase in penetration length from 4 to 5 cm had no significant effect. Withdrawal strength capacity in face has increased with increase of staples number. But, increase of staple number had no significant effect on withdrawal strength capacity in edge. Maximum withdrawal capacity was observed in joints fabricated with penetration length of staple 4 cm and number of 5 staples in face and minimum those were observed with penetration length 3 cm and number of 2 staples in edge.

Wood industries need abundant resources of wooden raw material and these industries could continue to productive activities with poplar consumption attitudes. Given the size and importance of poplar farming and its role in the economy of Kurdistan, study for evaluation of its value chain is essential. Since improving of the poplar value chain is a factor for the development of poplar farming given the current situation in Kurdistan providence value chain, in this research suitable value chains was identified for development. According to the study objectives, the effective criteria to prioritize research alternatives were identified through library studies and with the help of questionnaires were completed and confirmed, according to the experts. The experts were used to identify the interrelations between criteria. After completing the paired comparison questionnaire, weight of each criterion was measured and priorities were found by the ANP. Ultimately, the final results of alternatives ranking showed the most weight is related to the MDF chain with weight of 0.259. The next priorities were paper, straw and cellulose with respectively weights of 0.135, 0.134 and 0.115. The next priorities were furniture, particle board, plywood and matches, pallets, boxes, lumber and boards, with weights of 0.096, 0.077, 0.075, 0.073 and 0.019 respectively. Results of group decision-making using ANP showed that in the current situation with regard to the suitable market for MDF, proper future demand, appropriate market for processed products from MDF, condition of infrastructure in Kordestan province and feasibility of use of poplar wood in production of MDF, this industry is more important to develop in Kordestan province.

In this study the relationship between dynamic modulus of elasticity from longitudinal ývibration ýmethod with static modulus of elasticity and bending strength in two directions: the ýParallel ýmachine direction and machine direction have been investigated. For this purpose 4 ýplates of ýparticleboard with dimensions 124× 90 ×1.6 cm (length× width× thickness) were ýselected and free ýlongitudinal vibration test in PMD and MD were performed on each plates. ýAfter that the primary ýplates were cut to four plates with dimensions 62× 44 ×1.6 cm (length× ýwidth× thickness) and ýlongitudinal vibration test in PMD and MD were performed on each ýplates again. Finally each plates ýwere cut to the beams with dimensions 36× 1.6 ×1.6 cm and ýlongitudinal vibration test and and ýstatic bending test were performed on them. The results show ýthat good correlation between ýdynamic modulus of elasticity from longitudinal vibration test ýand static modulus of elasticity and ýbending strength (result of beams extracted from each ýplates) in both size of plates in two size ýý(124× 90 ×1.6 and 62× 44 ×1.6 cm) and beams ýextracted from each plates in two directions (PMD ýand MD). In addition there was good ýcorrelation between dynamic modulus of elasticity of ýlongitudinal vibration from two size plates ýý(124× 90 ×1.6 and 62× 44 ×1.6 cm). When the samples ýsmaller than primary plates, the ýdynamic modulus of elasticity values were increased, that it due to ýthe diffusion of waves in ýsamples with larger dimensions. In general, according to results of this ýresearch it can be ýconcluded that by applying the appropriate correction factors, longitudinal ývibration method an ýefficiency method for calculation of dynamic and static modulus of elasticity ýand estimate of ýthe modulus of rupture in plates in full sized.ý

In this study, effect of accelerated aging on adhesion strength of half-polyester and polyurethane transparent coatings were evaluated in maple and pine species. For this purpose, dried specimens with 12×110×550 millimeters were used. Sealer as substrate, and half-polyester and binary polyurethane as coatings were applied on wood. Coatings were implemented thereby film applicator and gun methods, and accelerated aging test of wood specimens was carried out according to ASTM D1037. Results indicated that maximum value of adhesion strength is belong to binary polyurethane in maple applied by film applicator and minimum for half-polyester in pine applied by gun method, in opposite. Due to thin film, velocity variations in gun method by painter person, and consequent rapid evaporation of thinner, adhesion decreased in comparison with film applicator method. Also it's found that accelerated aging diminished adhesion strength of coatings in both maple and pine species. It can be concluded during the accelerated aging test, the steam causes moisture absorption and swelling of the fibers near the surface and thus reduce the resistance of the coating adhesion.Long-term effect of humidity and aging makes Ecowool quickly lose their stickiness.And the effect of floating in the water samples, lignin degradation products in the process of steaming and freezing and heating washed by water And cause the loosening of the cellulosic fibers in the wood, resulting in wood adhesive strength is significantly reduced due to the accelerated aging test.

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.

Production of test liner and fluting from old corrugated containers, is one of the most common paper recycling processes in Iran. This type of papers, have high basis weight and also contain significant fine fibrous and non-fibrous materials; hence, the drainage and in addition, the retention of fine materials, are the obstacles these paper mills may encounter. In these cases, usually application of drainage/retention aids, such as nanoparticle systems can be of much help. In this due, colloidal silica and bentonite are the two of the most commonly used nano-particles with polyelectrolytes in papermaking wet-end. Therefore, in this research, the effect of bentonite and silica sol nano-particles on the performance of cationic starch was compared in terms of drainability, retention and strength properties of paperboard from recycled old corrugated containers. The analysis of the particle size for these two nanoparticles showed that although the thickness of bentonite platelets (maximum 22 nm) was less than nanosilica dimensions (less than 50 nm), the effect of bentonite-cationic starch was not significant in terms of retention, against the nanosilica. Regarding the drainability, following dosing of both silica and bentonite, the parameter much improved (up to 186% in the case of nanosilica). On the other hand, application of cationic starch containing systems in paper handsheets resulted in improvement in tensile and tear indices, however, these properties decreased following addition of nano-particles. Also, internal bonding (Scott- type) incredibly increased (up to 354%) by application of cationic starch and nanosilica. At last, generally in the case of OCC furnish, the nanosilica-cationic starch system had a better performance in terms of drainability, retention of fine materials and fiber fines and also strength properties, rather than cationic starch-bentonite.

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 potential of rose flower stalks for the production of particleboard was investigated. Three resin dosage gradients of 0, 2 and 4% (10% core: 10% surface; 9%core:11% surface and 8% core:12% surface) and three press times (3, 4 and 5 minutes) were selected as the variables and boards were produced. Then the mechanical and physical properties of the boards were measured and statistically analyzed. The results of modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding (IB) measurements showed that as the resin dosage gradient increases, these properties improved and boards produced using either 2 or 4% resin dosage gradients generated the highest values. The effect of resin dosage gradient on these properties was statistically significant. As the resin dosage gradient increases, both thickness swelling after 2 and 24 hours immersion in water was improved. The effect of press time on thickness swelling after 2 and 24 hours immersion in water was also statistically significant and these properties were improved when 5 minutes press time was used The results indicate that if 2 or 4% resin dosage gradients and either 4 or 5 minutes press time is applied for the manufacturing of particleboards using rose flower stalks residues, the specification of the boards will meet the EN specification.

Paper works are more attacked by biological agents such as fungi, bacteria and insects due to its organic nature. In ýarchives, most of the biological destruction of paper is related to fungi. The importance of paper works ýconservation has led to applying different methods to fungus removal. The chemical disinfection is of of the most ýcommon disinfection methods. In this research, the application of Thiophanate methyl in paper destructive fungi ýhas been studied. Laboratory studies to evaluate the effects of Thiophanate methyl on paper and fungus include ýaccelerated ageing, the evaluation of effectiveness of antifungal Thiophanate methyl on fungi such as ýAspergillusniger, Aspergillusflavus and Penicilliurnsp and determination of antifungal stability after accelerated ýageing. Examination shows that Thiophanate methyl has successfully prevented spread of fungus in all density of ýþ10þý, ýþ50þý, ýþ100,200þý and ýþ500þý ppm. Aspergillus flavus fungus had a slight growth at ýþ10þý ppm, but no growth were ýobserved in other density. Aspergillusniger fungus had no growth capacity in density more than ýþ100þý ppm. ýAccording to the results, treated papers are still able to control fungus growth after being in accelerated ageing ýcondition. In general, the results obtained by fungus growth halo and non-growth halo indicate that all fungi are ýcontrollable in density of ýþ200þý ppm.ý

The aim of study was accomplished on identification and comparison of chemical compounds in wood and bark of oak. For this purpose, the samples were chosen randomly from oak in Nowshahr forest region. Then, flour and ash were provided from heart wood, sap wood and bark of oak by TAPPI standards. For measured metallic ions, first the mineral compound of ash dissolved by 65% nitric acid and for it's identified by atomic adsorption method. The results showed that Fe, Zn and Cu ions in wood of oak were more than its bark and its Mn ion was lower. Then extractives were separated from wood flour by acetone and extractives residue transferred to glassy vial and was added BSTFA reactor to it. After samples prepared, its were injected by GC/MS for analyze. Identification of compounds was done by retention time of each compound, calculation of quartz index and Adams table. The result of GC-MS showed that there are 10, 42 and10 compounds in heart wood, sap wood and bark of oak, respectively. Comparison of chromatograms showed that Decan, Dodecan, Tetradecane and Bis(2-ethylhexyl)phthalate were exists as 4 common components in bark, sap wood and heart wood of oak and Silicic acid and 1,2-Benzenedicarboxylic acid were exists as 2 common components in bark and sap wood of oak. These compounds can very important in durability and consumption its.

The effect of compounding process applying two methods of one and two step mixing on the properties of nanocomposite is investigated. Nanocomposites were produced using polypropylene, cellulosic fibers, MAPP and nanolay as reinforcement. 1.5 and 3% MAPP and 0,2, and 4% nanoclay were used as the variable factor and 20% fibers was used. Melt flow index was measured on compounds produced using one or two steps mixing. Either compounds were mixed with fibers and MAPP and then the test specimens were made and tested according to ASTM test procedures. The results revealed that the two steps mixing increased the mechanical properties. The melt flow index of one step mixing was lower and the melt flow index of initial mixing of polypropylene with nanoclay was very high and it was reduced after compounding with fibers and MAPP. The results revealed that at higher dosages of the nanoclay tensile and bending modulus of the composite increased and tensile strength and modulus of rupture decreased.

Cellulose nanocrystals (CNC) are new class of cellulose materials that find wide applications in various research areas over the past two decades. These nanoparticles are usually made by acid hydrolysis of cellulose substances such as wood, cotton, Starch etc. The main aim of this study is to find the optimal conditions for obtaining an aqueous stable colloid suspension of cellulose nanocrystal (CNC) from α-cellulose with a high-yield procedure. Therefore various conditions of acid hydrolysis were evaluated as reaction temperature and reaction time. The percentage of yield was calculated for all suspensions. The morphology of the prepared CNC was characterized by Transmission Electron Microscopy (TEM), Environmental Scanning Electron Microscopy (ESEM) and the crystallinity was measured by X-ray diffraction (XRD). The results showed that highest yield of CNC (88%), was achieved from the reaction condition of 60 minutes at 60 °C. Generally, rod-like shape crystals achieved from α-cellulose with an average size of 35-50 nm and high crystallinity (92%) can be make it to a convenient and competitive source for the production of cellulose nanocrystal for various industries.