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

In this study, the possibility of making a composite from bagasse was investigated. Bagasse-polypropylene fiber samples with different bagasse percentages (15, 25, and 35%) and coupling agent (0, 1.5, and 3%) were made, and their mechanical properties were examined. The results showed that with an increase in bagasse fibers, the flexural strength and tensile modulus did not change significantly, but the modulus of elasticity and energy at the breaking point decreased significantly, but the tensile strength increased. The results of the impact resistance test showed that although the impact resistance decreased and increased slightly with an increase in the percentage of bagasse fibers and coupling agent, this amount of decrease and increase was very small and insignificant, and the results of this test were random and unrelated to the increase in raw materials. However, in the impact resistance test without a notch, a significant difference in the decrease in impact resistance was observed with an increase in fibers and its increase with an increase in coupling agent. Overall, all measured engineering properties in this study improved, except for impact resistance, which decreased with an increase in fibers. It is suggested that to improve the engineering properties of this type of composite, the bagasse percentage and coupling agent should be increased up to 30% and 3%, respectively.

Fibre-gypsum board is a composite, in which fiber used as the reinforcement in the matrix of gypsum. The purpose of this article is to investigate the effect of different amounts of waste paper fibers on the strength, resistance and the fracture behavior of fiber-gypsum board. For this purpose, amounts of zero, 5, 10, 15, 20, 25 and 35 percent of waste paper fibers have been used. The results of measuring bending strength, internal bonding and moisture absorption during one month exposure to 100% relative humidity show that increasing the percentage of fibers up to 20% has increased the mechanical properties. In general, By using twenty percent fibers the bending strength increased fifty percent and the internal bonding became double and half in comparison to the control samples. The load-displacement curve shows that an increase of 5 to 15 percent of fibers does not change the fracture behavior of the fiber-gypsum board and they had brittle fracture same as control samples. While in more substitution values, the flexibility increases and the failure becomes ductile. Therefore, the best conditions in terms of strength, resistance, and flexibility have been obtained in 20% replacement of gypsum with waste paper fibers.

In this study, the surface modification of cellulose fibers and its effect on the mechanical properties of fiber-cement composite was evaluated. The fiber modification was conducted through deposition of nano-silica at two levels 3 and 5 wt % (based on dry weight of cement) on the surface. The fibers and composites were characterized by emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrum (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Also, mechanical in wet and dry state of cement fiber composites was investigated. FE-SEM and EDS analysis of the modified fibers showed that the nano-silica deposited on the fiber surface, as observed by the increase of the Si peak in the EDS measurement, which proved the effective modification of cellulose fibers with well dispersed nano-silica on the fiber surface. The reaction of the hydroxyl groups of the cellulose fibers and chemical bonding between cellulose and silica was formed after superficial modification examined by FT-IR analysis. The crystallinity index of the fibers was reduced 15%. The mechanical results showed that the presence of nano-silica treated fibers in the matrix increased the modulus of rupture (MOR) in wet and dry states.

In this study, the effect of using maleic anhydride and oxidizer (dicumyl peroxide) in improving the properties of composites made of polypropylene and cellulose nanocrystal was investigated. Then, the mechanical, and morphological properties of these composite products were explored. Tensile strength increased with increasing cellulose nanocrystal, but it decreased slightly while 5% of cellulose nanocrystal were added. Due to the addition of maleic anhydride and oxidizer, the mechanical properties of the composite product were reduced which was not expected. Analysis of the contact angle of the samples also showed a decrease in wettability behavior due to increased use of nanocrystalline cellulose as well as maleic anhydride and dicumyl peroxide.

Considering the increase of environmental pollutant resulted from agglomerating rubbish and wastes containing stable petroleum-based polymers, substitution of these polymers with bio-polymers and solving their problems and defects in the production process as well as the final products is an important topic. In this study, the possibility of the production of poly lactic acid (PLA)-rice husk composite with acceptable properties, and also the effect of using flame retardant mineral fillers of aluminum three hydrates (ATH) and magnesium di-hydroxide (MDH) on physical and thermal properties of the produced composite were investigated. Results indicated that the density of PLA-rice husk composite was higher than petroleum-based polymers composites (PP/HDPE-rice husk composites); and flame retardant mineral fillers addition led to an increase in the composite density. Also, flame retardant mineral fillers addition decreased the composite water absorption and thickness swelling, in a way that they were comparable with petroleum-based polymers composites. Results of thermal gravimetric analysis (TGA) showed that flame retardant mineral fillers addition also decreased the temperature of the composite weight loss curve peaks, and the weight loss rate toward temperature rising.

In the present research, the mechanical and physical properties of poly lactic acid-canola stem flour composites made by compression molding technique were studied according to ASTM standards. According to the results achieved, it was found that modulus of rupture, tensile strength and impact strength were decreased by increasing the amount of Canola stem flour in comparison with pure PLA. In contrast, the elastic properties including Young's modulus, flexural modulus, and surface hardness increased. The addition of canola stem flour also increased water absorption and thickness swelling. Furthermore, a significant increase in the composite crystallinity degrees was observed in the study of thermal properties by DSC test. It can be concluded that the use of Canola stem as a cheap and renewable lignocellulose source can as well as having a filler role in making composites, improve some of the mechanical properties of the same composites.

The aim of current study is to determine the physical and mechanical properties of wood-based composites commonly used in Iran’s market before and after accelerated aging. Accelerated aging process performed based on ASTM D1037. Specimens of particleboard and medium-density fiberboard (MDF) made of wood and bagasse obtained from various factories. Physical properties including density, water uptake and thickness swelling (after long-term water soaking), and mechanical properties including flexural strength, modulus of elasticity and internal bonding before and after aging. The most density loss observed in MDF after aging, while particleboard specimens were less damaged. Water absorption and thickness swelling of MDF specimens were less than those of particleboards during long immersion, due to the smoother surface and lower permeability. After aging, water uptake and swelling increased in all boards due to hydrolysis of resin and bulking the boards. After aging process, highest reduction in flexural strength and modulus of elasticity observed in MDF although a significant reduction observed in particleboard. Internal bonding of specimens were higher than standard level before aging process; but after aging decreased significantly, due to hydrolysis of resin in alternating drying-wetting conditions.

This study investigated the effects of lignocellulosic materials (bagasse and rice straw) and four pulping processes as fiber’s treatment on physical and mechanical properties of natural fiber reinforced composites. lignocellulosic material in form of pulp flour (alkaline sulfite anthraquinone, soda anthraquinone, monoethanolamine, and chemical–mechanical pulping), 5 wt.% maleic anhydride polyethylene as coupling agent and High-density polyethylene (HDPE) were used to produce bio-composites by injection molding process. Polymer-to-fibers ratio for all reinforced composites was 60:40 wt.%. Mechanical properties including tensile properties, flexural properties, notched Izod impact strength and physical properties such as water absorption and thickness swelling were evaluated according to ASTM standards. The results showed that treated fibers compared to untreated fibers led to increase and decrease of flexural modulus in bagasse and rice straw reinforced composites, respectively. On the other hand, these treatments increased tensile modulus of both bagasse and rice straw reinforced composites. The results indicated that flexural and tensile strength of bagasse composites were significantly higher than rice straw composite. In contrast, rice straw composites showed higher impact strength, water absorption (WA), and thickness swelling (TS) in comparison with bagasse reinforced composites. The four pulping processes decreased WA and TS of both lignocellulosic composites.

The vast accumulation of materials and synthetic polymers, which can remain as contaminants in the environment and cannot be decomposed for a long time, is one of the problems in the plastic industry. The present study shows how synthetic polymers are replaced by natural ones through semi-industrial production method. Firstly, a masterbatch was prepared by mixing zein, nanocellulose and chitosan in a ratio of 3: 2: 5. A solution of chitosan and zein was prepared. Then nanocellulose was added to the suspension and the ternary mixture and composite was prepared. Then the masterbatch was dried and grinded and films were prepared by adding zein matrix in 1, 3 and 5 percent nanocellulose to 1.5 and 4.5 and 7.5 percent of chitosan by extruding and pressing. Storage and loss modulus and loss factor of the treatments were studied out by (assessing) Dynamic Mechanical Analysis (DMA) / Dynamic Mechanical Thermal Analysis (DMTA). It was observed that thermal properties was improved by increasing nanocellulose and chitosan to 3 and 4.5 percent, respectively. The glass transition temperature in this treatment was 88.3 °C. It was higher, in comparison with 5 and 1 percent nanocellulose and pure zein treatments, which were 85.6, 79.01 and 64.9, respectively. The peak of loss factor or the glass transition temperature of composites depends on the distribution of nanocellulose and better interaction of nanocellulose and chitosan and zein matrix. The glass transition temperature decreased in more and less than 3 percent nanocellulose that shows its lower thermal properties.

In this research was to use the effects micro cellulose, and Multi walled Carbon Nanotube on the mechanical properties of wood plastics composites. This article presents the application of Multi walled Carbon Nanotube in order to evaluate and compare their suitability as reinforcement for thermoplastics. The effects of loading micro cellulose and Multi walled Carbon Nanotube content on the mechanical properties were also studied.
The results showed that mechanical properties of the composites made with 50 micron cellulose and 1.5 and 2.5 % of Multi walled Carbon Nanotube were significantly superior to those of the lower length (20 micron) and control samples. Addition of Multi walled Carbon Nanotube could enhance the mechanical properties of the blends, due to the improvement of interface bond between the filler and matrix of wood plastics composites. The significant improvements in mechanical properties of the blends composites made with Multi walled Carbon Nanotube and micro cellulose were further supported by SEM and TEM micrographs.

In this study, the reinforcing effect of recycled newsprint paper (RNP) in cement boards has been investigated. The experimental design consisted of two variable factors namely RNP and calcium chloride (CaCl2). In the sample preparation, boards with density of 0.7 kg/m3 were manufactured using fiber/cement ratios of 10:90, 15:85, 20:80 and 25:75 by weight and 3% and 5% CaCl2 as accelerator. At least four boards (replications) were fabricated for each treatment, and the mechanical and physical properties of the boards were evaluated. The statistical analysis showed that the differences between the mean values of the RNP and CaCl2 contents among each of the groups (treatments) compared were significant. Test results showed that addition of CaCl2 tends to enhance both the mechanical and physical properties of the boards. All properties of the boards were improved when the CaCl2 content was increased from 3% to 5%. The rupture and elasticity moduli of the boards decreased with an increase in the RNP content, and the maximum values were obtained at RNP loading of 10%. The results also showed that as the fiber content was increased, significant increased in water absorption and thickness swelling occurred. Increasing RNP fiber content from 10% to 25% reduced both the mechanical and physical properties considerably. The optimum condition was obtained when the RNP and CaCl2 contents were 10% and 5%, respectively.

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.

At this research, the influence of Multi Walled Carbon Nano Tubes (Non-functionalized and functionalized) on mechanical properties of polypropylene – old corrugated container (OCC) fibers composites was investigated. OCC fibers polypropylene composites were prepared using 20% OCC fibers, 80% polypropylene and 3% MAPP. Three levels of multi walled carbon nano tubes (0% - 0.5% - 1%) were added. Acidic oxidation method was used to functionalize the MWCNTs. Mechanical properties were measured as defined in ASTM testing methods. The results indicated that at higher dosage of MWCNTs, the tensile strength properties of the composite were improved but the influence of the functionalizing was not statisitaclly significant. The bending strength and elasticity as wellas the izod impact were increased as the higher amount of nanotubes were added to the composite. Scanning Electron Microscopes showed the development of bonding between the composite components. Compostes without coupling agent showed lower bonding strength between polypropylene and fiber as indicated by fiber pull out. However, in the composites containing coupling agent, the fiber fracture was observed.

In this research, utilization of ZnO nanoparticles and eggshell powder on physical and mechanical properties of polypropylene/wood flour composite were investigated. For this purpose, wood flour and polypropylene was mixed at 60 to 40% by weight. Eggshell powder at three levels (0, 5 and 10) percent and nano ZnO at four levels (0, 1.5, 3 and 5) percent were considered as variable factors. Physical and mechanical properties including water absorption and thickness swelling after 2 and 24 hours immersion in water, flexural strength were measured in accordance with DIN-EN 310-2006 standard, and tensile strength were measured in accordance with ASTM D1037 standard. Scanning electron microscope (SEM) were 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. Results showed that increasing the mixing ratio of eggshell powder to wood flour decrease mechanical strengths but were improved in water absorption and thickness swelling after 2 and 24 hrs. Using 1.5% nano zno increased the strength properties to the maximum values and improved physical properties.

In this study, the effect of nanoclay particles content on creep behavior of wood flour/polypropylene composite was investigated. To meet this objective, wood flour was mixed with polypropylene at 60 % by weight fiber loading. The concentration was varied as 0, 3 and 5 per hundred compounds (phc) for nanoclay. The amount of coupling agent (PP-g-MA) was fixed at 2 phc for all formulations. The samples were made by melt compounding and injection molding. Firstly, the modulus of elasticity, flexural and tensile strength of composites was measured before performing the creep test. Then, the short term flexural and tensile creep test at 20% of ultimate bending load at 12 min was performed. The morphology of the nanocomposites has been examined by using x-ray diffraction and transmission electron microscopy. Results indicated that the creep deflection, relative creep and creep factor increases with increase of nanoclay up to 3 phc and then decreases with 5 phc nanoclay addition. Also, the effect of nanoclay was positive in terms of enhancing the mechanical properties of the composites. The morphological studies with XRD and TEM revealed that nanoclay distributed as intercalation structure in polymer matrix.

In this study, the physical and mechanical properties of polypropylene composites reinforced with alkaline sulfite-anthraquinone, soda-anthraquinone and monoethanolamine-anthraquinone pulping and chemical mechanical pulping produced from bagasse and pre-extracted bagasse with hot water by using a coupling agent MAPP (3%) were studied. Findings from pretreated and unpretreated bagasse composites were compared. The ratio of the polypropylene and reinforcement material (pulp) was considered at 50/ 50. The results showed that the pulping process has a significant effect on all physical and mechanical properties of produced composites. In general, composites that containing chemical pulps have greater dimensional stability and mechanical strengths but lower water absorption than that of mechanical pulp. Composites containing treated fibers with alkali sulfite-anthraquinone and soda pulp had the highest mechanical properties and dimensional stability. Composites made from fibers which their hemicelluloses were extracted and then were treated with chemical pulping processes had the highest mechanical strengths and dimensional stability among all of samples. The highest mechanical strengths and dimensional composites that reinforced with treated fibers compared with control samples containing untreated bagasse fibers are more resistant demonstrated. In general, the results showed the superior physical and mechanical characteristics for Pulp - Plastic composites compared with flour plastic composites.

In this research, the effect of the quantity of filler and coupling agent (MAPP) on the physical and mechanical properties of Polypropylene composite reinforced with flour from the annual pruning of palm leaves (Shahani species), were studied. For this purpose, the palm flour in three levels of 30%, 40%, 50% and two levels of Maleic anhydride grafted polypropylene 4% and 6% were used as variable factors. Then the Physical and mechanical properties of samples including, thickness swelling after 2 and 24 hours of immersion in water, bending strength, bending modulus, tensile strength, tensile modulus and impact strength were measured. The result of this research showed that by increasing palm flour, the bending strength, tensile strength and impact strength were decreased and on the other hand the thickness swelling, bending modulus, tensile modulus were increased. It was also found that by adding MAPP, thickness swelling, bending strength, bending modulus, tensile strength and tensile modulus were improved. This means that with increased consumption of palm flour, adding coupling agent leads to improve the quality of interface and significant changes; especially dimensional stability and MOE is achieved.

In this research was to use the effects micro cellulose length, and coupling agent (MAPP) on the mechanical and thermal properties of Nano/ wood plastics composites. The results showed that mechanical properties of the composites made with 50 micron cellulose and 5 % of MAPP were significantly superior to those of the lower length (20 micron) and 2.5% of MAPP. Addition of MAPP could enhance the mechanical and thermal properties of the blends, due to the improvement of interface bond between the filler and matrix of Nano/ wood plastics composites. The significant improvements in mechanical properties of the blends composites made with MAPP and NC were further supported by SEM and TEM micrographs. Nano/ clay particles distribution and thermo gravimetric analysis (TGA) indicated that the addition of 5% MAPP and the longer of micro cellulose remarkably increased the thermal stability of the blends compared to other treatments of Nano/ wood plastics composites.

In this investigation, tensile and physical properties of polypropylene (as matrix)/wheat straw fiber/paper mill sludge (as filler) composites was studied. For this aim, ratio of wheat straw fiber/ paper mill sludge include (40/0, 30/10, 20/20, 10/30 and 0/40) were used in composite. Also, for better compatibility between the two phases3% of grafted MA as coupling agent was used. Mixing process was done in internal mixer, and then composite samples manufactured by injection molding. Result indicated that the tensile modulus of elasticity improved with increase of two fillers and also observed that the toughness of composite increased when compared to the pure PP, while the highest tensile modulus of elasticity related to the higher percentage of paper mill sludge. Tensile strength of composite decreased with adding of 40% wheat straw fiber, but with addition of sludge tensile strength increased significantly. With addition of straw wheat in PP matrix and its hydrophilic properties highest rates of water absorption and thickness swelling was observed. While with adding of sludge and less amount of Lignocellulosic materials, water absorption and thickness swelling were noticeably decrease with addition of binder and better connection with two phases.

In order to develop the structural applications of natural fiber-polypropylene composites, achieving enough knowledge about their mechanical behavior is necessary. One method for describing flexural characteristics of a flexural section is using the moment-curvature analysis which is an alternative for stress-strain relationship in many analyses. In this study the effect of temperature on natural axis position and flexural stress distribution in section of flexural test specimens was investigated using a moment curvature analysis method. Flexural, tensile and compressive tests were conducted in temperatures ranging from room temperature to 80 oC. A FORTRAN program was used for analysis of moment-curvature in flexural section of flexural test specimens. In order to verify the results of the program, the predicted load-deflection and maximum moment data obtained from the program were compared with the experimental load-deflection and maximum moment data and results showed that the program was able to describe the flexural behavior of the studied composite. Results showed that non-uniform flexural stress distribution led to moving up the neutral axis toward compressive side. Also with increasing temperature, the balance between compressive and tensile strain is maintained with shifting the neutral axis to compressive side, and with elevating temperature, the movement of the neutral axis decreased.