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

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.

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.

In the present research the biodegradability Properties of poly-lactic acid-canola stem flour composites in three levels of 25, 35, and 45% canola stem flour made by compression molding technique were studied . In order to study the biocompatibility behavior of the composite, three methods of biological degradation were used for Trametes versicolor and Gloeophyllum trabeum fungi, long-term water absorption and composites burial in the soil for 4 months. The results of statistical analyzes showed that the amount of composites weight loss increased against the degradation by fungi and burial in the soil by increasing the amount of rapeseed canola stem flour while pure poly-lactic acid had a very high durability against these factors. In addition, there was no effect on the weight loss of samples in the long run leach test so that the weight of composites and poly- lactic acid samples was constantly increasing and there was no effect on weight and thickness loss. The growth of myceliums fungi was clearly detectable and detectable in reviewing the images of electron microscopy from the fracture properties of composites, unlike poly-lactic acid so that fungi crossed their polymer into rapeseed shoot flour and reduced the weight of the composites. The results of the FTIR spectroscopy on poly-lactic acid prepared before and after exposure to the Gloeophyllum trabeum fungus confirmed the validity of the above results. According to the results of this study, poly-lactic acid, as a biodegradable polymer, has been shown to be very durable against degradation by natural biological agents.

In this study, the tensile and dynamic-mechanical properties of composites made by poly-lactic acid polymer (PLA) and high density polyethylene (HDPE) as matrix and sawdust to reinforcement 30 % weight were investigated. Maleic anhydride bonded with polyethylene (MAPE) was used to increase coupling agent by 3%. The use of sawdust increased the stiffness of composites while the use of this material reduced the tensile strength of composites. The highest tensile properties (elastic modulus and tensile strength) were related to poly lactic acid /polyethylene / sawdust / coupling agent composites. The addition of natural fibers to both matrices (PLA and MAPE) increased the composite storage modulus compared to pure polymers, while the modulus of storage in pure polyethylene and its composite was higher. Simultaneous use of two polymers with an equal ratio (33.5% by weight) and composite sawdust have shown the stiffness between the composites made with single polymers. The use of natural fibers reduced the mobility of the molecular chain and transported the temperature of the composite to higher temperatures, which eventually moved the corresponding corners to the right and lower. However, in some cases, the transmission of pixels has not followed the normal process. The addition of the coupling agent (MAPE) makes bonding more common between two phases in all composites and ultimately increases stiffness.

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.

The effect of adding steamed and non-steamed fiber on physical and mechanical properties of the composites made of recycled polypropylene was investigated. Recycled polypropylene was used as a basic matrix at a 57% level, and poplar fibers were used at 180 °C for 1 h at a constant level of 40% in two forms: non-steamed and steamed. The ratio of steamed fibers to non-steamed fibers in composites was 100:0, 50:50, and 0:100, respectively. For all components, the coupling agent was maleic anhydride at a level of 3%. Mixing was done using an internal mixer at 180 °C and 60 rpm, and the samples were constructed by injection molding method. To investigate the effect of steam treatment on the fiber structure and crystallization, X-ray diffraction analysis and FTIR spectra were used. The results showed that the Steaming had no significant effect on resistance. But with steaming increased mechanical properties and physical properties of reduced.

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.

This research was done to study the thermal and colorimetric properties of bleached wheat straw/polyethylene biocomposites. Thus, wheat straw was firstly bleached using different natural and/or chemical bleaching methods. The bleached wheat straw and the pure polyethylene were then mixed in ratio of 40 to 60 by twin screw extrouder at 145OC. Maleic anhydride polyethylene was also applied in %10 of polyethylene weight.
Thermal and colorimetric properties of treatments were evaluated and compared to control sample (pure polyethylene). The results showed that the unbleached wheat straw composite had the lowest lightness value. Biocomposites containing bleached wheat straw pulp with xylanase and hydrogen peroxide 1% had the most lightness value after pure polyethylene. The results of the thermal behavior of the composites from DSC curves showed that the melting temperature of bleached wheat straw pulp with xylanase and hydrogen peroxide1% composite was higher than pure polyethylene and the others. The maximum and the minimum decomposition temperature of the composites belonged to the unbleached wheat straw (424.76°C) and the bleached wheat straw pulp (354.23°C), respectively.

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 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.

This study has been undertaken to investigate effects of synthetic waste fibers of polyester in improving mechanical properties of wood plastic composites. Two types of polyester fibers (carpet fibers and polish fibers), high density polyethylene along with 40 wt% wood flour of populus, 2 wt% of maleic anhydride grafted polyethylene (MAPE) and ethylene- glycidyl methacrylate copolymer (E-GMA) as coupling agent were used. After two-stage mixing, resulted granules were hot pressed (at160℃, under 10 Mpa pressures) to produce test boards measuring 20×20×0.7 cm in dimensions. Results from measurement of mechanical properties of the samples have shown that with increasing the amount of polyester fibers (carpet fibers and polish fibers), tensile modulus of elasticity of wood plastic composites decreases and increases his flexural modulus of elasticity. Also by increasing amount carpet fibers, the tensile, flexural strengths of wood plastic composites-carpet fibers increases and the maximum of flexural strength is in a sample that contained 20 wt% carpet fibers. But about the plush fiber, 10 wt% of it is efficient for increasing the flexural and tensile strengths of wood plastic composites-plush fibers. Then on the composites contained the optimal polyester (polish fiber 10% and carpet fibers 20%) for increasing the mechanical strength, TGA and DSC testes for experience the thermal behavior of the composites were analyzed. Thermal analyses results have shown that with addition of polyester in the wood composite plastic, are reduced the percentage of crystallization, temperature of crystallization and the temperature of stability and degradation thermal of the composite.Morphologic study by Scanning Electron Microscopy indicates that with the increasing percentage of polyester fibers, is more denser and smoother the integration between the fracture surface of the composite material.

In this study, the effect of fish waste powder, base material polyethylene, and also the quantity of coupling agent (MAPE) on physical and mechanical properties of wood-plastic composite were studied. For this purpose, wood powder at 40% was mixed with 60% of HDPE. Fish waste in three levels (5, 10 and 15%) mixed into wood powder and coupling agent on three levels (0, 2 and 4) of HDPE in a blender at 180 °C and a speed rotating of 50 rpm, and samples were made with using of injection molding for standard tests. The mechanical properties: tensile and bending strength, bending and tensile modulus were investigated according of ASTM standards. This result suggests that increasing the amount of fish powder waste to 10%, increased bending strength while other strengths diminished. The amounts of all strengths were increased by increasing in percentage of coupling agent to 4%.The results shows that fish waste was suitable as a new material for wood plastics composites.

This study seeks to investigate the possibility of producing polypropylene composite- cotton stalk flour with various percentages of cotton stalk flour. Determining the best treatment in terms of physical and mechanical properties and exploring the effect of using cotton stalks in the production of the composites were among the major objectives of this study. Six treatments consisting of Polypropylene, 40, 55 and 70 percent level of cotton stalks and two fillers (cotton stalks with and without barks) were developed. Maleic anhydride modified polypropylene (3% wt) was applied to each treatment. The mixing and granulation of the plastic and cotton silk flour was carried out using twin screw extruder model 4815. After preparing and shearing of samples, the mechanical properties of composites including tensile strength, rupture modulus and elasticity modulus were calculated in accordance with D-6109 and ASTM D-7031 standards. In addition, water absorption and thickness swelling tests were performed according to D-570-98 standard. The results showed that an increase in the flour of cotton stalk reduced the tensile strength and rupture modulus on the one hand, and increased the bending elasticity modulus on the other hand. In terms of the performance of the filler, there was a significant difference between values of rupture modulus and elasticity modulus at 95% level whereas this difference was not significant for tensile strength. Moreover, this difference was significant for values of water absorption and thickness swelling. The maximum tensile strength belonged to T4 with 40 percent of cotton stalk bark fibers.

Nowadays Paulownia as the fast growing species has noticed for wood industry in the world. In this research، Paulownia fortuni planted in Shaskolateh forest of Gorgan were studied. Two particle form، flour (60 mesh size) and fiber (RMP، L/D= 21/54) were prepared. 60 percent of this material with 37% of HDPE، 3% of MAPE were blended separately. Part from this material by internal mixer and other part by extruder blended. Output was prepared like pellets. Samples were prepared in dimensions of 30cm×30cm×1cm، and nominal density 1 g/cm3 by hot press. The mechanical testing of the panels (flexural، hardness، unnotched impact strength) and the physical testing of the panels (thickness swelling and water absorption after 2 & 24 hours immersion in water) were measured. The result showed that modulus of rupture، hardness، unnotched impact strength of composite made of fiber-PE were lower than composite made of flour-PE. Flexural elastic modulus of composite made of fiber-PE were higher than flour-PE. Water absorption and thickness swelling of composite made of fiber-PE were higher than flour-PE. Also physical and mechanical properties of composites blended by internal mixer improved in compared composites blended by extruder. Physical and mechanical properties of composite made of fiber-PE blended by internal mixer improved in compared composite made of fiber-PE blended by extruder.