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The purpose of this study was to evaluate the impact of brown rot fungus on mechanical and physical properties and biological resistance of thermally modified ash (Fraxinus Sp.) and spruce (Picea Sp.) woods. First, the wood specimens of both species were heat treated at 212 ºC for 3 hours. Then, heat-treated and untreated wood specimens were exposed to brown rot fungus for 16 weeks based on EN 313 and the functionality of fungal destructive agent and also its effect on physical and mechanical properties were analyzed. The results showed that the brown rot fungus had efficiently impacted the untreated specimens compared to thermally treated wood in both wood species and caused more destruction and weight loss. Moreover, the results revealed that the residual physical and mechanical properties including density, compression parallel to grain and impact strength of thermally heated specimens exposed to brown rot fungus were higher than unheated specimens. Evaluation of laccase activity which was produced by brown rot fungus was higher on controls than on heat treated specimens in both wood species. Based on the results, thermal modification can generally cause improvement of biological resistance, and reduction of some physical and mechanical properties. [ABSTRACT FROM AUTHOR]

Background and Objectives: Densification serves as a mechanical modification method aimed at enhancing the mechanical properties of cultivated fast-growing woods. However, a common challenge associated with densified wood is the reduced recovery of its initial form. Heat treatment has been widely adopted as a solution, but it often results in a decrease in mechanical properties. An alternative approach involves heat treatment with plant-functionalized oil, where the functional groups of the oil react with the hydroxyl groups in the wood. The objective of the current study was to address the loss of mechanical properties by combining densification and heat treatment using epoxidized soybean oil. Materials and Methods: In the current study, fast-grown poplar wood underwent impregnation with both raw and epoxidized soybean oil, followed by densification to a compression set of 30 percent. Subsequently, the oil-impregnated and densified samples were subjected to heat treatment in an oven at 180 °C for a duration of four hours. The aim was to comparatively investigate the mechanical properties of both the densified and non-densified samples, which were impregnated with either raw or epoxidized oil. Results: The calculation of oil uptake values for both raw and epoxidized soybean oil in both densified and non-densified samples revealed that the non-densified sample exhibited nearly twice the uptake of epoxidized oil compared to the raw oil. This can be attributed to the higher polarity and enhanced penetrating ability of the epoxidized oil. Densification resulted in a significant reduction of oil content in both cases; however, the densified sample treated with epoxidized oil exhibited higher oil uptake compared to the raw oil. The analysis of mechanical properties indicated that heat treatment with raw oil caused a 97 percent loss in flexural strength, while heat treatment with epoxidized oil resulted in a 7 percent loss. Additionally, heat treatment of densified wood using raw and epoxidized oil led to a 96 percent and 20 percent decrease in hardness values, respectively, compared to the non-heat-treated samples. Moreover, heat treatment of densified wood in the presence of epoxidized oil resulted in decreased flexibility and impact strength Conclusion: Impregnating wood with epoxidized oil, due to its permeation into the cell wall, resulted in a significant reduction in flexural strength and hardness. However, subsequent densification further increased these strengths. Heat treatment of the epoxidized oil-impregnated samples after densification resulted in a lesser decrease in flexural strength and hardness compared to samples impregnated with raw oil. However, this effect was not observed in terms of impact strength. In general, heat treatment in epoxidized soybean oil can be considered an effective method for reducing the spring back and water absorption of densified wood. This treatment also contributes to a lesser decrease in mechanical strength. Therefore, it can be recommended as an effective approach for mitigating these effects on densified wood. [ABSTRACT FROM AUTHOR]

In recent years, plant oils usage as matrix in natural fiber reinforced polymer composites, has been considered because of increasing environmental concern. In the present research work, acrylated epoxidized soybean oil combined with maleic anhydride and styrene as a matrix and wheat straw flour as filler was used for making a relatively biodegradable composite. In order to find the optimum synthesis time of resin, during reaction of maleic anhydride with acrylated epoxidized soybean oil, three time level of 60, 90 and 120 min, polymer was prepared and cross link density was determined with “solvent swelling” method. The optimum synthesis time of resin was obtained 90 min. Afterwards, maleated acrylated epoxidised soybean oil was mixed with 25% of styrene and 60 mesh wheat straw flour in three weight ratio of 20, 30 and 40% manually. The combination of resin and wheat straw flour was poured in a steel mold and pressing was applied manually. The die was placed in an oven at temperature of 140°C for one hour. Infrared spectroscopy, Thermogravimetric analysis tensile and impact test was conducted to evaluate and analyze the physical and mechanical properties of the resulted composite. Infrared spectroscopy results showed ether bond formation between hydroxyl groups of wheat straw and carbonyl groups of resin. Water absorption test results showed no statistical difference between water absorption values of three loading of wheat straw till 144 hours of immersion, however at 168 hours of immersion, water absorption values were increased with increase of wheat straw loading. There was no statistical difference between thickness swelling values of composites with different wheat straw loading. With increasing wheat straw loading, tensile strength and modulus was increased significantly. Also the impact strength increased as an increase of wheat straw loading. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of thermos-heat treatment on bio-durability and some physical and mechanical properties of beech (Fagus sp.) and pine (Pinus sp.) woods. Thermo-wood samples were prepared from beech and pine species based on thermo-D process. Heat-treated and untreated wood specimens were evaluated after exposing to brown rot fungus for 16 weeks. The laccase activity and its effect on mass loss and wood density were investigated. Results showed that deterrence value of heat treatment on mass loss caused by brown rot fungus have been 76.92% and 44.32% in beech and pine wood, respectively. So, laccase activity and its efficiency on mass loss of control specimens was more than heat treated wood. The results also showed that thermal modification at high temperatures reduced wood density. However, it had deterrent effect on the reduction of wood density caused by brown rot fungus activity. Moreover, some mechanical properties including impact strength and compression parallel to grain of wood specimens were measured. The results generally showed that thermal modification improves the bio-durability of both wood species. The results also revealed reduction of mechanical properties due to heat treatment except compression parallel to grain. [ABSTRACT FROM AUTHOR]

The use of self-compacting high performance composites due to its unique properties has attracted the attention of researchers.The high compressive strength and tensile strength, high flexural strength, have attracted the attention of researchers to this type of cement composites.In this research, in the form of a comprehensive experimental work, using six basic mixing designs, 24 rectangular composite slabs 300 to 400 mm, with two thicknesses of 30 and 50 mm, were built and tested under impact load. Compressive,tensile and flexural strength tests were made on each of the six mixing designs. Also, to determine the efficacy of high performance composite, slump flow, L-box, U-box and V-funnel on mix designs have been done. Steel fibers with percentages of 0, 0.5 and 1% by volume fraction, with lengths of 25 and 50 mm, were used for the construction of cementitious composites. The impact test apparatus was made from a 5.6 kilogram steel ball and a retaining system. The steel ball was raised to a height of 1.5 meters and was freed repeatedly until failure cracking in the samples have been Developed. According to the results of the experiment, It was noted that the maximum energy absorption in a slab with a thickness of 30 mm was 34.22 kJ, and in a slab with a thickness of 50 mm was 47.49 kJ. The results of this experiment shows the high effect of steel fibers on increasing the impact resistance and absorbed energy of the composite slabs.

In this study, the effect of walnut shell and charcoal flour on the applied characteristics of the resulting plastic composites was investigated. For this purpose, walnut shell and charcoal flour in three levels of 20, 30 and 40% were mixed with high density polyethylene using Brabender internal mixer during the melt mixing process, then standard test samples were made by injection molding method. Mechanical properties including tensile and flexural strength, tensile and flexural modulus and impact strength were measured. Physical properties including water absorption and thickness swelling after 24 hours immersion were evaluated and scanning electron microscopy images were also examined. The results showed that the flexural strength and impact strength of the wood plastic composite containing 40% walnut shell flour were higher than the samples containing 40% charcoal flour. Also, by increasing the walnut shell and charcoal flour from 20 to 30%, the flexural strength increased by 3.3% and 6.1%, respectively, and by increasing the walnut shell and charcoal flour from 20 to 40%, the flexural modulus increased by 51.9% and 63.8%, respectively. Other results of mechanical strength indicate that with increasing walnut shell charcoal from 20 to 40%, tensile strength and modulus increased to 22.9 and 109.7%, respectively, and with increasing walnut shell and charcoal flour from 20 to 40%, the impact strength decreased by 6.6 and 5.4%, respectively. The results of physical properties showed that with increasing walnut shell and charcoal flour from 20 to 40%, water absorption for 24 hours decreased by 19.2 and 8.4%, respectively, and thickness swelling by 24 hours decreased by 53.6 and 46.7%, respectively. [ABSTRACT FROM AUTHOR]

The importance of environmental issues has increased the use of biodegradable polymers which nowadays have become among main components in medical and biological applications. In the present study, a new combined method of fused filament fabrication (FFF) and batch foaming was introduced to improve the properties of poly lactic acid. For this purpose, FFF samples were produced with infill percentages of 100, 80 and 60 and then, foamed in batch process. Due to the importance and effect of the void fraction on structural and mechanical performance as well as the biodegradability of materials with porous structure, especially for medical purposes, void fraction and impact strength were evaluated. The results showed that the void fractions of FFF samples were 3%, 13% and 25% in infill percentages of 100, 80 and 60, respectively while after the foaming they reached to 14%, 19% and 30%. The findings revealed that the impact strength of FFF foamed samples was improved compared to FFF solid samples. For samples with 100 infill percentage, the impact strength improved from 207 to 506 J/m2 due to the foaming procedure with nano-sized cells created by the batch foaming. [ABSTRACT FROM AUTHOR]

Hypothesis: Polyamide 6 (PA6)/nitrile butadiene rubber (NBR) thermoplastic elastomer reinforced by nanoparticles has several applications in various industries. The addition of nanoparticles to thermoplastic elastomers will affect the tensile strength, impact strength, fracture mechanism and thermal properties of nanocomposites. There are different processes to fabricate these nanocomposites such as extruder, internal mixer, and friction stir process.Methods: PA6/NBR/clay nanocomposites were fabricated by internal mixer (IM) and friction stir process (FSP). The mechanical properties and fracture mechanisms of these nanocomposites were investigated by mechanical testing (tensile, impact, and hardness) and essential work of fracture (EWF) methodology. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the morphology of samples.Finding: The results indicated that with addition of nanoclay up to 5% in an elastomer containing internal mixer, the tensile strength increased, and beyond 5%, the tensile strength decreased. The friction stir process sample with 7% nanoclay showed a maximum tensile strength of 35.4 MPa. In the friction stir process sample with 7% nanoclay, the tensile modulus and total work of fracture, respectively, increased by 75% and 56%, while in the internal mixer sample, the modulus increased by 50% and total work of fracture decreased by 5%. With the addition of 7% nanoclay to PA6/NBR blend, the impact strength of friction stir process and internal mixer samples decreased by 4 and 18%, respectively. The addition of 7% nanoclay to PA6/NBR blend with friction stir process improved the thermal behavior as the crystallization temperature and melting temperature increased from 195.3 to 197.1°C and 221.3 to 222.5°C, respectively.

In the present study, the usability of high-density polyethylene (HDPE) based composites was investigated in medical applications under impact loads. Due to the importance of biocompatibility of composites in medical applications and the body environment, zinc oxide nanoparticles (ZnO) were selected as reinforcements. ZnO nanoparticles are generally safe and have superior antibacterial properties. A finite element simulation process with a new approach was used to study the composite impact properties in the standard Charpy impact test; moreover, in the experimental procedure, a new method was introduced for the production of HDPE/ZnO composites without the use of the compatibilizers. Fourier-transform infrared spectroscopy (FTIR) test was used to check the diffusion of particles in composites. Field emission scanning electron microscopy (FESEM) was utilized to examine the presence of particles in composites. The results of the simulation showed that the HDPE/1%ZnO composites have the best impact resistance in comparison to other composites. Experimental results also showed that HDPE/1%ZnO composites have the best performance in terms of impact strength with an error of about 11% compared to simulation results and are economical. Moreover, the results of the antibacterial test of HDPE/1%ZnO composites confirm the excellent performance of these composites against gram-positive and negative strains. [ABSTRACT FROM AUTHOR]

In this study, the mechanical properties of poly lactic acid samples produced by FDM 3D printing technique were investigated. The 3D printing process parameters were optimized using design of experiment (DOE) Taguchi approach for achieving the optimum mechanical performance. In this regard, infill percentage (at three levels of 30, 50, and 70%), raster angle (at three states of 0/90, -30/30, and -45/45 degree), and layer thickness (at three levels of 200, 250, and 300 μm) were considered as process parameters for optimization procedure. Their effects on density (as porosity degree), impact strength (as mechanical property), and specific impact strength (the impact strength to density ratio) were investigated. Analysis of variance (ANOVA) was utilized to find the most effective processing parameters. The findings revealed that the infill percentage was the most effective parameter on the density and the impact strength. The density and the impact strength were reduced with the decrease of the infill percentage. These decrements were in a way that their ratio, specific impact strength, was almost constant. The layer thickness had the most influence on the specific impact strength. The specific impact strength was improved by reducing the layer thickness due to the raster entanglement. The optimum conditions to achieve the highest mechanical performance were the raster angle of 30/-30 degrees and the layer thickness of 200 μm. The optimum infill percentage depended on the application. [ABSTRACT FROM AUTHOR]

Hypothesis: Polymer matrix composites (PMCs) have various structural applications. To improve the mechanical properties of PMCs, nanoparticles are usually added to polymer matrix as reinforcements to produce polymer matrix nanocomposites. This research investigates the effects of surface treatment of graphene nanoplatelets (GNPs) on the tensile and impact behavior of basalt fibers\ epoxy composites.Methods: For this purpose, surface treatment of GNPs was performed using (3-aminopropyl) trimethoxysilane. The presence of silicon and nitrogen elements, which are the main components of functionalization group on the surface of treated GNPs, was confirmed by EDX-SEM mapping analysis. The nanocomposites with different weight percentages of treated GNPs (0.2, 0.3, 0.4 and 0.5) were fabricated by hand lay-up method. Also, two composite samples, one without GNPs and the other with 0.4 wt% untreated GNPs were fabricated to compare with those reinforced with treated GNPs. Tensile and Charpy impact tests were performed on fully cured samples.Findings: The results showed 21.1, 3.6, 35.1 and 74.6 percent increase in tensile strength, modulus of elasticity, fracture energy and impact strength, in the order given, for nanocomposites reinforced with 0.4 wt% treated GNPs were obtained compared to those without GNPs. Also, 52.1, 37.5, 57.9 and 25.5 percent decrease in properties, in the stated order, were observed for nanocomposites with 0.4 wt% of untreated GNPs compared to those without GNPs. According to the SEM images, the increase in tensile properties could be related to the improvement in the adhesion between basalt fibers and epoxy resin, and also the toughening mechanism of treated GNPs. The surface treatment increased the interaction between the GNPs and the matrix, and also the presence of treated GNPs promoted crack deflection phenomenon that is one of the major toughening mechanisms of GNPs. The reduction in the mechanical properties of sample containing 0.4 wt% untreated GNPs was attributed to the uneven dispersion of GNPs in the epoxy matrix and the weak interactions between the graphene nanoplatelets and matrix and fiber.

The use of additives to modify the physical, chemical and mechanical properties of soil and soil stabilization is one of the most common methods that have a history. By adding one or more additives to the soil and carrying out the required measures, the engineering properties of soils could be improved due to chemical reactions. Selecting the type and amount of additive depends on several factors such as: soil type, stabilization purpose, additives inherent characteristics, etc.; these are determined based on the technical and economic aspects of the projects. In this study, the effects of the simultaneous use of three types of additives including lime, stone powder and polypropylene fibers on the unconfined compressive strength of a clayey soil were investigated. To do this, four different levels of lime (0, 2, 3 and 5 percent by weight of soil) and four different levels of stone powder waste (0, 2, 5 and 10 percent by weight of soil) and Polypropylene fibers with different percentages in five levels of 0, 0.25, 0.5 and 1 percent by weight of soil were added into a high plastic clay soil classified as CH. Then, some physical and mechanical characteristics of different mixtures including plasticity, compaction and unconfined compressive strength were determined. The results showed that the samples were stabilized with lime and stone powder waste and reinforcement them with polypropylene fibers modified Atterberg Limits, optimum moisture and maximum dry density of the mixtures. Also, it was found that a combination of waste stone powder, lime and polypropylene fibers containing 5, 5 and 1 percent by weight of soil increased the unconfined compressive strength 8-fold, as compared to the natural soil. The curing time also had a significant impact on the compressive strength of the treated samples in which the 28-day compressive strength of was found to be about 2 times of the 7-day samples. [ABSTRACT FROM AUTHOR]

In this article, the effects of normalization heat treatment on girth weld with containing titanium oxide and titanium carbide microparticles (X-65 grade of the gas pipeline) were evaluated. The Charpy test results show that in the normalized sample containing titanium oxide microparticles and titanium carbide microparticles compared to the no heat treatment sample (containing titanium carbide microparticles and titanium carbide microparticles), has been respectively increased by 33% and 18%. Also, the ultimate strength of normalized samples containing titanium oxide microparticles and titanium carbide microparticles compared to the no heat treatment sample (containing titanium oxide microparticles and titanium carbide microparticles) has been increased by 9% and 11%, respectively. The results show that the fatigue life in both normalized micro-alloy samples has been increased. The fatigue life in the normalized sample of titanium carbide microparticles has increased more than the titanium oxide microparticles. The fatigue test results show that the fatigue life (150- N force) has been increased by 36% in the normalized sample containing titanium carbide microparticles compared to the normalized sample containing titanium oxide microparticles. In this loading, the fatigue life (normalized sample containing titanium carbide microparticles compared to the no heat treatment sample) has been increased by 27%. The hole-drilling strain-gage results show that in the normalized sample containing titanium oxide and titanium carbide microparticles, hoop residual stresses have been respectively decreased by 12% and 8%compared to the no heat treatment sample (containing titanium oxide microparticles and titanium carbide microparticles). [ABSTRACT FROM AUTHOR]

Titanium is one of the most important microalloy elements used in the gas transmission industry. In this paper, titanium nano-oxide and titanium nano-carbide were added to two separate samples. Then the shielded metal arc welding (SMAW) was performed on highstrength low alloy steel according to welding procedure specification of the national Iranian gas company. The effects of annealing heat treatment on girth weld with containing titanium oxide and titanium carbide nanoparticles (X-65 grade of gas transmission pipeline) were evaluated. The Charpy test results show that in the annealed sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (Containing titanium carbide nanoparticles and titanium carbide nanoparticles), energy absorbed has been respectively increased by %13 and %9. Also, the ultimate strength of the annealed sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the non-heat treated sample has been respectively decreased by %8 and %3. The fatigue life in both annealed nano-alloy samples has been increased. Also, the fatigue life in the annealed sample of titanium carbide nanoparticles has increased more than fatigue life in the titanium oxide nanoparticles. The fatigue life (Annealed sample containing titanium carbide nanoparticles compared to the no heat treatment sample) has been increased by %16. The hole drilling strain gage results show that in the annealed sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the non-heat treated sample, hoop residual stresses has been respectively decreased by %31 and %19. [ABSTRACT FROM AUTHOR]

The effects of tempering heat treatment on girth weld containing titanium oxide and titanium carbide nanoparticles (X-65 grade of the gas pipeline) were evaluated. The Charpy results show that it has been respectively increased by 26% and 15% in the tempered sample containing titanium oxide and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium carbide and titanium carbide nanoparticles). Also, the ultimate strength tempered sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide and titanium carbide nanoparticles) has been respectively decreased by 6% and 4%. The results show that the fatigue life in both tempered nano-alloy samples has been increased. The fatigue life in the tempered sample of titanium carbide nanoparticles has increased more than the fatigue life in titanium oxide nanoparticles. The fatigue test results show that in the tempered sample containing titanium carbide nanoparticles compared to the tempered sample containing titanium oxide nanoparticles, fatigue life (150-N force) has been increased by 30%. In this loading, the fatigue life (tempered sample containing titanium carbide nanoparticles compared to the no heat treatment sample) has been increased by 19%. The hole drilling strain gage results show that in the tempered sample containing titanium oxide nanoparticles and titanium carbide nanoparticles, hoop residual stresses have been respectively decreased by 48% and 45% compared to the no heat treatment sample (containing titanium oxide and titanium carbide nanoparticles). [ABSTRACT FROM AUTHOR]

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, mechanical properties of high density polyethylene (as matrix) and olive mill sludge (as filler / reinforcement) composites were investigated. There levels of paper sludge (15, 30, 40 and 50 wt %) were used to produce composites. The effect of maleic anhydride grafted polyethylene (MAPE) as coupling agent on the mechanical properties composite was investigated and then, these composites (with coupling agent) were compared with composites without coupling agent. For blending materials from extruder and produce of mechanical standard sample from injection molding were used. Mechanical properties containing tensile properties (modulus of elasticity and tensile strength) and impact strength were studied. The result of obtaining from modulus of elasticity showed that with adding olive mill sludge to the polyethylene cause to signification increasing in modulus of elasticity were compared to pure polyethylene. Tensile strength composite increasing with adding olive mill sludge compared to pure polyethylene but maximum measure of tensile strength related to composites contain 30% olive mill sludge and coupling agent. Also adding 15% olive mill sludge to polyethylene cause to improved impact strength in compared pure polyethylene, but with adding more olive mill sludge (30, 40 and 50%), impact strength in composites were decreased. The used of coupling agent in the total manufactured composite cause to improved in impact strength of composites. The addition of a coupling agent (MAPE) to the composition resulted in an increase in mechanical properties of the composites that indicating enhanced matrix–olive mill sludge interfacial adhesion.

An ultra-glide twin screw extruder is employed to allow the quick and easy removal of the screws from the fixed processing section within few seconds, probing the current degree of the melting state, the dispersive anddistributive processing steps and finally the level of morphology development along extruder screws. For morphological studies the molten samples, collected from different points along the screw length, were quickly frozen in liquid nitrogen and observed under a scanning electron microscope. The morphology development along screws was studied for the compatibilized PA6/ABS blends with different ABS contents. It was observed that the co-continuous morphology was formed in an initial stage of mixing, which then transformed into a refined co-continuous structure and developed along the extruder. The level of co-continuity decreased at higher ABS content. In addition the effect of processing condition on morphology development was studied. In view of the mechanical properties, the effect of morphology on the impact strength could be elucidated. It was found that not only the co-continuous morphology but also the level of co-continuity plays an important role in determination of ultimate impact properties. The impact strength was lowered to 35 kJ/m2 from initial value of 47 kJ/m2 by increasing the ABS content from 60 to 70 wt%.

Wood anatomy in addition to genetic is affected by environmental factors. One of the environmental factors is soil erosion which affects anatomical properties of roots considerably. Juniperus excelsa is one of Iranin indigenous softwood and has longevity and anatomical properties of its root in two conditions: inside of soil and exposed one can reveal effects of soil erosion on wood anatomical properties of root. So many roots and barks of trees in inside of soils and exposed have been sampled and many micro-sections prepared by microtome and anatomical properties were investigated. Results showed that wood roots under soil conform of one row of late-wood and by exposing the lumen area of tracheids in early-wood and late-wood were decreased and the cells appear thicker and late-wood portion increased. The axial parenchyma inclusion of dark resins in exposed roots observed frequently. Meanwhile by exposing of roots the thickness of bark decreased and the thickness of phloem and periderm in exposed root is not as wide as normal roots.

In this study, using design of experiments, the effect of hybrid graphene nanosheets and nano clay and compatibilizer maleic anhydride- grafted- polypropylene (PP-g-MA) on the impact strength polypropylene- based nanocomposites were investigated. Design of experiments and analysis of experimental data with Minitab 16 software and response surface methodology were carried out. Producing nanocomposites, based on the melt mixing was performed. Statistical models provided by response surface methodology show good agreement with experimental results and with respect to the values of R-sq and R-sq (adj) are suitable. Statistical analysis showed that by increasing the percentage of nanoparticles, impact strength decreases. Compounds morphology was performed by Scanning Electron Microscopy (SEM). Micrographs showed better dispersion of the particles at lower percentages. Thermal analysis using differential scanning calorimetry (DSC) showed that the presence of graphene has little effect on the melting temperature of the sample being tested, but Tc of nanocomposites compared with pure PPincreased aboutͶpercent. Also, the crystallinity was reduced by adding graphene. In the non-graphene nanocomposites, the clay did not affect the melting temperature, but the crystallinity and crystallization temperature increased 10.73 Ψ and 2.23 Ψ respectively compared with pure PP, whichshowed nucleation effect of nano clay. [ABSTRACT FROM AUTHOR]