جستجوی مقالات مرتبط با کلیدواژه « پلی پروپیلن » در نشریات گروه « مواد و متالورژی »

In this research, the tensile properties of polypropylene/natural rubber composite reinforced with perlite nanoparticles were studied. The mathematical modeling of analysis of variance using the surface response method was used to confirm the experimental results. The role of each materials variable and the weight percentage of natural rubber and pearlite nanoparticles on the tensile properties of the nanocomposite samples was investigated. It was observed that the values of tensile strength and elongation at break by increasing the amount of natural rubber from 20 wt.% to 40 wt.% and the constant amount of perlite nanoparticles at 3 wt.%, decreased by 14.68% (from 8.92 to 7.61 MPa) and increased by 72% (from 51.05% to 87.81%), respectively. The results obtained from the parameters optimization showed that the maximum values of tensile strength and elongation at break are 8.332 MPa and 74.38% was obtained in the sample with 3.268 wt.% of natural rubber and 4.046 wt.% of perlite nanoparticles, respectively. The scanning electron microscope images showed the positive effect of adding nanoparticles to the polypropylene/natural rubber composite due to the reduction in the size of the elastomeric phase and as a result, the increase in the tensile strength of the composite samples. Also, the proper dispersion of nanoparticles in the polymer matrix phase occurred in the sample with 5 wt.% of perlite nanoparticles and 30 wt.% of natural rubber. However, with increasing the weight percentages of nanoparticles up to 9 wt.%, some agglomerations of pearlite nanoparticles were observed in the thermoplastic phase.

The present research has studied the effect of adding perlite and natural rubber nanoparticles with various weight percentages on the tensile modulus and impact strength of polypropylene. For this purpose, different samples were produced and tested using an internal mixer based on the standards of tensile and impact tests. Also, by using of response surface methodology (RSM), the role of input parameters on the responses was investigated in order to achieve optimal mechanical properties and predict these properties with mathematical models in the form of central composite five-level design (CCD). In addition, the SEM test was used to observe the changes made in the microstructure of the samples. The results showed that the addition of 7 wt.% of pearlite nanoparticles to the matrix containing 20 wt.% of natural rubber, the value of the tensile modulus increased by 11.27% and the impact strength by 52.01% compared to the addition of 3 wt.% of pearlite nanoparticles to the same matrix. The results of multiobjective optimization proved that the optimal weight percentage of pearlite nanoparticles and natural rubber was 4.04 and 35.26% wt. respectively. Is. In this case, the highest value obtained for tensile modulus was 508.04 MPa and impact strength was determined to be 108.52 J/m. By observing the SEM images, it was concluded that the change in the size of the elastomeric phase due to the use of different weight percentages of reinforcements has caused the results of the mechanical properties of the samples to differ from each other.

Non-isothermal crystallization kinetics of Polypropylene (PP) melt as a continuous phase of thermoplastic elastomers (TPEs) based on polypropylene / polybutadiene rubber (TPE1: PBR/PP) and polybutadiene rubber / acrylated-polybutadiene compatibizer / polypropylene (TPE2: PBR/ Ac-PBR /PP) as well as their the corresponding thermoplastic vulcanizate(TPV) samples (TPV1 and TPV2) were investigated using Ozawa's kinetic model. The results of the DSC data and the Ozawa model show that the Ac-PBR compatibilizer, increases the onset and the final temperature of crystallization and make the crystallization region narrower. Dynamic vulcanization also results in shifting the onset and the final crystallization temperatures to lower values. The temperature (Tc) and the half-time for crystallization (t_(1/2)) of all blends decrease with increasing cooling rate. The crystallization rate constant and the ozawa model exponent (m) for four different temperatures (110, 115, 120 and 130 C °) were obtained by linear regression method. The exponent of ozawa model changes with increasing degree of molten/crystal conversion. While the “m” value for the pure PP varies from (1.4 at 110℃) to (3 at 120 ℃), these values for TPE1 range from (1.7 at 110℃) to (3.3 at 120℃) and for TPE2 are higher and varies from (1.1 at 110℃) to (4 at 125℃). The maximum value of the crystallization rate constant (KC ) for all blends occurs at approximately 50% relative crystallinity; the highest crystallization rate constants obtains for TPE2.

Both physical and mechanical properties of a semi-crystalline polymer are highly related to the crystallization behavior and morphology development during processing. In the present work, non-isothermal crystallization of polypropylene/graphene nanoplatelets (PP/GnPs) nanocomposite fibers containing 0.1, 0.5, and 1% GnPs was investigated by differential scanning calorimetry (DSC). The Ozawa and Mo methods were used to fit the primary stage of non-isothermal crystallization of the samples. Moreover, the nucleation activity and the crystallization activation energy of GnPs in the PP matrix were calculated by Dobreva’s approach and Friedman’s method, respectively. The results show that the crystallization peak shifted to the lower temperatures with increasing cooling rate. Contrary to Ozawa method, it was observed that Mo approach could describe the non-isothermal crystallization process of PP and PP/GnPs nanocomposite fibers satisfactory. Furthermore, the maximum and minimum nucleation activity was observed for PP/G-0.1 and PP/G-1 nanocomposite fibers, respectively. Crystallization activation energy decreased in the presence of GnPs, indicating that it is easier for the PP/GnPs to crystallize. Although GnPs work as a nucleating agent, they also act as a barrier to molecular mobility and reduce the growth rate, resulting in a more depressed crystallization for PP/GnPs nanocomposite fibers.

In this study, tensile properties of nanocomposites based on polypropylene/ Carboxylated Nitrile Rubber /Silica nano powder (PP/XNBR/Sic) were studied by using response surface methodology(RSM). The design of the experiment was carried out using Box-Behnken of the RSM method. The samples were produced using a co-rotating twin screw extruder including 0,2,4 Wt.% of nano particles, 0, 5, 10 Wt.% of carboxylated Nitrile Rubber and 0,3,6 Wt.% of Polypropylene-g-glycidyl Methacrylate (PP-gMA) as comptabilizer. tensile test was carried out to obtain tensile strength, elastic modulus and elongation at break of nano composites. The results showed that elastic modulus and tensile strength of nanocomposites were increased with addition of nano silica powder by 45% and 9% respectively. Also, the presence of XNBR was increased elongation at break by 39% and increasing the comptabilizer factor (PP-gMA) has slightly increased the tensile strength. In addition, it was found that XNBR has the greatest effect on tensile strength and elongation at break and silica nano powder has the greatest effect on elastic modulus. Finally, a regression model was obtained for tensile strength, elastic modulus and elongation at break, respectively

Polypropylene has a poor toughness and impact strength. So, it needs to modification for some applications. Addition of elastomers to PP to enhance the toughness is a traditional way, but it causes to decrease of the modulus and tensile strength of products. In this research a hybrid composite system including PP, thermoplastic elastomer, nanoparticle and compatibilizer was prepared by melt mixing method. The interaction effect of nanoparticle, thermoplastic elastomer, and compatibilizer on the tensile and impact properties of composites were studied using the experimental design technique; response surface methodology. The results of microscopy analysis showed that the blends were two-phase, where thermoplastic elastomer was dispersed phase. The elastomeric particle size was in the range of 100-400 nm and by increasing the rubber content, rubber particle size increased. Nanosilica dispersed in the presence of compatibilizer had a particle size between 40-90 nm, while the lack of compatibilizer created some agglomerations of nanoparticles. As elastomer content increased, the strain of failure and impact strength of nanocomposites increased, while the Young modulus and tensile strength were decreased. Addition of nanosilica to the PP in the absence of compatibilizer lowered the tensile and impact strengths. While, addition of nanosilica along with compatibilizer improved the tensile modulus of blends. According to the experimental design results, some mathematical relations were presented to predict the mechanical properties. The optimal hybrid nanocomposite had significantly higher impact strength than pure PP while their moduli were in the same order.

In this study, mechanical and thermal properties of a two-phase polymeric matrix composite including polypropylene and EPDM, reinforced with glass fibers and graphene nanoplates is investigated. Compounds were containing 0, 1 and 2 wt.% of graphene nanoplates and 10, 20 and 30 wt.% of glass fibers and 10 and 15 wt.%EPDM, which were prepared by an internal mixer. Samples for mechanical testing were obtained by a hot press machine. Mechanical and thermal tests were performed to determine the impact strength, tensile strength, modulus of elasticity and melting and crystallization temperature of compounds. It was observed that by using of glass fibers, impact strength was increased 46% and tensile strength and elastic modulus were increased slightly compared to the basic ingredients PP / EPDM. By using of up to 1 wt% of graphene nanoplates, impact strength was increased 16%. The more graphene nanoplates used resulted in a decrease in intensile strength. Adding geraghene nanoplates generally increased elastic modulus up to 13%. Also by adding of EPDM, impact strength of the samples was increased 18% but theirother mechanical peorperties were decreased. Graphene nanoplates also slightly increased the crystallization temperature of samples but their melting temperature have not been affected

Several advantages such as low cost, availability of renewable natural resources and high stiffness are main reasons to pay attention to wood plastic composites. In this work, the blends of high density polyethylene (HDPE), polypropylene (PP) and recycled poly (ethylene terephthalate) (rPET) with maleated polyethylene (MAPE) and maleated polypropylene (MAPP) as the compatibilizer were used as the matrix of the wood-plastic composites (WPCs). WPCs has been prepared through an extrusion technology in two-step. In the first step, the bland of matrix (PP/HDPE/rPET) has been prepared, and in second step, the wood flour was added to polymer matrix to produce wood plastic granules. Wood plastic granules were converted to test samples through injection molding technology. The effects of rPET, wood flour and compatibilizer content on the mechanical properties (tensile strength, flexural strength, tensile modulus, elongation at break point and impact energy), density and water absorption resistance of WPCs were investigated. The results showed that the tensile modulus, density and water absorption of WPCs increased with rPET and wood flour, and impact strength and elongation at break point decreased. Tensile and flexural strength increased with rPET, whiles the strength significantly did not change with wood flour. Mechanical properties (elongation, impact energy, tensile modulus and flexural and tensile strength) and water absorption resistant improved with compatibilizer content. SEM images showed that rPET converted to micro fiber in matrix after second step of the extrusion.

In this study particulate composite based on polypropylene/ talc containing different amount of titan dioxide were produced. Titan dioxides powders were incorporated in nano and micro size. The effect of micro and nano size of titan dioxide were studied via mechanical (tensile and impact properties) and color matching tests. The samples were obtained using a co-rotating twin screw extruder. The results showed that the presence of titan dioxide has not considerable effect on melt flow index of the samples in both sizes. However, the different meaningful results were obtained in mechanical and optical testes due to different size (micro and nano) for the samples. The samples containing nano size titan dioxide showed better mechanical and optical test due to higher surface/volume ratio.

Nanocomposite gears based on Polyamide 6/Polypropylene (PA6/PP 67/33) blend containing 2.5 to 10 phr of nano-CaCO3 and 5 phr of maleated polypropylene (PP-g-MAH) as compatibilizer were produced by injection molding. The morphology was studied using scanning electron microscopy. The wear and temperature of gears teeth as well as gears working lives were characterized by employing a gear test rig under two different output torques including 8.9 and 14.8 Nm. In all experiments, the teeth’s temperature and wear values for driver gear were higher as compared to those of driven gear. The incorporation of 2.5 and 5 phr nano-CaCO3, led to the reduction of temperature and wear rate of gears. The wear rates of gears containing 2.5 phr of nano-CaCO3, under the torque of 8.9 and 14.8 Nm, were 60 and 83% lower than those of neat PA6 gears respectively. The maximum gear life under the torque of 14.8 Nm (63000 revolutions) was observed in nanocomposite gears containing 2.5 phr of nano-CaCO3 which was nearly 200% higher than that of neat PA6 gears (21000 revolutions). The raise of Polymer based gears performances as a result of CaCO3 nanoparticles inclusion may be attributed to the improvements of gear teeth flexural, wear and heat resistance

Nanocomposite gears based on Polyamide 6/Polypropylene (PA6/PP 67/33) blend containing 2.5 to 10 (wt%) of nano-CaCO3 and 5 (wt%) of maleated polypropylene (PP-g-MAH) as compatibilizer were prepared by injection molding. The wear and temperature of gears were characterized against the time by employing a gear testing rig. The ends of gears working lives at which the permanent deformation was happened and, as a consequence, power transmission interrupted, under output torque 14.8 Nm were obtained. The inclusion of nano-CaCO3 led to the 5 °C reduction of gears working temperatures. The maximum life under the torque of 14.8 Nm, was observed in nanocomposite gears containing 2.5 (wt%) of nano-CaCO3 was nearly 2.5 times higher than that of neat PA6 gears. The raise of gears durability by inclusion of CaCO3 nanoparticles was attributed to the improvements of gear teeth flexural and wear resistances.

In this study, the surface of polypropylene nonwoven was grafted with acrylic acid. Oxygen plasma treatment was used to create the peroxide radicals required to initiate the grafting of acrylic acid onto the fibers. Several analyses including ATR-FTIR, FESEM, EDS, XPS and AFM were performed on raw, plasma treated and acrylic acid grafted samples. All tests approved the grafting of acrylic acid on the surface of polypropylene nonwoven. The prepared product (AA-PP) was tested for removal of cationic dye from aqueous media. AA-PP removed more than 70% of methylene blue cationic dye from water in pH=11. It was found that the dye adsorption followed Freundlich isotherm. The rates of sorption were found to conform to pseudo-first-order kinetics with good correlation.

In this research, a super hydrophobic coating grade polypropylene (MFI6) with nanoparticles of ZnO was produced on glass by using solution casting technique and the optimal conditions were introduced as well. Solution casting as a simple and inexpensive method does not require any special equipment in order to produce super hydrophobic coatings. Therefore, the effect of two parameters namely, the concentration nanoparticles of ZnO and the drying temperature, on the final properties and performance hydrophobic coatings were investigated. Regarding the studies which have been done on coatings based on the hydrophobicity of the contact angle (CA), it was showed that the hydrophobicity of super hydrophobic coatings behavoirs were exhibited and according to observations of a scanning electron microscope (SEM) devise, a rough and hydrophobic surface was resulted. Thus, the rougher the surface, the higher contact angle is generated, and if this value reaches 150 to 180 °C, the surface would change to a super hydrophobic surface. Increasing the concentration of ZnO nanoparticles to polypropylene has led to more surface roughness. Therefore, the created surface roughness was in micro and nanoscale, while because of an extreme increase in ZnO nanoparticles, the surface roughness was reduced and hydrophobicity was decreased as well due to high accumulation.