Iranian Journal of Polymer Science and Technology 10163255 32 6 2020 02 20 Nanoscale Roughness on the Surface of Polyester Fibers Through Ultraviolet/Ozone Treatment Nanoscale Roughness on the Surface of Polyester Fibers Through Ultraviolet/Ozone Treatment 457 473 1701 10.22063/jipst.2020.1701 FA Fattahi Farnaz Sadat Department of Textile Engineering, Isfahan University of Technology, Isfahan, 84156-8311, Iran Akbar Khoddami Department of Textile Engineering, Isfahan University of Technology, Isfahan, 84156-8311, Iran Jalal Rahmatinejad Department of Textile Engineering, Isfahan University of Technology, Isfahan, 84156-8311, Iran Journal Article 2020 03 11 Hypothesis: In recent years, some modern techniques such as plasma, ultraviolet irradiation and ozone treatment have been used in surface modification of polymers. Surface modification of polymeric fibers is aimed to improve dying and to achieve desirable physical properties like high moisture absorption and lower anti-static. In this study in an attempt to modify the surface of polyester fibers, a new complex method through ultraviolet/ozone treatment in two wet and dry forms has been applied. Methods: Surface modification of polyester fibers was performed by ultraviolet/ozone treatment on dry samples, as well as on samples impregnated with water, hydrogen peroxide and hydrogen peroxide/sodium silicate solutions. In order to study and compare the functional groups and morphology of the polyester fibers with those of control sample, Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used. Also, the moisture absorption and static electricity of the samples were studied. Findings: The results of FTIR spectra revealed that by ultraviolet/ozone treatment the number of oxygen-containing functional groups has increased considerably. Also, nanoscale surface roughness of the treated samples was revealed by SEM images. Additionally, the results indicated that moisture absorption of the treated polyester fibers has risen and consequently their static electricity has decreased. According to the results, the impregnation of polyester fibers can remarkably enhance surface oxidation process. Hypothesis: In recent years, some modern techniques such as plasma, ultraviolet irradiation and ozone treatment have been used in surface modification of polymers. Surface modification of polymeric fibers is aimed to improve dying and to achieve desirable physical properties like high moisture absorption and lower anti-static. In this study in an attempt to modify the surface of polyester fibers, a new complex method through ultraviolet/ozone treatment in two wet and dry forms has been applied. Methods: Surface modification of polyester fibers was performed by ultraviolet/ozone treatment on dry samples, as well as on samples impregnated with water, hydrogen peroxide and hydrogen peroxide/sodium silicate solutions. In order to study and compare the functional groups and morphology of the polyester fibers with those of control sample, Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used. Also, the moisture absorption and static electricity of the samples were studied. Findings: The results of FTIR spectra revealed that by ultraviolet/ozone treatment the number of oxygen-containing functional groups has increased considerably. Also, nanoscale surface roughness of the treated samples was revealed by SEM images. Additionally, the results indicated that moisture absorption of the treated polyester fibers has risen and consequently their static electricity has decreased. According to the results, the impregnation of polyester fibers can remarkably enhance surface oxidation process.

http://jips.ippi.ac.ir/article_1701_0424aa6c013af897afdc08ebe28c8e51.pdf

Iranian Journal of Polymer Science and Technology 10163255 32 6 2020 02 20 Effect of Concentration and Size of Crumb Rubber on Rheological and Flexibility Properties of Bitumen Effect of Concentration and Size of Crumb Rubber on Rheological and Flexibility Properties of Bitumen 475 483 1702 10.22063/jipst.2020.1702 FA Vahid Haddadi Department of Chemistry, Islamshahr Branch, Islamic Azad University, P.O. Box19615-1194, Islamshahr, Iran Journal Article 2020 03 11 Hypothesis: Annually, large amounts of waste tire are disposed into environment. Since decomposition process of these tire materials takes a long time, the governments have imposed regulations to find environmentally-friendly solutions to recycle the waste tires. There are different approaches to take on the modification of physical and mechanical properties of bitumen or asphalt with crumb tires. The results of those studies have illustrated positive effect of crumb rubber on bitumen properties. Therefore, it is reasonable that concentration and size of crumb rubber could affect the bitumen properties. Methods: The effect of concentration (3%, 7% and 10 wt%) and size (1, 0.6, 0.3 and 0.1 mm) of crumb rubber was considered on the viscosity, physical and rheological properties of bitumen/rubber blends. Furthermore, to better decide on the use of crumb rubber for bitumen, the viscosity of modified bitumen was studied. Findings: The results of this study identified that high concentration and smaller dimension of crumb rubber improved cold flexibility and rheological properties of bitumen. Increasing in crumb rubber concentration to 10 wt% resulted in lowering flexibility temperature of bitumen from 20°C to 10°C and even, in smaller sizes (0.1 mm) the flexibility diminished to 8°C. Furthermore, this research showed that at higher concentration and smaller size of crumb rubber the resistance to rutting of bitumen enhanced from 35°C to 60°C. However, the viscosity results showed that a high level of crumb rubber (above 7 wt%) increased the viscosity dramatically and restricted its application. So, adding 7 wt% of crumb rubber with a size of less than 0.1 mm can optimize the physical and mechanical properties of bitumen. Hypothesis: Annually, large amounts of waste tire are disposed into environment. Since decomposition process of these tire materials takes a long time, the governments have imposed regulations to find environmentally-friendly solutions to recycle the waste tires. There are different approaches to take on the modification of physical and mechanical properties of bitumen or asphalt with crumb tires. The results of those studies have illustrated positive effect of crumb rubber on bitumen properties. Therefore, it is reasonable that concentration and size of crumb rubber could affect the bitumen properties. Methods: The effect of concentration (3%, 7% and 10 wt%) and size (1, 0.6, 0.3 and 0.1 mm) of crumb rubber was considered on the viscosity, physical and rheological properties of bitumen/rubber blends. Furthermore, to better decide on the use of crumb rubber for bitumen, the viscosity of modified bitumen was studied. Findings: The results of this study identified that high concentration and smaller dimension of crumb rubber improved cold flexibility and rheological properties of bitumen. Increasing in crumb rubber concentration to 10 wt% resulted in lowering flexibility temperature of bitumen from 20°C to 10°C and even, in smaller sizes (0.1 mm) the flexibility diminished to 8°C. Furthermore, this research showed that at higher concentration and smaller size of crumb rubber the resistance to rutting of bitumen enhanced from 35°C to 60°C. However, the viscosity results showed that a high level of crumb rubber (above 7 wt%) increased the viscosity dramatically and restricted its application. So, adding 7 wt% of crumb rubber with a size of less than 0.1 mm can optimize the physical and mechanical properties of bitumen.

http://jips.ippi.ac.ir/article_1702_93da341761d8483c6c66c19eca490654.pdf

Iranian Journal of Polymer Science and Technology 10163255 32 6 2020 02 20 The Influence of Fibers Diameter on Water Vapor Permeability, Waterproof and Windproof Properties of Electrospun Poly(vinylidene fluoride) Membrane The Influence of Fibers Diameter on Water Vapor Permeability, Waterproof and Windproof Properties of Electrospun Poly(vinylidene fluoride) Membrane 485 495 1703 10.22063/jipst.2020.1703 FA Golchehr Amini Department of Textile Engineering, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Iran Mohammad Karimi Department of Textile Engineering, Amirkabir University of Technology, P.O. Box , 15875-4413, Tehran, Iran Farzin Zokaee Ashtiani Department of Chemical Engineering, Amirkabir University of Technology,, P.O. Box 15875-4413, Tehran, Iran Journal Article 2020 03 11 Hypothesis: Waterproof breathable membranes are used in different fields such as protective clothing, hospital textiles and sport wears. Breathability is an important factor in clothing comfort. Methods: The influence of fiber diameter on breathability, waterproof and windproof properties of poly(vinylidene fluoride) membrane was investigated in this study. Hence, membranes composed of fiber with diameters of 133, 203, 551 and 1018 nm were produced through electrospinning process. It was attempted to use dimethyl sulfoxide as a green solvent in this process. Porosity, pore size, water contact angle, air permeability and hydrostatic pressure of the membranes were assessed. Thermogravimetric analysis (TGA) was employed to measure the water vapor permeability of the membranes. Findings: The hydrostatic pressure of the membranes increased from 10 kPa to 100 kPa by reducing the fibers' diameter (from 1018 nm to 133 nm) and subsequently the pores size of the membranes. The air permeability of the samples decreased from 9 mL/s.cm2 to 1.4 mL/s.cm2 (at pressure drop of 500 Pa) with decreasing fiber diameter. The results showed that the membranes composed of finer fibers have better waterproof and windproof properties. This is while the reduction in fiber diameter and subsequently reduction in the pore size have not led to reduction in the breathability, and the amount of water vapor permeability remained approximately 12.7 kg/m2.day. Hence, it seems that the ordinary diffusion (molecular diffusion) is the dominant mechanism of water vapor diffusion in pore size ranging from 761 nm to 3860 nm and it is independent of the fiber diameter in the membranes Hypothesis: Waterproof breathable membranes are used in different fields such as protective clothing, hospital textiles and sport wears. Breathability is an important factor in clothing comfort. Methods: The influence of fiber diameter on breathability, waterproof and windproof properties of poly(vinylidene fluoride) membrane was investigated in this study. Hence, membranes composed of fiber with diameters of 133, 203, 551 and 1018 nm were produced through electrospinning process. It was attempted to use dimethyl sulfoxide as a green solvent in this process. Porosity, pore size, water contact angle, air permeability and hydrostatic pressure of the membranes were assessed. Thermogravimetric analysis (TGA) was employed to measure the water vapor permeability of the membranes. Findings: The hydrostatic pressure of the membranes increased from 10 kPa to 100 kPa by reducing the fibers' diameter (from 1018 nm to 133 nm) and subsequently the pores size of the membranes. The air permeability of the samples decreased from 9 mL/s.cm2 to 1.4 mL/s.cm2 (at pressure drop of 500 Pa) with decreasing fiber diameter. The results showed that the membranes composed of finer fibers have better waterproof and windproof properties. This is while the reduction in fiber diameter and subsequently reduction in the pore size have not led to reduction in the breathability, and the amount of water vapor permeability remained approximately 12.7 kg/m2.day. Hence, it seems that the ordinary diffusion (molecular diffusion) is the dominant mechanism of water vapor diffusion in pore size ranging from 761 nm to 3860 nm and it is independent of the fiber diameter in the membranes

http://jips.ippi.ac.ir/article_1703_e88b0ea4ffea57f37e29d998086b40d2.pdf

Iranian Journal of Polymer Science and Technology 10163255 32 6 2020 02 20 Influence of Multi-Walled Carbon Nanotubes on Tensile Properties and Printing Quality of 3D-Printed Acrylonitrile-Butadiene-Styrene Nanocomposites Influence of Multi-Walled Carbon Nanotubes on Tensile Properties and Printing Quality of 3D-Printed Acrylonitrile-Butadiene-Styrene Nanocomposites 497 507 1705 10.22063/jipst.2020.1705 FA Zahra Soheilpour Additive Manufacturing Laboratory, Iran Polymer and Petrochemical Institute, P.O. Box 14975-112, Tehran, Iran Amir Masood Rezadoust Additive Manufacturing Laboratory, Iran Polymer and Petrochemical Institute, P.O. Box 14975-112, Tehran, Iran Mohammad Razavi-Nouri Additive Manufacturing Laboratory, Iran Polymer and Petrochemical Institute, P.O. Box 14975-112, Tehran, Iran Keyvan Garoosi Polymer Engineering Department, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Iran Seyed Reza Ghaffarian Polymer Engineering Department, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Iran Journal Article 2020 03 11 Hypothesis: Due to the nature of a fused deposition modeling (FDM), by which the parts are fabricated layer by layer, many defects are prone to occur during printing of the products. Therefore, a few efficient solutions are required to minimize the defects and other shortcomings. The increase in the physical and mechanical properties of the fabricated parts using nanoparticles seems to be one of the methods. Methods: To improve the mechanical properties of acrylonitrile-butadiene-styrene (ABS), which is one of the most common materials employed in FDM technique, various amounts (1, 3 and 5 wt%) of multi-walled carbon nanotubes (MWCNTs) were added to the matrix through a melt mixing process. The filaments containing different MWCNTs contents, required for fabricating of the samples, were then prepared by extrusion. Next, the samples were printed with the layer thicknesses of 0.05, 0.1 and 0.2 mm and raster angles of +45/-45° and 0/90°. Several experiments such as the tensile and rheological tests as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations were carried out to examine the nanocomposite samples. Finding: The SEM and TEM studies revealed that the nanoparticles were reasonably well dispersed throughout the matrix. The results of the tensile tests indicated that by addition of MWCNTs, the tensile strength and Young's modulus were increased by 21% and 103%, respectively, in comparison to those of the pristine material. It was also found that at a constant layer thickness, the maximum value of the tensile strength was obtained for the nanocomposite containing 3 wt% MWCNTs, however, the modulus progressively increased with the increase of the nanoparticles content. In addition, the change in raster angle showed no significant effect on the tensile properties, and the increasing of the layer thickness had an adverse effect on the properties for all the materials examined. Hypothesis: Due to the nature of a fused deposition modeling (FDM), by which the parts are fabricated layer by layer, many defects are prone to occur during printing of the products. Therefore, a few efficient solutions are required to minimize the defects and other shortcomings. The increase in the physical and mechanical properties of the fabricated parts using nanoparticles seems to be one of the methods. Methods: To improve the mechanical properties of acrylonitrile-butadiene-styrene (ABS), which is one of the most common materials employed in FDM technique, various amounts (1, 3 and 5 wt%) of multi-walled carbon nanotubes (MWCNTs) were added to the matrix through a melt mixing process. The filaments containing different MWCNTs contents, required for fabricating of the samples, were then prepared by extrusion. Next, the samples were printed with the layer thicknesses of 0.05, 0.1 and 0.2 mm and raster angles of +45/-45° and 0/90°. Several experiments such as the tensile and rheological tests as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations were carried out to examine the nanocomposite samples. Finding: The SEM and TEM studies revealed that the nanoparticles were reasonably well dispersed throughout the matrix. The results of the tensile tests indicated that by addition of MWCNTs, the tensile strength and Young's modulus were increased by 21% and 103%, respectively, in comparison to those of the pristine material. It was also found that at a constant layer thickness, the maximum value of the tensile strength was obtained for the nanocomposite containing 3 wt% MWCNTs, however, the modulus progressively increased with the increase of the nanoparticles content. In addition, the change in raster angle showed no significant effect on the tensile properties, and the increasing of the layer thickness had an adverse effect on the properties for all the materials examined.

http://jips.ippi.ac.ir/article_1705_c22dc5e2024b3a33e12aaa1ebb4041f2.pdf

Iranian Journal of Polymer Science and Technology 10163255 32 6 2020 02 20 Wollastonite as a Suitable Alternative to Glass Fibers in Acrylonitrile-Butadiene-Styrene Composites Wollastonite as a Suitable Alternative to Glass Fibers in Acrylonitrile-Butadiene-Styrene Composites 509 519 1706 10.22063/jipst.2020.1706 FA Mojtaba Zargoosh Department of Chemical Engineering, Hamedan University of Technology, P.O. Box 65155-579, Hamedan, Iran Hadi Sobhani Department of Chemical Engineering, Hamedan University of Technology, P.O. Box 65155-579, Hamedan, Iran Journal Article 2020 03 11 Hypothesis: Using glass fiber in acrylonitrile-butadiene-styrene (ABS) composites has its limitations by increasing the final price (cost) of the product, abrasions in processing machines, the environmental and health problems during recycling as well as the reduction in impact strength of the composite. This study was carried out to evaluate the effect of silane-treated wollastonite, with a needle structure similar to glass fiber, as an alternative to glass fiber in order to eliminate the drawbacks of ABS/glass fiber composites, on the mechanical properties of ABS/wollastonite composites and compared with ABS/glass fiber composites. Methods: The ABS composites were produced using two types of wollastonite with different geometrical specifications. Dispersion of wollastonite in ABS matrix was evaluated using the SEM micrographs, and the mechanical properties of the composites were determined based on tensile and Izod impact testes. Then, the suitable wollastonite was selected and the ABS/wollastonite composites properties such as tensile, impact strength, thermal and dynamic-mechanical properties were compared with the ABS/glass fiber composites properties at similar percentage of reinforcement phase. Findings: The experimental results showed that the geometrical specification, especially the length/diameter ratio of wollastonite has a significant effect on the impact strength of the ABS composite as a result of good interfacial interaction between the filler and polymer matrix. The results showed significant improvement in the impact strength of ABS/wollastonite composites compared with that of ABS/glass fibers, while the modulus and strength as well as the Vicat softening temperature were acceptable compared with those of ABS/glass fibers composites. According to the results, ABS/wollastonite composites can be a good alternative to ABS/glass fiber composites in many applications. Hypothesis: Using glass fiber in acrylonitrile-butadiene-styrene (ABS) composites has its limitations by increasing the final price (cost) of the product, abrasions in processing machines, the environmental and health problems during recycling as well as the reduction in impact strength of the composite. This study was carried out to evaluate the effect of silane-treated wollastonite, with a needle structure similar to glass fiber, as an alternative to glass fiber in order to eliminate the drawbacks of ABS/glass fiber composites, on the mechanical properties of ABS/wollastonite composites and compared with ABS/glass fiber composites. Methods: The ABS composites were produced using two types of wollastonite with different geometrical specifications. Dispersion of wollastonite in ABS matrix was evaluated using the SEM micrographs, and the mechanical properties of the composites were determined based on tensile and Izod impact testes. Then, the suitable wollastonite was selected and the ABS/wollastonite composites properties such as tensile, impact strength, thermal and dynamic-mechanical properties were compared with the ABS/glass fiber composites properties at similar percentage of reinforcement phase. Findings: The experimental results showed that the geometrical specification, especially the length/diameter ratio of wollastonite has a significant effect on the impact strength of the ABS composite as a result of good interfacial interaction between the filler and polymer matrix. The results showed significant improvement in the impact strength of ABS/wollastonite composites compared with that of ABS/glass fibers, while the modulus and strength as well as the Vicat softening temperature were acceptable compared with those of ABS/glass fibers composites. According to the results, ABS/wollastonite composites can be a good alternative to ABS/glass fiber composites in many applications.

http://jips.ippi.ac.ir/article_1706_b74f78d4f56d908c4ab0e05f4f4334c6.pdf

Iranian Journal of Polymer Science and Technology 10163255 32 6 2020 02 20 Radical Copolymerization of Vinylimidazole and Vinylphosphonic Acid: Sequence Distribution-Glass Transition Temperature Relationship in Copolymers Radical Copolymerization of Vinylimidazole and Vinylphosphonic Acid: Sequence Distribution-Glass Transition Temperature Relationship in Copolymers 521 534 1707 10.22063/jipst.2020.1707 FA Mojtaba Farrokhi Department of Polymer Reaction Engineering, Faculty of Chemical Engineering, Tarbiat Modares University, PO. Box: 14115-114, Tehran, Iran Mahdi Abdollahi Department of Polymer Reaction Engineering, Faculty of Chemical Engineering, Tarbiat Modares University, PO. Box: 14115-114, Tehran, Iran Journal Article 2020 03 11 Hypothesis: Copolymerization is the most successful and powerful method for making systematic changes in polymer properties. The utility of copolymerization is exemplified on the one hand by fundamental investigations of structure-property relations and on the other hand by the wide range of commercial applications. The elucidation of copolymer structure (copolymer composition, monomer sequence distribution) is the major concerns for the prediction of copolymer properties and the correlation between structure and properties. Methods: Homopolymers of poly(1-vinylimidazole) and poly(vinylphosphonic acid) were synthesized in presence of α,α´-azobisisobutyronitrile (AIBN) initiator for the former, and in presence of α,α´-azodiisobutyramidine dihydrochloride (AIBA) initiator for the latter. Poly(1-vinylimidazole/vinylphosphonic acid) copolymers at various molar ratios of monomers in initial feed were obtained by precipitation free radical polymerization in dimethyl formamide (DMF) as solvent at 80°C. The structure and microstructure of the polymers were investigated by spectroscopy methods. Afterwards, the glass transition temperatures of the homo- and copolymers were measured by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Findings: The reactivity ratio of 1-vinylimidazole and vinylphosphonic acid comonomers was obtained using extended Kelen-Todus method and the results of 1H NMR were 0.078 and 0.870, respectively. The reactivity ratio of the comonomers indicated their tendency to form an alternative copolymer. The microstructure of the copolymers, i.e. the diad sequence of monomers, was determined using the reactivity ratio of the comonomers and the theoretical relationships. Then, the glass transition temperature of the copolymers was predicted utilizing calculated sequences and Barton's relation that showed good agreement with the experimental values, and it was found that the microstructure of the copolymers had a significant effect on their glass transition temperature. Hypothesis: Copolymerization is the most successful and powerful method for making systematic changes in polymer properties. The utility of copolymerization is exemplified on the one hand by fundamental investigations of structure-property relations and on the other hand by the wide range of commercial applications. The elucidation of copolymer structure (copolymer composition, monomer sequence distribution) is the major concerns for the prediction of copolymer properties and the correlation between structure and properties. Methods: Homopolymers of poly(1-vinylimidazole) and poly(vinylphosphonic acid) were synthesized in presence of α,α´-azobisisobutyronitrile (AIBN) initiator for the former, and in presence of α,α´-azodiisobutyramidine dihydrochloride (AIBA) initiator for the latter. Poly(1-vinylimidazole/vinylphosphonic acid) copolymers at various molar ratios of monomers in initial feed were obtained by precipitation free radical polymerization in dimethyl formamide (DMF) as solvent at 80°C. The structure and microstructure of the polymers were investigated by spectroscopy methods. Afterwards, the glass transition temperatures of the homo- and copolymers were measured by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Findings: The reactivity ratio of 1-vinylimidazole and vinylphosphonic acid comonomers was obtained using extended Kelen-Todus method and the results of 1H NMR were 0.078 and 0.870, respectively. The reactivity ratio of the comonomers indicated their tendency to form an alternative copolymer. The microstructure of the copolymers, i.e. the diad sequence of monomers, was determined using the reactivity ratio of the comonomers and the theoretical relationships. Then, the glass transition temperature of the copolymers was predicted utilizing calculated sequences and Barton's relation that showed good agreement with the experimental values, and it was found that the microstructure of the copolymers had a significant effect on their glass transition temperature.

http://jips.ippi.ac.ir/article_1707_5d3f60bc9b15c23e3f06c017f967fd95.pdf