The structural, electronic, and optical properties of Cu2Zn1−xBaxSn1−ySiyS4 compounds have been calculated using GGA-PBE function within the framework of Density Functional Theory (DFT). In the present work, lattice p...The structural, electronic, and optical properties of Cu2Zn1−xBaxSn1−ySiyS4 compounds have been calculated using GGA-PBE function within the framework of Density Functional Theory (DFT). In the present work, lattice parameters remained the same, that is tetragonal crystal structure for 0% and 100% doping concentration. The electronic band gap of Cu2Zn1−xBaxSn1−ySiyS4 compounds has been gradually increased for continuous increment of doping concentration where the highest electronic band gap is 1.117 eV for Cu2BaSiS4 structure. Moreover, the band gap changes from direct to indirect band gap with the increase of doping concentration in the parent compound. The absorption coefficient has been found to be high (> 104 cm−1) in UV-region for all the doping concentration which makes the studied compound as a potential candidate of absorber layer in the UV detector. The theoretical study of the effect of double doping in the CZTS compound is very interesting for improving the quality of it and it would be a reference for the theoretical and experimental researchers.展开更多
In the present study, the effect of the exchange-correlation functional on the structural, mechanical, and optoelectronic properties of orthorhombic RbSrBr3 perovskite has been investigated using various functionals i...In the present study, the effect of the exchange-correlation functional on the structural, mechanical, and optoelectronic properties of orthorhombic RbSrBr3 perovskite has been investigated using various functionals in Density Functional Theory (DFT) with the CASTEP code. The optimized lattice parameters are quite similar for all the functionals. The electronic properties have shown that RbSrBr3 perovskite is a wide direct band gap compound with a band gap energy ranging from 4.296 eV to 4.494 eV for all the functionals. The mechanical parameters like elastic constants, Young’s modulus, Shear modulus, Poisson’s ratio, Pugh’s ratio, and an anisotropic factor reveal that the RbSrBr3 perovskite has ductile behavior and an anisotropic nature which signifies the mechanical stability of the compound. The Debye temperature might withstand lattice vibration heat. High absorption coefficient (>104 cm−1), high optical conductivity, and very low reflectivity have been found in the RbSrBr3 perovskite for all functions. The computed findings on the RbSrBr3 perovskite suggested that the presented studied material is potentially applicable for photodetector and optoelectronic devices.展开更多
Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion...Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion resistance. This study was carried out with composites prepared by hot press molding method using coconut spathe fiber as reinforcing material and HDPE (from HDPE can as obsolete polymer) as polymer matrix. Composites were made at 150°C under 60 kN load by taking diverse weight percentage (wt.%) of fiber from 0 to 20 of its total weight. In this research investigation, different properties of the composites such as bulk density, water absorption, tensile and flexural properties, impact strength and hardness test properties were carried out. The fiber content enhancement increases the bulk density in all composites. The rate of water absorption improves with the improvement of fiber addition with respect to HDPE in all composites. But the water absorption was not increased uniformly with the increase of fiber addition in composites. In all cases, composites absorbed water very rapidly up to 80 hrs and then water absorption is in saturated condition. The mechanical properties like tensile strength (TS), flexural strength (FS), impact strength (IS) and hardness were observed to be comparatively more enhanced for 5% composite, while further increasing of fiber addition, all mechanical properties changes irregularly. The irregular nature of change might be caused due to the over loading of fiber in polymer matrix.展开更多
The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180<span style="white-space:nowrap;...The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180<span style="white-space:nowrap;">°</span>C temperature and 50 KN load. Sawdust was collected from local saw mill of Savar, Dhaka, Bangladesh and ABS polymer was collected from local market of Dhaka, Bangladesh. In this study, different properties of composites like physical (bulk density and water absorption), mechanical (tensile properties and hardness) and structural (Fourier Transform Infrared Spectroscopy) properties were studied. The bulk density of composites was not altered consistently and it gave greater value for 5% and 20% composites. The water absorption enhanced for all composites with the accumulation of fiber content and soaking time. The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions. Maximum (%) of elongation was found for 5% composite, and then it gradually decreased;however, elastic modulus increased with the increased of fiber content in composites. Fourier Transform Infrared (FTIR) spectroscopy study was done for structural characterization. It was found that there was a new bond (C≡C) stretching formed for 20% composite;moreover, C-H rocking for 0% composite was broken for all other composites after the addition of sawdust in ABS polymer matrix.展开更多
Electromigration is a main challenge in the pursuit of power electronics, because physical limit to increase current density in power electronics is electromigration (EM), whereas much higher electrical current and vo...Electromigration is a main challenge in the pursuit of power electronics, because physical limit to increase current density in power electronics is electromigration (EM), whereas much higher electrical current and voltage are required for power electronics packaging. So the effect of EM is an important issue in applications where high current densities are used, such as in microelectronics and related structures (e.g., Power ICs). Since the structure size of integrated circuits (ICs) decreases and the practical significance of this effect increases, the result is EM failure. On the other hand, in the next generation power electronics technology electrical current density is expected to exceed 10<sup>7</sup> A/cm<sup>2</sup> which is another challenge. This review work has been carried out to identify the mechanism of EM damage in power electronics (e.g., pure metallization and solder joints) and also how to control this kind of damage.展开更多
Palm fiber (PF) reinforced acrylonitrile butadiene styrene (ABS) composite matrix was prepared by employing Injection Moulding Machine (IMM). Palm fiber was collected from ten different trees of different age group fr...Palm fiber (PF) reinforced acrylonitrile butadiene styrene (ABS) composite matrix was prepared by employing Injection Moulding Machine (IMM). Palm fiber was collected from ten different trees of different age group from Comilla region in Bangladesh. Three sets of samples were prepared for three different wt% (5%, 10% and 20%) of fiber contents. The mechanical (tensile strength, flexural stress, micro hardness, Leeb’s rebound hardness) and physical (bulk density and water absorption) properties were measured. The observed result reveals that the tensile strength (TS) and flexural stress (FS) were decreased with increasing fiber contents in the PF-ABS composites except 10% fiber content.展开更多
With the aid of Injection Moulding Machine (IMM) Palm fiber reinforced Acrylonitrile Butadiene Styrene (ABS) composites (PF-ABS) were prepared. Three sets of samples were prepared for three different wt% (5%, 10% and ...With the aid of Injection Moulding Machine (IMM) Palm fiber reinforced Acrylonitrile Butadiene Styrene (ABS) composites (PF-ABS) were prepared. Three sets of samples were prepared for three different wt% (5%, 10% and 20%) of fiber contents. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) experiments were performed to study the surface morphology, microstructure (if it crystalline or noncrystalline) and new bond formation after preparation of the composites. SEM pattern shows that after addition of palm fiber in PF-ABS composites the brittleness increased due to creation of voids in the composites except 10% fiber content in PF-ABS. From XRD pattern it is clear that the palm fiber, ABS and PF-ABS composites are amorphous in nature. Moreover FTIR spectrum shows that there is no new bond formed after addition of palm fiber in ABS polymeric matrix to create PF-ABS composites.展开更多
The activity concentrations of radionuclides in the sand and soil samples collected from Kuakata seabeach of Patuakhali district in Bangladesh have measured using a high resolution high purity germanium (HPGe) detecto...The activity concentrations of radionuclides in the sand and soil samples collected from Kuakata seabeach of Patuakhali district in Bangladesh have measured using a high resolution high purity germanium (HPGe) detector of relative efficiency 40%. The activity concentrations of 226Ra, 232Th and 40K were found in the sand samples of Kuakata seabeach varied from 2.82 ± 4.89 to 87.96 ± 4.45 Bq.Kg–1, 21.72 ± 16.27 to 290.93 ± 18.15 Bq.Kg–1 and 26.24 ± 0.35 to 852.05 ± 142.15 Bq.Kg–1 respectively. For soil samples the activity concentrations of corresponding radionuclides were found to be 20.98 ± 3.96 to 42.92 ± 4.76 Bq.Kg–1, 59.25 ± 15.62 to 144.34 ± 18.52 Bq.Kg–1 and 570.43 ± 100.3 to 1165 ± 166.27 Bq.Kg–1 respectively. The average absorbed dose rate due to radionuclides in sand was estimated to range from 51.84 to 246.55 nGy.h–1 with an average of 98.33 nGy.h–1. Also the average absorbed dose rate due to radionuclides in soil was estimated to range from 76.63 nGy.h–1 to 142.36 nGy.h–1 with an average of 110.04 nGy.h–1. Radium equivalent activities were calculated for the analyzed samples to assess the radiation hazards arising due to the presence of this radionuclide in the samples. Most of the calculated radium equivalent activities are lower than the limit set in the OECD report (370 Bq.kg–1). The measured representative level index values for the investigated samples varied in the range 0.8 to 3.75.展开更多
Natural fiber reinforced composite materials are replacing the conventional materials, owing to their excellent physical, mechanical, electrical, and thermal properties. Also they increase biodegradability, reduce cos...Natural fiber reinforced composite materials are replacing the conventional materials, owing to their excellent physical, mechanical, electrical, and thermal properties. Also they increase biodegradability, reduce cost and decrease environmental pollution and hazards. In this study, obsolete high density polyethylene (HDPE) has used as polymer matrix and banana fiber as reinforcement material. Composites (5%, 10%, 15% and 20% of fiber contents) were made by hot press molding method by using Paul-Otto Weber Hydraulic press machine. The physical, mechanical and thermal properties of banana fiber-HDPE composites were studied and investigated the increment or decrement nature of different properties due to addition of banana fiber in BF-HDPE composites. The bulk density of composites increased with the increase wt. (%) of fiber content in composites. Water absorption ability of banana fiber and BF-HDPE composites also increased with the increase of wt. (%) of fiber content in composites and with socking time. Tensile strength of the BF-HDPE composites increased with the increase of fiber content in both cases (continuous aligned fiber orientation and continuous bidirectional fiber orientation). Moreover, the tensile strength of BF-HDPE composites with continuous aligned fiber orientation was greater than that of continuous bidirectional fiber orientation. At first, the flexural strength increased for 5% BF-HDPE composites then the value decreased for other higher compositions. The flexural strength of continuous aligned fiber orientation was slightly greater than that of continuous bidirectional fiber orientation and composite with 5% banana fiber showed better flexural properties than others. Leeb’s rebound hardness decreased with the increase of fiber addition. Different thermal properties like TG/DTG, DTA of the obsolete HDPE and BF-HDPE composites were studied using thermo gravimetric analyzer and it was found that composite with 20% fiber content was more thermally stable than three other compositions.展开更多
The composite materials are replacing the conventional materials, owing to their excellent properties. The developments of new materials are on the anvil and are thriving day by day. Natural fiber composites such as p...The composite materials are replacing the conventional materials, owing to their excellent properties. The developments of new materials are on the anvil and are thriving day by day. Natural fiber composites such as palm fiber (PF) polymer composites became more enchanting because of their high specific strength, low weight and biodegradability. Mixing of natural fiber like PF with acrylonitrile butadiene styrene (ABS) polymer is finding increased applications. In this work, PF reinforced ABS composites PF-ABS was fabricated by Injection Moulding Machine. The effect of UV-Visible radiation on PF-ABS composites was studied by means of ultraviolet-visible spectroscopy in the wavelength 200 - 1000 nm at room temperature. The present investigation shows that the addition of palm fiber modifies the absorption property of the materials. The absorption ability is maximal for 10% PF-ABS composites while minimal for 20% PF-ABS composites in the visible region of the spectrum. Optical constant like direct band gap energy, Urbach energy and Steepness parameter were determined using absorbance data. The values of direct energy band gap, Urbach energy as well as Steepness parameter were found to be in the range 2.6 - 3.9 eV, 0.40 - 0.85 eV and 0.03 - 0.06, respectively. It was observed that the value of direct band gap energy as well as Urbach energy is higher while the value of Steepness parameter is lower for PF-ABS composites with 10% palm fiber.展开更多
Gold, nickel and copper are usually used in connector of the smart card. Since Au is expensive and Ni is an allergenic material, simulated (CES) and bibliographical work is carried out in order to replace the Au and N...Gold, nickel and copper are usually used in connector of the smart card. Since Au is expensive and Ni is an allergenic material, simulated (CES) and bibliographical work is carried out in order to replace the Au and Ni layer in smart card connectors without sacrificing reliability. During the work, mechanical and electrical properties, corrosion resistance, cost, toxicity and process compatibility of the samples have been taken into consideration. Cu alloying with Zn or Sn, Cr and stainless steel were selected for electrodeposition process. Secondly, carbides (WC, TiC, ZrC), Ti, TiN, borides (TiB2) and silicide (MoSi2) are considered as a vapour deposited materials and some Cu alloying with Al, N or Mg also considered via ion implantation processes. But, vapour deposition and implantation are high energy processes compared to the electrodeposition process, which is expensive. Therefore, electrodeposited materials such as, Cu alloys (Brass or bronze), Cr and stainless steel could be considered as promising candidate to replace the Au and Ni layer in smart card connectors.展开更多
As we move toward the 21st century,increasing awareness of environmental impact is driving a shift toward natural-fiber alternatives.This study explores the utilization of bamboo fiber as the reinforcement for ABS pol...As we move toward the 21st century,increasing awareness of environmental impact is driving a shift toward natural-fiber alternatives.This study explores the utilization of bamboo fiber as the reinforcement for ABS polymer and its impact on the composite’s properties and sustainability.Bamboo fiber rein-forced ABS polymer composite is a biodegradable composite which was pre-pared by using a hot press machine at 180℃ temperature and 50 KN load.Bamboo fiber was collected from local area of Savar,Dhaka,Bangladesh and ABS polymer was collected from local market of Dhaka,Bangladesh.In this study,different properties of composites like physical(bulk density and water ab sorption),mechanical(tensile properties and hardness)and structural(Fourier Transform Infrared Spectroscopy)properties were studied.The bulk density of composites was not altered consistently and it gave greater value for 5% and 15% composites.The water absorption enhanced for all composites with the accumulation of fiber content and soaking time.The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions.Maximum(%)of elongation was found for 5% and 10% composite,and then it was decreased for 15% composite;however,elastic modulus increased with the increased of fiber content in composites.Fourier Transform Infrared(FTIR)spectroscopy study was done for structural characterization.It was observed that,at 15% fiber loading,an extra O-H bond appeared,implying more hydroxyl groups were introduced with the increased fiber content.展开更多
文摘The structural, electronic, and optical properties of Cu2Zn1−xBaxSn1−ySiyS4 compounds have been calculated using GGA-PBE function within the framework of Density Functional Theory (DFT). In the present work, lattice parameters remained the same, that is tetragonal crystal structure for 0% and 100% doping concentration. The electronic band gap of Cu2Zn1−xBaxSn1−ySiyS4 compounds has been gradually increased for continuous increment of doping concentration where the highest electronic band gap is 1.117 eV for Cu2BaSiS4 structure. Moreover, the band gap changes from direct to indirect band gap with the increase of doping concentration in the parent compound. The absorption coefficient has been found to be high (> 104 cm−1) in UV-region for all the doping concentration which makes the studied compound as a potential candidate of absorber layer in the UV detector. The theoretical study of the effect of double doping in the CZTS compound is very interesting for improving the quality of it and it would be a reference for the theoretical and experimental researchers.
文摘In the present study, the effect of the exchange-correlation functional on the structural, mechanical, and optoelectronic properties of orthorhombic RbSrBr3 perovskite has been investigated using various functionals in Density Functional Theory (DFT) with the CASTEP code. The optimized lattice parameters are quite similar for all the functionals. The electronic properties have shown that RbSrBr3 perovskite is a wide direct band gap compound with a band gap energy ranging from 4.296 eV to 4.494 eV for all the functionals. The mechanical parameters like elastic constants, Young’s modulus, Shear modulus, Poisson’s ratio, Pugh’s ratio, and an anisotropic factor reveal that the RbSrBr3 perovskite has ductile behavior and an anisotropic nature which signifies the mechanical stability of the compound. The Debye temperature might withstand lattice vibration heat. High absorption coefficient (>104 cm−1), high optical conductivity, and very low reflectivity have been found in the RbSrBr3 perovskite for all functions. The computed findings on the RbSrBr3 perovskite suggested that the presented studied material is potentially applicable for photodetector and optoelectronic devices.
文摘Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion resistance. This study was carried out with composites prepared by hot press molding method using coconut spathe fiber as reinforcing material and HDPE (from HDPE can as obsolete polymer) as polymer matrix. Composites were made at 150°C under 60 kN load by taking diverse weight percentage (wt.%) of fiber from 0 to 20 of its total weight. In this research investigation, different properties of the composites such as bulk density, water absorption, tensile and flexural properties, impact strength and hardness test properties were carried out. The fiber content enhancement increases the bulk density in all composites. The rate of water absorption improves with the improvement of fiber addition with respect to HDPE in all composites. But the water absorption was not increased uniformly with the increase of fiber addition in composites. In all cases, composites absorbed water very rapidly up to 80 hrs and then water absorption is in saturated condition. The mechanical properties like tensile strength (TS), flexural strength (FS), impact strength (IS) and hardness were observed to be comparatively more enhanced for 5% composite, while further increasing of fiber addition, all mechanical properties changes irregularly. The irregular nature of change might be caused due to the over loading of fiber in polymer matrix.
文摘The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180<span style="white-space:nowrap;">°</span>C temperature and 50 KN load. Sawdust was collected from local saw mill of Savar, Dhaka, Bangladesh and ABS polymer was collected from local market of Dhaka, Bangladesh. In this study, different properties of composites like physical (bulk density and water absorption), mechanical (tensile properties and hardness) and structural (Fourier Transform Infrared Spectroscopy) properties were studied. The bulk density of composites was not altered consistently and it gave greater value for 5% and 20% composites. The water absorption enhanced for all composites with the accumulation of fiber content and soaking time. The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions. Maximum (%) of elongation was found for 5% composite, and then it gradually decreased;however, elastic modulus increased with the increased of fiber content in composites. Fourier Transform Infrared (FTIR) spectroscopy study was done for structural characterization. It was found that there was a new bond (C≡C) stretching formed for 20% composite;moreover, C-H rocking for 0% composite was broken for all other composites after the addition of sawdust in ABS polymer matrix.
文摘Electromigration is a main challenge in the pursuit of power electronics, because physical limit to increase current density in power electronics is electromigration (EM), whereas much higher electrical current and voltage are required for power electronics packaging. So the effect of EM is an important issue in applications where high current densities are used, such as in microelectronics and related structures (e.g., Power ICs). Since the structure size of integrated circuits (ICs) decreases and the practical significance of this effect increases, the result is EM failure. On the other hand, in the next generation power electronics technology electrical current density is expected to exceed 10<sup>7</sup> A/cm<sup>2</sup> which is another challenge. This review work has been carried out to identify the mechanism of EM damage in power electronics (e.g., pure metallization and solder joints) and also how to control this kind of damage.
文摘Palm fiber (PF) reinforced acrylonitrile butadiene styrene (ABS) composite matrix was prepared by employing Injection Moulding Machine (IMM). Palm fiber was collected from ten different trees of different age group from Comilla region in Bangladesh. Three sets of samples were prepared for three different wt% (5%, 10% and 20%) of fiber contents. The mechanical (tensile strength, flexural stress, micro hardness, Leeb’s rebound hardness) and physical (bulk density and water absorption) properties were measured. The observed result reveals that the tensile strength (TS) and flexural stress (FS) were decreased with increasing fiber contents in the PF-ABS composites except 10% fiber content.
文摘With the aid of Injection Moulding Machine (IMM) Palm fiber reinforced Acrylonitrile Butadiene Styrene (ABS) composites (PF-ABS) were prepared. Three sets of samples were prepared for three different wt% (5%, 10% and 20%) of fiber contents. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) experiments were performed to study the surface morphology, microstructure (if it crystalline or noncrystalline) and new bond formation after preparation of the composites. SEM pattern shows that after addition of palm fiber in PF-ABS composites the brittleness increased due to creation of voids in the composites except 10% fiber content in PF-ABS. From XRD pattern it is clear that the palm fiber, ABS and PF-ABS composites are amorphous in nature. Moreover FTIR spectrum shows that there is no new bond formed after addition of palm fiber in ABS polymeric matrix to create PF-ABS composites.
文摘The activity concentrations of radionuclides in the sand and soil samples collected from Kuakata seabeach of Patuakhali district in Bangladesh have measured using a high resolution high purity germanium (HPGe) detector of relative efficiency 40%. The activity concentrations of 226Ra, 232Th and 40K were found in the sand samples of Kuakata seabeach varied from 2.82 ± 4.89 to 87.96 ± 4.45 Bq.Kg–1, 21.72 ± 16.27 to 290.93 ± 18.15 Bq.Kg–1 and 26.24 ± 0.35 to 852.05 ± 142.15 Bq.Kg–1 respectively. For soil samples the activity concentrations of corresponding radionuclides were found to be 20.98 ± 3.96 to 42.92 ± 4.76 Bq.Kg–1, 59.25 ± 15.62 to 144.34 ± 18.52 Bq.Kg–1 and 570.43 ± 100.3 to 1165 ± 166.27 Bq.Kg–1 respectively. The average absorbed dose rate due to radionuclides in sand was estimated to range from 51.84 to 246.55 nGy.h–1 with an average of 98.33 nGy.h–1. Also the average absorbed dose rate due to radionuclides in soil was estimated to range from 76.63 nGy.h–1 to 142.36 nGy.h–1 with an average of 110.04 nGy.h–1. Radium equivalent activities were calculated for the analyzed samples to assess the radiation hazards arising due to the presence of this radionuclide in the samples. Most of the calculated radium equivalent activities are lower than the limit set in the OECD report (370 Bq.kg–1). The measured representative level index values for the investigated samples varied in the range 0.8 to 3.75.
文摘Natural fiber reinforced composite materials are replacing the conventional materials, owing to their excellent physical, mechanical, electrical, and thermal properties. Also they increase biodegradability, reduce cost and decrease environmental pollution and hazards. In this study, obsolete high density polyethylene (HDPE) has used as polymer matrix and banana fiber as reinforcement material. Composites (5%, 10%, 15% and 20% of fiber contents) were made by hot press molding method by using Paul-Otto Weber Hydraulic press machine. The physical, mechanical and thermal properties of banana fiber-HDPE composites were studied and investigated the increment or decrement nature of different properties due to addition of banana fiber in BF-HDPE composites. The bulk density of composites increased with the increase wt. (%) of fiber content in composites. Water absorption ability of banana fiber and BF-HDPE composites also increased with the increase of wt. (%) of fiber content in composites and with socking time. Tensile strength of the BF-HDPE composites increased with the increase of fiber content in both cases (continuous aligned fiber orientation and continuous bidirectional fiber orientation). Moreover, the tensile strength of BF-HDPE composites with continuous aligned fiber orientation was greater than that of continuous bidirectional fiber orientation. At first, the flexural strength increased for 5% BF-HDPE composites then the value decreased for other higher compositions. The flexural strength of continuous aligned fiber orientation was slightly greater than that of continuous bidirectional fiber orientation and composite with 5% banana fiber showed better flexural properties than others. Leeb’s rebound hardness decreased with the increase of fiber addition. Different thermal properties like TG/DTG, DTA of the obsolete HDPE and BF-HDPE composites were studied using thermo gravimetric analyzer and it was found that composite with 20% fiber content was more thermally stable than three other compositions.
文摘The composite materials are replacing the conventional materials, owing to their excellent properties. The developments of new materials are on the anvil and are thriving day by day. Natural fiber composites such as palm fiber (PF) polymer composites became more enchanting because of their high specific strength, low weight and biodegradability. Mixing of natural fiber like PF with acrylonitrile butadiene styrene (ABS) polymer is finding increased applications. In this work, PF reinforced ABS composites PF-ABS was fabricated by Injection Moulding Machine. The effect of UV-Visible radiation on PF-ABS composites was studied by means of ultraviolet-visible spectroscopy in the wavelength 200 - 1000 nm at room temperature. The present investigation shows that the addition of palm fiber modifies the absorption property of the materials. The absorption ability is maximal for 10% PF-ABS composites while minimal for 20% PF-ABS composites in the visible region of the spectrum. Optical constant like direct band gap energy, Urbach energy and Steepness parameter were determined using absorbance data. The values of direct energy band gap, Urbach energy as well as Steepness parameter were found to be in the range 2.6 - 3.9 eV, 0.40 - 0.85 eV and 0.03 - 0.06, respectively. It was observed that the value of direct band gap energy as well as Urbach energy is higher while the value of Steepness parameter is lower for PF-ABS composites with 10% palm fiber.
文摘Gold, nickel and copper are usually used in connector of the smart card. Since Au is expensive and Ni is an allergenic material, simulated (CES) and bibliographical work is carried out in order to replace the Au and Ni layer in smart card connectors without sacrificing reliability. During the work, mechanical and electrical properties, corrosion resistance, cost, toxicity and process compatibility of the samples have been taken into consideration. Cu alloying with Zn or Sn, Cr and stainless steel were selected for electrodeposition process. Secondly, carbides (WC, TiC, ZrC), Ti, TiN, borides (TiB2) and silicide (MoSi2) are considered as a vapour deposited materials and some Cu alloying with Al, N or Mg also considered via ion implantation processes. But, vapour deposition and implantation are high energy processes compared to the electrodeposition process, which is expensive. Therefore, electrodeposited materials such as, Cu alloys (Brass or bronze), Cr and stainless steel could be considered as promising candidate to replace the Au and Ni layer in smart card connectors.
文摘As we move toward the 21st century,increasing awareness of environmental impact is driving a shift toward natural-fiber alternatives.This study explores the utilization of bamboo fiber as the reinforcement for ABS polymer and its impact on the composite’s properties and sustainability.Bamboo fiber rein-forced ABS polymer composite is a biodegradable composite which was pre-pared by using a hot press machine at 180℃ temperature and 50 KN load.Bamboo fiber was collected from local area of Savar,Dhaka,Bangladesh and ABS polymer was collected from local market of Dhaka,Bangladesh.In this study,different properties of composites like physical(bulk density and water ab sorption),mechanical(tensile properties and hardness)and structural(Fourier Transform Infrared Spectroscopy)properties were studied.The bulk density of composites was not altered consistently and it gave greater value for 5% and 15% composites.The water absorption enhanced for all composites with the accumulation of fiber content and soaking time.The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions.Maximum(%)of elongation was found for 5% and 10% composite,and then it was decreased for 15% composite;however,elastic modulus increased with the increased of fiber content in composites.Fourier Transform Infrared(FTIR)spectroscopy study was done for structural characterization.It was observed that,at 15% fiber loading,an extra O-H bond appeared,implying more hydroxyl groups were introduced with the increased fiber content.
