Pub Date : 2021-04-08DOI: 10.15406/MSEIJ.2021.05.00155
O. Samuel, Ajayi R Oyelayo, P. A. Oghenekowho, Idubor I Fabian, Akpeji Bh, I. Emovon
The felling of wood has resulted in environmental problems such as deforestation and climatic change. One way of solving this problem of high demand is by sourcing alternative raw materials for the production of particleboards. In the prevailing literature, there is a lack of methodical studies including variation water adsorption of particleboards developed from sawdust and cassava waste (starch) in the tropics and exposure period, and trends of compaction and bulk density of the particleboard and cement fraction. In this research, for (i) enhancing the particleboard produced from sawdust waste and cassava starch, (ii) increasing use of cement fraction was employed, (1) key properties particleboard produced were determined according to ASTM standards, and (2) finally, regression models as a function of cement content were postulated for the water adsorption. The water-absorbent of the particleboard increased with the increase in the exposure period and cement content. Water adsorption (W a ) is correlated with cement fraction through the least square regression method. The quadratic equation is appropriate for W a at the different exposure periods. The R 2 values range from 0.9984 to 0.9996, expressing these equations marginally reflect the discrepancy of W a . The higher changes in the compressive strength and bulk density of the particleboards at the higher cement blend compared to those lower and no cement blends, implying better compaction between the mixture of sawdust-starch. The results of the study can help physical property collection for the particleboard industry and guide for improving the properties of particleboards in the tropics.
{"title":"Properties of particleboard produced from discard sawdust and cassava waste blends","authors":"O. Samuel, Ajayi R Oyelayo, P. A. Oghenekowho, Idubor I Fabian, Akpeji Bh, I. Emovon","doi":"10.15406/MSEIJ.2021.05.00155","DOIUrl":"https://doi.org/10.15406/MSEIJ.2021.05.00155","url":null,"abstract":"The felling of wood has resulted in environmental problems such as deforestation and climatic change. One way of solving this problem of high demand is by sourcing alternative raw materials for the production of particleboards. In the prevailing literature, there is a lack of methodical studies including variation water adsorption of particleboards developed from sawdust and cassava waste (starch) in the tropics and exposure period, and trends of compaction and bulk density of the particleboard and cement fraction. In this research, for (i) enhancing the particleboard produced from sawdust waste and cassava starch, (ii) increasing use of cement fraction was employed, (1) key properties particleboard produced were determined according to ASTM standards, and (2) finally, regression models as a function of cement content were postulated for the water adsorption. The water-absorbent of the particleboard increased with the increase in the exposure period and cement content. Water adsorption (W a ) is correlated with cement fraction through the least square regression method. The quadratic equation is appropriate for W a at the different exposure periods. The R 2 values range from 0.9984 to 0.9996, expressing these equations marginally reflect the discrepancy of W a . The higher changes in the compressive strength and bulk density of the particleboards at the higher cement blend compared to those lower and no cement blends, implying better compaction between the mixture of sawdust-starch. The results of the study can help physical property collection for the particleboard industry and guide for improving the properties of particleboards in the tropics.","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87848899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-11DOI: 10.15406/MSEIJ.2021.05.00148
A. M. C. Grisa, Tiago C. A. Colombo, A. J. Zattera, R. N. Brandalise
The development of biodegradable polymers has advanced in recent years, mainly due to the overwhelming need to reduce the impact of polymeric materials when improperly discarded in nature. However, there are major challenges to be surpassed, especially regarding characteristics such as mechanical strength and cost of such materials, when compared to commodity polymers widely used today. Motivated by this goal, this study focused on the development of a composite material consisting of a biodegradable polymer the poly(hydroxybutyrate-co-valerate) (PHBV) reinforced with cellulose fibers, which are cheap and abundant. Mechanical and thermal properties of the polymer reinforced with different fiber contents were analyzed and compared with the neat material. Also, a burial- soil test was carried out to evaluate the environmentally degradable characteristics of the compositions studied. Results showed that the incorporation of cellulose fibers into the biodegradable matrix can both optimize the mechanical properties in use, and accelerating the environmental degradation of the polymeric material after use, when properly disposed, showing that biodegradable composites are environmentally friendly.
{"title":"Thermal, mechanical and environmental degradation characteristics of polyhydroxybutyrate-co-valerate reinforced with cellulose fibers","authors":"A. M. C. Grisa, Tiago C. A. Colombo, A. J. Zattera, R. N. Brandalise","doi":"10.15406/MSEIJ.2021.05.00148","DOIUrl":"https://doi.org/10.15406/MSEIJ.2021.05.00148","url":null,"abstract":"The development of biodegradable polymers has advanced in recent years, mainly due to the overwhelming need to reduce the impact of polymeric materials when improperly discarded in nature. However, there are major challenges to be surpassed, especially regarding characteristics such as mechanical strength and cost of such materials, when compared to commodity polymers widely used today. Motivated by this goal, this study focused on the development of a composite material consisting of a biodegradable polymer the poly(hydroxybutyrate-co-valerate) (PHBV) reinforced with cellulose fibers, which are cheap and abundant. Mechanical and thermal properties of the polymer reinforced with different fiber contents were analyzed and compared with the neat material. Also, a burial- soil test was carried out to evaluate the environmentally degradable characteristics of the compositions studied. Results showed that the incorporation of cellulose fibers into the biodegradable matrix can both optimize the mechanical properties in use, and accelerating the environmental degradation of the polymeric material after use, when properly disposed, showing that biodegradable composites are environmentally friendly.","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"100 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77614152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-06DOI: 10.15406/MSEIJ.2021.05.00147
Kang Jinwu
and air pollutants are very important. In one article screen printed electrodes (SPEs) for gas sensors which are based on polymer/carbon nanostructures (multi wall carbon nanotubes and grapheme) were modified by polymers such as conductive polymer Poly Vinylidene Fluoride and biocompatible Poly Ethylene Glycol. The modified sensor electrodes exhibited excellent electrical properties, characterized by high conductivity and great potential application in the field of gas pollutants detection. In another article, Graphite oxide (GO) was used to anchor [PdCl2(TDA)2] and [RhCl(TDA)3] (TDA =NH2(CH2)12CH3) with 2wt% of metal load. The test results showed that [RhCl(TDA)3]/ GO was the best catalyst due to electronic and steric effects as well as the influence of the support.
{"title":"Editorial: science and engineering, two aspects of materials","authors":"Kang Jinwu","doi":"10.15406/MSEIJ.2021.05.00147","DOIUrl":"https://doi.org/10.15406/MSEIJ.2021.05.00147","url":null,"abstract":"and air pollutants are very important. In one article screen printed electrodes (SPEs) for gas sensors which are based on polymer/carbon nanostructures (multi wall carbon nanotubes and grapheme) were modified by polymers such as conductive polymer Poly Vinylidene Fluoride and biocompatible Poly Ethylene Glycol. The modified sensor electrodes exhibited excellent electrical properties, characterized by high conductivity and great potential application in the field of gas pollutants detection. In another article, Graphite oxide (GO) was used to anchor [PdCl2(TDA)2] and [RhCl(TDA)3] (TDA =NH2(CH2)12CH3) with 2wt% of metal load. The test results showed that [RhCl(TDA)3]/ GO was the best catalyst due to electronic and steric effects as well as the influence of the support.","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79086581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15406/mseij.2021.05.00170
J. D. Hernández, Fernando Andrés Londoño Badillo
This report comprises an outline of an experimental setting intended to provide insight into statistical concepts of great interest for engineering and science students. The main components of a DC voltage source are presented alongside measurements of voltage and current behaviours on the system with their corresponding uncertainties, and a brief statistical analysis of the data thereby obtained. It also encompasses a brief discussion on the influence of the measuring device on reported resistance values and provides experimental insight into Ohm’s law via regression analysis. Under the study of both DC voltages and direct currents, a typical example of a circuit is used to develop clear-cut methods relating to statistical treatments of regression and both direct- and indirect-measurement uncertainties.
{"title":"Learning of statistics in engineering with the study of a DC power supply","authors":"J. D. Hernández, Fernando Andrés Londoño Badillo","doi":"10.15406/mseij.2021.05.00170","DOIUrl":"https://doi.org/10.15406/mseij.2021.05.00170","url":null,"abstract":"This report comprises an outline of an experimental setting intended to provide insight into statistical concepts of great interest for engineering and science students. The main components of a DC voltage source are presented alongside measurements of voltage and current behaviours on the system with their corresponding uncertainties, and a brief statistical analysis of the data thereby obtained. It also encompasses a brief discussion on the influence of the measuring device on reported resistance values and provides experimental insight into Ohm’s law via regression analysis. Under the study of both DC voltages and direct currents, a typical example of a circuit is used to develop clear-cut methods relating to statistical treatments of regression and both direct- and indirect-measurement uncertainties.","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87828228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15406/MSEIJ.2021.05.00161
S. Mao, Sixue Zheng
electron microscope (TEM) nanomechanical testing opens up an avenue to directly observe the atomic-scale dislocation dynamics in nanoscale metals. Here we report an in situ atomic-scale observation of dislocation-mediated discrete plasticity in gold (Au) and tungsten (W) nanowires NW. 3,4 In the tensile test of Au NW loaded along [001] under a strain rate of 10 −3 s −1 and viewed along [ 1 planes were zigzag, while the ( 1 − 10) sur faces were atomically flat. At high strain level, there exist local strain concentration at surface facets of ( 1 1 − − 1) planes, favoring surface dislocation nucleation. Similar to face-centered cubic (FCC) and body-centered cubic (BCC) nanoscale metals, surface dislocation nucleation is also dominant in other nanostructured metals, including Au NWs with nanotwins, bi- and penta-twined silver (Ag) NWs, and bicrystalline Ag NWs. 6 In summary, our work offers atomic-scale insights into surface dislocation nucleation and the related dislocation dynamics in nanoscale metals, providing guidelines to fabricate nanomaterials with high performance to achieve their potential applications in nanoscale devices. To date, the effect of chemical passivation layer on surface dislocation nucleation remains experimentally unclear, which probably attracts a great deal of interest for future research. Nanoscale metals with superior mechanical properties are promising building blocks in the next generation flexible electronics. Due to the pronounced surface effect caused by the ultrahigh surface-to-volume ratio of nanocrystals, the mechanical behaviors of nanoscale metals are quite different from their bulk counterparts. Dislocation nucleation is demonstrated to be related to the microstructural length scale of materials. With decreasing the feature size, dislocation
{"title":"In situ atomic-scale observation of dislocation-mediated discrete plasticity in nanoscale crystals","authors":"S. Mao, Sixue Zheng","doi":"10.15406/MSEIJ.2021.05.00161","DOIUrl":"https://doi.org/10.15406/MSEIJ.2021.05.00161","url":null,"abstract":"electron microscope (TEM) nanomechanical testing opens up an avenue to directly observe the atomic-scale dislocation dynamics in nanoscale metals. Here we report an in situ atomic-scale observation of dislocation-mediated discrete plasticity in gold (Au) and tungsten (W) nanowires NW. 3,4 In the tensile test of Au NW loaded along [001] under a strain rate of 10 −3 s −1 and viewed along [ 1 planes were zigzag, while the ( 1 − 10) sur faces were atomically flat. At high strain level, there exist local strain concentration at surface facets of ( 1 1 − − 1) planes, favoring surface dislocation nucleation. Similar to face-centered cubic (FCC) and body-centered cubic (BCC) nanoscale metals, surface dislocation nucleation is also dominant in other nanostructured metals, including Au NWs with nanotwins, bi- and penta-twined silver (Ag) NWs, and bicrystalline Ag NWs. 6 In summary, our work offers atomic-scale insights into surface dislocation nucleation and the related dislocation dynamics in nanoscale metals, providing guidelines to fabricate nanomaterials with high performance to achieve their potential applications in nanoscale devices. To date, the effect of chemical passivation layer on surface dislocation nucleation remains experimentally unclear, which probably attracts a great deal of interest for future research. Nanoscale metals with superior mechanical properties are promising building blocks in the next generation flexible electronics. Due to the pronounced surface effect caused by the ultrahigh surface-to-volume ratio of nanocrystals, the mechanical behaviors of nanoscale metals are quite different from their bulk counterparts. Dislocation nucleation is demonstrated to be related to the microstructural length scale of materials. With decreasing the feature size, dislocation","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88710049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15406/mseij.2021.05.00167
Leonardo Tufaro, Luciano Buglioni, H. Svoboda
Friction Stir Welding (FSW) is a solid-state welding process which has revolutionized several industries in the last thirty years. The heat needed to produce the joint is generated by friction at the tool-workpiece interface and plastic deformation of the material, being affected by parameters like tool rotational speed, travel speed, axial load and tool geometry, among others. The objective of this work was to analyse the energy transformations during FSW of AA5083 aluminium alloy in order to achieve a better comprehension of the whole process, and particularly the heat generation mechanisms and material flow, which will define the quality of the joint. Experimental measurements of process parameters and conceptual analytical and numerical models were implemented. Consumed electric current, axial load and thermal cycles were acquired during FSW of AA5083 plates, for different rotational and travel speeds. From these measurements, different magnitudes (heat and torque) associated to the energy transformations were calculated. The relationships between welding parameters, generated heat and torque, sticking and sliding components and contact condition were analysed and related with material flow. The sticking heat was always higher than the sliding one, even when contact condition was closer to pure sliding. For a giving heat input, a higher sticking component produced an increase in the material flow.
{"title":"Effect of welding parameters on heat generation mechanisms in friction stir welding of AA5083 aluminium alloy","authors":"Leonardo Tufaro, Luciano Buglioni, H. Svoboda","doi":"10.15406/mseij.2021.05.00167","DOIUrl":"https://doi.org/10.15406/mseij.2021.05.00167","url":null,"abstract":"Friction Stir Welding (FSW) is a solid-state welding process which has revolutionized several industries in the last thirty years. The heat needed to produce the joint is generated by friction at the tool-workpiece interface and plastic deformation of the material, being affected by parameters like tool rotational speed, travel speed, axial load and tool geometry, among others. The objective of this work was to analyse the energy transformations during FSW of AA5083 aluminium alloy in order to achieve a better comprehension of the whole process, and particularly the heat generation mechanisms and material flow, which will define the quality of the joint. Experimental measurements of process parameters and conceptual analytical and numerical models were implemented. Consumed electric current, axial load and thermal cycles were acquired during FSW of AA5083 plates, for different rotational and travel speeds. From these measurements, different magnitudes (heat and torque) associated to the energy transformations were calculated. The relationships between welding parameters, generated heat and torque, sticking and sliding components and contact condition were analysed and related with material flow. The sticking heat was always higher than the sliding one, even when contact condition was closer to pure sliding. For a giving heat input, a higher sticking component produced an increase in the material flow.","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82743942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15406/MSEIJ.2021.05.00152
Sheleme Mosisa, Temesgen Batu
Sisal and Bamboo fibers are the most common fibers extracted from natural plants used to fabricate the bio-composite, environmentally friendly products. In this work, the Bamboo-Sisal fibers reinforced epoxy hybrid composite is fabricated to investigate and analyze the compression and hardness properties. The fibers were extracted mechanically and manually from bamboo and sisal plants. The 5% and 8% concentration of sodium hydroxide have been used to treat bamboo and sisal fibers respectively to eliminate lignin, cellulose, and other dirty particles in order to increase interfacial bonding of epoxy to fibers, and performance of the composite. Taguchi experimental approach is used to design composite by considering basic parameters such as weight fraction of sisal, fibers orientation, and curing temperature which affect composite performance. Compression molding and hand lay-up techniques have been used to fabricate the composite. The compression and hardness tests ware predicted on the specimen of hybrid bamboo/sisal fiber reinforced epoxy composites prepared with ASTM standard. The analyzed result revealed that the composite contains a 20/15% volume fraction of sisal to bamboo fibers and fabricated with fiber plies orientation of [0 S /0 B /0 S /0 B /0 S /0 B ] and curing temperature at 40ºC record a high compression strength. While the better hardness strength obtained from composite contain 15/20% volume fraction of sisal to bamboo fibers, and fabricated with fiber plies orientation of [0 S /0 B /0 S /0 B /0 S /0 B ] and cured at 55ºC. as matrix fabricated by hand layup and compression
剑麻和竹纤维是从天然植物中提取的最常见的纤维，用于制造生物复合材料，环保产品。本文制备了竹剑麻纤维增强环氧复合材料，对其压缩性能和硬度进行了研究和分析。纤维是通过机械和人工从竹子和剑麻中提取的。用5%和8%浓度的氢氧化钠分别对竹纤维和剑麻纤维进行处理，去除木质素、纤维素等脏颗粒，提高环氧树脂与纤维的界面结合，提高复合材料的性能。采用田口实验法，综合考虑剑麻质量分数、纤维取向、固化温度等影响复合材料性能的基本参数，设计复合材料。压缩成型和手工铺层技术已被用于制造复合材料。对按ASTM标准制备的竹/剑麻纤维增强环氧复合材料试样进行了压缩和硬度试验。分析结果表明，在纤维层向为[0 S /0 B /0 S /0 B /0 S /0 B]、固化温度为40℃的条件下，剑麻/竹纤维体积分数为20/15%的复合材料具有较高的抗压强度。当剑麻与竹纤维的体积分数为15/20%时，纤维层向为[0 S /0 B /0 S /0 B /0 S /0 B]，并在55℃下固化，可获得较好的硬度强度。由手工铺层和压缩制成的基质
{"title":"Investigation of mechanical properties of bamboo/sisal fiber reinforced hybrid composite materials","authors":"Sheleme Mosisa, Temesgen Batu","doi":"10.15406/MSEIJ.2021.05.00152","DOIUrl":"https://doi.org/10.15406/MSEIJ.2021.05.00152","url":null,"abstract":"Sisal and Bamboo fibers are the most common fibers extracted from natural plants used to fabricate the bio-composite, environmentally friendly products. In this work, the Bamboo-Sisal fibers reinforced epoxy hybrid composite is fabricated to investigate and analyze the compression and hardness properties. The fibers were extracted mechanically and manually from bamboo and sisal plants. The 5% and 8% concentration of sodium hydroxide have been used to treat bamboo and sisal fibers respectively to eliminate lignin, cellulose, and other dirty particles in order to increase interfacial bonding of epoxy to fibers, and performance of the composite. Taguchi experimental approach is used to design composite by considering basic parameters such as weight fraction of sisal, fibers orientation, and curing temperature which affect composite performance. Compression molding and hand lay-up techniques have been used to fabricate the composite. The compression and hardness tests ware predicted on the specimen of hybrid bamboo/sisal fiber reinforced epoxy composites prepared with ASTM standard. The analyzed result revealed that the composite contains a 20/15% volume fraction of sisal to bamboo fibers and fabricated with fiber plies orientation of [0 S /0 B /0 S /0 B /0 S /0 B ] and curing temperature at 40ºC record a high compression strength. While the better hardness strength obtained from composite contain 15/20% volume fraction of sisal to bamboo fibers, and fabricated with fiber plies orientation of [0 S /0 B /0 S /0 B /0 S /0 B ] and cured at 55ºC. as matrix fabricated by hand layup and compression","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"82 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80287952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15406/mseij.2021.05.00171
Hakemi H
In this study, we investigated the effect of concentration of TNO623, TNO403 and E43 liquid crystals on the morphology of flexible PDLC films. The PDLC films were prepared on ITO-PET support rolls by Polymerization Induced Phase Separation (PIPS) through UV radiation curing technique. We found that, regardless of the type of liquid crystal and process conditions, the liquid crystal micro-droplet morphology, including the dimensions, number densities and weight fractions, were mostly exhibited the same dependency trends on liquid crystal concentration in PDLC formulation.
{"title":"The effect of liquid crystal concentration on the morphology of few flexible polymer dispersed liquid crystals","authors":"Hakemi H","doi":"10.15406/mseij.2021.05.00171","DOIUrl":"https://doi.org/10.15406/mseij.2021.05.00171","url":null,"abstract":"In this study, we investigated the effect of concentration of TNO623, TNO403 and E43 liquid crystals on the morphology of flexible PDLC films. The PDLC films were prepared on ITO-PET support rolls by Polymerization Induced Phase Separation (PIPS) through UV radiation curing technique. We found that, regardless of the type of liquid crystal and process conditions, the liquid crystal micro-droplet morphology, including the dimensions, number densities and weight fractions, were mostly exhibited the same dependency trends on liquid crystal concentration in PDLC formulation.","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77100828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15406/MSEIJ.2021.05.00162
P. Ajwang
warming be at the same time responsible for cooling? Climate is normally defined in terms of six variables; temperature, rainfall/ precipitation, humidity, solar radiation, air pressure and wind. Air composition or quality is also increasingly considered as an element of climate. When there is erratic or excessive change in the core variables, then scientists have been quick to point at changing climate. In predicting climate, historical data is analyzed and developed into models for predicting the future. The data can be applied under the architecture of a mechanistic model that uses the underlying thermophysical processes to relate input and output. The term energy and mass balance may be used to describe such mechanistic models. Computational fluid dynamics packages based on these energy and mass balances are also being used nowadays. Alternatively, the inputoutput behavior of the system may be related without considering the underlying thermo-physical processes in the system. Such data-based models are commonly referred to as black-box models. Large sets of input-output data can easily be developed into prediction models through ‘system identification’ which is essentially regression models for large data sets.
{"title":"Long-term global climate prediction; rogue science?","authors":"P. Ajwang","doi":"10.15406/MSEIJ.2021.05.00162","DOIUrl":"https://doi.org/10.15406/MSEIJ.2021.05.00162","url":null,"abstract":"warming be at the same time responsible for cooling? Climate is normally defined in terms of six variables; temperature, rainfall/ precipitation, humidity, solar radiation, air pressure and wind. Air composition or quality is also increasingly considered as an element of climate. When there is erratic or excessive change in the core variables, then scientists have been quick to point at changing climate. In predicting climate, historical data is analyzed and developed into models for predicting the future. The data can be applied under the architecture of a mechanistic model that uses the underlying thermophysical processes to relate input and output. The term energy and mass balance may be used to describe such mechanistic models. Computational fluid dynamics packages based on these energy and mass balances are also being used nowadays. Alternatively, the inputoutput behavior of the system may be related without considering the underlying thermo-physical processes in the system. Such data-based models are commonly referred to as black-box models. Large sets of input-output data can easily be developed into prediction models through ‘system identification’ which is essentially regression models for large data sets.","PeriodicalId":18241,"journal":{"name":"Material Science & Engineering International Journal","volume":"99 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76987406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15406/MSEIJ.2021.05.00150
P. Ctibor, J. Sedláček, K. Neufuss
Selected silicate materials were sprayed by plasma in the past and characterized from the standpint of their sprayability, chemical composition and crystallographic phases, structure and mechanical properties as well as thermal stability. Present work is concentrated on dielectric properties of these thick films. Synthetic mullite, mullite mixture with glass, and pure glass were produced using the water-stabilized plasma system (WSP ® ). The deposits were striped-out, ground and polished to produce planparallel plates, i.e. flat samples with a smooth surface. These samples serve in principle like monoblock capacitors. All of them were tested in the alternating electric field at low voltage to examine their capacity and loss tangent in the frequency range between 100 Hz and 1 MHz. Relative permittivity was calculated based on the measured capacity. It is shown that the relative permitivity and loss tangent of plasma-sprayed glass and glass-ceramics is similarly stable as for bulk polycrystalline dielectric materials of the same composition. The family of silicon oxide based ceramics and glass is often used in electrical industry, particularly as insulators. Sintered silicate materials exhibit extraordinary volume resistivity and small dielectric losses during a wide range electric
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