Y. Imai, K. Nishitani, Gabriel Y. Fortin, A. Ohtani, H. Hamada
This article presents an experimental study that clarifies the relationship between the initial fracture stress and fatigue limit of glass fiber reinforced unsaturated polyester resin specimens with a laminated structure taken from a pultruded square pipe. Quasi-static bending and tension tests are performed with acoustic emission (AE) measurements to identifying the occurrence of initial fracture during testing. AE and observation results have clarified the occurrence of initial fracture was detected by maximum acoustic energy values and corresponding fiber breakage in the unidirectional (UD) bundles. Moreover, the ratio of initial fracture stress to ultimate strength is 32% in bending and 26% in tension, when comparing stress and strains on the tension side of the UD layer. These values are in good agreement with each other and with the measured tensile fatigue limit when the cyclic stress is at 25% of the tensile strength. Initial fracture stress obtained by static tests is close values to the fatigue limit which will greatly contribute to the prediction of the fatigue limit.
{"title":"Relationship between the Initial Fracture Stress and Fatigue Limit—Simple Prediction Method of Tensile Fatigue Limit of Composite","authors":"Y. Imai, K. Nishitani, Gabriel Y. Fortin, A. Ohtani, H. Hamada","doi":"10.4236/ojcm.2019.94021","DOIUrl":"https://doi.org/10.4236/ojcm.2019.94021","url":null,"abstract":"This article presents an experimental study that clarifies the \u0000relationship between the initial fracture stress and fatigue limit of glass \u0000fiber reinforced unsaturated polyester resin specimens with a laminated \u0000structure taken from a pultruded square pipe. Quasi-static bending and tension \u0000tests are performed with acoustic emission (AE) measurements to identifying the \u0000occurrence of initial fracture during testing. AE and observation results have \u0000clarified the occurrence of initial fracture was detected by maximum acoustic \u0000energy values and corresponding fiber breakage in the unidirectional (UD) \u0000bundles. Moreover, the ratio of initial fracture stress to ultimate strength is \u000032% in bending and 26% in tension, when comparing stress and strains on the tension \u0000side of the UD layer. These values are in good agreement with each other and \u0000with the measured tensile fatigue limit when the cyclic stress is at 25% of the \u0000tensile strength. Initial fracture stress obtained by static tests is close values \u0000to the fatigue limit which will greatly contribute to the prediction of the \u0000fatigue limit.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48092829","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}
M. Phiriyawirut, Phatthanachai Hankham, Ratchanok Butsukhon, Udomporn Pongvichai
The research study properties of the starch-based foam from mixed between tapioca starch and octenyl succinate starch (OSA starch), have addition alpha-chitin prepared by hot compression molding method. Tapioca starch with 50% OSA starch was investigated. For composite foam tapioca starch mixed by adding alpha-chitin at 5% - 30% of starch weight, it was found that water absorption was reduced. The higher alpha-chitin content in blending foam, the denser of foam structure observed which resulted in increasing of the foam density. The maximum bending stress of composite starch was decreased, but increasing the maximum bending strain.
{"title":"Biomass-Based Composite Foam from Tapioca Starch/Octenyl Succinate Starch Blended with Alpha-Chitin","authors":"M. Phiriyawirut, Phatthanachai Hankham, Ratchanok Butsukhon, Udomporn Pongvichai","doi":"10.4236/ojcm.2019.94022","DOIUrl":"https://doi.org/10.4236/ojcm.2019.94022","url":null,"abstract":"The research study properties of the \u0000starch-based foam from mixed between tapioca starch and octenyl succinate \u0000starch (OSA starch), have addition alpha-chitin prepared by hot compression \u0000molding method. Tapioca starch with 50% OSA starch was investigated. For composite foam tapioca starch mixed by adding \u0000alpha-chitin at 5% - 30% of starch weight, it \u0000was found that water absorption was reduced. The higher alpha-chitin content in blending foam, the denser of foam \u0000structure observed which resulted in increasing of the foam density. The \u0000maximum bending stress of composite starch was \u0000decreased, but increasing the maximum bending strain.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48708363","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}
Construction projects require cement, which must have definite qualities so as to play its part separately in structure. The compressive strength of cement and, consequently, its physical properties could vary as a result of variations in the raw materials, as well as in manufacturing conditions. Therefore, an experimental study has been checked out herein by investigating the mechanical and physical properties of concrete specimens by means of four different types of Ordinary Portland Cements, namely Black Bull, Lucky, Pak Land and DG obtained from the market of Sindh Pakistan. Based on obtained results, it was found that Lucky cement type performed well when compared to other three types both in compressive and tensile strength of concrete. Although there were some differences in the physical properties of cement used in this study, however, they all meet with the requirements of international standards.
{"title":"Assessment of Physical and Mechanical Properties of Concrete Produced from Various Portland Cement Brands","authors":"A. Soltani, S. Khoso, M. A. Keerio, A. Formisano","doi":"10.4236/ojcm.2019.94020","DOIUrl":"https://doi.org/10.4236/ojcm.2019.94020","url":null,"abstract":"Construction \u0000projects require cement, which must have definite qualities so as to play its \u0000part separately in structure. The compressive strength of cement and, \u0000consequently, its physical properties could vary as a result of variations in \u0000the raw materials, as well as in manufacturing conditions. Therefore, an \u0000experimental study has been checked out herein by investigating the mechanical \u0000and physical properties of concrete specimens by means of four different types \u0000of Ordinary Portland Cements, namely Black Bull, Lucky, Pak Land and DG obtained from the market of Sindh \u0000Pakistan. Based on obtained results, it was found that Lucky cement type \u0000performed well when compared to other three types both in compressive and tensile strength of concrete. Although \u0000there were some differences in the physical properties of cement used in this study, however, they all \u0000meet with the requirements of international standards.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49599349","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}
Bridges, especially highway bridges, are a key factor in nations’ development and flourish. Thus, great care should be taken to maintain and inspect their safety and serviceability. An immediate repair will prevent the loss of life and vehicles damage while crossing underpass and overpassing the heavy deteriorated bridges. Reinforced or pre-stressed concrete bridge girders become structurally deficient because of severed reasons including, increasing in the load requirements, corrosion of pre-stressing strands or reinforcement bars and collision of over-height trucks with the bulb of the concrete girders. The purpose of this case study is to evaluate and assess the damages of the highway bridges in Jordan. Since there is no mandatory program in Jordan for inspection of bridges and evaluating their conditions, this paper presents an inspection and assessment of two highway bridges along the desert highway which is the essential nerve connecting Jordan cities, and it also serves as an international road between many middle east countries. These two Bridges have never been investigated or checked since their construction in the late 1980s. The study results showed that the main factor causing the deterioration of these bridges is the collision of the over-height trucks with their elements. Relying on the collected data, solutions and repair methods were introduced to rehabilitate these bridges and assure their structural safety.
{"title":"Inspection and Assessment of Highway Bridges in Jordan along the Desert Highway: A Case Study","authors":"H. Al-Baijat, Mohammad A. A. Alhawamdeh","doi":"10.4236/OJCM.2019.93014","DOIUrl":"https://doi.org/10.4236/OJCM.2019.93014","url":null,"abstract":"Bridges, especially highway bridges, are a key factor in nations’ development and flourish. Thus, great care should be taken to maintain and inspect their safety and serviceability. An immediate repair will prevent the loss of life and vehicles damage while crossing underpass and overpassing the heavy deteriorated bridges. Reinforced or pre-stressed concrete bridge girders become structurally deficient because of severed reasons including, increasing in the load requirements, corrosion of pre-stressing strands or reinforcement bars and collision of over-height trucks with the bulb of the concrete girders. The purpose of this case study is to evaluate and assess the damages of the highway bridges in Jordan. Since there is no mandatory program in Jordan for inspection of bridges and evaluating their conditions, this paper presents an inspection and assessment of two highway bridges along the desert highway which is the essential nerve connecting Jordan cities, and it also serves as an international road between many middle east countries. These two Bridges have never been investigated or checked since their construction in the late 1980s. The study results showed that the main factor causing the deterioration of these bridges is the collision of the over-height trucks with their elements. Relying on the collected data, solutions and repair methods were introduced to rehabilitate these bridges and assure their structural safety.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43543146","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}
Y. Imai, Gabriel Y. Fortin, Badin Pinpathomrat, K. Nishitani, A. Memon, Yuqiu Yang, A. Ohtani, H. Hamada
This paper explores quasi-static flexural properties and fracture behavior of a pultruded glass fiber/unsaturated polyester square pipe for automotive structural applications. Three-point flexural testing is performed in an Instron Universal Testing Machine with steel jigs supporting the top and bottom surfaces of the pipe. Acoustic emission (AE) measurements are recorded during flexural testing to evaluate initial fracture in the pipe structure. After final fracture, five cross-sections of the pipe are cut at 50-mm intervals along the longitudinal axis, with the first cut located at the mid-span of the pipe. Cross-sections of a pipe from an interrupted test where initial fracture is detected from the AE method are also prepared. Damage locations and behavior on each cross-section are observed. The flexural testing results show that the cumulative AE counts increase rapidly from 2.5 kN, that final failure occurs at a maximum load of approximately 13 kN, and that corresponding initial and final failure occurs in the two corner regions on the compressive side of flexural loading. Failure initiates by stress concentrations due to the upper jig on the top surface during bending. The cross-sectional observations also reveal clear deformation behavior of the pipe where failure is present, marked by inward bending of the top surface and upper corners located on the compressive side, near the jig. The locations of maximum stresses and deformations obtained from finite element analysis of this pipe structure are in very good agreement with the experimental observations.
{"title":"Quasi-Static Flexural Properties of a Pultruded Glass Fiber/Unsaturated Polyester Square Pipe","authors":"Y. Imai, Gabriel Y. Fortin, Badin Pinpathomrat, K. Nishitani, A. Memon, Yuqiu Yang, A. Ohtani, H. Hamada","doi":"10.4236/OJCM.2019.93016","DOIUrl":"https://doi.org/10.4236/OJCM.2019.93016","url":null,"abstract":"This paper explores quasi-static flexural properties and fracture behavior of a pultruded glass fiber/unsaturated polyester square pipe for automotive structural applications. Three-point flexural testing is performed in an Instron Universal Testing Machine with steel jigs supporting the top and bottom surfaces of the pipe. Acoustic emission (AE) measurements are recorded during flexural testing to evaluate initial fracture in the pipe structure. After final fracture, five cross-sections of the pipe are cut at 50-mm intervals along the longitudinal axis, with the first cut located at the mid-span of the pipe. Cross-sections of a pipe from an interrupted test where initial fracture is detected from the AE method are also prepared. Damage locations and behavior on each cross-section are observed. The flexural testing results show that the cumulative AE counts increase rapidly from 2.5 kN, that final failure occurs at a maximum load of approximately 13 kN, and that corresponding initial and final failure occurs in the two corner regions on the compressive side of flexural loading. Failure initiates by stress concentrations due to the upper jig on the top surface during bending. The cross-sectional observations also reveal clear deformation behavior of the pipe where failure is present, marked by inward bending of the top surface and upper corners located on the compressive side, near the jig. The locations of maximum stresses and deformations obtained from finite element analysis of this pipe structure are in very good agreement with the experimental observations.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46257569","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}
P. Kulkarni, B. Siddeswarappa, Kariyappla Shivashankar Hemanth Kumar
In the present day availability of agricultural waste products is very huge quantity. Most of the industries prefer Metal matrix composite (MMC) due to their density, high strength to weight ratio, hardness, corrosion resistance, fatigue and creep resistance. Hence they are widely used in structural applications along with aerospace and automobile industry, marine, sports, electronic and automation industries. In the present paper a study is focused on the mechanical, tribological and corrosion behavior of the metal matrix composite using different agro waste ash which is easily available. Agro waste ash like Rice Husk, groundnut shell, bamboo leaf, coconut shell can be used as reinforcement and applicable for various applications like automotive, structural components. From this current study, it’s clearly identified that addition of agro waste ash as reinforcement with Aluminium improves the properties of metal matrix composite. Aluminium metal with such reinforcement materials has shown a high specific strength, yield strength and ultimate tensile strength, also it will increase hardness, satisfactory levels of corrosion resistance.
{"title":"A Survey on Effect of Agro Waste Ash as Reinforcement on Aluminium Base Metal Matrix Composites","authors":"P. Kulkarni, B. Siddeswarappa, Kariyappla Shivashankar Hemanth Kumar","doi":"10.4236/OJCM.2019.93019","DOIUrl":"https://doi.org/10.4236/OJCM.2019.93019","url":null,"abstract":"In the present day availability of agricultural waste products is very huge quantity. Most of the industries prefer Metal matrix composite (MMC) due to their density, high strength to weight ratio, hardness, corrosion resistance, fatigue and creep resistance. Hence they are widely used in structural applications along with aerospace and automobile industry, marine, sports, electronic and automation industries. In the present paper a study is focused on the mechanical, tribological and corrosion behavior of the metal matrix composite using different agro waste ash which is easily available. Agro waste ash like Rice Husk, groundnut shell, bamboo leaf, coconut shell can be used as reinforcement and applicable for various applications like automotive, structural components. From this current study, it’s clearly identified that addition of agro waste ash as reinforcement with Aluminium improves the properties of metal matrix composite. Aluminium metal with such reinforcement materials has shown a high specific strength, yield strength and ultimate tensile strength, also it will increase hardness, satisfactory levels of corrosion resistance.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47457624","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}
J. Schuster, David Müller, Ming-Hong Chen, Q. Govignon
Kissing bonds are defects in the adhesive bonds with intimate contact of touching surface but considerably lowered shear strength. Their detection specifically in the aerospace area is so not satisfactory. Usually, kissing bonds are inconspicuous in ultrasonic C-scans. However, the determination of attributes in the time domain and the frequency domain of an ultrasound signal provides the opportunity to derive a pattern for bonded area. Deviations from the pattern found in inconspicuous bonding areas indicate kissing bonds. The survey described here deals with the manufacturing of adhesively joint samples that purposefully include kissing bonds, as well as potential solutions for detecting them through ultrasonic testing combined with pattern recognition. The properties of the epoxy-based adhesive were varied by changing the mixing ratios between resin and hardener. Samples with a mixing ratio far apart from the manufacturer’s recommendation with an inconspicuous appearance in a C-scan, but low shear strength values were taken for further evaluation. After a definition and learning phase, a 100 percent hit rate to separate good bondings from kissing bonds could be derived in a blind test. The discriminating feature found is due to the frequency shift between good and kissing bonds as well as the relative amplitude of the second peak.
{"title":"Ultrasonic Testing Combined with Pattern Recognition for the Detection of Kissing Bonds","authors":"J. Schuster, David Müller, Ming-Hong Chen, Q. Govignon","doi":"10.4236/OJCM.2019.93015","DOIUrl":"https://doi.org/10.4236/OJCM.2019.93015","url":null,"abstract":"Kissing bonds are defects in the adhesive bonds with intimate contact of touching surface but considerably lowered shear strength. Their detection specifically in the aerospace area is so not satisfactory. Usually, kissing bonds are inconspicuous in ultrasonic C-scans. However, the determination of attributes in the time domain and the frequency domain of an ultrasound signal provides the opportunity to derive a pattern for bonded area. Deviations from the pattern found in inconspicuous bonding areas indicate kissing bonds. The survey described here deals with the manufacturing of adhesively joint samples that purposefully include kissing bonds, as well as potential solutions for detecting them through ultrasonic testing combined with pattern recognition. The properties of the epoxy-based adhesive were varied by changing the mixing ratios between resin and hardener. Samples with a mixing ratio far apart from the manufacturer’s recommendation with an inconspicuous appearance in a C-scan, but low shear strength values were taken for further evaluation. After a definition and learning phase, a 100 percent hit rate to separate good bondings from kissing bonds could be derived in a blind test. The discriminating feature found is due to the frequency shift between good and kissing bonds as well as the relative amplitude of the second peak.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48997997","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}
R. Manjunatha, D. Ravishankar, Govinda Panduranga Murthy Setty, B. S. Rakesh, Chalya Mallappaji Shiva Prasad, R. Kumar
Metal matrix composites (MMCs) are gaining widespread recognition in numerous technological fields owing to its superior mechanical properties when compared with conventional metals/alloys. The aluminium based hybrid composites are increasingly being used in the transport, aerospace, marine, automobile and mineral processing industries, owing to the improved strength, stiffness and wear resistance properties. In the present research work, the composites were prepared using the liquid metallurgy technique, in which 2 - 10 weight percentage of Al2O3 particulates and 1 weight percentage of Graphite were dispersed in the base Al6061 alloy. The Casted hybrid composites were subjected to machining process to prepare the specimens according to ASTM standards. Then, the prepared specimens are subjected for assessing the Microstructure followed by its Mechanical behaviors such as, Hardness, Tensile strength, Compressive strength respectively. The microstructure analysis confirms that homogenous distribution of Al2O3 and Gr in the Al6061 matrix alloy and there was a momentous enhancement in decisive tensile strength, compressive strength and hardness properties of the hybrid composite. However, a substantial increase in the compressive strength was noticed in graphite reinforced composites as the graphite content was increased and there was a significant diminution in hardness coupled with monotonic increases in the ductility. Further, the ultimate tensile strength and compressive strength of the composite was noticed; thus the outcome of the study will provide explicit rationalizations for these observable facts. Therefore, the proposed way out in the study can provide ample of approaches to minimize the existing problem by employing this newer hybrid composites.
{"title":"Evaluation on Microstructure and Mechanical Behaviour of Al6061-Al2O3-Gr Hybrid Composites","authors":"R. Manjunatha, D. Ravishankar, Govinda Panduranga Murthy Setty, B. S. Rakesh, Chalya Mallappaji Shiva Prasad, R. Kumar","doi":"10.4236/OJCM.2019.93017","DOIUrl":"https://doi.org/10.4236/OJCM.2019.93017","url":null,"abstract":"Metal matrix composites (MMCs) are gaining widespread recognition in numerous technological fields owing to its superior mechanical properties when compared with conventional metals/alloys. The aluminium based hybrid composites are increasingly being used in the transport, aerospace, marine, automobile and mineral processing industries, owing to the improved strength, stiffness and wear resistance properties. In the present research work, the composites were prepared using the liquid metallurgy technique, in which 2 - 10 weight percentage of Al2O3 particulates and 1 weight percentage of Graphite were dispersed in the base Al6061 alloy. The Casted hybrid composites were subjected to machining process to prepare the specimens according to ASTM standards. Then, the prepared specimens are subjected for assessing the Microstructure followed by its Mechanical behaviors such as, Hardness, Tensile strength, Compressive strength respectively. The microstructure analysis confirms that homogenous distribution of Al2O3 and Gr in the Al6061 matrix alloy and there was a momentous enhancement in decisive tensile strength, compressive strength and hardness properties of the hybrid composite. However, a substantial increase in the compressive strength was noticed in graphite reinforced composites as the graphite content was increased and there was a significant diminution in hardness coupled with monotonic increases in the ductility. Further, the ultimate tensile strength and compressive strength of the composite was noticed; thus the outcome of the study will provide explicit rationalizations for these observable facts. Therefore, the proposed way out in the study can provide ample of approaches to minimize the existing problem by employing this newer hybrid composites.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42550887","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}
This study provides an overview on green composites degradability. Practically, the main drawbacks of using natural fibers are their poor dimensional stability, degradability and high degree of moisture absorption. While, end use of product from natural fiber filled or reinforced composites has become subject of concern to material engineers and scientist. The major properties of natural fiber reinforced polymer composites are greatly dependent on the hydrophilic tendency and dimensional stability of the fibers used, morphology aspect ratio for long fiber, while voids for powder fibers. The effects of chemical treatments on cellulosic fibers that are used as reinforcements for thermoplastics were studied. The chemical source for the treatments is alkalization. The significance of chemically-treated natural fibers is seen through the improvement of mechanical properties. The untreated fiber composites degrade faster in municipal soil compared to treated fiber composites.
{"title":"The Green Composites: Millet Husk Fiber (MHF) Filled Poly Lactic Acid (PLA) and Degradability Effects on Environment","authors":"A. A. Hammajam, A. M. El-jummah, Z. Ismarrubie","doi":"10.4236/OJCM.2019.93018","DOIUrl":"https://doi.org/10.4236/OJCM.2019.93018","url":null,"abstract":"This study provides an overview on green composites degradability. Practically, the main drawbacks of using natural fibers are their poor dimensional stability, degradability and high degree of moisture absorption. While, end use of product from natural fiber filled or reinforced composites has become subject of concern to material engineers and scientist. The major properties of natural fiber reinforced polymer composites are greatly dependent on the hydrophilic tendency and dimensional stability of the fibers used, morphology aspect ratio for long fiber, while voids for powder fibers. The effects of chemical treatments on cellulosic fibers that are used as reinforcements for thermoplastics were studied. The chemical source for the treatments is alkalization. The significance of chemically-treated natural fibers is seen through the improvement of mechanical properties. The untreated fiber composites degrade faster in municipal soil compared to treated fiber composites.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43663420","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}
Maryam Jahan, Richard Inakpenu, Kuo Li, Guang‐lin Zhao
Microwave absorption (MWA) materials such as graphene nanoplatelet (GNP)/epoxy are mostly used as coatings on existing structures without considering mechanical properties. In this work, we aim to enhance the mechanical strength of the composite for multifunctional potentials. We used carbon fiber (four layers) to reinforce GNP/epoxy composite (2 mm thick) and investigated their multifunctional properties with GNP loading from 3 to 7 wt%. We measured the tensile strength, hardness, and MW absorption (26.5 - 40 GHz) of composite samples. Our results showed an increase in tensile strength to 109.1 ± 7.9 MPa with 7 wt% GNP in the composite from 15.3 MPa for pure epoxy. The hardness of the composites was also substantially enhanced with GNP loading up to 7 wt%. A MW absorption ratio of 72% was attained for the sample with 7 wt% GNP loading near 40 GHz. The homogenous dispersion of GNPs in the matrix reduces the stress concentration and minimizes the influence of the defects. The high MW absorption and large transmission loss together with enhanced mechanical strength provides a novel multifunctional material for potential applications.
{"title":"Enhancing the Mechanical Strength for a Microwave Absorption Composite Based on Graphene Nanoplatelet/Epoxy with Carbon Fibers","authors":"Maryam Jahan, Richard Inakpenu, Kuo Li, Guang‐lin Zhao","doi":"10.4236/OJCM.2019.92013","DOIUrl":"https://doi.org/10.4236/OJCM.2019.92013","url":null,"abstract":"Microwave absorption (MWA) materials such as graphene nanoplatelet (GNP)/epoxy are mostly used as coatings on existing structures without considering mechanical properties. In this work, we aim to enhance the mechanical strength of the composite for multifunctional potentials. We used carbon fiber (four layers) to reinforce GNP/epoxy composite (2 mm thick) and investigated their multifunctional properties with GNP loading from 3 to 7 wt%. We measured the tensile strength, hardness, and MW absorption (26.5 - 40 GHz) of composite samples. Our results showed an increase in tensile strength to 109.1 ± 7.9 MPa with 7 wt% GNP in the composite from 15.3 MPa for pure epoxy. The hardness of the composites was also substantially enhanced with GNP loading up to 7 wt%. A MW absorption ratio of 72% was attained for the sample with 7 wt% GNP loading near 40 GHz. The homogenous dispersion of GNPs in the matrix reduces the stress concentration and minimizes the influence of the defects. The high MW absorption and large transmission loss together with enhanced mechanical strength provides a novel multifunctional material for potential applications.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41590049","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}
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