The effect of interfacial modification on flexural strength of epoxy composites filled with modified ZrB2-Al2O3 composite fillers was investigated in order to explore the stress distribution of modified composites und...The effect of interfacial modification on flexural strength of epoxy composites filled with modified ZrB2-Al2O3 composite fillers was investigated in order to explore the stress distribution of modified composites under external load. The mechanical performance of epoxy composites filled with 0 vol%, 1 vol%, 3 vol% and 5 vol% unmodified and modified ZrB2-Al2O3 fillers was characterized by three point bending(TPB) tests. The fracture surfaces of epoxy composites were observed by scanning electronic microscope(SEM). The results showed that the epoxy composite reinforced by 1 vol%modified fillers exhibited the optimal mechanical performance. According to the Von Mises stress contours simulated by finite element models(FEM) and the SEM images, it was shown that the modified ZrB2-Al2O3 multiphase fillers could homogenize the stress in the epoxy composites due to the transition effect resulted from the interfacial modification layers on the surfaces of multiphase fillers. It contributed to the improvement of mechanical performance of epoxy composites further.展开更多
PLLA-magnesium composites have been widely investigated as potential biodegradable materials for bone implants.Lower/higher corrosion resistance of the crystalized/amorphous magnesium alloys allows tailoring of biodeg...PLLA-magnesium composites have been widely investigated as potential biodegradable materials for bone implants.Lower/higher corrosion resistance of the crystalized/amorphous magnesium alloys allows tailoring of biodegradability rate.In this work,the amorphous Mg_(65)Zn_(30)Ca_(5)was investigated versus traditional crystalized Mg_(65)Zn_(30)Ca_(5),and a PLLA-Mg_(65)Zn_(30)Ca_(5)composite has been successfully fabricated using hot injection process.Furthermore,the high corrosion resistance of the amorphous Mg_(65)Zn_(30)Ca_(5)prevented the high alkalization and deterioration of mechanical strength.In addition,the high Zn content intended to improve the glass forming ability,also enhances the anti-bacterial property of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite.The remarkable performance of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite shows its promising application in bone repair and tissue regeneration.展开更多
The long-term properties of continuous fiber reinforced composite materials are increasingly important as applications in airplanes, cars, and other safety critical structures are growing rapidly. Although a clear und...The long-term properties of continuous fiber reinforced composite materials are increasingly important as applications in airplanes, cars, and other safety critical structures are growing rapidly. Although a clear understanding has been established for initiation, growth and accumulation of damage, it is still unclear when and how the interactions of these local events lead to the development of a “critical” fracture path resulting in a sudden change of global properties and possible rupture. In the present paper, we simulate damage development in a neat polymeric resin using X-FEM analysis, and conduct concomitant dielectric response analysis with a COMSOLTM simulation model to study the collective defect structure as it develops in a model system. Our studies reveal inflection points in the predicted global dielectric response vs. strain that are related to changes in local damage growth rates and modes that clearly indicate impending fracture and capture the progressive change in material state.展开更多
This study presents an analytical shear-lag model to illustrate the interface crack propagation of carbon nanotube (CNT) reinforced polymer-matrix composites (PMCs) using representative volume element (RVE). In the mo...This study presents an analytical shear-lag model to illustrate the interface crack propagation of carbon nanotube (CNT) reinforced polymer-matrix composites (PMCs) using representative volume element (RVE). In the model, a 3D cylindrical RVE is picked to present the nanocomposite in which CNT/polymer chemically non-bonded interface is taken into consideration. In the non-bonded interface, the stress transfer of CNT is generally considered to be controlled by the combined contribution of mechanical interlocking, thermal residual stress, Poisson’s contraction and van der Waals (vdW) interaction. Since CNT/matrix interface becomes debonded due to crack propagation, vdW interaction which is a function of relative radial displacement of the CNT/matrix interface makes the modeling of the interface tricky and challenging. In order to solve this complexity, an iterative approach is proposed to calculate the vdW interaction for debonded CNT/matrix interface accurately. The analytical results aim to obtain the characteristics load displacement relationship in static crack propagation for CNT reinforced PMCs.展开更多
The toughening of epoxy resin(EP)and the interlaminar toughening of carbon fiber reinforced composite(CF/EP)laminates have been widely concerned.In this work,the needle-likeγ-FeOOH nanoparticles were prepared by liqu...The toughening of epoxy resin(EP)and the interlaminar toughening of carbon fiber reinforced composite(CF/EP)laminates have been widely concerned.In this work,the needle-likeγ-FeOOH nanoparticles were prepared by liquid phase deposition-air oxidation method,and then were calcined under different conditions to obtainγ-FeOOH andγ-Fe_(2)O_(3) hybrid nanoparticles(γ-FeOOH@Fe_(2)O_(3)).Effect of calcination condition ofγ-FeOOH@-Fe_(2)O_(3) and magnetic field assistance on fracture toughness(KIC)of EP was systematically investigated.Then the selectedγ-FeOOH@Fe_(2)O_(3) with the best toughening effect were used to improve the mode I interlaminar fracture toughness(GIC)of CF/EP laminate.The resultingγ-FeOOH@Fe_(2)O_(3) have a length of around 1μm,a diameter of around 100 nm and the Ms of 8.99–45.96 emu/g.After calcinated at 250℃ for 1 h,theγ-FeOOH@Fe_(2)O_(3) containing 24 wt%FeOOH and 76 wt%Fe_(2)O_(3) achieved the best toughening effect.Under a magnetic field of 0.09 T,the KIC of theγ-FeOOH@Fe_(2)O_(3)/EP composite(2.45 MPa m^(1/2)) is 81.7%and 66.7%higher than that of neat epoxy and the composite without magnetic field induction,respectively.Furthermore,the GIC of theγ-FeOOH@Fe_(2)O_(3)/CF/EP composite(0.914 kJ/m^(2)) is also significantly increased by 88.8%and 51.8%compared to that of CF/EP and the corresponding composite without magnetic field induction,respectively.展开更多
Poly(vinyl alcohol)(PVA)/1-butyl-3-methylimidazolium trifluoromethanesulfonate(BMIMOTf)/Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)solid-state composite electrolyte(SSCE)membranes were synthesized for solid-state lith...Poly(vinyl alcohol)(PVA)/1-butyl-3-methylimidazolium trifluoromethanesulfonate(BMIMOTf)/Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)solid-state composite electrolyte(SSCE)membranes were synthesized for solid-state lithium metal battery application.The garnet-type LLZTO nanoparticles were surface-coated with the polydopamine layer of 8-10 nm thickness to enhance the dispersion status of LLZTO particles in the PVA matrix.The hydrophilic BMIMOTf ionic liquid(IL)was added along with LLZTO nanoparticles to enhance the ionic conductivity and electrochemical stability of the SSCE membranes.The synthesized composite electrolyte membrane containing 7 wt%of LLZTO and 60 wt%of BMIMOTf showed the outstanding Li+conductivity of 2×10^(-3)S cm^(-1)and the lithium transference number of 0.76 at room temperature in the firm and flexible solid state with the tensile strength of 8 MPa.Such a high single ion conduction characteristic led to the quite low interfacial resistance of 39Ωbetween the composite electrolyte and the lithium anode.Owing to these superior properties of composite membranes,the LiFePO_(4)|SSCE|Li cell exhibited an excellent discharge capacity of 165 mAh g^(-1)at 0.2 C,maintaining the coulombic efficiency of 98%after 100 cycles at room temperature.展开更多
Carbon Nanotubes(CNTs)reinforced Polymer-Matrix Composites(PMCs)is widely used as insulation materials in thermal protection system of aerospace propulsion.However,CNTs are prone to oxidation and have high thermal con...Carbon Nanotubes(CNTs)reinforced Polymer-Matrix Composites(PMCs)is widely used as insulation materials in thermal protection system of aerospace propulsion.However,CNTs are prone to oxidation and have high thermal conductivities,which makes it difficult to improve the ablation resistance of insulation materials that contain CNTs.SiO_(2)was encapsulated onto the surface of CNTs(CNTs@SiO_(2)),which were then added to Ethylene Propylene Diene Monomer(EPDM)rubber to prepare the insulation materials.Thermogravimetric analysis and ablation test were used to evaluate the resistance of the insulation materials to thermal oxidation and ablation.Additionally,scanning electron microscopy was performed to analyze their microstructures.Results revealed that the addition of CNTs@SiO_(2)could visibly reduce the effects of hot corrosion and ablation on insulation materials.The C-CNTs@SiO_(2)-1 formulation had the best ablative resistance.Further,compared with the unencapsulated formulation(C-CNTs-10),the C-CNTs@SiO_(2)-1 formulation reduced the line ablation rate by 51%to 0.0130 mm/s after oxygen-acetylene experiments.Lastly,the ablation mechanism was investigated based on the effects of the CNTs@SiO_(2)additive on their properties.Thus,the improvement in ablation performance may be attributed to CNTs@SiO_(2)-induced decreases in thermal conductivity,improvement in the hot corrosion resistance in the char layer,and changes in the microstructure.展开更多
Polymer composites reinforced with the biofibers are found to have improved applications in many fields and also they can reduce the environmental effect. In this work, caryota-a new natural fiber for polymer composit...Polymer composites reinforced with the biofibers are found to have improved applications in many fields and also they can reduce the environmental effect. In this work, caryota-a new natural fiber for polymer composites is fabricated and their tensile, flexural and impact properties are estimated to be used in economical and lightweight load carrying structures. Laminates at different weight fraction (wt%) of 10 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt% and 45 wt% are manufactured using a compression molding technique. Results asserted that the unidirectional arrangement having 40 wt% fiber posses good properties. Also the dynamic characteristics such as natural frequency and damping study are carried out for different wt% of unidirectional caryota fiber reinforced composite laminates by ex? perimental modal analysis. From this study, it has been asserted that by using the caryota fiber reinforced polyester composites, the traditional synthetic fiber can be replaced especially in automobile sector. If the caryota fiber reinforced composite material is applied properly, then its application fields will be improved.展开更多
This work proposes a facile fabrication strategy for thermally conductive graphite nanosheets/poly(lactic acid) sheets with ordered GNPs(o-GNPs/PLA) via fused deposition modeling(FDM) 3 D printing technology.Further c...This work proposes a facile fabrication strategy for thermally conductive graphite nanosheets/poly(lactic acid) sheets with ordered GNPs(o-GNPs/PLA) via fused deposition modeling(FDM) 3 D printing technology.Further combinations of o-GNPs/PLA with Ti_(3) C_(2) T_(x) films prepared by vacuum-assisted filtration were carried out by "layer-by-layer stacking-hot pressing" to be the thermally conductive Ti_(3) C_(2) T_(x)/(oGNPs/PLA) composites with superior electromagnetic interference shielding effectiveness(EMI SE).When the content of GNPs was 18.60 wt%and 4 layers of Ti_(3) C_(2) T_(x)(6.98 wt%) films were embedded,the in-plane thermal conductivity coefficient(λ_(Ⅱ)) and EMI SE(EMI SE_(Ⅱ)) values of the thermally conductive Ti_(3) C_(2) T_(x)/(o-GNPs/P LA) composites significantly increa sed to 3.44 W·m^(-1)·K^(-1) and 65 d B(3.00 mm),increased by 1223.1% and2066.7%,respectively,compared with λ_(Ⅱ)(0.26 W·m^(-1)·K^(-1)) and EMI SE_(Ⅱ)(3 d B) of neat PLA matrix.This work offers a novel and easily route for designing and manufacturing highly thermally conductive polymer composites with superior EMI SE for broader application.展开更多
It is well known that voids have detrimental effects on the performance of composites. This study aims to provide a practical method for predicting the effects of process induced voids on the properties of composites....It is well known that voids have detrimental effects on the performance of composites. This study aims to provide a practical method for predicting the effects of process induced voids on the properties of composites. Representative volume elements （RVE） for carbon fibre/epoxy composites of various fibre volume fractions and void contents are created, and the moduli and strengths are derived by finite element anal- ysis （FEA）. Regression models are fitted to the FEA data for predicting composite properties including tensile, compressive and shear. The strengths of composite laminates including tensile strngth and interlaminar shear strength （ILSS） are calculated with the aid of the developed models. The model predictions are compared with various experimental data and good agreement is found. The outcome from this study provides a useful optimisation and robust design tool for realising affordable composite prod- ucts when process induced voids are taken into account.展开更多
The potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2%, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to pr...The potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2%, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to produce high value products that have technical and environmental demand. The two treatment methods used for rice straw are alkali and acidic treatments of rice straw. The removal of impurities and waxy substances from fiber surface avoid creation of rougher topography after treatment and improves the quality of fiber, also content of hemi cellulose and lignin decrease so increase effectiveness of fiber due to dispersing of fiber in matrix. The reinforcing material is embedded in the matrix material to enhance tensile and flexural behaviors of the synthesized composite. The result of investigating these two mechanical properties, using statistical analysis & design of experiments, showed an enhancement in the mechaniccal properties of the virgin polymer composite compared to the virgin polymer. The flexural stress of the composite increased three times the virgin flexural stress, while the tensile stress increased eight times the original tensile stress.展开更多
Herein,a strong extensional and shearing field was introduced to construct highly oriented hybrid networks of silicon carbide(SiC)-packed boron nitride(BN)platelets to fabricate high-performance wearresistant PA6 comp...Herein,a strong extensional and shearing field was introduced to construct highly oriented hybrid networks of silicon carbide(SiC)-packed boron nitride(BN)platelets to fabricate high-performance wearresistant PA6 composites.Results show that in-plane and through-plane thermal conductivity(TC)of the prepared PA6 composites with a total filler loading of 20 wt.%reached 1.31 and 0.35 W/(m K),352%and 25%higher than those of pure PA6,respectively.It is attributed to the highly oriented hybrid network that facilitates the formation of efficient thermal conductivity pathways.Temperature monitoring results during friction confirm that high TC favors the friction heat dissipation performance.Meanwhile,the yield strength of PA6 composites increased by 39.1%and they still have excellent ductility with an elongation at break of 207.1%.Finally,the wear rate of PA6 composites decreased sharply by 92.5%.This method can be used to manufacture advanced linear bearing and guideway parts,etc。展开更多
基金Funded by National Natural Science Foundation of China(No.51273044)
文摘The effect of interfacial modification on flexural strength of epoxy composites filled with modified ZrB2-Al2O3 composite fillers was investigated in order to explore the stress distribution of modified composites under external load. The mechanical performance of epoxy composites filled with 0 vol%, 1 vol%, 3 vol% and 5 vol% unmodified and modified ZrB2-Al2O3 fillers was characterized by three point bending(TPB) tests. The fracture surfaces of epoxy composites were observed by scanning electronic microscope(SEM). The results showed that the epoxy composite reinforced by 1 vol%modified fillers exhibited the optimal mechanical performance. According to the Von Mises stress contours simulated by finite element models(FEM) and the SEM images, it was shown that the modified ZrB2-Al2O3 multiphase fillers could homogenize the stress in the epoxy composites due to the transition effect resulted from the interfacial modification layers on the surfaces of multiphase fillers. It contributed to the improvement of mechanical performance of epoxy composites further.
基金supported by National Natural Science Foundation of China(Grant No.51471120)
文摘PLLA-magnesium composites have been widely investigated as potential biodegradable materials for bone implants.Lower/higher corrosion resistance of the crystalized/amorphous magnesium alloys allows tailoring of biodegradability rate.In this work,the amorphous Mg_(65)Zn_(30)Ca_(5)was investigated versus traditional crystalized Mg_(65)Zn_(30)Ca_(5),and a PLLA-Mg_(65)Zn_(30)Ca_(5)composite has been successfully fabricated using hot injection process.Furthermore,the high corrosion resistance of the amorphous Mg_(65)Zn_(30)Ca_(5)prevented the high alkalization and deterioration of mechanical strength.In addition,the high Zn content intended to improve the glass forming ability,also enhances the anti-bacterial property of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite.The remarkable performance of the PLLA-Mg_(65)Zn_(30)Ca_(5)composite shows its promising application in bone repair and tissue regeneration.
文摘The long-term properties of continuous fiber reinforced composite materials are increasingly important as applications in airplanes, cars, and other safety critical structures are growing rapidly. Although a clear understanding has been established for initiation, growth and accumulation of damage, it is still unclear when and how the interactions of these local events lead to the development of a “critical” fracture path resulting in a sudden change of global properties and possible rupture. In the present paper, we simulate damage development in a neat polymeric resin using X-FEM analysis, and conduct concomitant dielectric response analysis with a COMSOLTM simulation model to study the collective defect structure as it develops in a model system. Our studies reveal inflection points in the predicted global dielectric response vs. strain that are related to changes in local damage growth rates and modes that clearly indicate impending fracture and capture the progressive change in material state.
文摘This study presents an analytical shear-lag model to illustrate the interface crack propagation of carbon nanotube (CNT) reinforced polymer-matrix composites (PMCs) using representative volume element (RVE). In the model, a 3D cylindrical RVE is picked to present the nanocomposite in which CNT/polymer chemically non-bonded interface is taken into consideration. In the non-bonded interface, the stress transfer of CNT is generally considered to be controlled by the combined contribution of mechanical interlocking, thermal residual stress, Poisson’s contraction and van der Waals (vdW) interaction. Since CNT/matrix interface becomes debonded due to crack propagation, vdW interaction which is a function of relative radial displacement of the CNT/matrix interface makes the modeling of the interface tricky and challenging. In order to solve this complexity, an iterative approach is proposed to calculate the vdW interaction for debonded CNT/matrix interface accurately. The analytical results aim to obtain the characteristics load displacement relationship in static crack propagation for CNT reinforced PMCs.
基金the National Natural Science Foundation of China(51763006)the Foundation of Guangxi Key Laboratory of Structure Activity Relationship for Electronic Information Materials(201018-K)the Natural Science Foundation of Guangxi Province(2019GXNSFGA245005)for financial support for this work.
文摘The toughening of epoxy resin(EP)and the interlaminar toughening of carbon fiber reinforced composite(CF/EP)laminates have been widely concerned.In this work,the needle-likeγ-FeOOH nanoparticles were prepared by liquid phase deposition-air oxidation method,and then were calcined under different conditions to obtainγ-FeOOH andγ-Fe_(2)O_(3) hybrid nanoparticles(γ-FeOOH@Fe_(2)O_(3)).Effect of calcination condition ofγ-FeOOH@-Fe_(2)O_(3) and magnetic field assistance on fracture toughness(KIC)of EP was systematically investigated.Then the selectedγ-FeOOH@Fe_(2)O_(3) with the best toughening effect were used to improve the mode I interlaminar fracture toughness(GIC)of CF/EP laminate.The resultingγ-FeOOH@Fe_(2)O_(3) have a length of around 1μm,a diameter of around 100 nm and the Ms of 8.99–45.96 emu/g.After calcinated at 250℃ for 1 h,theγ-FeOOH@Fe_(2)O_(3) containing 24 wt%FeOOH and 76 wt%Fe_(2)O_(3) achieved the best toughening effect.Under a magnetic field of 0.09 T,the KIC of theγ-FeOOH@Fe_(2)O_(3)/EP composite(2.45 MPa m^(1/2)) is 81.7%and 66.7%higher than that of neat epoxy and the composite without magnetic field induction,respectively.Furthermore,the GIC of theγ-FeOOH@Fe_(2)O_(3)/CF/EP composite(0.914 kJ/m^(2)) is also significantly increased by 88.8%and 51.8%compared to that of CF/EP and the corresponding composite without magnetic field induction,respectively.
基金supported by the National Research Foundation of Korea(NRF 2018M3D1A1058624)funded by the Ministry of Science and ICT。
文摘Poly(vinyl alcohol)(PVA)/1-butyl-3-methylimidazolium trifluoromethanesulfonate(BMIMOTf)/Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)solid-state composite electrolyte(SSCE)membranes were synthesized for solid-state lithium metal battery application.The garnet-type LLZTO nanoparticles were surface-coated with the polydopamine layer of 8-10 nm thickness to enhance the dispersion status of LLZTO particles in the PVA matrix.The hydrophilic BMIMOTf ionic liquid(IL)was added along with LLZTO nanoparticles to enhance the ionic conductivity and electrochemical stability of the SSCE membranes.The synthesized composite electrolyte membrane containing 7 wt%of LLZTO and 60 wt%of BMIMOTf showed the outstanding Li+conductivity of 2×10^(-3)S cm^(-1)and the lithium transference number of 0.76 at room temperature in the firm and flexible solid state with the tensile strength of 8 MPa.Such a high single ion conduction characteristic led to the quite low interfacial resistance of 39Ωbetween the composite electrolyte and the lithium anode.Owing to these superior properties of composite membranes,the LiFePO_(4)|SSCE|Li cell exhibited an excellent discharge capacity of 165 mAh g^(-1)at 0.2 C,maintaining the coulombic efficiency of 98%after 100 cycles at room temperature.
基金supported by the National Natural Science Foundation of China(Nos.51576165,51876177)。
文摘Carbon Nanotubes(CNTs)reinforced Polymer-Matrix Composites(PMCs)is widely used as insulation materials in thermal protection system of aerospace propulsion.However,CNTs are prone to oxidation and have high thermal conductivities,which makes it difficult to improve the ablation resistance of insulation materials that contain CNTs.SiO_(2)was encapsulated onto the surface of CNTs(CNTs@SiO_(2)),which were then added to Ethylene Propylene Diene Monomer(EPDM)rubber to prepare the insulation materials.Thermogravimetric analysis and ablation test were used to evaluate the resistance of the insulation materials to thermal oxidation and ablation.Additionally,scanning electron microscopy was performed to analyze their microstructures.Results revealed that the addition of CNTs@SiO_(2)could visibly reduce the effects of hot corrosion and ablation on insulation materials.The C-CNTs@SiO_(2)-1 formulation had the best ablative resistance.Further,compared with the unencapsulated formulation(C-CNTs-10),the C-CNTs@SiO_(2)-1 formulation reduced the line ablation rate by 51%to 0.0130 mm/s after oxygen-acetylene experiments.Lastly,the ablation mechanism was investigated based on the effects of the CNTs@SiO_(2)additive on their properties.Thus,the improvement in ablation performance may be attributed to CNTs@SiO_(2)-induced decreases in thermal conductivity,improvement in the hot corrosion resistance in the char layer,and changes in the microstructure.
文摘Polymer composites reinforced with the biofibers are found to have improved applications in many fields and also they can reduce the environmental effect. In this work, caryota-a new natural fiber for polymer composites is fabricated and their tensile, flexural and impact properties are estimated to be used in economical and lightweight load carrying structures. Laminates at different weight fraction (wt%) of 10 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt% and 45 wt% are manufactured using a compression molding technique. Results asserted that the unidirectional arrangement having 40 wt% fiber posses good properties. Also the dynamic characteristics such as natural frequency and damping study are carried out for different wt% of unidirectional caryota fiber reinforced composite laminates by ex? perimental modal analysis. From this study, it has been asserted that by using the caryota fiber reinforced polyester composites, the traditional synthetic fiber can be replaced especially in automobile sector. If the caryota fiber reinforced composite material is applied properly, then its application fields will be improved.
基金financial support from the National Natural Science Foundation of China (Nos. 51773169 and 51973173)Technical Basis Scientific Research Project (Highly Thermally Conductive Non-metal Materials)+2 种基金Guangdong Basic and Applied Basic Research Foundation (No. 2019B1515120093)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China (No. 2019JC-11)financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars。
文摘This work proposes a facile fabrication strategy for thermally conductive graphite nanosheets/poly(lactic acid) sheets with ordered GNPs(o-GNPs/PLA) via fused deposition modeling(FDM) 3 D printing technology.Further combinations of o-GNPs/PLA with Ti_(3) C_(2) T_(x) films prepared by vacuum-assisted filtration were carried out by "layer-by-layer stacking-hot pressing" to be the thermally conductive Ti_(3) C_(2) T_(x)/(oGNPs/PLA) composites with superior electromagnetic interference shielding effectiveness(EMI SE).When the content of GNPs was 18.60 wt%and 4 layers of Ti_(3) C_(2) T_(x)(6.98 wt%) films were embedded,the in-plane thermal conductivity coefficient(λ_(Ⅱ)) and EMI SE(EMI SE_(Ⅱ)) values of the thermally conductive Ti_(3) C_(2) T_(x)/(o-GNPs/P LA) composites significantly increa sed to 3.44 W·m^(-1)·K^(-1) and 65 d B(3.00 mm),increased by 1223.1% and2066.7%,respectively,compared with λ_(Ⅱ)(0.26 W·m^(-1)·K^(-1)) and EMI SE_(Ⅱ)(3 d B) of neat PLA matrix.This work offers a novel and easily route for designing and manufacturing highly thermally conductive polymer composites with superior EMI SE for broader application.
文摘It is well known that voids have detrimental effects on the performance of composites. This study aims to provide a practical method for predicting the effects of process induced voids on the properties of composites. Representative volume elements （RVE） for carbon fibre/epoxy composites of various fibre volume fractions and void contents are created, and the moduli and strengths are derived by finite element anal- ysis （FEA）. Regression models are fitted to the FEA data for predicting composite properties including tensile, compressive and shear. The strengths of composite laminates including tensile strngth and interlaminar shear strength （ILSS） are calculated with the aid of the developed models. The model predictions are compared with various experimental data and good agreement is found. The outcome from this study provides a useful optimisation and robust design tool for realising affordable composite prod- ucts when process induced voids are taken into account.
文摘The potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2%, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to produce high value products that have technical and environmental demand. The two treatment methods used for rice straw are alkali and acidic treatments of rice straw. The removal of impurities and waxy substances from fiber surface avoid creation of rougher topography after treatment and improves the quality of fiber, also content of hemi cellulose and lignin decrease so increase effectiveness of fiber due to dispersing of fiber in matrix. The reinforcing material is embedded in the matrix material to enhance tensile and flexural behaviors of the synthesized composite. The result of investigating these two mechanical properties, using statistical analysis & design of experiments, showed an enhancement in the mechaniccal properties of the virgin polymer composite compared to the virgin polymer. The flexural stress of the composite increased three times the virgin flexural stress, while the tensile stress increased eight times the original tensile stress.
基金supported by the National Natural Science Foundation of China(No.51790501)the Sichuan Science and Technology Program(No.2022YFH0090)the Fundamental Research Funds for the Central Universities.
文摘Herein,a strong extensional and shearing field was introduced to construct highly oriented hybrid networks of silicon carbide(SiC)-packed boron nitride(BN)platelets to fabricate high-performance wearresistant PA6 composites.Results show that in-plane and through-plane thermal conductivity(TC)of the prepared PA6 composites with a total filler loading of 20 wt.%reached 1.31 and 0.35 W/(m K),352%and 25%higher than those of pure PA6,respectively.It is attributed to the highly oriented hybrid network that facilitates the formation of efficient thermal conductivity pathways.Temperature monitoring results during friction confirm that high TC favors the friction heat dissipation performance.Meanwhile,the yield strength of PA6 composites increased by 39.1%and they still have excellent ductility with an elongation at break of 207.1%.Finally,the wear rate of PA6 composites decreased sharply by 92.5%.This method can be used to manufacture advanced linear bearing and guideway parts,etc。
