Wearable and stretchable strain sensors have potential values in the fields of human motion and health monitoring,flexible electronics,and soft robotic skin.The wearable and stretchable strain sensors can be directly ...Wearable and stretchable strain sensors have potential values in the fields of human motion and health monitoring,flexible electronics,and soft robotic skin.The wearable and stretchable strain sensors can be directly attached to human skin,providing visualized detection for human motions and personal healthcare.Conductive polymer composites(CPC)composed of conductive fillers and flexible polymers have the advantages of high stretchability,good flexibility,superior durability,which can be used to prepare flexible strain sensors with large working strain and outstanding sensitivity.This review has put forward a comprehensive summary on the fabrication methods,advanced mechanisms and strain sensing abilities of CPC strain sensors reported in recent years,especially the sensors with superior performance.Finally,the structural design,bionic function,integration technology and further application of CPC strain sensors are prospected.展开更多
Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their composites.However,the thermal conductivity coefficient(λ)va...Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their composites.However,the thermal conductivity coefficient(λ)values of prepared thermally conductive polymer composites are still difficult to achieve expectations,which has become the bottleneck in the fields of thermally conductive polymer composites.Aimed at that,based on the accumulation of the previous research works by related researchers and our research group,this paper proposes three possible directions for breaking through the bottlenecks:(1)preparing and synthesizing intrinsically thermally conductive polymers,(2)reducing the interfacial thermal resistance in thermally conductive polymer composites,and(3)establishing suitable thermal conduction models and studying inner thermal conduction mechanism to guide experimental optimization.Also,the future development trends of the three above-mentioned directions are foreseen,hoping to provide certain basis and guidance for the preparation,researches and development of thermally conductive polymers and their composites.展开更多
Functional polymer composites(FPCs)have attracted increasing attention in recent decades due to their great potential in delivering a wide range of functionalities.These functionalities are largely determined by funct...Functional polymer composites(FPCs)have attracted increasing attention in recent decades due to their great potential in delivering a wide range of functionalities.These functionalities are largely determined by functional fillers and their network morphology in polymer matrix.In recent years,a large number of studies on morphology control and interfacial modification have been reported,where numerous preparation methods and exciting performance of FPCs have been reported.Despite the fact that these FPCs have many similarities because they are all consisting of functional inorganic fillers and polymer matrices,review on the overall progress of FPCs is still missing,and especially the overall processing strategy for these composites is urgently needed.Herein,a"Toolbox"for the processing of FPCs is proposed to summarize and analyze the overall processing strategies and corresponding morphology evolution for FPCs.From this perspective,the morphological control methods already utilized for various FPCs are systematically reviewed,so that guidelines or even predictions on the processing strategies of various FPCs as well as multi-functional polymer composites could be given.This review should be able to provide interesting insights for the field of FPCs and boost future intelligent design of various FPCs.展开更多
A polymer-based carbon nano-tubes (CNTs) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and with high mechanical property is developed for packaging of electronic modulus or devices.The ...A polymer-based carbon nano-tubes (CNTs) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and with high mechanical property is developed for packaging of electronic modulus or devices.The liquid crystal polymers (LCP) and melamine formaldehydes (MF) polymer are used to study the orientation effect of CNTs in various polymeric matrix.The influences of orientation,aspect ratio,and mass fraction of CNTs upon the shielding effectiveness (SE) of CNTs-composites are investigated.The higher the orientation,aspect ratio,and weight percentages of nano-materials are, the higher the SE of the carbon composites.The highest SE for the CNTs/LCP nano composite obtained is more than 62 dB. This results may lead to the developing for CPU IC chip packaging.展开更多
Material selection has become a critical part of design for engineers,due to availability of diverse choice of materials that have similar properties and meet the product design specification.Implementation of statist...Material selection has become a critical part of design for engineers,due to availability of diverse choice of materials that have similar properties and meet the product design specification.Implementation of statistical analysis alone makes it difficult to identify the ideal composition of the final composite.An integrated approach between statistical model and micromechanical model is desired.In this paper,resultant natural fibre and polymer matrix from previous study is used to estimate the mechanical properties such as density,Young’s modulus and tensile strength.Four levels of fibre loading are used to compare the optimum natural fibre reinforced polymer composite(NFRPC).The result from this analytical approach revealed that kenaf/polystyrene(PS)with 40%fibre loading is the ideal composite in automotive component application.It was found that the ideal composite score is 1.156 g/cm^(3),24.2 GPa and 413.4 MPa for density,Young’s modulus and tensile strength,respectively.A suggestion to increase the properties on Young’s modulus are also presented.This work proves that the statistical model is well incorporated with the analytical approach to choose the correct composite to use in automotive application.展开更多
Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the 1920s.The effects of particle shape,filler amount,dispersion state of fillers,and interfacial th...Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the 1920s.The effects of particle shape,filler amount,dispersion state of fillers,and interfacial thermal barrier on the thermal conductivity of filled polymer composites were investigated,and the agreement of experimental data with theoretical models in literatures was discussed.Silica with high thermal conductivity was chosen to mix with polyvinyl-acetate (EVA) copolymer to prepare SiO2/EVA co-films.Experimental data of the co-films' thermal conductivity were compared with some classical theoretical and empirical models.The results show that Agari's model,the mixed model,and the percolation model can predict well the thermal conductivity of SiO2/EVA co-films.展开更多
Polymeric materials usually present some viscoelastic behavior. To improve the mechanical behavior of these materials, ceramics materials are often filled into the polymeric materials in form of fiber or particle. A m...Polymeric materials usually present some viscoelastic behavior. To improve the mechanical behavior of these materials, ceramics materials are often filled into the polymeric materials in form of fiber or particle. A micromechanical model was proposed to estimate the overall viscoelastic behavior for particulate polymer composites, especially for high volume concentration of filled particles. The method is based on Laplace transform technique and an elastic model including two-particle interaction. The effective creep compliance and the stress and strain relation at a constant loading rate are analyzed. The results show that the proposed method predicts a significant stiffer response than those based on Mori-Tanaka's method at high volume concentration of particles.展开更多
The corrosion condition of flue gas desulfurization (FGD) equipment for the coal-fired power plant was defined as the strong corrosion grade. The lining system of hybrid polymer composite was used in internal cylinder...The corrosion condition of flue gas desulfurization (FGD) equipment for the coal-fired power plant was defined as the strong corrosion grade. The lining system of hybrid polymer composite was used in internal cylinder of steel chimney, and a corrosion-resistant and heat-resistant protective layer was formed on the metal surface. The corrosion-resistant and ageing-resistant properties of hybrid polymer composite prepared at low temperature after four years of practical use were investigated by differential scanning calorimeter (DSC), scanning electron microscopy (SEM) and measurement of gravimetric variation, contact angle, abrasion resistance, bonding strength and tensile strength. The properties of hybrid polymer composites prepared at 25℃ and –15℃ were comparatively analyzed in the paper.展开更多
The investigation focusing on the mechanical behaviors at the microstructural level in composite materials can provide valuable insight into the failure mechanisms at larger scales.A micromechanics damage model which ...The investigation focusing on the mechanical behaviors at the microstructural level in composite materials can provide valuable insight into the failure mechanisms at larger scales.A micromechanics damage model which comprises the coupling of the matrix constitutive model and the cohesive zone(CZM)model at fiber-matrix interfaces is presented to evaluate the transverse tensile damage behaviors of unidirectional(UD)fiber-reinforced polymer(FRP)composites.For the polymeric matrix that exhibits highly non-linear mechanical responses,special focus is paid on the formulation of the constitutive model,which characterizes a mixture of elasticity,plasticity as well as damage.The proposed constitutive model includes the numerical implementation of a fracture plane based ellipse-parabola criterion that is an extension of the classic Mohr-Coulomb criterion,corresponding post-yield flow rule and post-failure degradation rule in the fully implicit integration scheme.The numerical results are in good agreement with experimental measurements.It is found that directly using the matrix properties measured at the ply level to characterize the mechanical responses at the constituent level may bring large discrepancies in homogenized stress-strain responses and dominant failure mechanisms.The distribution of fracture plane angles in matrix is predicted,where it is shown to provide novel insight into the microscopic damage initiation and accumulation under transverse tension.展开更多
Glass Fiber Reinforced Polymeric (GFRP)</span><span style="font-family:""> </span><span style="font-family:Verdana;">Composites are most commonly used as bumpers for ve...Glass Fiber Reinforced Polymeric (GFRP)</span><span style="font-family:""> </span><span style="font-family:Verdana;">Composites are most commonly used as bumpers for vehicles, electrical equipment panels, and medical devices enclosures. These materials are also widely used for structural applications in aerospace, automotive, and in providing alternatives to traditional metallic materials. The paper fabricated epoxy and polyester resin composites by using silicon carbide in various proportions along with GFRP. The hand lay-up technique was used to fabricate the laminates. To determine the properties of fabricated composites, </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">tensile, impact, and flexural tests were conducted. This method of fabrication was very simple and cost-effective. Their mechan</span><span style="font-family:Verdana;">ical properties like yield strength, yield strain, Young’s modulus, flexural</span><span style="font-family:Verdana;"> mod</span><span style="font-family:Verdana;">ulus, and impact energy </span></span><span style="font-family:Verdana;">were</span><span style="font-family:Verdana;"> investigated. The mechanical properties of the</span><span style="font-family:""><span style="font-family:Verdana;"> GFRP composites were also compared with the fiber volume fraction. The fiber volume fraction plays a major role in the mechanical properties of GFRP composites. Young’s modulus and tensile strength of fabricated composites </span><span style="font-family:Verdana;">were modelled and compared with measured values. The results show that</span><span style="font-family:Verdana;"> composites </span><span style="font-family:Verdana;">with epoxy resin demonstrate higher strength and modulus compared to</span><span style="font-family:Verdana;"> composites with polyester resin.展开更多
In recent years, the demand direction for electronic equipment has expanded into embedded and miniaturized devices. The heat radiation problem has become one of the most significant factors for hindering the developme...In recent years, the demand direction for electronic equipment has expanded into embedded and miniaturized devices. The heat radiation problem has become one of the most significant factors for hindering the development of electronic devices. Since heat radiation material is one of the important components in electronic devices, the demand for enhancing thermal conductivity is also increasingly urgent. Research on thermal conductive polymer composites has become a major direction for developing functional composites. This work reviewed the recent progress in the fabrication of thermal conductive polymer composites. Five different structures are presented, including the using of single fillers,hybrid fillers, double threshold percolation structure, segregated structure and other complex multiphase structures. Specifically, the preparation of high-performance thermal conductive polymer composites was introduced through the combination of various thermal conductive fillers.Finally, the development direction of high thermal conductive polymer composites was briefly explored.展开更多
Achieving high strength,deformability and toughness in polymers is important for practical industrial applications.This has remained challenging because of the mutually opposing effects of improvements to each of thes...Achieving high strength,deformability and toughness in polymers is important for practical industrial applications.This has remained challenging because of the mutually opposing effects of improvements to each of these properties.Here,a self-assembling nacre-like polymer composite is designed to achieve ex-tremely tough with increasing strength.This special design significantly improved polymer’s mechanical properties,including an ultra-high fracture strain of 1180%,a tensile strength of 55.4 MPa and a toughness of 506.9 MJ/m^(3),which far exceed the highest values previously reported for polymer composites.This ex-cellent combination of properties can be attributed to a novel toughening mechanism,achieved by the synergy of the domain-limiting effect of metallic glass fragments with the strain-gradient-induced orien-tation and crystallisation within the polymer during stretching.Our approach opens a promising avenue for designing robust polymer materials in armour and aerospace engineering for a range of innovative applications.展开更多
This study presents the multifunctional characteristics of multi-walled carbon nanotube(MWCNT)/polypropylene random copolymer(PPR) composites enabled via fused filament fabrication(FFF) under monotonic and quasi-stati...This study presents the multifunctional characteristics of multi-walled carbon nanotube(MWCNT)/polypropylene random copolymer(PPR) composites enabled via fused filament fabrication(FFF) under monotonic and quasi-static cyclic compression. Utilizing in-house MWCNT-engineered PPR filament feedstocks, both bulk and cellular composites were realized. The morphological features of nanocomposites were examined via scanning electron microscopy, which reveals that MWCNTs are uniformly dispersed. The uniformly dispersed MWCNTs forms an electrically conductive network within the PPR matrix, and the resulting nanocomposite shows good electrical conductivity(~10^(-1)S/cm), improved mechanical performance(modulus increases by 125% and compressive strength increases by 25% for 8 wt% MWCNT loading) and pronounced piezoresistive response(gauge factor of 27.9-8.5 for bulk samples)under compression. The influence of strain rate on the piezoresistive response of bulk samples(4 wt% of MWCNT) under compression was also measured. Under repeated cyclic compression(2% constant strain amplitude), the nanocomposite exhibited stable piezoresistive performance up to 100 cycles. The piezoresistive response under repeated cyclic loading with increasing strain amplitude of was also assessed.The gauge factor of BCC and FCC cellular composites(4 wt% of MWCNT) with a relative density of 30%was observed to be 46.4 and 30.2 respectively, under compression. The higher sensitivity of the BCC plate-lattice could be attributed to its higher degree of stretching-dominated deformation behavior than the FCC plate-lattice, which exhibits bending-dominated behavior. The 3D printed cellular PPR/MWCNT composites structures were found to show excellent piezoresistive self-sensing characteristics and open new avenues for in situ structural health monitoring in various applications.展开更多
Substrates or encapsulants in soft and stretchable formats are key components for transient,bioresorbable electronic systems;however,elastomeric polymers with desired mechanical and biochemical properties are very lim...Substrates or encapsulants in soft and stretchable formats are key components for transient,bioresorbable electronic systems;however,elastomeric polymers with desired mechanical and biochemical properties are very limited compared to nontransient counterparts.Here,we introduce a bioresorbable elastomer,poly(glycolide-co-ε-caprolactone)(PGCL),that contains excellent material properties including high elongation-at-break(<1300%),resilience and toughness,and tunable dissolution behaviors.Exploitation of PGCLs as polymer matrices,in combination with conducing polymers,yields stretchable,conductive composites for degradable interconnects,sensors,and actuators,which can reliably function under external strains.Integration of device components with wireless modules demonstrates elastic,transient electronic suture system with on-demand drug delivery for rapid recovery of postsurgical wounds in soft,time-dynamic tissues.展开更多
A detailed computational investigation,based on density functional theory,of the interaction of polyani-line(PANI)and graphene nanoribbons(GNRs)with SrTiO_(3) is presented.The adsorption of PANI in var-ious oxidation ...A detailed computational investigation,based on density functional theory,of the interaction of polyani-line(PANI)and graphene nanoribbons(GNRs)with SrTiO_(3) is presented.The adsorption of PANI in var-ious oxidation states and co-adsorption with GNRs is found to be thermodynamically favourable.Ad-sorbed PANI introduces N and C 2p states into the SrTiO_(3) bandgap,while co-adsorption of PANI and GNRs leads to a bridging of the gap and semi-metallic behaviour,thus rendering the electrical properties highly sensitive to the loading of the GNRs/PANI in the composites.Modelling the lattice dynamics of the composites predicts a 68-88%reduction in the lattice thermal conductivity due to reduced phonon group velocities.Taken together,these findings provide insight into the growing number of experimental studies highlighting the enhanced thermoelectric performance of oxide-polymer composites and indicate co-adsorption with graphene as a facile direction for future research.展开更多
In this study,the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equ...In this study,the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equations superior to those previously reported.The contact resistance and nanocomposite conductivity are modeled by several influencing factors,including stack properties,interphase depth,tunneling size,and contact diameter.The developed model's accuracy is verified through numerous experimental measurements.To further validate the models and establish correlations between parameters,the effects of all the variables on contact resistance and nanocomposite conductivity are analyzed.Notably,the contact resistance is primarily dependent on the polymer tunnel resistivity,contact area,and tunneling size.The dimensions of the graphene nanosheets significantly influence the conductivity,which ranges from 0 S/m to90 S/m.An increased number of nanosheets in stacks and a larger gap between them enhance the nanocomposite's conductivity.Furthermore,the thicker interphase and smaller tunneling size can lead to higher sample conductivity due to their optimistic effects on the percolation threshold and network efficacy.展开更多
Because inferior mechanical strength of granite polymer composite(GPC)has become the main drawback limiting its application and popularization,Mo fibers were added into(GPC)to improve its mechanical strength.Mechanica...Because inferior mechanical strength of granite polymer composite(GPC)has become the main drawback limiting its application and popularization,Mo fibers were added into(GPC)to improve its mechanical strength.Mechanical properties of matrix materials with different mass ratio of resin and stabilizer(MRRS)were investigated systematically.The influences of MRRS on interface bonding strength of Mo fiber-matrix,wettability and mechanical strength of GPC were discussed,respectively,and the theoretical calculation result of MRRS k was obtained,with the optimal value of k=4.When k=4,tensile strength,tensile strain and fracture stress of the cured resin achieve the maximum values.But for k=7,the corresponding values reach the minimum.With the increase of MRRS k,surface free energy of the cured resin first increases and then decreases,while contact angles between Mo sample and matrix have displayed the opposite trend.Wettability of resin to Mo fiber is the best at k=4.Pulling load of Mo fiber and interface bonding strength appear the maximum at k=4,followed by k=5,k=3 the third,and k=7 the minimum.When k=4,mechanical properties of Mo fiber-reinforced GPC are optimal,which is consistent with the result of theoretical calculation.This study is of great significance to get better component formulas of Mo fiber reinforced GPC and to improve its application in machine tools.展开更多
The rapid development of aerospace weapons and equipment,wireless base stations and 5G communication technologies has put forward newer and higher requirements for the comprehensive performances of polymer-based elect...The rapid development of aerospace weapons and equipment,wireless base stations and 5G communication technologies has put forward newer and higher requirements for the comprehensive performances of polymer-based electromagnetic interference(EMI)shielding composites.However,most of currently prepared polymer-based EMI shielding composites are still difficult to combine high performance and multi-functionality.In response to this,based on the research works of relevant researchers as well as our research group,three possible directions to break through the above bottlenecks are proposed,including construction of efficient conductive networks,optimization of multi-interfaces for lightweight and multifunction compatibility design.The future development trends in three directions are prospected,and it is hoped to provide certain theoretical basis and technical guidance for the preparation,research and development of polymer-based EMI shielding composites.展开更多
The integration and miniaturization of chips lead to inevitable overheating and increasing electromagnetic interference (EMI) problems, which threaten the performance, stability, and lifetime of electroniccomponents. ...The integration and miniaturization of chips lead to inevitable overheating and increasing electromagnetic interference (EMI) problems, which threaten the performance, stability, and lifetime of electroniccomponents. Therefore, it is important to improve the heat dissipation and EMI shielding performancein device packaging for the steady operation of electronic products. In recent years, due to its intrinsic superior thermal conductivity, proper electrical conductivity, light-weight, and structural adjustability,graphene has been widely used as high thermal and conductive fillers incorporated in the polymer matrix to improve the thermal conductivity and electrical conductivity of composites. This review concludesthe recent development of graphene/polymer composites by using graphene as fillers to improve thethermal conductivity and EMI shielding effectiveness (EMI SE). The structure of graphene embedded inthe composites varies from zero-dimension (0D), one-dimension (1D) to two-dimensions (2D). Moreover,highly thermally and electrically conductive fillers with different dimensions were also modified on thegraphene to improve the composite performance. Finally, this review also makes prospects for the development trend of graphene/polymer composites with high thermal conductivity and EMI SE in the future.展开更多
An innovational method that poly(styrene-co-maleic anhydride)(SMA),a compatibilizer of immiscible nylon6/polystyrene(PA6/PS) blends,was first reacted with carbon black(CB) and then blended with PA6/PS,has been employe...An innovational method that poly(styrene-co-maleic anhydride)(SMA),a compatibilizer of immiscible nylon6/polystyrene(PA6/PS) blends,was first reacted with carbon black(CB) and then blended with PA6/PS,has been employed to prepare the PA6/PS/(SMA-CB) composites of which CB localized at the interface.In PA6/PS/CB blends,CB was found to preferentially localize in the PA6 phase.However,in the PA6/PS/(SMA-CB) blends,it was found that CB particles can be induced by SMA to localize at the interface.The electrical porperties of PA6/PS/(SMA-CB) composites were investigated.The results showed that the composites exhibited distinct triple percolation behavior,i.e.the percolation is governed by the percolation of CB in SMA phase,the continuity of SMA-CB at the interface and the continuity of PA6/PS interface.The percolation threshold of PA6/PS/(SMA-CB) was only 0.15 wt%,which is much lower than that of PA6/PS/CB.Moreover,the PTC(positive temperature coefficient) intensity of PA6/PS/(SMA-CB) composites was stronger than that of PA6/PS/CB and the negative temperature coefficient(NTC) effect was eliminated.The electrical properties of PA6/PS/(SMA-CB) were explained in terms of its special interface morphology:SMA and CB localize at interphase to form the conductive pathways.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2021R1A2C1008380)Nano Material Technology Development Program[NRF-2015M3A7B6027970]+1 种基金the Chey Institute for Advanced Studies'International Scholar Exchange Fellowship for the academic year of 2021-2022supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea government(MOTIE)(20215710100170).
文摘Wearable and stretchable strain sensors have potential values in the fields of human motion and health monitoring,flexible electronics,and soft robotic skin.The wearable and stretchable strain sensors can be directly attached to human skin,providing visualized detection for human motions and personal healthcare.Conductive polymer composites(CPC)composed of conductive fillers and flexible polymers have the advantages of high stretchability,good flexibility,superior durability,which can be used to prepare flexible strain sensors with large working strain and outstanding sensitivity.This review has put forward a comprehensive summary on the fabrication methods,advanced mechanisms and strain sensing abilities of CPC strain sensors reported in recent years,especially the sensors with superior performance.Finally,the structural design,bionic function,integration technology and further application of CPC strain sensors are prospected.
基金National Natural Science Foundation of China(51773169 and 51973173)Guangdong Basic and Applied Basic Research Foundation(2019B1515120093)+2 种基金Technological Base Scientific Research ProjectsNatural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(2019JC-11)Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their composites.However,the thermal conductivity coefficient(λ)values of prepared thermally conductive polymer composites are still difficult to achieve expectations,which has become the bottleneck in the fields of thermally conductive polymer composites.Aimed at that,based on the accumulation of the previous research works by related researchers and our research group,this paper proposes three possible directions for breaking through the bottlenecks:(1)preparing and synthesizing intrinsically thermally conductive polymers,(2)reducing the interfacial thermal resistance in thermally conductive polymer composites,and(3)establishing suitable thermal conduction models and studying inner thermal conduction mechanism to guide experimental optimization.Also,the future development trends of the three above-mentioned directions are foreseen,hoping to provide certain basis and guidance for the preparation,researches and development of thermally conductive polymers and their composites.
基金National Natural Science Foundation of China(51922071,51773139).
文摘Functional polymer composites(FPCs)have attracted increasing attention in recent decades due to their great potential in delivering a wide range of functionalities.These functionalities are largely determined by functional fillers and their network morphology in polymer matrix.In recent years,a large number of studies on morphology control and interfacial modification have been reported,where numerous preparation methods and exciting performance of FPCs have been reported.Despite the fact that these FPCs have many similarities because they are all consisting of functional inorganic fillers and polymer matrices,review on the overall progress of FPCs is still missing,and especially the overall processing strategy for these composites is urgently needed.Herein,a"Toolbox"for the processing of FPCs is proposed to summarize and analyze the overall processing strategies and corresponding morphology evolution for FPCs.From this perspective,the morphological control methods already utilized for various FPCs are systematically reviewed,so that guidelines or even predictions on the processing strategies of various FPCs as well as multi-functional polymer composites could be given.This review should be able to provide interesting insights for the field of FPCs and boost future intelligent design of various FPCs.
文摘A polymer-based carbon nano-tubes (CNTs) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and with high mechanical property is developed for packaging of electronic modulus or devices.The liquid crystal polymers (LCP) and melamine formaldehydes (MF) polymer are used to study the orientation effect of CNTs in various polymeric matrix.The influences of orientation,aspect ratio,and mass fraction of CNTs upon the shielding effectiveness (SE) of CNTs-composites are investigated.The higher the orientation,aspect ratio,and weight percentages of nano-materials are, the higher the SE of the carbon composites.The highest SE for the CNTs/LCP nano composite obtained is more than 62 dB. This results may lead to the developing for CPU IC chip packaging.
文摘Material selection has become a critical part of design for engineers,due to availability of diverse choice of materials that have similar properties and meet the product design specification.Implementation of statistical analysis alone makes it difficult to identify the ideal composition of the final composite.An integrated approach between statistical model and micromechanical model is desired.In this paper,resultant natural fibre and polymer matrix from previous study is used to estimate the mechanical properties such as density,Young’s modulus and tensile strength.Four levels of fibre loading are used to compare the optimum natural fibre reinforced polymer composite(NFRPC).The result from this analytical approach revealed that kenaf/polystyrene(PS)with 40%fibre loading is the ideal composite in automotive component application.It was found that the ideal composite score is 1.156 g/cm^(3),24.2 GPa and 413.4 MPa for density,Young’s modulus and tensile strength,respectively.A suggestion to increase the properties on Young’s modulus are also presented.This work proves that the statistical model is well incorporated with the analytical approach to choose the correct composite to use in automotive application.
基金supported by the High-Tech Research and Development Program of China (863 Program) (No.2006AA050203)
文摘Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the 1920s.The effects of particle shape,filler amount,dispersion state of fillers,and interfacial thermal barrier on the thermal conductivity of filled polymer composites were investigated,and the agreement of experimental data with theoretical models in literatures was discussed.Silica with high thermal conductivity was chosen to mix with polyvinyl-acetate (EVA) copolymer to prepare SiO2/EVA co-films.Experimental data of the co-films' thermal conductivity were compared with some classical theoretical and empirical models.The results show that Agari's model,the mixed model,and the percolation model can predict well the thermal conductivity of SiO2/EVA co-films.
基金Project supported by the National Natural Science Foundation of China (No.10325210)
文摘Polymeric materials usually present some viscoelastic behavior. To improve the mechanical behavior of these materials, ceramics materials are often filled into the polymeric materials in form of fiber or particle. A micromechanical model was proposed to estimate the overall viscoelastic behavior for particulate polymer composites, especially for high volume concentration of filled particles. The method is based on Laplace transform technique and an elastic model including two-particle interaction. The effective creep compliance and the stress and strain relation at a constant loading rate are analyzed. The results show that the proposed method predicts a significant stiffer response than those based on Mori-Tanaka's method at high volume concentration of particles.
文摘The corrosion condition of flue gas desulfurization (FGD) equipment for the coal-fired power plant was defined as the strong corrosion grade. The lining system of hybrid polymer composite was used in internal cylinder of steel chimney, and a corrosion-resistant and heat-resistant protective layer was formed on the metal surface. The corrosion-resistant and ageing-resistant properties of hybrid polymer composite prepared at low temperature after four years of practical use were investigated by differential scanning calorimeter (DSC), scanning electron microscopy (SEM) and measurement of gravimetric variation, contact angle, abrasion resistance, bonding strength and tensile strength. The properties of hybrid polymer composites prepared at 25℃ and –15℃ were comparatively analyzed in the paper.
基金support by National Science Foundation for Young Scientists of China under Grant[No.11802116].
文摘The investigation focusing on the mechanical behaviors at the microstructural level in composite materials can provide valuable insight into the failure mechanisms at larger scales.A micromechanics damage model which comprises the coupling of the matrix constitutive model and the cohesive zone(CZM)model at fiber-matrix interfaces is presented to evaluate the transverse tensile damage behaviors of unidirectional(UD)fiber-reinforced polymer(FRP)composites.For the polymeric matrix that exhibits highly non-linear mechanical responses,special focus is paid on the formulation of the constitutive model,which characterizes a mixture of elasticity,plasticity as well as damage.The proposed constitutive model includes the numerical implementation of a fracture plane based ellipse-parabola criterion that is an extension of the classic Mohr-Coulomb criterion,corresponding post-yield flow rule and post-failure degradation rule in the fully implicit integration scheme.The numerical results are in good agreement with experimental measurements.It is found that directly using the matrix properties measured at the ply level to characterize the mechanical responses at the constituent level may bring large discrepancies in homogenized stress-strain responses and dominant failure mechanisms.The distribution of fracture plane angles in matrix is predicted,where it is shown to provide novel insight into the microscopic damage initiation and accumulation under transverse tension.
文摘Glass Fiber Reinforced Polymeric (GFRP)</span><span style="font-family:""> </span><span style="font-family:Verdana;">Composites are most commonly used as bumpers for vehicles, electrical equipment panels, and medical devices enclosures. These materials are also widely used for structural applications in aerospace, automotive, and in providing alternatives to traditional metallic materials. The paper fabricated epoxy and polyester resin composites by using silicon carbide in various proportions along with GFRP. The hand lay-up technique was used to fabricate the laminates. To determine the properties of fabricated composites, </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">tensile, impact, and flexural tests were conducted. This method of fabrication was very simple and cost-effective. Their mechan</span><span style="font-family:Verdana;">ical properties like yield strength, yield strain, Young’s modulus, flexural</span><span style="font-family:Verdana;"> mod</span><span style="font-family:Verdana;">ulus, and impact energy </span></span><span style="font-family:Verdana;">were</span><span style="font-family:Verdana;"> investigated. The mechanical properties of the</span><span style="font-family:""><span style="font-family:Verdana;"> GFRP composites were also compared with the fiber volume fraction. The fiber volume fraction plays a major role in the mechanical properties of GFRP composites. Young’s modulus and tensile strength of fabricated composites </span><span style="font-family:Verdana;">were modelled and compared with measured values. The results show that</span><span style="font-family:Verdana;"> composites </span><span style="font-family:Verdana;">with epoxy resin demonstrate higher strength and modulus compared to</span><span style="font-family:Verdana;"> composites with polyester resin.
基金financially supported by Graduate Innovation Fund of Wuhan Institute of Technology,Natural Science Foundation of Hubei Province (No.2022CFB630)Open Fund of Key Laboratory of Green Preparation and Application for Functional Materials,Ministry of Education (Hubei University) (No.202105)。
文摘In recent years, the demand direction for electronic equipment has expanded into embedded and miniaturized devices. The heat radiation problem has become one of the most significant factors for hindering the development of electronic devices. Since heat radiation material is one of the important components in electronic devices, the demand for enhancing thermal conductivity is also increasingly urgent. Research on thermal conductive polymer composites has become a major direction for developing functional composites. This work reviewed the recent progress in the fabrication of thermal conductive polymer composites. Five different structures are presented, including the using of single fillers,hybrid fillers, double threshold percolation structure, segregated structure and other complex multiphase structures. Specifically, the preparation of high-performance thermal conductive polymer composites was introduced through the combination of various thermal conductive fillers.Finally, the development direction of high thermal conductive polymer composites was briefly explored.
基金This work was financially supported by the Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shen-zhen Park Project(No.HZQB-KCZYB-2020030)the RGC Gen-eral Research Fund(No.AoE/M-402/20,CityU 11209918)+1 种基金the RGC Theme-based Research Scheme(No.T13-402/17-N)the Ma-jor Program of Changsha Science and Technology Project(No.kh2003023).
文摘Achieving high strength,deformability and toughness in polymers is important for practical industrial applications.This has remained challenging because of the mutually opposing effects of improvements to each of these properties.Here,a self-assembling nacre-like polymer composite is designed to achieve ex-tremely tough with increasing strength.This special design significantly improved polymer’s mechanical properties,including an ultra-high fracture strain of 1180%,a tensile strength of 55.4 MPa and a toughness of 506.9 MJ/m^(3),which far exceed the highest values previously reported for polymer composites.This ex-cellent combination of properties can be attributed to a novel toughening mechanism,achieved by the synergy of the domain-limiting effect of metallic glass fragments with the strain-gradient-induced orien-tation and crystallisation within the polymer during stretching.Our approach opens a promising avenue for designing robust polymer materials in armour and aerospace engineering for a range of innovative applications.
基金financial support from the Abu Dhabi National Oil Company (ADNOC), United Arab Emirates under Award No: EX2016-000010。
文摘This study presents the multifunctional characteristics of multi-walled carbon nanotube(MWCNT)/polypropylene random copolymer(PPR) composites enabled via fused filament fabrication(FFF) under monotonic and quasi-static cyclic compression. Utilizing in-house MWCNT-engineered PPR filament feedstocks, both bulk and cellular composites were realized. The morphological features of nanocomposites were examined via scanning electron microscopy, which reveals that MWCNTs are uniformly dispersed. The uniformly dispersed MWCNTs forms an electrically conductive network within the PPR matrix, and the resulting nanocomposite shows good electrical conductivity(~10^(-1)S/cm), improved mechanical performance(modulus increases by 125% and compressive strength increases by 25% for 8 wt% MWCNT loading) and pronounced piezoresistive response(gauge factor of 27.9-8.5 for bulk samples)under compression. The influence of strain rate on the piezoresistive response of bulk samples(4 wt% of MWCNT) under compression was also measured. Under repeated cyclic compression(2% constant strain amplitude), the nanocomposite exhibited stable piezoresistive performance up to 100 cycles. The piezoresistive response under repeated cyclic loading with increasing strain amplitude of was also assessed.The gauge factor of BCC and FCC cellular composites(4 wt% of MWCNT) with a relative density of 30%was observed to be 46.4 and 30.2 respectively, under compression. The higher sensitivity of the BCC plate-lattice could be attributed to its higher degree of stretching-dominated deformation behavior than the FCC plate-lattice, which exhibits bending-dominated behavior. The 3D printed cellular PPR/MWCNT composites structures were found to show excellent piezoresistive self-sensing characteristics and open new avenues for in situ structural health monitoring in various applications.
基金supported by the KIST Institutional Program (Project No.2E32501-23-106)the KU-KIST Graduate School of Converging Science and Technology Program+3 种基金the National Research Foundation of Korea (NRF) grant funded by the Korean government (the Ministry of Science, ICT, MSIT) (RS-2022-00165524)the development of technologies for electroceuticals of the National Research Foundataion (NRF) funded by the Korean government (MSIT) (RS-2023-00220534)the Ministry of Science and ICT (MSIT), Korea, under the ICT Creative Consilience program (IITP-2023-2020-0-01819) supervised by the IITP (Institute for Information and Communications Technology Planning and Evaluation)Start up Pioneering in Research and Innovation(SPRINT) through the Commercialization Promotion Agency for R&D Outcomes(COMPA) grant funded by the Korea government(Ministry of Science and ICT) (1711198921)
文摘Substrates or encapsulants in soft and stretchable formats are key components for transient,bioresorbable electronic systems;however,elastomeric polymers with desired mechanical and biochemical properties are very limited compared to nontransient counterparts.Here,we introduce a bioresorbable elastomer,poly(glycolide-co-ε-caprolactone)(PGCL),that contains excellent material properties including high elongation-at-break(<1300%),resilience and toughness,and tunable dissolution behaviors.Exploitation of PGCLs as polymer matrices,in combination with conducing polymers,yields stretchable,conductive composites for degradable interconnects,sensors,and actuators,which can reliably function under external strains.Integration of device components with wireless modules demonstrates elastic,transient electronic suture system with on-demand drug delivery for rapid recovery of postsurgical wounds in soft,time-dynamic tissues.
基金NDW thanks the EPSRC DTP competition 2018-19 at the University of Huddersfield for funding(EP/R513234/1)JMS is currently supported by a UKRI Future Leaders Fellowship(MR/T043121/1)+2 种基金previously held a University of Manchester Presidential Fellowship.Calculations were performed on the Orion computing fa-cility and the Violeta HPC at the University of Huddersfield,and the THOMAS and YOUNG facilities at the UK Materials and Molecular Modelling Hub(MMM Hub)which is partially funded by the EPSRC(EP/P020194/1 and EP/T022213/1)via our membership of the UK’s HEC Materials Chemistry Consortium(MCC),which is also funded by the EPSRC(EP/R029431/1 and EP/X035859/1).
文摘A detailed computational investigation,based on density functional theory,of the interaction of polyani-line(PANI)and graphene nanoribbons(GNRs)with SrTiO_(3) is presented.The adsorption of PANI in var-ious oxidation states and co-adsorption with GNRs is found to be thermodynamically favourable.Ad-sorbed PANI introduces N and C 2p states into the SrTiO_(3) bandgap,while co-adsorption of PANI and GNRs leads to a bridging of the gap and semi-metallic behaviour,thus rendering the electrical properties highly sensitive to the loading of the GNRs/PANI in the composites.Modelling the lattice dynamics of the composites predicts a 68-88%reduction in the lattice thermal conductivity due to reduced phonon group velocities.Taken together,these findings provide insight into the growing number of experimental studies highlighting the enhanced thermoelectric performance of oxide-polymer composites and indicate co-adsorption with graphene as a facile direction for future research.
基金the Basic Science Research Program through the National Research Foundation(NRF)of Korea funded by the Ministry of Education,Science,and Technology(No.2022R1A2C1004437)the Ministry of Science and ICT(MSIT)of Korea Government(No.2022M3J7A1062940)。
文摘In this study,the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equations superior to those previously reported.The contact resistance and nanocomposite conductivity are modeled by several influencing factors,including stack properties,interphase depth,tunneling size,and contact diameter.The developed model's accuracy is verified through numerous experimental measurements.To further validate the models and establish correlations between parameters,the effects of all the variables on contact resistance and nanocomposite conductivity are analyzed.Notably,the contact resistance is primarily dependent on the polymer tunnel resistivity,contact area,and tunneling size.The dimensions of the graphene nanosheets significantly influence the conductivity,which ranges from 0 S/m to90 S/m.An increased number of nanosheets in stacks and a larger gap between them enhance the nanocomposite's conductivity.Furthermore,the thicker interphase and smaller tunneling size can lead to higher sample conductivity due to their optimistic effects on the percolation threshold and network efficacy.
基金Fouded by the National Natural Science Foundation of China(No.51175308)the National Science and Technology Major Project of China(No.2012ZX04010032)。
文摘Because inferior mechanical strength of granite polymer composite(GPC)has become the main drawback limiting its application and popularization,Mo fibers were added into(GPC)to improve its mechanical strength.Mechanical properties of matrix materials with different mass ratio of resin and stabilizer(MRRS)were investigated systematically.The influences of MRRS on interface bonding strength of Mo fiber-matrix,wettability and mechanical strength of GPC were discussed,respectively,and the theoretical calculation result of MRRS k was obtained,with the optimal value of k=4.When k=4,tensile strength,tensile strain and fracture stress of the cured resin achieve the maximum values.But for k=7,the corresponding values reach the minimum.With the increase of MRRS k,surface free energy of the cured resin first increases and then decreases,while contact angles between Mo sample and matrix have displayed the opposite trend.Wettability of resin to Mo fiber is the best at k=4.Pulling load of Mo fiber and interface bonding strength appear the maximum at k=4,followed by k=5,k=3 the third,and k=7 the minimum.When k=4,mechanical properties of Mo fiber-reinforced GPC are optimal,which is consistent with the result of theoretical calculation.This study is of great significance to get better component formulas of Mo fiber reinforced GPC and to improve its application in machine tools.
基金The authors are grateful for the supports from the National Natural Science Foundation of China(U21A2093)Y.L.Zhang would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2021107)+1 种基金This work is also financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin ScholarsOpen access funding provided by Shanghai Jiao Tong University
文摘The rapid development of aerospace weapons and equipment,wireless base stations and 5G communication technologies has put forward newer and higher requirements for the comprehensive performances of polymer-based electromagnetic interference(EMI)shielding composites.However,most of currently prepared polymer-based EMI shielding composites are still difficult to combine high performance and multi-functionality.In response to this,based on the research works of relevant researchers as well as our research group,three possible directions to break through the above bottlenecks are proposed,including construction of efficient conductive networks,optimization of multi-interfaces for lightweight and multifunction compatibility design.The future development trends in three directions are prospected,and it is hoped to provide certain theoretical basis and technical guidance for the preparation,research and development of polymer-based EMI shielding composites.
基金The authors are grateful for the financial support by the National Natural Science Foundation of China(No.52102055)China Postdoctoral Science Foundation(No.2020M681965)+6 种基金Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2019-3)the Project of the Chinese Academy of Sciences(Nos.XDC07030100,XDA22020602,KFZD-SW-409 and ZDKYYQ20200001)CAS Youth Innovation Promotion Association(No.2020301),Science and Technology Major Project of Ningbo(Nos.2018B10046 and 2016S1002)the Natural Science Foundation of Ningbo(No.2017A610010)Foundation of State Key Laboratory of Solid lubrication(No.LSL-1912)National Key Laboratory of Science and Technology on Advanced Composites in Special Environments(No.6142905192806)the K.C.Wong Education Foundation(No.GJTD-2019-13)。
文摘The integration and miniaturization of chips lead to inevitable overheating and increasing electromagnetic interference (EMI) problems, which threaten the performance, stability, and lifetime of electroniccomponents. Therefore, it is important to improve the heat dissipation and EMI shielding performancein device packaging for the steady operation of electronic products. In recent years, due to its intrinsic superior thermal conductivity, proper electrical conductivity, light-weight, and structural adjustability,graphene has been widely used as high thermal and conductive fillers incorporated in the polymer matrix to improve the thermal conductivity and electrical conductivity of composites. This review concludesthe recent development of graphene/polymer composites by using graphene as fillers to improve thethermal conductivity and EMI shielding effectiveness (EMI SE). The structure of graphene embedded inthe composites varies from zero-dimension (0D), one-dimension (1D) to two-dimensions (2D). Moreover,highly thermally and electrically conductive fillers with different dimensions were also modified on thegraphene to improve the composite performance. Finally, this review also makes prospects for the development trend of graphene/polymer composites with high thermal conductivity and EMI SE in the future.
基金supported by the Natural Science Foundation of Education Department of Henan Province (No.2009A430008)
文摘An innovational method that poly(styrene-co-maleic anhydride)(SMA),a compatibilizer of immiscible nylon6/polystyrene(PA6/PS) blends,was first reacted with carbon black(CB) and then blended with PA6/PS,has been employed to prepare the PA6/PS/(SMA-CB) composites of which CB localized at the interface.In PA6/PS/CB blends,CB was found to preferentially localize in the PA6 phase.However,in the PA6/PS/(SMA-CB) blends,it was found that CB particles can be induced by SMA to localize at the interface.The electrical porperties of PA6/PS/(SMA-CB) composites were investigated.The results showed that the composites exhibited distinct triple percolation behavior,i.e.the percolation is governed by the percolation of CB in SMA phase,the continuity of SMA-CB at the interface and the continuity of PA6/PS interface.The percolation threshold of PA6/PS/(SMA-CB) was only 0.15 wt%,which is much lower than that of PA6/PS/CB.Moreover,the PTC(positive temperature coefficient) intensity of PA6/PS/(SMA-CB) composites was stronger than that of PA6/PS/CB and the negative temperature coefficient(NTC) effect was eliminated.The electrical properties of PA6/PS/(SMA-CB) were explained in terms of its special interface morphology:SMA and CB localize at interphase to form the conductive pathways.