Study of the Diffusion Behavior of Seawater Absorption in Multi-Walled Carbon Nanotubes/Halloysite Nanotubes Hybrid Nanofillers Modified Epoxy-Based Glass/Carbon Fiber Composites

In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.

Investigation on the thermal conductivity of HDPE/MWCNT composites by laser pulse method

Thermal conductivity (TC) of high density polyethylene/multiwall carbon nanotube (HDPE/MWCNT) composite films was measured by laser pulse method. It is found that the TC increased quickly with the increase of MWCNT fraction when the volume fraction of MWCNT was below 3.35%. However,as the volume fraction of MWCNT was over 3.35%,the increasing rate became slow. A new percolation model was proposed based on the effect of MWCNT network to simulate the TC of HDPE/MWCNT composite films. The simulation result was in good agreement the experimental data well. In addition,the relationship of TC with the increase of temperature was also discussed.

Fabrication and mechanical properties of MWCNTs-reinforced aluminum composites by hot extrusion

Over the past decade,the interest in aluminum composites reinforced with carbon nanotubes has grown significantly.Studies have been carried out to overcome problems with uniform dispersion,interfacial bonding,void formation and carbide formation of the composites.In the present work,multi-wall carbon nanotubes(MWCNTs) aluminum composites were produced.High-energy ball milling with the aim at developing well-dispersed MWCNTs Al composites was followed by cold compaction,sintering,and hot extrusion at 500 ℃.Different amounts of stearic acid as processing control agent(PCA) is used in order to minimize cold welding of the Al particles,and to produce finer particles.Differential scanning calorimetry(DSC),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray diffraction(XRD) were employed to analyze the MWCNTs,the aluminum powder,and the composites’ microstructural behavior.The hardness and tensile properties of the composites are also evaluated.The results showed 500% increase in yield stress after the addition of 1 wt% MWCNTs in Al-MWCNTs based composite.The ball-milling time of 4 h is found to be sufficient as excessive milling time destroys a vast number of MWCNTs.

Properties of paper mill sludge–wood fiber–HDPE composites after exposure to xenon-arc weathering

We used paper mill sludge（PMS） to substitute for part of the wood fibers（WF） used to reinforce high density polyethylene（HDPE）.The resulting composites were subjected to xenon-arc weathering.The composite filled with limited PMS（under 10 %） had mechanical properties and aging resistance similar to those without PMS.The composites containing more PMS faded and cracked more readily than those without PMS.Based on the carbonyl index,crystallinity,and wood index,PMS appeared to accelerate the degradation of composites during weathering.Adding PMS to WF–HDPE composites reduced the weathering resistance,and this reduction was not significant if the PMS content did not exceed 20 % of the wood fibers.Therefore,PMS could be used as a reinforcement in wood-plastic composites at levels less than20 % of the wood fiber content.

An investigation on the hardness and corrosion behavior of MWCNT/Mg composites and grain refined Mg

In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical behavior.Microstructural observations showed that the thickness of the produced composite layer was in the range of 2500μm.FSP resulted uniform distribution of CNT near the surface while agglomerated layers in the subsurface.Grain refinement of Mg achieved by FSP improved the hardness but significant enhancement in the hardness value was observed for FSPed MWCNT/Mg composites.Potentiodynamic polarization studies revealed that the increase in corrosion current density was observed for MWCNT/Mg composite compared with grain refined Mg and pure Mg,implying the significance of secondary phase(MWCNT)in decreasing the corrosion resistance of the composite.

Printability of HDPE/Natural Fiber Composites with High Content of Cellulosic Industrial Waste

In this paper, a continuous polymeric matrix highly filled with fiber of sugarcane bagasse has been obtained and its feasibility as an ink-absorbing material has been evaluated. In order to study the effect of the amount of cellulose fiber on the surface printability, contact angle measurement using different liquids—water-based inks, ethanol and ink for ink-jet printers—and printing tests were performed on composites of high density polyethylene (HDPE) and sugarcane bagasse (SCB). The composites were processed in a Haake internal mixer, using the SCB without any previous chemical treatment or compatibilizer. The differential scanning calorimetry (DSC) and derivative thermogravimetry (TG/ DTG) revealed an increase in the thermal stability and in the degree of crystallinity of the HDPE. The optical microscopy (OM) and scanning electron microscopy (SEM) showed that the cellulosic material was homogeneously embedded within the HDPE matrix. In order to assess the resistance of the composite sample to the pull strength of the printer, tensile tests were applied to the composites and the results were compared to known paper samples. The best result was achieved in the composite with the highest content of SCB, as well as the shortest drying time.

HDPE管内衬盾构隧道复合式衬砌结构极限承载力试验研究

为研究采用HDPE双壁缠绕管作为内衬的盾构隧道复合衬砌结构的破坏机理,依托桃浦污水处理厂初期雨水调蓄工程涉铁段排水隧道工程,开展整环足尺试验研究,得到如下结论:(1)复合衬砌结构破坏过程经历协调变形阶段和各自承载阶段,弹性极限点为顶底部纵缝处界面的剥离脱开,各纵缝及管片本体相继发生破坏,纵缝处填充层混凝土发生拉剪或压剪破坏;(2)复合衬砌结构的薄弱位置为各纵缝处的界面及填充层混凝土,其中顶部和腰部纵缝处最为薄弱;(3)复合衬砌结构不同位置纵缝处的界面破坏和填充层破坏形态均源自于纵缝转动变形导致刚度差异引起的界面应力和填充层应力突变。

Effects of temperature on MWCNTs/PDMS composites based flexible strain sensors

Conductive polymer composites(CPCs)are widely used in the flexible strain sensors due to their simple fabrication process and controllable sensing properties.However,temperature has a significance impact on the strain sensing performance of CPCs.In this paper,the strain sensing characteristics of MWCNTs/PDMS composites under temperature loading were systematically studied.It was found that the sensitivity decreased with the increase of temperature and the phenomenon of shoulder peak also decreased.Based on the theory of polymer mechanics,it was found that temperature could affect the conductive network by changing the motion degree of PDMS molecular chain,resulting in the change of sensing characteristics.Finally,a mathematical model of the resistance against loading condition(strain and temperature),associated with the force−electrical equivalent relationship of composites,was established to discuss the experimental results as well as the sensing mechanism.The results presented in this paper was believed helpful for the further application of strain sensors in different temperature conditions.

Electrocatalytic Reduction of Oxygen at Perovskite (BSCF)-MWCNT Composite Electrodes

A composite paste electrode based on Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF)—initially synthesized by solgel method—and multiwall carbon nanotube (MWCNT) as a cathode in fuel cells is developed. The composite pastes are prepared by the direct mixing of BSCF:MWCNT at 90:10, 80:20 and 70:30 (% w/W). These electrodes are then characterized by the x-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherm, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The XRD and SEM confirm the inclusion and the uniform dispersal of the MWCNT within BSCF, respectively. The nitrogen adsorption isotherm study shows that the porosity of the composite paste electrode has been improved by two-fold from the BSCF electrode. The EIS and CV demonstrate that the higher ratios of MWCNT in the composites are critical in improving the electronic conductivity as well as the kinetics. It is also noticeable that the electrode has increased the catalysis of oxygen in 0.1 M KOH (pH 12.0). Cyclic voltammetric studies on the oxygen reduction reaction (ORR) suggest that the incorporation of MWCNT is vital in improving the electrode (cathode) properties of a fuel cell.

HDPE复合稳定剂的研究

高密度聚乙烯(HDPE)广泛应用于建材、电器产品、封装材料、工业农业等多个领域。而HDPE的耐老化性能较差,在热氧作用下,会出现力学性能劣化,在户外使用过程中,受大气、紫外光等作用下,易出现黄变、脆化甚至力学性能丧失。为拓宽HDPE的应用领域,使其在严苛环境下具有更长的使用寿命及综合性能,通过添加剂复配共混,加工成复合稳定剂母粒,来实现HDPE光热稳定的综合提升,为制备复合耐老化性能优异的HDPE材料提供参考。

Optimization of Extrusion Process Parameters of Recycled High-Density Polyethylene-Thermoplastic Starch Composite for Fused Filament Fabrication

High-density poly-ethylene (HDPE) is a nonbiodegradable recyclable plastic which is widely utilized in single use packaging applications. Consequently, it constitutes a significant amount of plastic waste found in landfills. From literature, it has been shown that parts produced using composites of HDPE with carbohydrate-based polymers, such as thermoplastic starch (TPS), experience mechanical degradation through hydrolytic degradation process. The possible utilization of recycled-HDPE (rHDPE) and TPS composite in nonconventional manufacturing processes such as Fused filament fabrication (FFF) has however not been explored. This study explores the potential application of rHDPE and TPS composites in FFF and optimizes the extrusion process parameters used in rHDPE-TPS filament production process. Taguchi method was utilized to analyze the extrusion process. The extrusion process parameters studied were the spooling speed, extrusion speed and the extrusion temperatures. The response variable studied was the filament diameter. In this research, the maximum TPS content achieved during filament production was 40 wt%. This filament was however challenging to use in FFF printers due to frequent nozzle clogging. Printing was therefore done with filaments that contained 0 - 30 wt% TPS. The experimental results showed that the most significant parameter in extrusion process was the spooling speed, followed by extrusion speed. Extrusion temperature had the least significant influence on the filament diameter. It was observed that increase in TPS content resulted in reduced warping and increased rate of hydrolytic degradation. Mechanical properties of printed parts were investigated and the results showed that increasing TPS content resulted in reduction in tensile strength, reduction in compression strength and increase in stiffness. The findings of this research provide valuable insights to plastic recycling industries and researchers regarding the utilization of recycled HDPE and TPS composites as substitute materials in FFF.

Facile Preparation, Characterization of Flexible Organic Solar Cells Using P3HT-MWCNTS Composite Photoactive Layer

Multiwalled carbon nanotubes (MWCNTs) mixed in poly(3-hexylthiophene) (P3HT) were used as a photoactive layer for organic solar cells (OSC). The flexible OSCs of a structure of PET/rGO-P3HT/P3CT/PCBM/LiF-Al were prepared by spincoating. The UV-Vis absorption spectra of the photoactive films and current-voltage characteristics of the OSCs showed the advantage of the composite devices above the pristine-polymeric ones. Under illumination of light with a 100 mW/cm2-powerdensity, the photoelectrical conversion efficiency (PCE) of the OSCs with 3.0 wt% MWNCTs embedded in the photoactive layer possess a value as large as 2.35%. The obtained results suggest further useful applications of the flexible large-area solar cells.

MWCNTs/ZIF-67复合材料的制备及其催化性能研究

通过简便、经济的方法合成了MWCNTs/ZIF-67复合材料,并运用SEM、TEM、XRD、XPS等技术手段对该复合材料进行了表征。为了评估MWCNTs/ZIF-67催化剂的催化活性,在NaBH_(4)存在下进行了对硝基苯酚(4-NP)的还原实验。结果表明,MWCNTs/ZIF-67催化剂具有很好的催化性能,在6min内对4-NP的催化效率高达99.82%,表观速率系数达到0.4973min^(-1)。此外,该材料可以通过磁铁从水溶液中收集,便于回收和再利用。且经过5次循环后,复合材料的催化活性仍很高,表明该复合材料有较好的稳定性,可以作为去除环境污染物的新型催化材料。

Self-assembled gel-assisted preparation of high-performance hydrophobic PDMS@MWCNTs/PEDOT:PSS composite aerogels for wearable piezoresistive sensors

The conductive polymer poly(3,4-thylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)exhibits po-tential in the development of flexible devices due to its unique conjugated structure and water-solubility characteristics.To address the incompressibility of the original PEDOT:PSS aerogel without compromis-ing its high conductivity,a stable interpenetrating polymer network(IPN)was self-assembled by guiding the molecular motion within PEDOT:PSS and introducing multi-walled carbon nanotubes(MWCNTs).By combining critical surface removal,directional freeze-drying,and polydimethylsiloxane(PDMS)reinforce-ment processes,a hydrophobic PDMS@MWCNTs/PP aerogel with a highly oriented porous structure and high strength was prepared.Under the synergistic effect of MWCNTs/PEDOT:PSS electroactive scaffold,the composite aerogel exhibited a high sensitivity of up to 16.603 kPa^(-1) at 0-2 kPa,a fast response time of 74 ms,and excellent repeatability.Moreover,the sensor possessed hydrophobicity with a good water contact angle of 137°The sensor could serve as a wearable electronic monitoring device to achieve ac-curate and sensitive detection of human motion including large-scale human activities and tiny muscle movements.Therefore,our findings provide a new direction to fabricate high-performance piezoresistive sensors based on three-dimensional(3D)conductive polymer active scaffolds,demonstrating their great potential for flexible electronics,human-computer interaction,and a wide range of applications under special working conditions.

PTFE原位成纤对PP/MWCNTs/PTFE复合材料发泡性能和力学性能的影响

采用共混造粒和微孔发泡注塑成型工艺,制备了聚四氟乙烯(PTFE)原位成纤增强的聚丙烯/多壁碳纳米管/聚四氟乙烯(PP/MWCNTs/PTFE)微孔复合材料,并对其结晶、流变、微孔发泡和力学性能进行了测试和表征。结果表明:与不加PTFE的PP/MWCNTs复合材料相比,PTFE的加入可以提高PP/MWCNTs/PTFE复合材料的结晶度,增大储能模量,降低损耗因子;PTFE的加入可以改善PP/MWCNTs/PTFE复合材料的泡孔结构,使泡孔密度增大,泡孔直径减小;相比PP/MWCNTs复合材料,当PFTE的加入量为1%(质量分数)时,PP/MWCNTs/PTFE复合材料的断裂伸长率提高了67.5%,抗拉强度提高了21.1%,杨氏模量提高了12.5%。

The effect of Poly-ethylene-co-glycidyl methacrylate efficiency and clay platelets on thermal and rheological properties of wood polyethylene composites.

Global ecological concerns have resulted in an interest in renewable natural materials. Composites based on high density polyethylene (HDPE), wood fiber (Veneer) and containing coupling agents like nanoclay (NC) and poly-ethylene-co-glycidyl methacrylate (PEGMA) were made by melt compounding and then injection molding. In this study, the effects of two variable parameters namely nanoclay and coupling agent on the rheological and thermal properties of wood polyethylene composites (WPECs) were investigated. The study investigates the morphology phase, rheology behaviors and thermal properties by scanning electron microscope, capillary rheometer and thermal gravimetric analyzer. The SEM micrographs of the composites showed that the outer surfaces of the wood were coated by a section of amorphous lignin. The state of dispersion in HDPE/pine/clay composites was improved by EGMA because it could interact with pine flour in addition to clay. The interaction of reinforcement with coupling agent and HDPE matrix is strong based on the observation of the fracture surface of composites when EGMA is present. However the addition of 2.5% clay slightly lowered the initial degradation temperature (Td) but did not improve the thermal stability. Obviously, all the composites materials exhibit viscoelastic values greater than those of neat HDPE.

Structure and Properties of Self-assembled Narural Rubber/Multi-walled Carbon Nanotube Composites

Natural rubber （NR）/multi-walled carbon nanotube （MWCNTs） composites were prepared by combining self-assembly and latex compounding techniques.The acid-treated MWCNTs （H2SO4：HNO3=3：1,volume ratio） were self-assembled with poly （diallyldimethylammonium chloride） （PDDA） through electrostatic adhesion.In the second assembling,NR/MWCNTs composites were developed by mixing MWCNTs/PDDA solution with NR latex.The results show that MWCNTs are homogenously distributed throughout the NR matrix as single tube and present a great interfacial adhesion with NR phase when MWCNTs contents are less than 3 wt%.Moreover,the addition of the MWCNTs brings about the remarkable enhancement in tensile strength and crosslink density compared with the NR host,and the data peak at 2 wt% MWCNTs loadings.When more MWCNTs are loaded,aggregations of MWCNTs are gradually generated,and the tensile strength and crosslink both decrease to a certain extent.

Detection of illegal dyes in foods using a polyethersulfone/multi-walled carbon nanotubes composite membrane as a cleanup method

In this paper, a polyethersulfone （PES）/multi-walled carbon nanotubes （MWCNTs） composite membrane was prepared us- ing phase inversion. The surface morphology and internal structure of the membrane were observed by scanning electron microscopy （SEM）. The effects of MWCNTs content on various aspects of membrane performance such as porosity, water flux, and antifouling characteristics were investigated. Results showed that proper addition of MWCNTs would improve the properties of the membrane. MWCNTs had a strong adsorption capacity for industrial dyes and the composite membrane could be used as an effective method to identify and clean up illegal dyes in foods. In addition, this new method for iden- tifying dyes is rapid： the cleanup procedure in the determination of illegal dyes in foods by the composite membrane was shortened to 30 min or less compared to 6-8 h for traditional methods.

Improvement of Mechanical,Dynamic-Mechanical and Thermal Properties for Noil Ramie Fiber Reinforced Polyethylene Composites

Noil discarded fibers from fiber production for textile industry have short length and are always considered less valuable.Here,noil ramie fibers/HDPE composite is prepared using twin-screw extruder and the dynamic mechanical and thermal properties are studied.The influence of ramie fiber and maleic anhydride-grafted polyolefin(MA-g-PO)on mechanical,dynamic mechanical and thermal properties is investigated.It is observed that the tensile,flexural and impact properties of the composites treated with MA-g-PO are all improved in comparison to the untreated composites.Dynamic mechanical properties of the composite with MA-g-PO show an increase in the storage modulus with a higherαrelaxation peak,together with the micromorphology analysis,indicating an improved interfacial bonding between fiber and matrix by the MA-g-PO addition.Furthermore,the change in TGA thermograms of composite caused by MA-g-PO exhibits that the addition of MA-g-PO is also helpful to increase the thermal stability of noil ramie fiber/HDPE composites.

基于ZnAl-LDH/MWCNT@MXene的柔性压力/温度双功能传感器

锌铝层状双氢氧化物/多壁碳纳米管(ZnAl-LDH/MWCNT)包覆金属碳化物MXene作为复合导电材料制备上下电极,以微结构聚二甲基硅氧烷(PDMS)为介电层,构建了一种柔性双功能传感器。通过器件输出电容信号监测压力,利用单电极的温阻变化监测温度。该柔性电容式传感器的导电层材料为ZnAl-LDH/MWCNT@MXene,搭配微结构为80目的介电层,其性能达到最优。在0~50 kPa时传感器的灵敏度高达1.57%/kPa。温度传感的灵敏度为2.3%/℃,工作温度范围为20~40℃。该器件实现了压力/温度两种物理量的传感,同时可以运用于人体运动和健康状态的实时检测。解决了柔性传感器功能单一的问题,为柔性传感器实现多功能应用提供基础。