表面复合纳米SiO_2和碳纳米管玻璃纤维增强尼龙6的结构与性能

利用静电相互作用在玻璃纤维(GF)表面分别复合纳米二氧化硅(SiO2)和多壁碳纳米管(MWNTs),制备了GF-SiO2、GF-MWNTs复合增强体,并通过转矩流变仪制备了尼龙6(PA6)/GF-SiO2和尼龙6(PA6)/GF-MWNTs复合材料.利用扫描电子显微镜(SEM),示差扫描量热仪(DSC),热机械分析仪(DMA)等手段研究了复合材料的微观结构、热学及力学性能.结果表明,静电复合的方法可以使纳米二氧化硅(nano-SiO2)、多壁碳纳米管(MWNTs)在GF表面达到均匀吸附,复合增强体能加快尼龙6的结晶速度,并使材料的玻璃化温度、动态模量、拉伸强度、结晶温度等明显提高,其中GF-MWNTs对复合材料性能的提高最明显,拉伸强度提升了21%,模量提高了28%.     

Mechanical and viscoelastic properties of chitin fiber reinforced poly(ε-caprolactone)

Poly(ε-caprolactone)/chitin fiber (PCL-CF) composites as potential bone substitutes were prepared using a simple melt-processing method. The results from differential scanning calorimetry and dynamic mechanical thermal analysis (DMTA) showed that there was interaction between PCL and CF. Static mechanical testing showed that tensile strength, Young’s modulus and flexural strength were increased by the addition of CF. The measurements from DMTA and an advanced rheometric expansion system showed that both the storage modulus and loss modulus were enhanced by CF. The PCL-CF composite with CF of 45% by mass had the best properties among all the tested composites.     

The mechanical properties of plasma‐treated carbon fiber reinforced PA6 composites with CNT

The aim of this work is the evaluation of the effects of plasma treatment and the addition of CNT on the mechanical properties of carbon fibre/PA6 composite. A powder impregnation process with integrated inline continuous plasma of carbon fibers was used to produce CF/PA6 composite. CF/PA6 composite was processed into test laminates by compression moulding, and interface dominated composite properties were studied. The tensile and impact strength of composites containing CNT and plasma‐treated carbon fibres improved obviously. The tensile strength of nanocomposite largely increases with the increasing of the CNT content and then decreases when the CNT content is over 2%. The hydroxyl groups of the fibers surface are in favor of the wettability of carbon fibers by the polar matrix resin, which is resulting in a further interaction of the fiber surface with the curing system of the matrix resin.     

Modification effects of short carbon fibers on mechanical properties and fretting wear behavior of UHMWPE composites

The present work comparatively studied the modification effects of short carbon fiber (CF) on the mechanical properties and fretting wear behavior of ultra‐high molecular weight polyethylene (UHMWPE)/CF composites. The interactions between CFs and UHMWPE interface were also investigated in detail. The results showed that, with the increase in fiber content, the compressive modulus and hardness of the composites increased, while its impact strength decreased. It was found that filling of CF can reduce the friction and wear of UHMWPE. In addition, the UHMWPE‐based composites reinforced with nitric acid‐treated CF exhibited better mechanical properties, lower friction coefficient, and higher wear resistance than those of untreated UHMWPE/CF composites. This was attributed to the improvement of interfacial adhesion and compatibility between CF and UHMWPE matrix caused by surface chemical modification of CF. Copyright © 2015 John Wiley & Sons, Ltd.     

The addition of clay on the mechanical properties of surface‐treated CF‐filled PA66 composites

Polyamide 66 (PA66) composites filled with clay and carbon fiber (CF) were prepared by twin‐screw extruder in order to study the influence of nanoparticle reinforcing effect on the mechanical behavior of the PA66 composites (CF/PA66). The mechanical property tests of the composites with and without clay were performed, and the fracture surface morphology was analyzed. The results show that the fracture surface area of the clay‐filled CF/PA66 composite was far smoother than that of the CF/PA66 composite, and there formed a tense interface on the CF surface after the addition of clay. The tensile and flexural strength of CF/PA66 composites with clay was improved. The impact strength decreased because of the high interfacial adhesion. In conclusion, the addition of clay favored the improvement of the higher interface strength and so had good effect on improving the tensile and flexural properties of the composites. Copyright © 2017 John Wiley & Sons, Ltd.     

Complementary effects of multiwalled carbon nanotubes and conductive carbon black on polyamide 6

This article introduces a newly innovative idea for preparation of superconductive ternary polymeric composites of polyamide 6 (PA6), conductive carbon black (CCB), and multiwalled carbon nanotubes (MWCNTs) with different weight ratios by a melt‐mixing technique. The complementary effects of CCB and MWCNTs at different compositions on rheological, physical, morphological, thermal, and dynamic mechanical and electrical properties of the ternary composites have been examined systematically. We have used a novel formulation to produce high‐weight fraction ternary polymer composites that show extremely higher conductivity when compared with their corresponding binary polymer composites at the same carbon loading. For example, with an addition of 10 wt % MWCNTs into the CCB/PA6 composite preloaded with 10 wt % CCB, the electrical conductivity of these ternary composites was about 5 S/m, which was 10 times that of the CCB/PA6 binary composite (0.5 S/m) and 125 times that of the MWCNT/PA6 binary composite (0.04 S/m) at 20 wt % carbon loading. The incorporation of the MWCNTs effectively enhanced the thermal stability and crystallization of the PA6 matrix in the CCB/PA6 composites through heterogeneous nucleation. The MWCNTs appeared to significantly affect the mechanical and rheological properties of the PA6 in the CCB/PA6 composites, a way notably dependent on the MWCNT contents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1203–1212, 2010     

Simultaneously improving the flame retardancy and mechanical properties for polyamide 6/aluminum diethylphosphinate composites by incorporating of 1,3,5‐triglycidyl isocyanurate

The effect of 1,3,5‐triglycidyl isocyanurate (TGIC) as a synergistic agent on the fire retardancy, thermal, and mechanical properties for polyamide 6/aluminium diethylphosphinate (PA6/AlPi) composites were investigated in detail by limiting oxygen index; vertical burning (UL‐94); cone calorimeter; thermal gravimetric analysis; rheological measurements; and the tests of tensile, flexural, and Izod impact strength. The morphologies and chemical compositions of the char residue were investigated by scanning electron microscopy, X‐ray photoelectron spectroscopy, and Fourier transform infrared spectra. The results demonstrated that AlPi and TGIC exerted an evident synergistic effect for flame retardant PA6 matrix, and the PA6/AlPi/TGIC composites with the thickness of 1.6 mm successfully passed UL‐94 V‐0 rating with the limiting oxygen index value of 30.8% when the total loading amount of AlPi/TGIC with the mass fraction of 97:3 was 11 wt%. However, the samples failed to pass the UL‐94 vertical burning tests when AlPi alone is used to flame retardant PA6 matrix with the same loading amount. The thermal gravimetric analysis data revealed that the introduction of TGIC promoted the char residue formation at high temperature. The rheological measurement demonstrated that the incorporation of TGIC improved the storage modulus, loss modulus, and complex viscosity of PA6/AlPi/TGIC composites comparing with that of neat PA6 and PA6/AlPi composites due to the coupling reaction between TGIC and the terminal groups of PA6 matrix. The morphological structures of char residues demonstrated that TGIC benefited to the formation of more homogenous and integrated char layer with no defects and holes on the surface comparing with that of PA6/AlPi composites during combustion. The higher melt viscosity of composites and the integrated and sealed char layer effectively inhibited the volatilization of flammable gas into the combustion zone and then led to the reduction of the heat release. The results of mechanical properties revealed that the incorporation of TGIC enhanced the mechanical properties for PA6/AlPi/TGIC composites comparing with that of PA6/AlPi composites with the same loading amount of flame retardant caused by the chain extension effect of TGIC. As a result, the flame retardancy and mechanical properties of PA6/AlPi composites simultaneously enhanced due to the introduction of TGIC.     

尼龙66-盐与碳纤维复合-固态缩聚的研究

本工作借助偏光显微镜,扫描电子显微镜和热分析方法(DSC,TGA)研究了尼龙66盐与碳纤维复合-固态缩聚反应历程及纤维-树脂之间的界面效应。发现对尼龙66盐的“原位固态缩聚”存有如碳纤维表面的成核结晶和催化效应之类的界面效应。讨论了碳纤维的界面效应对尼龙66基体的外延结晶和熔融行为及其热氧化稳定作用的影响。     

Study of the carbon fiber–Poly(Ether–Ether–Ketone) (PEEK) interfaces, 3: influence and properties of interphases

The aim of this third part is to analyze the structure and properties of the interfacial region between carbon fibers and PEEK as a function of different thermal conditioning treatments. First, it is shown by means of optical microscopy that the interfacial zone is not different from the bulk matrix when standard cooling conditions are used. On the contrary, a transcrystalline interphase is formed near the carbon fiber surface in systems that have been subjected to isothermal treatments. By comparison with previous results concerning the mechanical properties of the fiber–matrix interface, it appears that the interfacial shear strength decreases in the presence of a transcrystalline interphase or when the crystallization rate of PEEK increases. Moreover, it seems that the “constraint state” of the amorphous phase of PEEK near the fiber surface could also play a role in the interfacial shear strength. Secondly, a method is proposed in order to estimate the elastic modulus of crystalline interphases. It seems that this modulus is strongly dependent on the crystallization rate of the polymer. Finally, the determination of the stress-free temperature, defined as the temperature at which a longitudinal compressive stress just appears on the carbon fiber during the processing of the composites, is performed by recording the acoustic events corresponding to the fragmentation process in single-fiber composites. The results confirm that the crystallization rate and the “constraint state” of the amorphous phase of the matrix play an important role in the mechanical behavior of carbon fiber–PEEK interfaces.     

原位缩聚法制备碳纳米管/尼龙11复合材料

用原位缩聚法制备了碳纳米管增强的尼龙11复合材料,用X射线衍射仪、红外(FTIR)、扫描电镜(SEM)、热重(TGA)、机械拉伸测试仪等对其结构、形貌、热性能及机械性能进行了表征测试.扫描电镜结果显示碳纳米管均一地分散在尼龙11/碳纳米管复合材料中.复合材料的拉伸模量比纯尼龙11有较大的提高.当复合材料中碳纳米管含量分别为1%,5%,10%时,材料的拉伸模量分别提高了34.5%,92.9%和113,7%.同时,复合材料的储能模量也有提高.热分析结果显示当复合材料中碳纳米管含量为1%时,其失重5%和10%的温度分别由纯尼龙11的404℃、424℃提高到414℃和437℃.示差扫描量热分析(DSC)显示复合材料的结晶温度随碳纳米管的加入而升高,而结晶度则降低.     

Rapeseed oil as main component in synthesis of bio-polyurethane-polyisocyanurate porous materials modified with carbon fibers

Porous polyurethane-polyisocyanurate (PUR-PIR) composites have been synthesized using two types of rapeseed oil-based bio-polyols. The bio-polyols from rapeseed oil were synthesized using two methods: (i) transesterification and (ii) epoxidation followed by oxirane ring opening. The PUR-PIR porous materials were prepared with two isocyanate indices, 150 and 250, and were modified with carbon fibres (CF) in an amount of 3 and 6 wt% of the total foam mass. The structure of the composites was examined using scanning electron microscopy. Thermal and mechanical properties of the composites were determined through a thermogravimetric analysis and measurements of the thermal conductivity, compressive strength, and Young modulus. The influence of CF on the composite flammability was analyzed using oxygen index and cone calorimeter tests. The investigations of the mechanical properties have shown that the compressive strength is the most beneficial in the case of the PUR-PIR foams modified with 6 wt % of CF. The studies have shown that the oxygen index of the composites increases with an increasing CF content and isocyanate index. An addition of CF reduces the heat rate release, especially for the materials with an isocyanate index of 250. An introduction of CF into the PUR-PIR foam structure is a way to improve the thermal stability and to decrease the flammability of final porous composites.     

Structure and Properties of β-Polypropylene Reinforced by Polypropylene Fiber and Polyamide Fiber

Matrix/fiber composites of β-form isotactic polypropylene(iPP) matrix and α-iPP or PA6 fibers were prepared by laminating technique under different preparation temperatures. The mechanical properties and interfacial morphologies of these composites were studied by tensile test, optical microscopy and scanning electron microscopy, respectively. The experimental results show that the tensile yield load and tensile modulus of β-iPP/PA6 matrix/fiber systems increased significantly at the expense of elongation at break. These mechanical properties show essentially no dependence on the sample preparation temperature. On the other hand, the mechanical properties of iPP matrix/fiber single polymer composites depend strongly on the sample preparation temperature. At low sample preparation temperature, e.g., 172 ℃, the solid α-iPP fiber induces α-iPP crystallization, leading to the formation of α-iPP transcrystalline layer around the fiber. This results in a remarkable increment of the tensile yield load and tensile modulus. The elongation at break is also much better than that of the iPP/PA6 matrix/fiber system. It reflects a better interfacial adhesion of the single polymer composite compared with the iPP/PA6 composite. At higher sample preparation temperature, e.g., 174 ℃ or 176 ℃, the partial surface melting of the oriented fiber allows interdiffusion of iPP molecular chains in the molten fiber and matrix melt. The penetration of matrix chains into the molten iPP fiber results in some iPP molecular chains being included partially in the recrystallized fiber and the induced β-transcrystalline layers. This kind of configuration leads to an improvement of interfacial adhesion between the fiber and matrix, which causes a simultaneous increase of the tensile yield load, tensile modulus and elongation at break of β-iPP.     

Short carbon fiber reinforced aromatic polydisulfide derived from cyclic (4,4′‐oxybis(benzene)disulfide) via ring‐opening polymerization

Morphology, mechanical and thermal properties of short carbon fiber reinforced poly(arylene disulfide) synthesized by ring‐opening reaction of cyclic(arylene disulfide) oligomers were studied. These macrocyclic oligomers were prepared from 4,4′‐oxybis(benzenethiol) by oxidation coupling cyclization. Ring‐opening polymerization (ROP) was carried out by in situ melt molding in air. Oxidation reaction during the ROP was detected using the Raman spectrum technique. Three‐point bending tests were performed to determine the flexural properties of neat polymers and the composites. The results showed that the flexural strength and modulus of poly(arylene disulfide)/carbon fiber composites were greatly enhanced with the carbon fiber addition. The maximum weight loss peak temperatures of the composites increased with increasing short carbon fiber content. Good adhesion between carbon fiber and the matrix was observed using scanning electron microscopy (SEM) technique. Copyright © 2005 John Wiley & Sons, Ltd.     

Structure–property relationships in polyamide 6/multi‐walled carbon nanotubes nanocomposites

Polyamide 6 (PA6)/multi‐walled carbon nanotubes (MWCNT) nanocomposites were produced by diluting a masterbach containing 20 wt % nanotubes using melt mixing. The influence of the addition of well dispersed MWCNT (as indicated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM)) on the thermal transitions, and crystallization behavior of the PA6 matrix is investigated. Differential scanning calorimetry (DSC) results show a reduction in heat capacity jump at the glass transition which is interpreted by an immobilized interfacial layer near the nanotubes. Furthermore, both DSC and X‐ray diffraction (XRD) measurements indicate that nanotubes favor the formation of the α crystalline form of PA6. These findings are correlated with the observed improvement of the storage modulus as revealed by dynamic mechanical thermal analysis (DMTA). Additionally, a new crystallization peak appears when MWCNT are added, and is attributed to the formation of a different morphology of the same type crystallite around the nanotubes walls (trans‐crystallinity). Finally, water sorption measurements show an increase of water content, normalized to the amorphous polymer fraction, in the nanocomposites. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 764–774, 2009     

Effects of electrically inert fillers on the properties of poly(<Emphasis Type="Italic">m</Emphasis>-xylene adipamide)/multiwalled carbon nanotube composites

The effects of three types of electrically-inert fillers, calcium carbonate (CaCO₃), talc and glass fiber (GF), on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly(m-xylene adipamide) (MXD6)/multiwalled carbon nanotube (MWCNT) composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO₃, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.     

Influence of maleic anhydride-grafted EPDM and flame retardant on interfacial interaction of glass fiber reinforced PA-66

In this paper, the effects of melamine polyphosphate flame retardant (MPP-FR) and maleic anhydride-grafted EPDM (MA-EPDM) on the interfacial interaction of PA66/GF were investigated by means of scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), rheological behavior and mechanical properties. The experimental results demonstrate that MPP-FR and MA-EPDM could effectively improve interfacial interactions between the PA66 and GF. Based on SEM, good interfacial adhesion between PA66 and GF in PA66/GF/FR and PA66/GF/FR/MA-EPDM composites was observed, however, MPP-FR destroyed the PA66 matrix. DMA results show that MPP-FR increased glass transition temperature (T_g) and storage modulus, and lower tan δ, while MA-EPDM showed a little effect on them in PA66/GF/FR/MA-EPDM composite compared with PA66/GF/FR. MPP-FR made PA66 crystallization temperature and the activation energy of the macromolecular segments transport increase clearly, and enhanced crystallization degree of PA66 according to DSC results. These results demonstrate MPP-FR presented the nucleate effect for the crystallization of PA66. At the low shear rate, MPP-FR and MA-EPDM obviously enhanced apparent viscosities of the composites. This is attributed that MPP-FR improved the interfacial interaction of the composites, and MA-EPDM promoted the formation of high molecular weight structures by the reactions between MA and amine groups. All results in this paper were consistent, and showed the good interaction among PA66, GF, MPP and MA-EPDM, which were proved by the mechanical properties of the composites.     

Improvement of interfacial adhesion in PP/PS blends enhanced with supersonic atmosphere plasma spraying surface‐treated carbon fiber

The effects of surface treatment of a carbon fiber (CF) by supersonic atmosphere plasma spraying (SAPS) on the interfacial adhesion behavior and morphology of polypropylene/polystyrene (PP/PS) matrix blends filled CF composites were investigated. Effects of surface treated a commercial CF on mechanical properties are studied. Contact angle was measured to examine the changes in wettability of the CF. The chemical and morphological changes were characterized by using X‐ray photoelectron spectroscopy and scanning electron microscopy. PP/PS/CF composites were fabricated with and without SAPS treatment, and their interlaminar fracture toughnesses were compared. The results showed that the interlaminar shear strength of composites has been greatly improved filled SAPS modification CF. The water contact angle of resin sample decreased 50% after addition of SAPS surface‐treated CF. Scanning electron microscopy results on the fractured surface exhibited PP/PS blends adhered well around the CFs of the SAPS‐treated specimen compared with that of the untreated specimen. This attributed to the CF interlock, and it improves the wetting between fibers and resins. Copyright © 2017 John Wiley & Sons, Ltd.     

Effects of Electrically Inert Fillers on the Properties of Poly(m-xylene adipamide)/Multiwalled Carbon Nanotube Composites

The effects of three types of electrically-inert fillers, calcium carbonate(CaCO_3), talc and glass fiber(GF), on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly(m-xylene adipamide)(MXD6)/multiwalled carbon nanotube(MWCNT) composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO_3, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.     

Improving the interfacial property of carbon fibre/epoxy resin composites by grafting amine-capped cross-linked poly-itaconic acid

To improve the interfacial properties of carbon fibre-reinforced polymer composites, a surface treatment was used to cap cross-linked poly-itaconic acid onto carbon fibres via in-situ polymerization after itaconic acid grafting. The chemical composition of the modified carbon fiber (CF) surface was characterized by X-ray photoelectron spectral and Fourier-transform infrared spectroscopy. Scanning electron microscopy and atomic force microscopy images showed that the poly-itaconic acid protective sheath was uniformly capped onto the CF surface and that the surface roughness was obviously enhanced. Chemical bonds also played a key role in the interfacial enhancement. The results showed that the interfacial shear strength of the composites with poly-itaconic acid on the carbon fibres (72.2 MPa) was significantly increased by 89.5% compared with that of the composites with pristine CF (38.1 MPa). Moreover, the poly-itaconic acid sheath promoted a slight increase in mono-fibre tensile strength. In addition, the interfacial mechanisms were also discussed. Meanwhile, the mechanical property of the functionalized CF/epoxy resin composites was also significantly improved.     

Effects of surface synergy for the dispersion of short carbon fibers sized by adipic acid modified epoxy resin potassium

The carbon fiber (CF) surface plays a critical role in the performance of CF composite materials. Adipic acid modified epoxy resin potassium (AAEK) prepared with epoxy resin and adipic acid, and KOH was employed as the CF sizing agent. Then, series of surface properties of AAEK‐treated carbon fiber (CF‐AAEK) including surface charge, morphology, and groups were characterized by using Faraday cup, friction coefficient gauge, atomic force microscopy, X‐ray photoelectron spectroscopy, and thermogravimetry. The results indicated that the dispersion coefficient of CF‐AAEK was increased by 1.72 times and there were synergistic effects for the dispersion of short CFs during the sizing treatment process with AAEK. In addition, the flexural strength of treated short CF composite proved to increase by 168%, which evaluated that the better CF dispersion in the matrix was a critical factor for the mechanical property improvement of short CF‐AAEK/epoxy resin composites.