Fabrication and Properties of Ti3SiC2/SiC Composites

Ti3SiC2/SiC composites were fabricated by reactive hot pressing method. Effects of hot pressing temperature, the content and particle size of SiC on phase composition, densification, mechanical properties and behavior of stress-strain of the composites were investigated. The results showed that ： （ 1 ） Hot-pressing temperature influenced the phase composition of Ti3SiC2/SiC composites. The flexural strength and fracture toughness of composites increased with hot pressing temperature. （2） It became more difficult for the composites to densify when the content of SiC in composites increased. It need be sintered at higher temperature to get denser composite. The flexural strength and fracture toughness of composites increased when the content of SiC added in composites increased. However, when the content of SiC reached 50 wt%, the flexural strength and fracture toughness of composites decreased due to high content of pore in composites. （3） When the content of SiC was same, Ti3SiC2/SiC composites were denser while the particle size of SiC added in composites is 12. 8 μm compared with the composites that the particle size of SiC added is 3 μm. The flexural strength and fracture toughness of composites increased with the increase of particle size of SiC added in composites. （4） Ti3SiC2/SiC composites were non-brittle fracture at room temperature.     

Preparation of graphene oxide/natural rubber composites by latex cocoagulation: Relationship between microstructure and reinforcement

Graphene oxide(GO) has recently attracted substantial interest as a possible reinforcing agent for next generation rubber composite materials. In this research, GO was incorporated in natural rubber(NR) composites through latex co-coagulation technique. The microstructures of GO/NR composites were characterized through a combination of transmission electron microscope, scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and Differential scanning calorimeter. The results showed that highly exfoliated GO sheets were finely dispersed into NR rubber matrix with strong interface interaction between GO and NR. The mechanical properties of the GO/NR composites were further evaluated. The results showed that the tensile strength, tear strength and modulus can be significantly improved at a content of less than 2 phr. Especially,GO exhibited specific reinforce mechanism in NR due to the stress-induced crystallization effects of NR. The stress transfer from the NR to the GO sheets and the hindrance of GO sheets to the stress-induced crystallization of NR were further displayed in stress–strain behavior of GO/NR composites. These enhanced properties were attributed to the high surface area of GO sheets and highly exfoliated microstructures of GO sheets in NR.     

油酸修饰纳米CaCO3对PP结晶行为和力学性能的影响

Oleic acid (OA)-modified CaCO3 nanoparticles were prepared using surface modification method. Infrared spectroscopy (IR) was used to investigate the structure of the modified CaCO3 nanoparticles, and the result showed that OA attached to the surface of CaCO3 nanoparticles with the ionic bond. Effect of OA concentration on the dispersion stability of CaCO3 in heptane was also studied, and the result indicated that modified CaCO3 nanoparticles dispersed in heptane more stably than unmodified ones. The optimal proportion of OA to CaCO3 was established. The effect of modified CaCO3 nanoparticles on crystallization behavior of polypropylene (PP) was studied by means of DSC. It was found that CaCO3 significantly increased the crystallization temperature, crystal-lization degree and crystallization rate of PP, and the addition of modified CaCO3 nanoparticles can lead to the for-mation of β-crystal PP. Effect of the modified CaCO3 content on mechanical properties of PP/CaCO3 nanocompo-sites was also studied. The results showed that the modified CaCO3 can effectively improve the mechanical proper-ties of PP. In comparison with PP, the impact strength of PP/CaCO3 nanocomposites increased by about 65% and the flexural strength increased by about 20%.     

Comparison of the effect of carbon,halloysite and titania nanotubes on the mechanical and thermal properties of LDPE based nanocomposite films

In this study, titania nanotubes(TNTs) were prepared by hydrothermal method with the aim to compare the properties of these one-dimensional tubular nanostructures' reinforced nanocomposites with the carbon and halloysite nanotubes'(CNTs and HNTs, respectively) reinforced nanocomposites. Low density polyethylene(LDPE) was used as the matrix material. The prepared nanocomposites were characterized and compared by means of their morphological, mechanical and thermal properties. SEM results showed enhanced interfacial interaction and better dispersion of TNTs and HNTs into LDPE with the incorporation of a MAPE compatibilizer,however, these interactions seem to be absent between CNTs and LDPE, and the CNTs remained agglomerated.Contact angle measurements revealed that CNT filled nanocomposites are more hydrophilic than HNT composites, and less than TNT composites. CNTs provided better tensile strength and Young's modulus than HNT and TNT nanocomposites, a 42% increase in tensile strength and Young's modulus is achieved compared to LDPE.Tear strength improvement was noticed in the TNT composites with a value of 35.4 N·mm~(-1), compared to CNT composites with a value of 25.5 N·mm~(-1)·s~(-1). All the prepared nanocomposites are more thermally stable than neat LDPE and the best improvement in thermal stability was observed for CNT reinforced nanocomposites.CNTs depicted the best improvement in tensile and thermal properties and the MAPE compatibilizer effectiveness regarding morphological. mechanical and thermal properties was only observed for TNT and HNT systems.     

超临界二氧化碳渗透聚丙烯成核剂的初步研究

Impregnation of isotactic polypropylene （iPP） with nucleating agent （NA21） using supercritical carbon dioxide as the swelling agent at different temperature and pressure and its non-isothermal crystallization kinetics were investigated. The results showed that NA21 was dispersed at a nanometer-scale in the PP matrix, resulting in the formation of different types .of crystal phases of iPP and the enhancement of its mechanical properties.     

两步共混工艺制备聚碳酸酯/聚丙烯/针状硅酸盐三元纳米复合材料：降解与形态

The method of two-step melt blending was used to prepare polycarbonate/polypropylene/attapulgite ternary nanocomposite, and the various techniques including gel permeation chromatography, rheometer, transmission electron microscope, dynamic mechanical analysis were used to examine the degradation of polycarbonate （PC） and the nanocomposite morphology. The results showed that the molecular weight degradation of PC triggered by attapulgite （AT） during the direct blending process was inhibited effectively by using two-step melt blending, in which AT was blended with polypropylene （PP） prior to compound with PC. The morphology of encapsulation was formed in the PC matrix, where PP encapsulates AT fibrillar single crystals to form a core-shell inclusion. Dynamic mechanical analysis （DMA） measurements showed that the PC/PP/AT ternary nanocomposites were more effective than conventional PC/PP blends in reinforcement, meanwhile the addition of AT in the ternary nanocomposites shifted the glass transition temperature of the PP phase to a higher value.     

Thermal conductivity of natural rubber nanocomposites with hybrid fillers

Natural rubber nanocomposites filled with hybrid fillers of multi-walled carbon nanotubes(CNTs) and carbon black(CB) were prepared. CNTs were ultrasonically modified in mixture of hydrogen peroxide(H_2O_2) and distilled water(H_2O). The functional groups on the surface of CNTs, changes in nanotube structure and morphology were characterized by Fourier transform infrared spectroscopy(FT-IR), Raman Spectroscopy, and transmission electron microscopy(TEM). It shows that hydroxyl(OH·) is successfully introduced. The surface defects of modified CNTs were obviously higher than those of original CNTs, and the degree of agglomeration was greatly reduced. Thermal conductivity of the composites was tested by protection heat flow meter method. Compared with unmodified CNTs/CB filling system, the thermal conductivity of hybrid composites is improved by an average of 5.8% with 1.5 phr(phr is parts per hundred rubber) of hydroxyl CNTs and 40 phr of CB filled. A three-dimensional heat conduction network composed of hydroxyl CNTs and CB, as observed by TEM, contributes to the good properties. Thermal conductivity of the hybrid composites increases as temperature rises. The mechanical properties of hybrid composites are also good with hydroxyl CNTs filled nanocomposites; the tensile strength, 100% and 300% tensile stress are improved by 10.1%, 22.4% and 26.2% respectively.     

Influence of binder systems on sintering characteristics,microstructures, and mechanical properties of PcBN composites fabricated by SPS

Cubic boron nitride(cBN)with high hardness,thermal conductivity,wear resistance,and chemical inertness has become the most promising abrasive and machining material.Due to the difficulty of fabricating pure cBN body,generally,some binders are incorporated among cBN particles to prepare polycrystalline cubic boron nitride(PcBN).Hence,the binders play a critical factor to the performances of PcBN composites.In this study,the PcBN composites with three binder systems containing ceramic and metal phases were fabricated by spark plasma sintering(SPS)from 1400 to 1700℃.The sintering behaviors and mechanical properties of the composites were investigated.Results show that the effect of binder formulas on mechanical properties mainly related to the compactness,mechanical performances,and thermal expansion coefficient of binder phases,which affect the carrying capacity of the composites and the bonding strength between binder phases and cBN particles.The PcBN composite with SiAlON phase as binder presented optimal flexural strength(465±29 MPa)and fracture toughness(5.62±0.37 MPa·m^1/2),attributing to the synergistic effect similar to transgranular and intergranular fractures.Meanwhile,the excellent mechanical properties can be maintained a comparable level when the temperature even rises to 800℃.Due to the weak bonding strength and high porosity,the PcBN composites with Al₂O₃–ZrO₂(3Y)and Al–Ti binder systems exhibited inferior mechanical properties.The possible mechanisms to explain these results were also analyzed.     

Synthesis and characterization of copolymers of poly(m-xylylene adipamide) and poly(ethylene terephthalate) oligomers by melt copolycondensation

Poly(m-xylylene adipamide)/poly(ethylene terephthalate)(MXD6/PET) copolymers are synthesized by melt copolycondensation with 1–5 wt% low molecular weight PET oligomers into the MXD6 oligomers at 260 °C.FR-IR and1 H NMR analysis results indicate that the interchange reaction has occurred between MXD6 oligomers and PET oligomers. The thermal behavior of copolymers shows that the melting temperature of MXD6/PET copolymers decreases with the increasing of amount of PET oligomers, while the crystallization temperature accordingly increases. And the equilibrium temperature Tm0 is evaluated to be 251.8 °C for the copolymers with5 wt% PET oligomer adding, which is very close to that of neat MXD6. The tensile and impact strength of MXD6/PET copolymers are significantly improved than that of pure MXD6 by mechanical properties test, and the microfibril structure in the impact fracture sample's surface reveals the feature of ductile fracture.     

N-己基-甲基吡咯烷酮溴盐与N-丁基-甲基吡咯烷酮溴盐在不同温度下的密度、电导率和粘度的实验数据(英文)

The densities, conductivities, and viscosities were measured for ternary solutions of N-hexyl, methylpyrrolidinium bromide ([PP1,6]Br)-N-butyl,methylpyrrolidinium bromide ([PP1,4]Br)-H2O and its binary subsystems [PP1,6]Br-H2O and [PP1,4]Br-H2O at (298.15, 303.15, 308.15, and 313.15) K, respectively. The results were used to test the predictability of the simple equations established for the prediction of density, conductivity, and viscosity of the mixed electrolyte solutions. The results show that the examined simple equations can offer good predictions for density, conductivity, and viscosity of the mixed ionic liquid solutions in terms of the corre-sponding properties of its binary subsystems of equal ionic strength.     

环状氯化磷腈微胶囊阻燃剂的研究

以甲苯2,4-二异氰酸酯和己二胺为原料,采用界面聚合法,制备了囊心为环状氯化磷腈、囊壁为聚脲的微胶囊阻燃剂。热重分析表明:微胶囊阻燃剂的热分解温度比环状氯化磷腈大大提高。将所制微胶囊阻燃剂应用于聚丙烯,阻燃、抑烟效果优于环状氯化磷腈,且聚丙烯/环状氯化磷腈微胶囊复合材料的力学性能大大优于聚丙烯/环状氯化磷腈材料的性能。     

Effects of zinc borate and microcapsulated red phosphorus on mechanical properties and flame retardancy of polypropylene/magnesium hydroxide composites

In this paper, the mechanical properties and flame retardancy of zinc borate (ZB) and microcapsulated red phosphorus (MRP) with modified magnesium hydroxide (MH) in flame-retardant polypropylene (PP) were studied by mechanical properties test, UL-94 test, and thermogravimetric analysis (TGA). The crystallization behaviors of the composites were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The addition of ZB could improve tensile strength and elongation at break of PP/MH composite. The MRP powders had a little effect on the mechanical properties of the PP composites. DSC results showed the addition of ZB and MRP weakened the heterogeneous nucleation effect of MH on PP. The addition of ZB and MRP had a great effect on the flammability of the PP/MH/EG composites. The thermal stability of PP/MH/ZB and PP/MH/ZB/MRP composites was better than that of PP/MH composite.     

钛酸酯偶联剂在膨胀型阻燃聚丙烯中的偶联作用

研究了钛酸酯偶联剂（TTOPP）对聚丙烯/膨胀型阻燃剂（PP/IFR）复合材料阻燃性能和力学性能的影响,并采用扫描电子显微镜、偏光显微镜和X射线衍射研究了复合材料的微观形态和结晶行为。结果表明,加入TTOPP后,IFR在PP中的分散更加均匀,PP球晶的大小趋于一致,适量的TTOPP改善了IFR与PP间的相容性,促进了IFR对PP形成β晶的诱导作用。当PP/IFR/TTOPP为75/25/0.375时,复合材料的综合性能最佳,自熄时间降到24 s,拉伸强度和冲击强度比PP/IFR分别提高了14.0 %和12.0 %。     

聚丙烯/埃洛石纳米管复合材料的力学及阻燃性能

通过熔融共混的方法制备了聚丙烯/埃洛石纳米管(PP/HNTs)复合材料,并表征了复合材料的力学性能、界面性能和阻燃性能。结果表明,HNTs对阻燃PP发挥进一步阻燃作用,当HNTs含量为2 %时,其极限氧指数可达32.0 %,较阻燃PP提高了2 %;其垂直燃烧性能可达UL 94 V-0级;尤其重要的是,HNTs的加入显著提高了材料的力学性能,含2 %HNTs的复合材料的综合性能最佳,冲击强度为5.4 kJ/m2,拉伸强度为36.5 MPa,弯曲强度为41.4 MPa。     

丙烯酸改性卤锑阻燃PP的力学性能

在过氧化二异丙苯(DCF)存在或不存在条件下,制备了丙烯酸(AA)改性Sb2O3／聚丙烯(PP)母料、十溴联苯醚／PP母料及其相应的卤锑阻燃PP。研究了Sb2O3、十溴联苯醚和不同含量卤锑阻燃剂对PP力学性能的影响。结果表明,随Sb2O3含量增加,PP的拉伸和弯曲性能提高,缺口冲击强度降低。对于改性阻燃PP,无DCP时,加入AA有利于阻燃PP拉伸强度提高。但对其他力学性能影响不大。添加DCP提高了PP的弯曲强度。但AA用量高时,缺口冲击强度降低。AA改性阻燃PP的力学性能随着DCP用量增加而降低,尤其缺口冲击强度。退火处理使阻燃PP力学性能提高。     

Mechanical and thermal properties of polypropylene/modified basalt fabric composites

Basalt fabric (BF) was first treated with silane coupling agent KH550, modified basalt fabric (MBF) was obtained. Then MBF were molded with polypropylene (PP) matrix, and polypropylene/modified basalt fabrics (PP/MBF) composites were obtained. The influence of concentration and treating time of KH550 on MBF were characterized by hydrophilicity and lipophilicity. The tensile strength and morphology of basalt fabric were tested by single filament strength tester and scanning electron microscopy. The mechanical properties of composites were measured with electronic universal testing machine and impact testing machine, and the thermal properties were tested by thermogravimetric analysis and dynamic mechanical analysis. The results showed that the lipophilicity of MBF is improved significantly by KH550 while the tensile is nearly damaged. The mechanical properties of composites are larger than that of pure PP, among which the impact property was improved the most, showing 194.12% enhancement. The thermal stability and dynamic viscoelasticity were better than pure PP; furthermore, the concentration of KH550 virtually had no effect on the thermal stability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42504.     

Mechanical properties of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

Modified Mg(OH)₂/polypropylene (PP) composites were prepared by the addition of functionalized polypropylene (FPP); and acrylic acid (AA) and by the formation of in situ FPP. The effects of the addition of FPP and AA and the formation of in situ FPP on the mechanical properties of Mg(OH)₂/PP composites were investigated. Experimental results indicated that the addition of Mg(OH)₂ markedly reduced the mechanical properties of PP. The extent of reduction in notch impact strength of PP was higher than that in flexural strength and tensile strength. However, tensile modulus and flexural modulus increased with increased Mg(OH)₂ content. The addition of FPP facilitated the improvement in the flexural strength and tensile strength of Mg(OH)₂/PP composites. The higher the Mg(OH)₂ content was, the more significant the effect of FPP was. The incorporation of AA resulted in further increased mechanical properties, in particular the flexural strength, tensile strength, and notch impact strength of Mg(OH)₂/PP composites containing high levels of Mg(OH)₂. It not only improved mechanical properties but also increased the flame retardance of Mg(OH)₂/PP composites. Although the mechanical properties of composites modified by the formation of in situ FPP were lower than those of composites modified by only the addition of AA in the absence of diamylperoxide, the mechanical properties did not decline with increased Mg(OH)₂ content. Moreover, the mechanical properties increased with increasing AA content. The addition of an oxidation resistant did not influence the mechanical properties of the modified Mg(OH)₂/PP composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2139–2147, 2003     

Mechanical properties and morphology of impact modified polypropylene–wood flour composites

The mechanical properties and morphology of polypropylene/wood flour (PP/WF) composites with different impact modifiers and maleated polypropylene (MAPP) as a compatibilizer have been studied. Two different ethylene/propylene/diene terpolymers (EPDM) and one maleated styrene–ethylene/butylene–styrene triblock copolymer (SEBS–MA) have been used as impact modifiers in the PP/WF systems. All three elastomers increased the impact strength of the PP/WF composites but the addition of maleated EPDM and SEBS gave the greatest improvements in impact strength. Addition of MAPP did not affect the impact properties of the composites but had a positive effect on the composite unnotched impact strength when used together with elastomers. Tensile tests showed that MAPP had a negative effect on the elongation at break and a positive effect on tensile strength. The impact modifiers were found to decrease the stiffness of the composites. Scanning electron microscopy showed that maleated EPDM and SEBS had a stronger affinity for the wood surfaces than did the unmodified EPDM. The maleated elastomers are, therefore, expected to form a flexible interphase around the wood particles giving the composites better impact strength. MAPP further enhanced adhesion between WF and impact-modified PP systems. EPDM and EPDM–MA rubber domains were homogeneously dispersed in the PP matrix, the diameter of domains being between 0.1–1 μm. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1503–1513, 1998     

玻璃纤维增强聚丙烯的力学性能研究

研究了玻璃纤维(GF)和马来酸酐接枝聚丙烯(PP-g-MAH)对聚丙烯力学性能的影响。结果表明:随着GF与PP的质量比增加,玻璃纤维增强聚丙烯的拉伸强度增加,冲击强度总体呈下降趋势。当PP与GF的质量比为55∶45时,拉伸强度最高,达到45MPa。当PP与GF的质量比一定时,在玻璃纤维增强聚丙烯复合材料中添加增容剂马来酸酐接枝聚丙烯(PP-g-MAH),可使其拉伸强度得到很大的提高,但是冲击性能却下降。当PP与GF的质量比为75∶25时,随PP-g-MAH与PP/GF复合材料的质量比增加,其拉伸强度先增大后减小,其冲击性能总体呈下降趋势。当PP-g-MAH,PP和GF的质量比为15∶75∶25时,其综合性能最优,拉伸强度为50.5MPa,冲击强度为4.3kJ/m2。     

Polypropylene and potato starch biocomposites: Physicomechanical and thermal properties

To determine the possibility of using starch as biodegradable filler in the thermoplastic polymer matrix, starch‐filled polypropylene (PP) composites were prepared by extrusion of PP resin with 5, 10, 15, and 20 wt % of potato starch in corotating twin‐screw extruder. The extruded strands were cut into pellets and injection molded to make test specimens. These specimens were tested for physicomechanical properties such as tensile and flexural properties, Izod impact strength, density, and water absorption. These PP composites were further characterized by melt flow index (MFI), vicat softening point (VSP), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques. It was found that, with increase in starch content, tensile modulus, flexural strength, and flexural modulus of the PP composites increased along with the increase in moisture, water absorption, and density, while retaining the VSP; but, tensile strength and elongation, impact strength, hardness, and MFI of the PP composites also decreased. DSC analysis of the PP composite revealed the reduction in melting temperature, heat of fusion, and percentage of crystallization of PP with increase in starch content. Similarly, TGA traces display enhanced thermal degradability for PP as starch content increases. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011