Preparation and characterization of Nylon-6/exfoliated graphite composite via a combination method of in situ polymerization and thermal expansion

Nylon-6/exfoliated graphite (Nylon-6/EG) composite was prepared via a combination method of in situ polymerization and thermal expansion and characterized via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Otherwise, the resistivity value of Nylon-6/EG composite was measured, and the volume resistivity value was calculated as well as. The characterization showed that Nylon-6/EG composite had the morphology of the graphite worm and was structured by EG and Nylon-6, which covered on the surface of EG. The result exhibited that the volume resistivity of Nylon-6/EG composite would decrease when the dosage of EG increased. When the mass percent of EG was 1%, the the volume resistivity value of Nylon-6/EG composite could reach 2.3 × 10⁶ Ω cm. This shows that the combination method not only is very effective and reliable but also can play an important role in preparing antistatic Nylon-6 composite.     

Preparation and characterization of polyaniline/cerium dioxide (CeO2) nanocomposite via in situ polymerization

Crystalline ceria (CeO₂) nanoparticles have been successfully synthesized by a microwave-assisted solution method. Polyaniline (PANI)/cerium dioxide (CeO₂) nanocomposite was synthesized by in situ polymerization of aniline in the presence of CeO₂ nanoparticles. Characterization of CeO₂ and PANI/CeO₂ nanomaterials are carried out using various studies such as powder X-ray diffraction, infrared spectral and UV–Vis absorption spectral analyses, scanning electron microscopic and high-resolution transmission electron microscopic (HRTEM) studies and thermal analysis. The HRTEM of the images indicate that the CeO₂ nanoparticles were embedded in the PANI matrix forming the core–shell structure.     

Preparation and characterization of novel polypyrrole-nanotube/polyaniline free-standing composite films via facile solvent-evaporation method

Polyaniline (PANI) is an important conducting polymer and has drawn much attention for its inexpensiveness and chemical stability in the conducting state but its conductivity is rather low. Another well-known conducting polymer is polypyrrole (PPy) with a much higher electrical conductivity but it is hard to prepare films using PPy alone due to its poor film-forming ability. In this work, novel polypyrrole-nanotube (PPy-NT)/polyaniline (PANI) composite films are prepared via a facile solvent-evaporation method. The influence of the PPy-NT content is examined on the film structure, morphology, electrical and mechanical properties. It is shown that PPy nanotubes (PPy-NTs) are uniformly distributed in the PANI matrix. The electrical conductivity is greatly enhanced by 10.2 times by the addition of 10 wt.% PPy nanotubes. Moreover, the mechanical ductility is significantly increased by the addition of PPy nanotubes.     

原位悬浮乳液聚合制备聚苯胺/纳米金刚石复合微球及结构表征

利用原位乳液聚合的方法合成得到了聚苯胺(PANI)/纳米金刚石复合微球.用X射线衍射(XRD)、热重-差热(Tg-DTA)、透射电子显微镜(TEM)、粒径分析(PSD)、比表面积分析(BET)、红外光谱(FT-IR)及紫外-可见光谱(UV-Vis)等技术分别对获得的PANI/纳米金刚石复合微球进行了结构、形貌、表面表征.结果表明,在PANI/纳米金刚石复合微球中,纳米金刚石为立方相,复合微球介于10～30nm,粒径分布窄,分散性良好,比表面积可达270m2/g,且具有较好的热稳定性.结构分析证实在PANI/纳米金刚石复合物中,PANI与纳米金刚石之间存在氢键键合机制.     

剥离型纳米蒙脱土/聚酰亚胺复合材料的制备与表征

利用二苯基甲烷-4,4’-二异氰酸酯（MDI）与酸化的蒙脱土（MMT）表面的羟基进行反应制得了MMT-MDI;进一步利用己内酰胺（CPL）对MMT-MDI进行插层并对多余的异氰酸酯端基进行封端,制得了MMT-MDI-CPL。采用预聚体溶液插层法,利用聚酰胺酸（PAA）在二甲基乙酰胺（DMAC）溶剂中分别对MMT-MDI和MMT-MDI-CPL进行预聚体插层,制得了剥离型纳米MMT/聚酰亚胺（PI）复合材料。通过电感耦合等离子体发射光谱（ICP-OES）、FTIR、TG、XRD和SEM对改性MMT和纳米MMT/PI复合材料进行了表征。结果表明：MDI与MMT表面羟基反应而被成功接枝于MMT上;MDI对MMT的改性、CPL对MMT-MDI的插层和封端使MMT层间距得到逐步扩大;MMT/PI复合材料的XRD和断面SEM表明,MMT在PI基体中得到了充分剥离。     

超声无皂乳液原位合成Pd-P(MMA-AMPS)复合微球及其表征

将超声波作用于含有2-丙烯酰氨基-2-甲基丙磺酸(AMPS)和甲基丙烯酸甲酯(MMA)的氯化钯水溶液中,在不加任何引发剂、乳化剂和还原剂的条件下,合成带有酰胺基、磺酸基等官能基团的Pd-P(MMA -AMPS)复合微球。考察了单体质量配比对复合微球形貌的影响,用XRD、TGA、FTIR、TEM和粒度分析仪等技术对样品进行表征,并探讨了合成反应机制。结果表明,超声辐射可实现Pd2+的还原与单体聚合的同步进行,并且金属钯与基体P(MMA - AMPS)共聚物之间存在一定的相互作用。优化条件下制得的复合微球,钯质量分数为20%左右,粒径约0.76μm,还原得到的钯粒子均匀分散于聚合物微球内。     

Preparation and microwave absorbing properties of nickel-coated carbon fiber with polyaniline via in situ polymerization

Electric conductive and microwave absorbing material PANI/Ni/CF was prepared by in situ polymerization of polyaniline on the surface of nickel-coated carbon fiber (Ni/CF). The morphologies and structures of CF, Ni/CF, PANI and PANI/Ni/CF were characterized by scanning electron microscope and X-ray diffraction. Results show that the CF was wrapped tightly around the nickel layer, and the Ni/CF was coated by PANI. Measurement of four probes resistance tester indicates that the electrical conductivity of PANI/Ni/CF was great improved compared with PANI and PANI/CF. Vibrating sample magnetometry shows that the magnetic saturation intensity of Ni/CF and PANI/Ni/CF was 13.8 and 2.3 emu/g, respectively. According to the vector network analyzer, the microwave absorbing properties of PANI/Ni/CF were better than those of PANI and PANI/CF, and its minimum loss value is ?12.4 dB at 8.8 GHz.     

CdSe/聚苯胺导电复合材料的制备与表征

通过固相法合成了CdSe纳米粒子,采用化学氧化聚合法,在十二烷基苯磺酸钠(NaDBS)存在的条件下,采用氧化剂(同时也是催化剂)过硫酸铵(APS)氧化苯胺(An),制得了CdSe/聚苯胺导电复合材料,并探讨了CdSe的掺入量对导电复合材料的影响.Cdse/聚苯胺导电复合材料用X射线粉末衍射(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和四探针电导率测试仪进行了表征.     

聚苯胺/TiO_2纳米复合膜的制备及表征

利用溶胶-凝胶法和浸渍-提拉法于载玻片表面沉积了TiO2纳米薄膜,然后通过化学氧化法得到了聚苯胺/TiO2纳米复合膜。借助XRD、AFM、UV-Vis、XPS等方法对复合膜进行了表征。结果表明,所得TiO2薄膜由规则立方体外形的纳米TiO2组成,颗粒直径为20nm。包覆后所得聚苯胺/TiO2复合膜由不规则球形颗粒组成,颗粒直径增大为35nm。薄膜的UV-Vis光谱分析表明,聚苯胺/TiO2复合膜的吸收带边约为390nm,对可见光的吸收显著增强。XPS分析结果表明,复合膜中N+/N之比高达0.63,高于块体聚苯胺的0.57和理想的本征态盐中的0.5,表明掺杂程度高。     

聚苯胺/MCM-41介孔分子筛导电复合材料的制备及其表征

利用MCM-41介孔分子筛单分散孔道特性作为"纳米反应器",在其孔道内合成聚苯胺.讨论了HCl浓度、(NH4)2SO8浓度和聚合温度对复合材料导电性的影响,得到最佳的聚合条件:HCl:1.5mol/L,(NH4)2SO8:1.0mol/L,聚合温度:15℃,此时的电导率为0.61s/cm.在最佳合成条件下,对聚苯胺/MCM-41介孔分子筛导电复合材料进行SEM、红外光谱分析.     

乳液聚合法制备聚苯胺/纳米石墨薄片/Eu3+纳米复合材料及其导电性能

与传统乳液聚合法不同,采用现场乳液聚合法,直接将纳米石墨薄片在超声条件下有机改性.将无机物的有机改性、对甲苯磺酸的掺杂及苯胺单体的聚合同步进行,即制得目标产物.通过红外光谱(FT-IR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和热重(TG)对该复合材料进行了表征和分析.结果表明,聚苯胺成功插层到纳米石墨薄片中,并形成了纳米薄膜,Eu3 分散在纳米膜中.热重(TG)分析和电导率测试结果表明,复合材料的热稳定性和导电性均较纯聚苯胺高.     

Preparation of silica/polyacrylamide/polyethylene nanocomposite via in situ polymerization

SiO₂/polyacrylamide (PAM) composite was prepared via the polymerization of acrylamide in the presence of silica sol in water/hexane emulsion, and pure SiO₂ was also prepared without the use of acrylamide in the same way. Field emission scanning electron micrographs (FESEM) showed that PAM covered the silica nanoparticles to form SiO₂/PAM nanospheres, which loosely agglomerated to form SiO₂/PAM secondary particles, while SiO₂ secondary particles were made up of tightly agglomerated silica nanoparticles. Metallocene catalyst was then immobilized over SiO₂ and SiO₂/PAM respectively to prepare supported metallocene catalyst for ethylene polymerization. Transmission electron micrographs (TEM) showed that support particles broke up to smaller particles and even nanoparticles in polyethylene (PE) matrix when the support particles were the fragile SiO₂/PAM secondary particles, which shows a novel way to prepare silica/polyacrylamide/polyethylene nanocomposite.     

壳核型聚苯胺/钛酸钡复合电流变材料的制备及表征

采用溶液聚合的方法,在经过硅烷偶联剂表面修饰的钛酸钡微粉表面原位聚合聚苯胺,得到聚苯胺/钛酸钡壳核结构(BaTiO3/PAn)的有机-无机复合粒子.借助SEM、XRD、FT-IR、DSC-TG等分析手段研究了复合粒子的形貌、结构及热性能.利用改装后的旋转粘度计分别对钛酸钡和聚苯胺/钛酸钡复合颗粒的电流变性能进行研究.结果表明利用硅烷偶联剂成功地在钛酸钡粒子表面接枝合成聚苯胺,聚苯胺/钛酸钡复合颗粒电流变液的电流变性能明显比纯钛酸钡的电流变性能有所提高.     

Modeling,processing, and characterization of exfoliated graphite nanoplatelet-nylon 6 composite fibers

We present theoretical and experimental studies on the effects of platelet-like filler orientation on the mechanical properties of melt-spun exfoliated graphite nanoplatelet(xGnP)-nylon 6(PA6) composite fibers. In numerical studies, the Mori–Tanaka micromechanics model was employed to formulate analytical models to predict the mechanical properties of xGnP-PA6 composite fibers with varying xGnP orientations in a three-dimensional spatial domain. Simulation results showed that the predicted properties of xGnP-PA6 composite fibers were highly affected by xGnP orientation and were correlated with the measured properties of composite fibers treated with varying draw ratios. The tensile moduli of composite fibers at varying xGnP contents showed significant improvements, which is attributed to the drawing-induced alignment of PA6 molecular chains as well as the alignment of xGnPs. Both as-received and acid-treated xGnPs were incorporated in PA6, and mechanical test results suggested that acid-treated xGnPs provide stronger interfacial bonding with PA6.     

原位合成羟基磷灰石/明胶复合材料及表征

以Ca(NO3)2、(NH4)2HPO4和明胶为起始原料,采用原位合成的方法,制备与自然骨成分和结构相似的羟基磷灰石/明胶复合材料(HA/Gel).采用各种分析手段对样品进行表征.红外结果表明HA/Gel中波数为1339cm-1的酰胺基团向低波数发生了红移;X射线衍射证明HA/Gel复合材料中的元机相主要为低结晶度、晶粒尺寸细小的羟基磷灰石;热重结果证明本试验制备的HA/Gel中Gel的含量达到15%左右;采用扫描电镜观察HA/Gel复合材料的微观形貌.扫描电镜观察发现HA颗粒定向分布在Gel连续相基体上,本试验结果证明HA与Gel形成键性结合,是一种颇有前途的骨组织替换材料.     

Preparation of low-density polyethylene/low-temperature expandable graphite composites with high thermal conductivity by an in situ expansion melt blending process

A facile strategy with the advantages of low cost and ease of mass production was presented to prepare low-density polyethylene (LDPE)/low-temperature expandable graphite (LTEG) composites with relatively high thermal conductivity by an in situ expansion melt blending process. LTEGs were expanded and delaminated into graphite multi-layers and graphite nanoplatelets during processing which synergistically created more thermo-conducting paths in the composites and hence led to great improvements in thermal conductivity. Thermal conductivity of the composite with 60 wt% of LTEG loading was increased by 23 times as compared to the pure LDPE, increasing from 0.47 to 11.28 W/mK. The incorporation of LTEG decreased the melting temperature and the degree of crystallinity of LDPE. Percolation threshold of both the electrical conductivity and rheological measurements was observed at about 8 vol% of LTEG loading. Moreover, the LDPE/LTEG composites showed better thermal stability compared to the pure LDPE.     

Structural characterization, thermal and mechanical properties of polyurethane/CoAl layered double hydroxide nanocomposites prepared via in situ polymerization

Dodecyl sulfate (DS), one kind of sulfate anion, was intercalated in the interlayer space between CoAl layered double hydroxide (CoAl-LDH) layers, and then polyurethane (PU) based nanocomposites were prepared by in situ intercalation polymerization with different amounts of the organo-modified CoAl-LDH. An exfoliated dispersion of CoAl-LDH layers in PU matrix was verified by the disappearance of the (0 0 3) reflection of the XRD results when the LDH loading was less than 2.0 wt%. Tensile testing indicated that excellent mechanical properties of PU/LDH nanocomposites were achieved. The weak alkaline catalysis of DS to polyurethane chains, combined with the dehydration and structural degradation of the LDH below 300 °C, accounted for the process of proceeded degradation as shown in TGA results. The real-time FTIR revealed that the as-prepared nanocomposites had a slower thermo-oxidative rate than neat PU from 160 °C to 340 °C, probably due to the barrier effect of LDH layers. These results suggested potential applications of CoAl-LDH as a promising flame retardant in PUs.     

Study on the interface of phenolic resin/expanded graphite composites prepared via in situ polymerization

Phenolic resin/expanded graphite (EG) composites were synthesized via in situ condensation polymerization of the monomers in the presence of foliated graphite. SEM observation showed that the graphite flakes were well dispersed in the phenolic resin matrix. The electrical conductivity of the composites was investigated as a function of the foliated graphite fraction. The composites containing graphite sheets exhibited an electrical conductivity percolation threshold with 3.2 wt% graphite content in polymer matrix. Inverse gas chromatography (IGC) measurements were carried out to characterize the surface of the foliated graphite before and after condensation polymerization of phenolic resin using a series of both non-polar and polar acid–base probe gases. The data obtained indicated that the character of graphite surface changed after the polymerization of phenolic resin. The dispersive component of surface free energy decreased greatly. Before polymerization the graphite surface is predominantly acidic while the surface turns to basic after polymerization. The increased polarity of surface contributed to the stronger interactions between graphite and phenolic resin and the fine dispersion of expanded graphite in the matrix, and resulted in the low conductivity percolation threshold.