丙三醇解聚废弃聚酯制备纳米复合固化剂的研究

采用丙三醇解聚废弃聚酯产物制备了纳米复合环氧树脂固化剂:用透射电镜观察蒙脱土K10在基体中的分散状况;用红外光谱表征了纳米复合固化剂的结构;用差示扫描量热法分析和讨论了固化剂玻璃化转变以及蒙脱土对其熔融性能的影响;用热重分析对比加入蒙脱土K10前后固化剂热稳定性能的变化。结果表明,制备得到的纳米复合固化剂中,蒙脱土分散均匀,剥离效果明显,固化剂热稳定性能得到提高。     

原位聚合法制备尼龙66/蒙脱土纳米复合材料及其性能

采用原位聚合法制备了尼龙66/有机蒙脱土纳米复合材料,利用TEM观察了复合材料的微观结构,测试了其力学性能、热稳定性和阻燃性能,探讨了复合材料结构与性能之间的关系。研究结果表明:蒙脱土以纳米尺度均匀分散在尼龙66基体中,蒙脱土的加入改善了材料的力学性能、热稳定性和阻燃性能。     

聚氨酯/聚甲基丙烯酸甲酯/有机蒙脱土纳米复合材料的制务、结构与性能

首次将插层纳米复合技术与互穿聚合物网络（IPN）技术相结合,通过同步插层聚合法制备了聚氨酯/聚甲基丙烯酸甲酯/有机蒙脱土（PU/PMMA/OMMT）纳米复合材料.XRD、SEM、TGA等研究表明,在聚氨酯/有机蒙脱土（PU/OMMT）体系中蒙脱土以40～700 nm的团聚体不均匀地分散在聚氨酯基体中,且部分蒙脱土被插层,其层间距增加了0.95nm,体系为插层型纳米复合材料.PU/PMMA/OMMT体系中蒙脱土以20～80nm的粒子分布于聚合物基体中,且蒙脱土的插层效果显著,是PU/OMMT体系的2.5倍,形成了插层型纳米复合材料.同时,蒙脱土的加入使得聚氨酯和聚甲基丙烯酸甲酯的互穿聚合物网络（PU/PMMA-IPN）体系中PU相与PMMA相间相分离更明显,塑性相畴粒子尺寸显著增加,且各相中两组分相互作用加强,分布更均匀.PU/PMMA/OMMT纳米复合材料的热稳定性高于其他材料.同时对其力学性能进行了研究,发现其力学性能明显优于聚氨酯、基于聚氨酯和PU/PMMA-IPN和PU/OMMT纳米复合材料.     

UP/Na-MMT纳米复合材料的制备与性能

研究了UP／Na-MMT纳米复合材料的制备与性能，并考察了插层剂种类、有机蒙脱土加入量及离子交换量对复合材料性能的影响。结果表明，UP／Na-MMT纳米复合材料的XRD曲线中蒙脱土晶体结构的布拉格衍射峰已经消失，说明其晶层已被树脂撑开，达到纳米级分散；复合材料的耐热性能得到明显改善，其冲击强度和拉伸强度均有较大提高。     

LLDPE/HDPE/MMT纳米复合材料的制备及性能研究

以线性低密度聚乙烯(LLDPE)、高密度聚乙烯(HDPE)、有机改性的蒙脱土(MMT)为主要原料,选用乙烯-醋酸乙烯酯接枝马来酸酐(EVA-g-MAH)作为增容剂,采用熔融插层法制备了线性低密度聚乙烯/高密度聚乙烯/蒙脱土(LLDPE/HDPE/MMT)纳米复合材料。通过X射线衍射(XRD)分析蒙脱土在聚乙烯基体中的分散情况,并研究蒙脱土的含量对其在基体中分散效果的影响。TG实验结果表明,蒙脱土的加入使LLDPE/HDPE/MMT纳米复合材料的热稳定性得到很大的提高。由DSC曲线可以得出,加入蒙脱土的复合材料相比于纯聚合物,其熔点和热分解温度都有很大的提高,提高程度与蒙脱土的含量有关。     

异氰酸酯改性蒙脱土的制备及其对铸型尼龙6性能的影响

通过二苯基甲烷-4,4'-二异氰酸酯(MDI)改性钠基蒙脱土(Na-MMT),使Na-MMT呈纳米级剥离态分散,制得MDI改性Na-MMT(M-MMT)。将M-MMT加入至铸型尼龙6体系中原位聚合成型,以解决有机蒙脱土在铸型尼龙6体系中热降解的问题,提高复合材料的耐热性。利用FITR、GC-MS、XRD和TEM研究了改性机理和Na-MMT的分散情况。通过TG、维卡软化、热变形温度测试、力学性能测试和SEM观察,研究了M-MMT/铸型尼龙6复合材料的耐热性、力学性能和微观形貌。结果表明:MDI能与Na-MMT层间的羟基以及水反应使M-MMT呈剥离态分散。虽然在铸型尼龙6体系引发剂定量的情况下,MDI消耗体系引发剂,引起M-MMT/铸型尼龙6复合材料分子量的下降,导致各项力学性能有所下降,但M-MMT的纳米级效应使复合材料的耐热性得到提高,维卡软化点提高至224℃,在1.82MPa负荷条件下,热变形温度提高至96℃。      

醋酸纤维素/蒙脱土生物纳米复合材料的结构与力学性能

采用熔融插层法在聚乙二醇的增塑作用下制备了醋酸纤维素/蒙脱土(CA/MMT)生物纳米复合材料。利用X射线衍射和透射电镜表征了CA/MMT纳米复合材料的插层结构。X射线衍射结果表明,复合后蒙脱土的层间距增大;透射电镜照片显示,蒙脱土在CA基体中达到纳米级分散,且分散均匀。CA/MMT纳米复合材料的力学性能得到较大提高,加入5 phr有机蒙脱土时,复合材料的拉伸强度从纯增塑CA的38.8 MPa增到48.2 MPa。动态力学测试表明复合材料的储能模量增大,玻璃化转变温度提高。     

尼龙1010/蒙脱土纳米复合材料的合成与表征

通过插层聚合制备了尼龙1010／蒙脱土纳米复合材料，测试了材料的力学性能，耐溶剂性，并通过SEM，WAXD，DSC等分析手段，研究了蒙脱土在聚合物基体中的分散情况及聚合物的结晶行为。实验结果表明，通过单体插层聚合方法所制得的复合物，其性能较尼龙1010有较大提高，蒙脱土在聚合物中基本达到了纳米级分散。     

低密度聚乙烯/蒙脱土复合材料的制备及隔声性能

以有机改性蒙脱土(OMMT)作为纳米隔声填料,分别通过熔融共混法和溶液共混法制备了LDPE/OMMT复合材料,研究了蒙脱土含量和制备方法对复合材料的隔声性能的影响。采用多级拉伸共挤出装置改善蒙脱土在基体中的分散,研究不同力场大小作用下蒙脱土分散形态及复合材料的隔声性能。结果表明,少量蒙脱土的加入可以大幅度改善LDPE的隔声性能,但是随着蒙脱土含量的增加,蒙脱土团聚严重,复合材料的隔声性能变差,与熔融共混相比,由于溶液共混法更能使蒙脱土在基体中分散,制备的复合材料的隔声性能更好。随着分割叠加单元个数的增加,蒙脱土在LDPE基体中分散改善,当分割-变形-叠加单元(LME)个数达到8个时,蒙脱土纳米级分散在基体中,复合材料的隔声性能最佳。     

苯乙烯-N苯基马来酰亚胺共聚物/蒙脱土纳米复合材料的制备与表征

分别使用无机蒙脱土和有机蒙脱土用乳液插层的方法制备了苯乙烯-N苯基马来酰亚胺共聚物／蒙脱土纳米复合材料，并用FT-IR、XRD、DSC、TGA对其进行了表征。结果表明，两种蒙脱土在St-NP-MI共聚物基体中，均已达到纳米分散，而且复合材料的热稳定性较纯St-NPMI共聚物有很大提高，尤其是有机蒙脱土纳米复合材料，其Ta提高60℃以上。     

The composite of carbon nanotubes and cobalt(II)-intercalated montmorillonite for enhanced electrocatalytic oxygen reduction

Abstract

Due to the rapid development of fuel cells, the fabrication of electrocatalysts for oxygen reduction (ORR) with high performance and low-cost is of great significance. Herein, cobalt cations-intercalated montmorillonite (Co-MMT) was prepared by a simple cation-exchange reaction between Na-MMT and cobalt cations. A detailed ORR investigation indicates that the as-prepared nanocomposite of Co-MMT and multiwalled carbon nanotubes (Co-MMT/MWCNT) exhibits better ORR catalytic activity in aqueous alkaline medium with a 4e-route mechanism than Na-MMT, Co-MMT and MWCNT, suggesting the synergistic effect between Co-MMT and MWCNT. Moreover, further research shows that Co-MMT/MWCNT hybrid demonstrated more positive onset potential for ORR, higher oxygen reduction peak current than commercial 5% Pt/C ORR electrocatalyst.     

电纺制备聚丙烯腈/聚偏氟乙烯复合纤维膜及其空气过滤性能

以聚偏氟乙烯(PVDF)为芯层,聚丙烯腈(PAN)为皮层,通过同轴法静电纺丝技术制备PAN/PVDF纳米复合纤维膜。通过向纤维膜的皮层中加入纳米硅粉、气相白炭黑、硅溶胶三种不同的纳米粒子和改变皮芯层溶液挤出速度对PAN/PVDF纳米纤维膜进行结构优化。同时,采用BET、SEM、水接触角、纤维强度仪等对纤维膜的孔结构参数、表面形貌、亲水性、力学性能等进行研究。结果表明:在皮层中加入硅溶胶后的溶液导电能力达到32.90 μL/cm,PAN/PVDF纤维膜力学性能最好,纵向断裂强度达到13.02 MPa。含有硅溶胶的口罩布的品质因子达到0.0236,远大于纯聚丙烯(PP)无纺布的品质因子(0.0127),过滤性显著提高。      

Facile fabrication of CdTe/montmorillonite nanocomposite films with stable photoluminescence properties

We report herein the facile synthesis of CdTe/montmorillonite (MMT) nanocomposite films via charge-charge interactions between the CdTe quantum dots (QDs) and MMT platelets. Firstly, negatively charged CdTe QDs were prepared with the use of thioglycolic acid (TGA) as ligand. Then hybrid of the as-prepared TGA-stabilized CdTe QDs with sodium montmorillonite (Na-MMT) and cetyltrimethylammonium-modified montmorillonite (CTA-MMT), respectively, afforded novel CdTe/MMT nanocomposite films. The structure and optical properties of CdTe/MMT nanocomposite films were thoroughly investigated by scanning electron microscope (SEM), ultraviolet transmittance reflection and photoluminescence (PL) measurements. Results showed that CdTe/(CTA-MMT) nanocomposite films exhibited highly enhanced PL intensity compared with CdTe/(Na-MMT) nanocomposite films. More importantly, CdTe QDs in CdTe/(CTA-MMT) nanocomposite films well maintained PL properties even after thermal annealing at 100 °C for 10 h.     

聚丙烯/蒙脱土纳米复合材料的制备及结构

本文对钠基蒙脱土(Na—MMT)和经有机化处理过的有机蒙脱土(Org—MMT)分别与PP熔融共混进行研究，发现钠基蒙脱土和有机蒙脱土对PP力学性能有大幅度提高。同时，Na-MMT诱发了PP部分结晶晶型转变，经X射线衍射(XRD)和扫描电子显微镜(SEM)观察，发现Na—MMT和Org-MMT填充PP的粒子形态和界面形态有显著差别。     

有机磷氮系蒙脱土/LDPE纳米复合材料的制备及阻燃性能

以三氯氧磷和新戊二醇等为原料, 合成了一种新型磷氮型季铵盐(PAHAC), 通过红外光谱(FTIR)、 核磁共振氢谱(1H-NMR)和高分辨质谱(HRMS)表征化合物结构。利用PAHAC与钠基蒙脱土(Na-MMT)离子交换反应制备有机磷氮系蒙脱土阻燃剂(PAHACMMT)。FTIR和X射线衍射(XRD)研究表明: PAHAC通过离子交换对蒙脱土进行了有机化改性, 经20%质量分数的PAHAC改性后的MMT(20%PAHAC-MMT)层间距增至1.87nm, 20%PAHACMMT的热分解温度在310℃以上。透射电镜(TEM)分析结果表明, 20%PAHACMMT经LDPE熔融插层, 形成了插层剥离型纳米复合材料。锥形量热测试结果表明有机磷氮系蒙脱土/LDPE纳米复合材料具有良好的阻燃性能, 其中20%PAHACMMT(7%)/LDPE的热释放速率峰值(PHRR)比LDPE降低了21%, 热释放总量(THR)下降了9.5%。炭层的扫描电镜(SEM)分析结果表明, 20%PAHACMMT/LDPE燃烧后能形成致密的炭层, 起到良好的阻燃作用。      

Preparation and tribological performance of chemically-modified reduced graphene oxide/polyacrylonitrile composites

Interface control and dispersion of graphene base nanomaterials in polymer matrix are challenging to develop high comprehensive nanocomposites due to their strong interlayer cohesive energy and chemical inertia. In this research, an efficient approach is presented to functionalize reduced graphene oxide nanosheets by N-[3-(trimethoxylsilyl)propyl]ethylenediamine, which is dispersed into polyacrylonitrile to prepare N-[3-(trimethoxylsilyl)propyl]ethylenediamine – reduced graphene oxide/polyacrylonitrile nanocomposites. A thermogravimetric analysis technique was employed to evaluate thermal properties of the nanocomposites. The tribological properties of the polyacrylonitrile/graphene nanocomposites were investigated. The morphologies and volume of the worn surface were examined using a 3D profilometer. The impact of loading ratio on friction coefficient, carry-bearing capacity and durability were studied. The N-[3-(trimethoxylsilyl)propyl]ethylenediamine – reduced graphene oxide/polyacrylonitrile nanocomposite with appropriate loading ratio of reduced graphene oxide exhibited a high load-bearing capacity and durability. Therefore, the polyacrylonitrile/graphene nanocomposite shows promising potential to industrial applications involving the lubrication and anti-wear.     

Preparation and properties of nitrile rubber/montmorillonite nanocomposites via latex blending

The nitrile rubber (NBR)/unmodified montmorillonite (Na-MMT) clay nanocomposites were prepared by latex blending method followed by melt mixing of compounding ingredients by using two-roll mill. The X-ray diffraction (XRD) studies showed an increase in the basal spacing and broadening of peak corresponding to crystal structure of Na-MMT indicating the formation of intercalated/exfoliated clay layers in the NBR matrix. Increase in clay content of nanocomposite increased the XRD peak height due to the formation of many of clay tactoids at higher loading. The transmission electron microscopy (TEM) strengthened the XRD finding by showing the presence of intercalated/exfoliated morphology of clay platelets having good dispersion. The modulus and tensile properties of the nanocomposites were improved with addition of Na-MMT which is proportional to clay concentration. The retention of tensile properties of aged nanocomposites, with all clay concentration, was superior to either pure NBR and carbon black filled NBR composite. The dynamic mechanical analysis showed proportional increase in storage modulus analogous to Na-MMT loading at all the temperature ranges due to the confinement of polymer chains between the clay layers. Nanocomposites with different proportions of clay showed a decrease in tan δ_max peak height with a shift towards higher temperature indicating the reduction in the segmental mobility of polymer chain. A linear model was proposed to correlate the influence of Na-MMT content on storage modulus of nanocomposites. Differential scanning calorimetry indicated a linear increase in glass transition of nanocomposites which is proportional to clay loading. Thermogravimetric analysis revealed a small improvement in the thermal stability of nitrile rubber/clay nanocomposites.     

In situ growth of Prussian blue nanocubes on polypyrrole nanoparticles: facile synthesis,characterization and their application as fiber optic gas sensor

Polypyrrole (PPy) and polypyrrole/Prussian blue (PPy–PB) nanocomposite-based fiber optic gas sensors are developed for gas sensing application. Prussian blue (PB) nanocubes are successfully grown on polypyrrole (PPy) nanoparticles by in situ oxidative polymerization method to obtain PPy–PB nanocomposite. PPy and PPy–PB are evaluated based on structural, morphological and electrical properties. The characteristic peaks present in the FTIR spectra of pure PPy and PB nanoparticles are also present in the FTIR spectrum of PPy–PB nanocomposite with small shifts in the absorption maximum. The XRD pattern reveals the semicrystalline structure of PPy–PB nanocomposite with an average crystallite size of 22 nm, and the morphology (FESEM) shows the formation of PB nanocubes over PPy matrix. AC conductivity measurements show slight improvement in the conductivity value of PPy–PB in comparison with PPy. Dielectric studies in the frequency range of 50 Hz–5 MHz reveal that PPy–PB nanocomposite is a high-k dielectric material. At 50 Hz, PPy–PB exhibits high dielectric constants of 1149 and 766 with low dielectric loss values of 9.9 and 4.6 at 150 and 120 °C, respectively. Further, their application as fiber optic gas sensors in sensing various gases is studied using fiber optic technique. The spectral response is studied for various concentrations (0–500 ppm) of ammonia, acetone and ethanol gases at room temperature. The study shows that the spectral intensity increases linearly with different concentrations of all gases. The clad-modified fiber optic sensor with PPy–PB nanocomposite exhibits enhanced sensitivity for ethanol than clad-modified fiber optic sensor with PPy nanoparticles. TGA studies reveal the high thermal stability of PPy–PB nanocomposite. Hence, PPy–PB-based fiber optic sensors can be used to sense toxic ethanol vapor not only at room temperature but also in a composite environment where a temperature variation is expected.     

蒙脱土填充补强丁苯橡胶及对橡胶硫化特性的影响

以十八烷基三甲基溴化铵为插层处理剂改性蒙脱土。分别采用有机蒙脱土(C₁₈-MMT) 和Na-蒙脱土(Na-MMT) 填充补强丁苯橡胶, 用XRD 和TEM 对复合材料的结构进行表征。结果表明: 蒙脱土在橡胶基体中的分散取决于蒙脱土的亲油性, 亲油性越强, 蒙脱土的片层在橡胶中的分散越均匀, 完全有机化处理的蒙脱土能够被剥离成厚度为20 nm 左右的片层并均匀分散在橡胶基体中。蒙脱土的存在对橡胶的硫化反应有一定的影响, 有机蒙脱土对橡胶硫化反应有催化作用, 但不改变硫化反应的活化能; Na-蒙脱土片层阻碍了橡胶的硫化交联, 使交联反应对温度的敏感性降低, 导致表观活化能减小。有机蒙脱土填充补强丁苯橡胶, 由于提高了橡胶的交联密度, 同时有机蒙脱土具有高比表面积和滑移性, 大大提高了橡胶的机械性能, 其拉伸强度和300 %定伸应力与炭黑N330 补强橡胶相当, 而断裂伸长率较炭黑补强橡胶有大幅度的提高, 在替代炭黑作为橡胶的补强剂方面具有广泛的应用前景。