具有包藏结构的三元聚丙烯纳米复合材料结构与性能关系的研究

制备了一种新型聚丙烯 丁苯橡胶 纳米碳酸钙三元纳米复合材料 .研究结果显示 ,复合材料中的大多数纳米碳酸钙粒子被包藏在丁苯橡胶中 ,并与之共同形成分散于聚丙烯树脂中的分散相 ,这种聚丙烯纳米复合材料具有高刚性、高韧性、高耐热性和高的结晶速率 .系统研究了成核剂苯甲酸钠的加入和纳米碳酸钙的用量对该类纳米复合材料相态结构、结晶形态和结晶动力学的影响 ,以及具有包藏结构的分散相粒径和PP中β晶含量对材料性能的影响 .结果表明 ,苯甲酸钠的加入和纳米碳酸钙用量的提高均可使体系中分散相粒径减小 ,结晶速率加快 ,进而使材料的韧性、刚性和耐热性提高 .     

聚合物基无机纳米复合材料的制备方法Ⅱ.直接分散法和同时形成法

聚合物基无机纳米复合材料制备的关键问题是无机纳米粒子在聚合物基体中保持其纳米尺度的分散,本文主要讨论直接分散法、同时形成法制备聚合物基无机纳米材料的基本原理和技术要点。     

低剪切混合方法制备炭黑/聚丙烯纳米复合材料及其电性能研究

采用一种在低剪切应力场下纳米复合材料的加工方法,制备得到纳米炭黑(CB)粒子在聚丙烯(PP)中以纳米尺度分散的聚合物导电复合材料.扫描电镜观察表明CB粒子在纳米复合材料中以纳米尺度存在,并均匀的分布在PP基体中.电性能测试发现,通过这种低剪切混合方法得到的纳米复合材料具有非常低的导电逾渗阈值(vc=2.49vol%)和较高的临界电阻指数(t=5.82),很大的偏离了普适逾渗理论.基于隧道逾渗模型对体系的电导率进行了模拟,并对CB的分散状态与导电网络的关系进行了分析.发现当纳米CB粒子以纳米尺度分散于基体中时,并不遵从接触导电机理,而是隧道逾渗机理在CB/PP纳米复合材料中起主导作用.     

疏水上转换纳米晶的均相体系聚合物包覆及在发光检测中的应用

选用水解的十八碳烯-马来酸酐共聚物(PMAO)为表面修饰分子,发展了一种以疏水纳米粒子吸附表面活性剂十二烷基磺酸钠(Na YF_4-SDS)为中间体的均一液相聚合物包覆纳米粒子方法.该方法解决了油溶性纳米晶与弱极性聚合物分子难以在单一体系下均匀分散的问题,实现了在均一液相体系下对疏水纳米晶的单分散包覆以及表面羧酸官能团修饰.红外光谱与表面Zeta电位测试结果表明纳米晶已被聚合物包覆,粒子表面为强电负性的羧酸基团.电镜结果表明聚合物包覆的上转换纳米晶粒径无明显的变化,具有良好的单分散性.发射光谱表明聚合物包覆前后粒子的发射谱带无显著变化,保持了原油相粒子的发光性能.进一步的特异性识别荧光显微成像实验证实聚合物包覆后的粒子(Na YF_4-PMAO)可用于生物学检测.     

聚丙烯/PMMA/CaCO3纳米复合材料的制备、结构与力学性能

分别将经不同表面处理的纳米碳酸钙粒子与聚合物PP共混,制备PP／CaCO3和PP／PMMA／CaCO3纳米复合材料。用TEM观察了表面处理后纳米粒子的粒径与分散情况,发现复合粒子分散较均匀。用DSC与WAXD研究了复合材料的结晶行为,发现原位聚合制备的PMMA／CaCO3纳米复合粒子与PP共混后,PP有异相成核作用,出现了不稳定的PPβ晶型。PP／PMMA／CaCO3纳米复合材料力学性能有大幅度的提高。     

纳米无机粒子/聚合物复合材料界面结构的研究

纳米粒子具有许多特性,聚合物中加入纳米粒子可以制备得到性能更加优异的复合材料,其中纳米粒子和聚合物基体间的界面对决定纳米复合材料的性能起着重要作用.本文综述了近些年来表征纳米无机颗粒/聚合物复合材料中界面结构的研究手段,如红外光谱(FTIR)、热重(TGA)、电子显微镜、小角中子散射(SANS)及小角X射线散射(SAXS)等,及界面结构与复合材料力学性能和热稳定性关系的研究进展.同时也介绍了纳米粒子对复合材料的渗透、光催化、阻燃、介电及导电性能的影响.最后对这一领域的研究进行了展望.     

纳米SiO2的表面处理及其在聚合物基纳米复合材料中的应用进展

简要介绍了纳米二氧化硅(SiO2)粒子的制备方法、结构和特性,对近年来国内外纳米SiO2的表面处理方法及聚合物/SiO2纳米复合材料的制备方法进行了阐述,并针对不同改性方法和制备方法的特点加以分析比较;讨论了SiO2粒子的分散机理和增强机理,并对未来的研究内容及方向提出展望。     

石墨烯/二氯化镁负载钛系齐格勒-纳塔催化剂制备及其乙烯聚合性能

石墨烯自2004年发现以来,由于其独一无二的优异性迅速成为科学家们的研究热点.由于石墨烯具有极其优异的电学、力学和热学等性能,因此被广泛应用于高性能聚合物基复合材料的制备.众所周知,纳米填料在聚合物中的分散状态以及与基体间的界面作用是构筑高性能聚合物纳米复合材料的关键因素.由于石墨烯极易团聚,难以通过传统的熔融共混法制备均匀分散的石墨烯增强-聚烯烃纳米复合材料.另一方面,聚烯烃通常需要在较高温度下才能溶于部分有毒溶剂(如:三氯苯和二甲苯等),因此溶液共混法也不适用于聚烯烃-石墨烯纳米复合材料的制备.有鉴于此,本文开发了一种共沉积法制备石墨烯/二氯化镁负载钛系齐格勒-纳塔催化剂的路线.通过原位聚合直接制备出石墨烯均匀分散的聚烯烃/石墨烯纳米复合材料.考察了石墨烯的加入量对催化剂形态及其催化乙烯聚合行为的影响.当石墨烯加入量较低时,多个石墨烯片被包裹于较大的催化剂粒子中.随着石墨烯加入量的增加,催化剂趋向于在石墨烯表面聚集.继续增加石墨烯量将导致石墨烯包裹催化剂粒子,降低过渡金属钛的负载效率.通过三乙基铝活化后,所制备的催化剂具有非常高的乙烯催化活性,所生成的聚乙烯/石墨烯纳米复合材料复制了催化剂的片状结构.同时,通过对所制备的聚乙烯/石墨烯纳米复合材料进行电子显微镜和X射线衍射分析可知,石墨烯均匀分散于聚乙烯基体中,并且没有任何团聚现象发生.该复合材料的热重分析表明,仅加入非常少量的石墨烯就可以使其具有比纯聚乙烯更高的热稳定性,当石墨烯加入量为0.66 wt%时,其5 wt%热分解温度较纯聚乙烯升高了54°C.同时,所制备聚乙烯/石墨烯纳米复合材料具有更优异的机械性能.因此,本研究提供了一个简单高效的高性能聚烯烃/石墨烯纳米复合材料的制备方法.     

原位聚合法制备聚合物/纳米SiO_2复合材料的研究进展

纳米SiO_2改性聚合物制备的关键在于提高纳米粒子与聚合物基体的相容性及分散性;对纳米SiO_2进行不同的表面改性及选择合适的复合材料制备方法可以改变纳米粒子与聚合物基体的界面结合方式以及相容性和分散性,进而在不同程度上影响材料的性能.本文介绍了改性前后纳米SiO_2与聚合物基体的多种界面结合方式,对近年来利用原位聚合法制备聚合物/纳米SiO_2复合材料的研究现状和进展进行了综述.     

Preparation and Storage of Silver Nanoparticles in Aqueons Polymers

以水溶性聚合物为保护剂,采用化学还原法制备了银纳米粒子,分别利用透射电子显微镜、紫外可见光谱、同步光散射光谱等手段对其进行了表征,并探索了制备银纳米粒子的最佳实验条件。通过将银纳米粒子-聚合物溶液进行脱水,得到含有银纳米粒子的固态聚合物膜。将固态聚合物膜重新溶解于水,其水溶液的紫外可见光谱与脱水前的溶液进行了比较,发现两者性质并无明显差异。因此,将银纳米粒子分散固定在聚合物膜中是一种崭新而有效的银纳米粒子制备和存储方法。     

高分子/单链高分子纳米粒子复合体系中的界面性质

高分子与纳米粒子复合是改善高分子材料性能的有效途径.近20年来关于高分子/纳米粒子复合物的研究引起了学术界广泛的兴趣.然而由于此类体系中的影响因素复杂,虽然学者们在相关材料性能的研究方面取得了重要进展,但是相关理论的发展却相对滞后,其中一个重要原因是实验上表征手段的缺失,导致对体系中纳米粒子与本体高分子链相互作用规律的认识(尤其是两者界面性质的认识)不够.本文总结和阐述了我们近几年利用分子动力学模拟技术研究高分子/单链高分子纳米粒子复合体系的主要结果,并围绕此类复合体系中的界面结构及动力学性质,讨论并总结了纳米粒子对本体高分子链的作用范围及影响规律,指出单链纳米粒子对熔体链的作用范围与纳米粒子的自身尺寸相当,而与熔体高分子链的分子量没有直接的关系.该结论将为纳米复合体系高分子理论的发展提供重要参考.     

A novel method for making ultra-fine metal fibers and particles

A novel method based on plastic processing and equipment for preparing ultra-fine metal fibers and particles is reported. With this new method, metal fibers and particles can both be produced on the same equipment and the surfaces of the fibers and particles can be protected from oxidation by the polymers or solvents during the preparation process. Metal-alloy powders with lower melt point were filled into polymer by an extruder, followed by a die-drawing process at a temperature lower than the melt temperature of the metal alloy. Metal fibers or particles were obtained after the polymer matrix was washed away. Metal alloy fibers can be obtained when a polymer that strongly interacts with metal alloy, such as a special polyvinyl alcohol with a low alcoholysis degree, is used as the polymer matrix. Metal-alloy particles can be obtained when a polymer with weak interaction with metal alloy, such as polyethylene (PE), is used as the polymer matrix. Based on the principle of this new method, it is possible to produce finer or even nano-sized metal fibers and particles with higher melting points.     

An overview of boron nitride based polymer nanocomposites

Recently, boron nitride (BN) based materials have received significant attention in both academic and industrial sectors due to its interesting properties like large energy band gap, good resistance to oxidation, excellent thermal conductivity, thermal stability, chemical inertness, significant mechanical property and widespread applications. This review article deals with the preparation and properties of boron nitride and its nanocomposites with various polymers. Diverse polymers have been explored for the preparation of boron nitride filled polymer nanocomposites by adopting different mixing methods. Properties of the resulting polymer nanocomposites mainly depend up on filler size and dispersion, mixing conditions and type of interaction between polymer matrix and the filler. Herein, the structure, preparation and properties of various boron nitride based polymer nanocomposites are reviewed in detail along with a brief overview of different classes of BN nanomaterials.     

利用原位微纤化技术控制聚合物形态的研究进展

综述了利用原位微纤化技术控制聚合物形态的研究进展,简要介绍了原位微纤化共混物的概念、制备方法、影响成纤的因素及常见原位微纤化体系等,讨论了原位微纤化技术对碳纳米管(CNTs)/聚碳酸酯(PC)/聚乙烯(PE)、碳黑(CB)/对苯二甲酸乙二醇酯(PET)/PE及纳米碳酸钙(nano-CaCO3)/CB/PET/PE等体系的形态调控以及体系形态与力学性能、电学性能的关系,简要介绍了原位微纤化技术在废旧塑料回收方面的应用,最后阐述了原位微纤化技术的重要性并展望了其应用前景.     

Solvent effect in polymer analysis by MALDI-TOF mass spectrometry

Solvent effect is one of the important factors in sample preparation which may affect matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra of synthetic polymers. MALDI imaging, a useful imaging tool for discovering biomarkers in tissues, is applied here for better comprehension of solvent effect in polymer analysis by MALDI-TOF mass spectrometry. Nylon-6 was chosen as a model polymer for the study of solvent effect. Its MALDI mass spectra in different solvents were performed. MALDI imaging analysis was performed for studying the incorporation of analytes into matrix crystals in different solvent combinations. Specifically, the colocalization of matrix and analyte was obtained through Pearson’s correlation (PC) coefficient analysis of their MALDI images. The results demonstrated that satisfactory spectra were obtained in higher PC value conditions. PC decreased along with an increase in the ratio of poor solvent, which suggested that we should minimize the poor solvent ratio to obtain better MALDI spectra.     

PERFORMANCE IMPROVEMENT OF POLYMERS BY THE ADDITION OF GRAFTED NANO-INORGANIC PARTICLES

An irradiation grafting method was applied for the modification of nanoparticles so that the latter can be added topolymeric materials for improving their mechanical performance using existing compounding techniques. The followingitems are discussed in this paper: (a) chemical interaction between the grafting monomers and the nanoparticles duringirradiation, (b) properties including modulus, yield strength, impact strength and fracture toughness of the resultantcomposites, and (c) possible morphological changes induced by the addition of nanoparticles. Though irradiation graftingpolymerization, nanoparticle agglomerates turn into a nano-composite microstructure (comprised of the nanoparticles and thegrafted, homopolymerized secondary polymer), which in turn builds up a strong interfacial interaction with the surrounding,primary polymeric matrix during the subsequent mixing procedure. Due to the fact that different grafting polymers broughtabout different nanoparticle/matrix interfacial features, microstructures and properties of the ultimate composites could thusbe tailored. It was found that the reinforcing and toughening effects of the nanoparticles on the polymer matrix can be fullybrought into play at a rather low filler loading in comparison to conventional particulate filled composites.     

Effect of polycarbonate structure and reduction time on graphene oxide dispersion

Polycarbonate (PC)/graphene oxide (GO) composites with different GO reduction time and PC types were prepared by using a twin screw extruder at 260 °C after solution mixing with chloroform. The chemical reaction degree of PC/GO composites with GO reduction time was confirmed by C–H stretching peak at 3000 cm ^?1, and the chemical reaction degree decreased with GO reduction time. The slope for storage (G′) versus loss (G″) modulus plot decreases with an increase in heterogeneous property of the polymer melts. So we can check the GO dispersion of the PC/GO composites using by the slop for G′–G″ plot. According to the G′–G″ slopes for PC/GO composite with GO reduction time, GO was well dispersed within PC matrix when the reduction time decreased. It was re‐confirmed by atomic force microscope (AFM) results. Based on the degradation temperature by Thermogravimetric analysis, G′–G″ slopes, and surface roughness by AFM, the branched PC was better than linear PC for the GO dispersion within PC matrix. The fact was also confirmed by tensile test results that the Young's modulus increased with the improvement of GO dispersion. Copyright © 2015 John Wiley & Sons, Ltd.     

Structure Analysis of PVC Nanocomposites

In this paper poly(vinyl chloride)/clay nanocomposites were prepared by melt intercalation using a single screw extruder. Problems with thermal stability of these nanocomposites during compounding were largely eliminated by pre-treatment of the organoclay with plasticizer (dioctyl phthalate), which created a barrier between polymer and quaternary amine. These nanocomposite materials were analyzed with respect to their morphology. The intercalation, exfoliation, nano-phase dispersion and orientation were investigated using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Moreover, different types of sample preparation for these techniques were tested as well. It was found that partially intercalated and disordered structure arose in poly (vinyl chloride) composites containing sodium type of montmorillonite, while a fine dispersion of partial to nearly full exfoliation of individual montmorillonite layers in poly (vinyl chloride) matrix was observed when this clay was organically modified. Finally, the influence of different mixing time (in extruder) on nano-phase morphology was surveyed.     

Polymeric nanoparticles based on polylactide and related copolymers

The preparation of nanoparticle suspensions was carried out by using commercial biodegradable polymers as poly(d,l-lactide), poly(d,l-lactide-co-glycolide) and poly(d,l-lactide-co-ϵ-caprolactone). The method of preparation was based on the controlled addition of polymer organic solution to an aqueous phase containing dispersing agents. Poly(ethylene glycol) (10, 20, and 35 kDa grade), Tween 20, and Pluronic F-127 were used as dispersing agents in the aqueous phase. Content and type of both polymeric matrix and dispersing agent resulted of paramount relevance for the attainment of monodispersed nanoparticles with average diameter of about 130 nm. The addition of a steric stabilizer allowed for nanoparticle purification and isolation while preventing their agglomeration. The best results were obtained by using 35 kDa grade poly(ethylene glycol) as dispersing agent and either mannitol or glycidylisopropylidenglyceryl-β-cyclo-dextrin as steric stabilizer. The adopted procedure afforded biodegradable nanoparticle suspensions that could be used for the incapsulation and intravenous administration of biologically active proteins and oligopeptides.     

Multisample preparation methods for the solvent-free MALDI-MS analysis of synthetic polymers

A limitation of any current approach using solvent-free MALDI mass spectrometry is that only one sample at a time can be prepared and transferred to the MALDI-plate. For this reason, multiple-sample preparation approaches for solvent-free MALDI MS analysis of synthetic polymers were developed that are simple and practical. One approach multiplexed sample preparation by simultaneously preparing multiple samples. With this approach, as many as 384 samples could be prepared by addition of analyte, matrix, salt, and 1-mm metal beads to each well of a 384-well disposable bacti plate, capping the plate with the lid and homogenizing all samples simultaneously using a common laboratory vortex device. Besides the time savings achieved by a single vortex step for multiple samples, an additional advantage of this method relative to previously reported solvent-free preparation methods is that the mixing volume per sample is reduced, which allows a reduction in the amount of analyte required. This method, however, still requires the transfer of each homogenized sample to the MALDI plate for subsequent analysis. Here we report a novel approach that combines multiple simultaneous solvent-free sample preparation with automatic sample transfer to the MALDI target plate. This approach reduces the possibility of cross-contamination, the amount of sample and matrix consumed for an analysis, and the time required for preparation of multiple samples. These methods were shown to provide high-quality mass spectra for various synthetic polymer standards with M(n) values to 10 kDa. The methods are efficient in that small sample amounts are required, the sample/salt/matrix ratio is not critical, and the time necessary to achieve sufficient homogenization of multiple samples is less than 5 min.