纳米ATO在聚合物改性中的应用研究

综述了纳米锑掺杂二氧化锡(ATO)改性聚合物[包括聚对苯二甲酸乙二醇酯(PET)、聚甲基丙烯酸甲酯(PMMA)、聚氨酯(PU)、聚乙烯醇缩丁醛(PVB)等]的研究进展。主要从导电性能、抗静电性能、光学性能、热学性能等方面对纳米ATO改性聚合物的优势及效果进行了叙述,并展望了纳米ATO/聚合物复合材料的应用和发展前景。     

Step-scan DSC研究PET/纳米CaCO3复合材料的结晶和熔融行为

采用纳米碳酸钙(CaCO3)浆料直接分散于聚对苯二甲酸乙二醇酯(PET)的单体乙二醇中,原位聚合制备出分散均匀的聚对苯二甲酸乙二醇酯(PET)/CaCO3纳米复合材料。分别利用传统的差示扫描量热仪(DSC)和步进扫描DSC(Step-scan DSC)技术研究了CaCO3含量变化对PET结晶和熔融行为的影响及非等温结晶动力学过程。结果表明,纳米粒子与PET的相互作用较弱,对PET结晶主要起促进作用,使结晶更加完善,碳酸钙的含量达到3%时,相对结晶速率达到最大。结晶初期,纳米粒子异相成核作用占优势,这种优势随着纳米粒子含量的增加而有所减弱;结晶后期,纳米粒子对高分子运动的牵制作用比较明显。     

纳米重晶石对聚对苯二甲酸乙二醇酯力学性能及结晶的影响

通过熔融共混法制备了聚对苯二甲酸乙二醇酯/重晶石纳米复合材料,研究了纳米重晶石用量对聚对苯二甲酸乙二醇酯力学性能和结晶行为的影响。结果表明,纳米重晶石对聚对苯二甲酸乙二醇酯有明显的增强作用,在纳米重晶石用量为3%(质量分数)时,对比纯聚对苯二甲酸乙二醇酯,复合材料拉伸强度提高了9.4%,弯曲强度和弯曲模量分别提高了10.8%和21.9%,聚对苯二甲酸乙二醇酯复合材料弯曲强度最高可提高15.8%。在复合材料中,纳米重晶石起到异相成核的作用,提高了聚对苯二甲酸乙二醇酯的结晶速率和结晶度,减少了聚对苯二甲酸乙二醇酯的晶粒尺寸。     

嵌段齐聚物修饰纳米SiO2对PET结晶性能的影响

采用溶液聚合法在纳米 SiO2表面接枝两种不同性质的齐聚物聚乙二醇(PEG)和聚对苯二甲酸乙二酯低聚物(LMPET),通过 FTIR、1 H-NMR、XPS 和 HR-TEM 对其结构形貌进行表征。采用熔融共混制备 PET 纳米复合材料,并利用 DSC 和 XRD 对改性纳米 SiO2对 PET 结晶性能的影响进行研究。结果表明,LMPET 通过 PEG 成功接枝到 SiO2表面,粒径尺寸为40~50 nm;纳米 SiO2可作为成核剂诱导 PET 的结晶提高结晶速率,当添加量为2%(质量分数)时,结晶温度得到明显提高。     

新型聚酯PMT等温结晶动力学研究

聚对苯二甲酸甲二酯 (PMT)是一种新型芳香族聚酯 ,本文以DSC差示扫描量热计对PMT的等温结晶动力学进行了研究 ,用Avrami方程对实验数据进行了分析 ,结果发现 :PMT的Avrami指数n在 2 4～ 2 6之间 ,为非整数且接近于 3,说明PMT结晶时倾向于异相成核 ;在实验温度范围内 ,随着等温结晶温度Tc的升高 ,PMT的结晶速率常数K减小 ,半结晶时间t1/ 2 增加。PMT的熔点与聚对苯二甲酸乙二酯 (PET)接近 ,但高于聚对苯二甲酸丙二酯 (PTT)和聚对苯二甲酸丁二酯 (PBT) ,与结构分析得到的结论一致     

纳米Al2O3/玻璃纤维/聚对苯二甲酸丁二醇酯复合材料非等温结晶行为研究--(Ⅰ)结晶与熔融行为

通过熔融共混法制备了纳米A l2O3/玻璃纤维(GF)/聚对苯二甲酸丁二醇酯(PBT)复合材料,利用差示扫描量热仪(DSC)对其非等温结晶过程、熔融行为及结晶度进行了研究。结果发现,纳米A l2O3粒子的异相成核作用有利于复合材料结晶速率的增加,使得非等温结晶温度提高,双熔融峰现象中的低温熔融峰的熔融温度也有所提高。同时,在PBT基体中,纳米A l2O3粒子在一定程度上可以改变玻璃纤维对复合材料结晶行为的影响而使结晶度发生改变。     

r-PTFE对PBT非等温结晶动力学的影响

以回收聚四氟乙烯(r-PTFE)为成核剂,对聚对苯二甲酸丁二醇酯(BPT)进行成核结晶改性,采用差示扫描量热仪(DSC)研究了PBT/r-PTFE复合材料的非等温结晶行为,考察了不同降温速率对PBT/r-PTFE共混物结晶行为的影响,并对其DSC扫描数据采用Jeziorny法和Liu-Mo法进行处理,采用Kissiinger法计算体系结晶活化能。结果表明:r-PTFE对PBT具有异相成核作用,可明显提高PBT的结晶度及其结晶速率,且加入r-PTFE并不会改变PBT的成核和增长方式。由Kissinger法计算得出的结晶活化能结果表明,加入r-PTFE树脂能够明显降低PBT的结晶活化能,进一步验证r-PTFE对PBT具有成核促进作用。     

结晶促进剂和成核剂对PET结晶性能的影响

研究了结晶促进剂(聚醚)和成核剂对聚对苯二甲酸乙二醇酯(PET)结晶过程的影响及其在PET、结晶过程中的作用．结晶促进剂(聚醚)主要是对PET、链段进行“解冻”，提高了链段的活动能力，从而有利于PET结晶，并且使PET结晶更加完善，但不能促进PET的成核结晶，对结晶速度影响小．成核剂的引入起到了成核结晶的作用，从而加快了PET的结晶速度。     

PET/有机蒙脱土纳米复合材料等温结晶动力学过程研究

用DSC方法研究了具有反应活性的有机蒙脱土与聚对苯二甲酸乙二酯（PET）原位聚合和熔融共混后的两种插层复合材料的等温结晶行为。结果表明，有机蒙脱土起异机成核作用，使PET的结晶过程更加复杂，对聚合样由于有机处理剂参与PET链的反应，特殊的结构有利于成核过程，但对总的结晶速率有一定影响，结晶速率的提高程度依赖于有机蒙脱土的添加量；有机蒙脱土使共混样品的结晶速率大大加快。     

PET/SiO2纳米复合材料的研究进展

聚对苯二甲酸乙二醇酯(PET)是一种应用广泛的工程塑料,为进一步提升材料性能以拓宽其工程应用领域,采用无机纳米二氧化硅(SiO_2)粒子填充改性已成为最为有效的途径之一。针对PET/SiO_2纳米复合材料,主要从纳米SiO_2表面改性、复合材料制备以及复合材料性能三方面综述其研究进展。在此基础上,对PET/SiO_2纳米复合材料的研究方向进行了展望。     

抗静电PET/ATO纤维的制备及材料的性能

采用原位聚合的方法制备了抗静电涤纶(PET)/锑掺杂二氧化锡(ATO)纳米复合材料。结果显示,ATO在PET中分散良好,团聚体尺寸小于200 nm;加入ATO没有影响PET的流动曲线类型,随着ATO含量的增加,在相同的剪切频率下,熔体黏度均呈先增加后减小的趋势;加入ATO提高了材料的热性能,利于熔融纺丝。采用熔融纺丝法制备了抗静电纳米复合纤维。ATO含量为1.0%(质量分数,下同)时纤维的比电阻由2.7×1013Ω.cm下降到4.9×108Ω.cm。抗静电纤维的渗滤阈值为1.05%,低于传统抗静电填料。     

Nonisothermal crystallization kinetics of poly(ethylene terephthalate) nanocomposites

This article reports the nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET) nanocomposites. The non-isothermal crystallization behaviors of PET and the nanocomposite samples are studied by differential scanning calorimetry (DSC). Various models, namely the Avrami method, the Ozawa method, and the combined Avrami-Ozawa method, are applied to describe the kinetics of the non-isothermal crystallization. The combined Avrami and Ozawa models proposed by Liu and Mo also fit with the experimental data. Different kinetic parameters determined from these models prove that in nanocomposite samples intercalated silicate particles are efficient to start crystallization earlier by nucleation, however, the crystal growth decrease in nanocomposites due to the intercalation of polymer chains in the silicate galleries. Polarized optical microscopy (POM) observations also support the DSC results. The activation energies for crystallization has been estimated on the basis of three models such as Augis-Bennett, Kissinger and Takhor methods follow the trend PET/2C20A < PET/1.3C20A < PET, indicating incorporation of organoclay enhance the crystallization by offering large surface area.     

Electrical and Mechanical Properties of PMMA/nano-ATO Composites

Conducting nanocomposites of poly (methyl methacryiate) (PMMA) and antimony doped tin oxide (ATO)were prepared by solution blending. The influences of ATO content on the electrical conductivity, thermal stability, and mechanical properties of the nanocomposites were investigated. A homogeneous dispersion of silane coupling agent modified ATO was achieved in PMMA matrix as evidenced by scanning electron microscopy. The resultant PMMA/silane-ATO nanocomposites were electrically conductive with significant conductivity enhancement at 4 wt pct. It was found that the composition at 4 wt pct ATO gave the higher tensile strength. Furthermore, it gave the largest elongation at break value among all the compositions.Thermal stability of the nanocornposites was remarkably enhanced by the incorporation of silane-ATO.     

Characterization of PAN/ATO nanocomposites prepared by solution blending

Conducting nanocomposites of polyacrylonitrile (PAN) and antimony-doped tin oxide (ATO) were prepared by solution blending. Electrical properties of the nanocomposites were characterized by means of electrical conductivity measurements and the phase structures were investigated via scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analyses (TGA) and dynamical mechanical analysis (DMA). This study unveiled a remarkable, interpenetrating network of chainlike nano-ATO within the PAN matrix, consistent with the existence of connected conducting paths at content as low as 4 wt% of the nano-ATO. The storage modulus of the nanocomposites increased with increasing content of ATO, due to formation of immobilized layer between polymer and filler. The interactions between ATO and PAN molecules resulted in high tan δ for the PAN/ATO nanocomposites. Thermal stability of the nanocomposites was found remarkably enhanced by the incorporation of nano-ATO.     

Thermal and morphological characterization of poly(ethylene terephthalate)/calcium carbonate nanocomposites

Nanocomposites composed of poly(ethylene terephthalate) (PET) filled with calcium carbonate particles of nanometer scale were prepared by polymerizing the polyester in the presence of the nanosized fillers. Besides plain calcium carbonate, carbonate nanoparticles coated with stearic acid were also used, in order to improve the compatibility between the polymeric matrix and nanofillers. Morphological analysis evidenced a good dispersion of both the nanopowders into the PET matrix, especially in the case of coated calcium carbonate. The strong interfacial adhesion between the two phases is also responsible for the increase of the glass transition and melting temperatures in the nanocomposites compared to plain PET. Finally, non-isothermal crystallization studies revealed that the coated CaCO₃ is a good nucleating agent for PET. Analysis of non-isothermal crystallization data with the Ozawa theory was successful for plain PET and PET/un-CaCO₃, but this method failed to describe the dynamic solidification of the PET/c-CaCO₃ nanocomposite.     

碳纳米管/聚对苯二甲酸乙二酯纳米复合材料热降解动力学

用原位聚合的方法制备了聚对苯二甲酸乙二醇酯(PET),带羧基的多壁碳纳米管/PET(MWNTs-COOH/PET)纳米复合材料和带羟基的多壁碳纳米管/PET(MWNTS-OH/PET)纳米复合材料。用热重分析(TG)仪测试了三种样品的热降解稳定性,用Friedman法和Ozawo法对测试结果进行了热降解动力学分析。结果表明,通过加入MWNTs,两种MWNTs/这PET纳米复合材料的热稳定性都有不同程度的提高。MWNTs-COOH/PET的稳定性从开始降解到结束都比纯PET高,MWNTs-OH/PET开始降解阶段的稳定性不如纯PET,而在降解后期稳定性明显比纯PET高。     

退火处理对PET/粘土纳米复合材料结晶行为的影响

利用差示扫描量热法测试了PET、PET/粘土纳米复合材料、增粘PET/粘土纳米复合材料在退火的热历史条件下的一些结晶行为,对其冷结晶峰、熔融温度分别进行对比,结果表明:PET/粘土纳米复合材料的冷结晶温度高低顺序为:PET/粘土纳米复合材料<增粘PET/粘土纳米复合材料相似文献   

PET/SiO2纳米复合材料的结晶和形貌研究

利用X射线衍射仪、DSC和扫描电子显微镜研究了纳米SiO2不同含量的PET/SiO2复合材料在恒温条件下的结晶度、熔化温度和晶体形貌。结果发现,SiO2纳米粒子含量对复合材料的结晶速度有很大影响;球晶尺寸与SiO2纳米粒子添加量密切相关。     

聚乙烯/有机蒙脱土纳米复合材料结晶动力学

采用熔融插层法制备了聚乙烯/有机蒙脱土纳米复合材料,利用示差扫描量热法(DSC)研究了复合材料的等温及非等温结晶行为,并与纯聚乙稀进行了比较.通过Avrami方程,修正Avrami方程的Jeziorny法及Ozawa法分别对等温及非等温结晶过程进行了处理.结果表明:蒙脱土片层在复合材料结晶过程中起到了异相成核作用,复合材料的成核机理与生长方式已不同于聚乙烯;在相同结晶条件下,复合材料的结晶速率明显比聚乙烯快;纯PE的表观活化能为142.14 kJ/mol,而复合材料为158.38 kJ/mol,复合材料的活化能有一定程度提高;对非等温结晶过程分析,Jeziorny方法适用,而Ozawa方法不适用.     

Preparation of electrically conductive fibres by new surface coating method

Abstract

In the present research, a new surface coating method (dissolving-coating method) that is on the basis of dissolution mechanism was designed. Substantially transparent antimony doped tin oxide (ATO) particles were used instead of carbon black as conductive particles. ATO coated polyester (PET) fibres and ATO coated polycaprolactam (PA6) fibres were prepared by the traditional coating method and the dissolving–coating method respectively. The electrical conductivity, mechanical property and launderability of the coated fibres were discussed. For the characterisation, a laser particle size distribution analyser was used to analyse the size distribution of ATO. Scanning electron microscopy (SEM) and transmittance electron microscopy (TEM) were used for the observation of ATO particles and fibre surface. Electron probe was carried out to make an elemental analysis of the fibre.