LLDPE/纳米ZnO复合材料的制备与工艺优化研究

讨论了利用硅烷偶联剂对纳米ZnO粒子表面改性的机理与方法,按照标准正交表L9(34)的实验方案,采用熔融共混方法制备LLDPE/纳米ZnO复合材料,并测试其拉伸强度和断裂伸长率.通过正交实验分析法得到较优的工艺参数组合,同时基于正交实验数据通过神经网络和遗传算法优化得到一组工艺参数组合,并分别在两组工艺参数下进行实验分析.结果表明,正交实验、神经网络和遗传算法三者结合优化复合材料制备工艺参数的方法更理想;在较优的工艺条件下,LLDPE基体中适当填充改性纳米ZnO粒子,拉伸强度和断裂伸长率同时提高,能够起到增强增韧的作用.     

EVA/TiO2纳米复合材料的制备与性能

采用两种方法优化EVA/TiO2纳米复合材料的制备方法与工艺参数,选取性能最佳的一步法制备样本,进一步应用FESEM方法表征纳米粒子的粒径及分散状态,并测试材料力学性能。研究发现,基于神经网络和遗传算法的优化方法比正交实验分析优化方法更佳;纳米TiO2微粒在EVA基体中分散良好,拉伸强度、断裂伸长率和弹性模量均有所提高,起到了增强增韧作用。纳米TiO2填充量为5%时,拉伸强度提高最多;纳米TiO2填充量为1%时,断裂伸长率提高最多;随着纳米TiO2填充量的增加,弹性模量整体呈上升趋势。     

EVA/纳米TiO_2复合材料的性能及其数值模拟

采用一步法制备EVA/TiO2纳米复合材料,应用FESEM和SEM方法研究分散状态和断面形貌,并测试纳米复合材料的力学性能。进一步利用均匀化理论和有限元相结合的方法模拟EVA/TiO2纳米复合材料的有效性能。结果表明:纳米TiO2微粒在EVA基体中分散良好,拉伸强度、断裂伸长率和弹性模量均有所提高,起到了增强增韧作用;填充圆形和方形TiO2颗粒的复合材料有效性能,均随填充量的增加而增加;同一填充量时,填充颗粒为方形的大于填充颗粒为圆形的材料的有效性能;等效弹性模量与实验所得的结果基本趋势一致,圆形颗粒的计算结果更接近实验结果。     

EVA/TiO2纳米复合材料的制备与性能研究

采用一步法制备出EVA/TiO2纳米复合材料,利用FESEM、FTIR、SEM等测试手段表征纳米TiO2微粒在EVA基体中的分散性,并研究其力学性能及流变性能.结果表明,TiO2微粒以20～60 nm的粒径分散于EVA基体之中,并与EVA形成化学键合结构,断裂时脆性转变为韧性.当纳米TiO2填充量为5%时,拉伸强度提高22.6%,纳米TiO2填充量为1%时,断裂伸长率提高10.1%.本实验中制备的纳米复合熔体表观粘度低于纯EVA,熔点变化较少,有效改善了加工流动性.     

针形纳米碳酸钙的表面改性及在PVC中的应用

对自制直径为30 nm~40 nm,长径比10~15的针形纳米碳酸钙进行表面改性后,将其应用于聚氯乙烯(PVC)的改性研究中,考察了改性针形纳米碳酸钙/PVC复合材料的力学性能。与未填充的PVC相比,纳米碳酸钙填充量为2.69%(体积分数)时,复合材料的拉伸强度、冲击强度和断裂伸长率分别提高了5.7%、11.3%和33.7%。改性后的纳米碳酸钙与PVC之间的界面作用与未改性碳酸钙相比有所减弱。扫描电镜照片(SEM)显示,添加了改性针形碳酸钙的聚氯乙烯断裂为韧性断裂,冲击断面呈现明显的拉丝现象。     

LLDPE/Al_2O_3纳米复合材料的形态、结构及力学性能

在超声作用下利用异丙基十二烷基磺酰钛酸酯改性Al2O3纳米粒子,然后把改性纳米Al2O3粒子及LLDPE颗粒引入密炼机中,以熔融共混方法制备LLDPE/纳米Al2O3复合材料.采用FESEM对复合材料中纳米粒子的分散形态进行表征,结果表明,当纳米Al2O3粒子含量为3%时,绝大多数的纳米粒子以<100nm的尺寸均匀分散在基体中;采用FTIR对纳米复合材料的结构进行表征,结果表明,纳米Al2O3与LLDPE之间形成了化学键合结构;力学分析表明,纳米复合材料的拉伸强度及断裂伸长率均有所增加;采用SEM观察拉伸断裂面的形貌,结果表明,适量的纳米Al2O3粒子可以增强、增韧聚合物基体,而基体和纳米粒子的相容性差时,会逐渐引入缺陷.     

淀粉/聚乳酸挤出片材的制备及性能

采用挤出工艺制备了淀粉/聚乳酸复合片材。通过拉伸强度、断裂伸长率并结合断面形貌研究了淀粉结构、淀粉用量、硅烷偶联剂(KH-550)及甘油增塑剂的用量对挤出淀粉/聚乳酸复合片材性能的影响。结果表明,采用接枝甲基丙烯酸甲酯的改性淀粉作为填充剂,并添加适量KH-550硅烷偶联剂和甘油增塑剂及采用造粒后共挤等工艺可有效改善淀粉/聚乳酸复合片材的兼容性,提高复合材料拉伸强度和断裂伸长率,当改性淀粉含量为20份时样品的拉伸强度和断裂伸长率最大,分别为35.3 MPa和37%。     

亲水性聚氨酯复合材料的制备与表征

选用湿态纳米羟基磷灰石（HA）与脂肪族聚氨酯（PU）为原料,采用溶液共混法和溶剂挥发法制备了亲水性羟基磷灰石/聚氨酯（HA/PU）纳米复合材料,并采用SEM、吸水实验和力学实验等方法对该复合材料的形貌和性能进行了研究。结果表明磷灰石晶体以纳米状态均匀地分布在PU基质中,过高含量的纳米HA易使纳米粒子团聚,不利于其在PU基体中的均匀分散;在制备PU的多元醇原料中引入亲水性较强的聚乙二醇,可提高PU表面和整体的亲水性;随着硬段含量的增加,复合材料的拉伸强度和弹性模量呈上升趋势,断裂伸长率下降;随着软段中聚乙二醇含量的升高,弹性模量大幅下降,拉伸强度和断裂伸长率先升高后下降;纳米HA的添加可同时提高复合材料的拉伸强度和断裂伸长率,当纳米HA的质量分数为30%时,复合材料的综合力学性能达到最佳。     

SYNTHESIS AND MECHANICAL PROPERITIES OF REACTABLE NANO-SILICA/PA1010 HYBRID COMPOSITES

以可反应性纳米SiO2(RNS)为填料, 用熔融共混法制备SiO2/尼龙1010纳米复合材料, 表征其力学性能并研究了增强和增韧机理. 结果表明,在熔融共混过程中RNS与尼龙1010发生了强烈的界面相互作用, 提高了材料的拉伸强度、断裂伸长率和弹性模量; 而纳米SiO2的表面有机修饰层使材料的韧性有所提高.纳米SiO2质量分数为1.0 %的复合材料拉伸强度最大, 比纯尼龙1010的高4%;而0.7%纳米SiO2 的复合材料断裂伸长率和弹性模量最大, 分别比纯尼龙的高16.6%和13.4%.     

可反应性纳米SiO2/尼龙1010复合材料的制备和力学性能

以可反应性纳米SiO2(RNS)为填料,用熔融共混法制备SiO2/尼龙1010纳米复合材料,表征其力学性能并研究了增强和增韧机理.结果表明,在熔融共混过程中RNS与尼龙1010发生了强烈的界面相互作用,提高了材料的拉伸强度、断裂伸长率和弹性模量;而纳米SiO2的表面有机修饰层使材料的韧性有所提高.纳米SiO2质量分数为1.0%的复合材料拉伸强度最大,比纯尼龙1010的高4%;而0.7%纳米SiO2的复合材料断裂伸长率和弹性模量最大,分别比纯尼龙的高16.6%和13.4%.     

LLDPE/EPDM共混物的超临界CO2微孔发泡研究

研究了线性低密度聚乙烯(LLDPE)/三元乙丙橡胶(EPDM)橡塑共混物在超临界CO_2中的微孔发泡行为。利用扫描电子显微镜对发泡样品的泡孔形貌进行了分析和表征;采用差示扫描量热仪分析了共混物的热性质;分别利用旋转流变仪和万能试验机分析得到样品的流变性能和力学性能。采用一定量的LLDPE与EPDM共混,压制标准试样,然后在高压反应釜中进行发泡,讨论了LLDPE/EPDM共混物中橡塑的质量比、饱和温度、饱和压力对材料泡孔结构和泡孔均匀性的影响。利用超临界CO_2作物理发泡剂,对发泡条件进行优化,可得到泡孔尺寸规整、泡孔密度高且回弹性和韧性较好的发泡闭孔材料。     

LLDPE/EVA/ZnO纳米复合材料的制备与BP-Markov性能预测研究

制备了LLDPE/EVA/ZnO纳米复合材料,并测试了其力学性能.结合BP 神经网络和Markov链建立了BP-Markov模型,并利用此模型对LLDPE/EVA/ZnO纳米复合材料的多指标性能进行了预测.结果表明BP-Markov模型应用于聚合物/无机物纳米复合材料的多指标性能预测具有较高的精度和可靠性,Markov链解决了神经网络在做多指标性能预测时误差的随机性和波动性问题,充分的发挥了神经网络与Markov链预测模型的优点,为在数据有限且具有随机因素的情况下实验数据的分析提供了一种新的思路.     

Mechanical and Barrier Properties of LLDPE/Chitosan Blown Films for Packaging

The blends of linear low‐density polyethylene and chitosan were prepared by using a two‐step melt‐compounding process and then were made into blown films for packaging. LLDPE‐g‐MAH was used as compatilizer to enhance the dispersing effect of chitosan in the matrix. Fourier transform infrared spectra and scanning electron microscope images of the blown films confirmed that there were new amide bonds formed between chitosan and LLDPE‐g‐MAH. The mechanical and barrier properties of the LLDPE/chitosan blown films were investigated. The result indicated that the breaking strength and elongation decreased as the chitosan content increased. In addition, the water vapour permeability of the blend films could be improved up to 200% with the increment of chitosan content, and the oxygen permeability decreased about 20% compared with the films without chitosan. It was found that LLDPE‐g‐MAH had obvious effects on the mechanical properties and oxygen permeability apart from the water vapour resistance. Copyright © 2015 John Wiley & Sons, Ltd.     

SiO2不同的掺杂方式对聚氨酯树脂材料性能的影响

采用溶胶凝胶法制备纳米SiO2颗粒,然后在聚氨酯弹性体/SiO2复合材料的不同制备方法方面进行了尝试,并针对SiO2不同的掺杂方式对聚氨酯树脂材料性能的影响进行了研究,为聚氨酯弹性体性能的优化提供了一条最佳的思路和方法.利用红外分光光度计(IR)、万能电子试验机、动态力学分析仪(DMA)、量热示差扫描仪(DSC)、紫外/可见/近红外分光光度计(UV/VIS/VIR)分别表征了纳米复合树脂材料的结构、力学性能、热稳定性、展色性和干爽性.     

Influence of ZnO/graphene nanolaminate periodicity on their structural and mechanical properties

Structural, electronic and mechanical properties of ZnO/Graphene (ZnO/G) nanolaminates fabricated by low temperature atomic layer deposition (ALD) and chemical vapor deposition (CVD) were investigated. We performed scanning and transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), Raman spectroscopy, X-Ray photoelectron spectroscopy (XPS) and nanoindentation to characterize the ZnO/G nanolaminates. The main structural and mechanical parameters of ZnO/G nanolaminates were calculated. The obtained results were analyzed and interpreted taking into account mechanical interaction and charge effects occurring at the G-ZnO interface. The influence of graphene sublayers number on the mechanical behavior of the ZnO/G nanolaminates was studied. By reducing the bilayer thickness, the mechanical parameters of the films can be tuned (Young’s modulus 100–200 GPa, hardness 3–9 GPa). The softer response of the multilayers as compared to the single layers of ZnO and graphene was attributed to the structural changes in the ZnO layer and the interfaces. This study shows the mechanical behavior of ZnO/G nanolaminates and their influence on the development of novel electro-optical devices based on these structures.     

Producing toughened PP/HA-LLDPE ternary bio-composite using a two-step blending method

The mechanical and morphological properties of polypropylene/hydroxyapatite/linear low density polyethylene ternary bio-composites which were produced by blending of polypropylene (PP), hydroxyapatite, modified and unmodified linear low density polyethylene (LLDPE) were studied. In this research, effects of LLDPE weight percent, modification of PP/LLDPE interface by a high crystallizable high density polyethylene, and the method of blending on tensile strength, Young’s modulus and impact absorbed energy of composites were investigated. Results of mechanical tests showed that by adding LLDPE to these composites, ultimate tensile strength and Young’s modulus of the composites dropped slightly, while their impact strength was increased significantly. Mechanical properties of composites were improved by modification of PP/LLDPE interface and changing from one-step blending to two-step blending. However, for the composites produced by two-step blending, by adding modified LLDPE (15 wt.%), the impact strength was 90% more than that of pure PP/HA composites. Fractography of the surface fractures of the impact samples for both types of composites were performed using a scanning electron microscope (SEM). Two different toughening mechanisms of these composites were distinguished by drawing a schematic sketch of the mechanisms.     

PAN基碳纤维原丝梯级凝固成型的研究

碳纤维是增强复合材料力学性能的重要材料,优质的PAN原丝是制备高性能碳纤维的前提,而原丝的结构主要决定于纤维成形阶段。本文以相图为指导,采用湿法纺丝得到了不同成型条件下的纤维原丝,并利用扫描电镜研究了纤维的横截形貌和皮芯结构。研究表明经过梯级凝固成型后,可以得到结构均匀致密且具有较优物理机械性能的原丝,证实了在相图中梯级凝固成型路线是较优的热力学路线。     

ZnO准一维纳米结构生长形态的演化机理

利用气相生长系统,通过调控实验参数,制备了多种形貌的ZnO准一维结构,如纳米条带、[011-0]和[21-1-0]取向的单侧生齿的梳状纳米条带、微米尺度的梳状结构,由多节状六角棱柱和八角棱柱组装成的微米条带等.通过X射线衍射、扫描电子显微镜及其所加载的能谱分析和背散射电子衍射仪、高分辨透射电子显微镜等分析技术, 对其中具有代表性的介观结构进行了系统的形貌分析和细致的结构解析.分析出基本的结构单元及其复合体, 揭示了显微尺度下ZnO晶体的外形多样性以及其形态演化中的关联和规律,即ZnO纳米条带、梳状结构和多节状微米条带具有晶体结构上的同一性.     

Facile synthesis, optical and photoconductive properties of novel ZnO nanocones

Large-scale, uniform ZnO nanocones with tips about 200 nm and length about 50 μm have been synthesized by a facile hydrothermal method. The morphology and structures were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HR-TEM). The effects of reaction time and PEG-400 on the morphology of ZnO nanostructures were investigated, also an oriented attachment mechanism has been briefly proposed. The optical properties were investigated by lasing confocal microscope and photoluminescence spectrum, a strong near band edge emission peak centered at 387 nm from the ZnO nanocones was observed in photoluminescence spectrum. Finally, we have fabricated UV photodetector based on single ZnO nanocone, which present good switching properties by turning the UV light on and off.