纳米ZnO改性沥青的制备及性能研究

为探究纳米ZnO改性沥青的路用性能,采用高速剪切法制备了纳米ZnO掺量分别为2%,4%,6%及8%的改性沥青,并通过光学显微镜、傅里叶红外光谱仪(FTIR)及差示扫描量热仪(DSC)对改性沥青的微观形貌、化学构成及热稳定性等性能进行表征与分析,再采用动态剪切流变仪和布氏粘度计分别对改性沥青的高温流变性能及黏温特性进行测试。结果表明,纳米ZnO能够均匀分散于基质沥青中,且与沥青发生交联反应,生成一种空间网状结构;纳米ZnO对基质沥青既有物理改性也有化学改性;随着纳米ZnO掺量的增大,改性沥青的低温性能及热稳定性均得到不同程度的改善;改性沥青呈现出更优的高温抗车辙能力及黏温特性。     

纳米ZnO改性沥青的制备及性能研究

为探究纳米ZnO改性沥青的路用性能,采用高速剪切法制备了纳米ZnO掺量分别为2%,4%,6%及8%的改性沥青,并通过光学显微镜、傅里叶红外光谱仪(FTIR)及差示扫描量热仪(DSC)对改性沥青的微观形貌、化学构成及热稳定性等性能进行表征与分析,再采用动态剪切流变仪和布氏粘度计分别对改性沥青的高温流变性能及黏温特性进行测试。结果表明,纳米ZnO能够均匀分散于基质沥青中,且与沥青发生交联反应,生成一种空间网状结构;纳米ZnO对基质沥青既有物理改性也有化学改性;随着纳米ZnO掺量的增大,改性沥青的低温性能及热稳定性均得到不同程度的改善;改性沥青呈现出更优的高温抗车辙能力及黏温特性。     

橡胶改性道路沥青及其微观结构

介绍了橡胶改性道路沥青以达到高性能的改性技术,主要有废橡胶粉改性技术、丁苯橡胶乳液改性技术、SBS改性技术等,各类技术都能有效地提高沥青的路用性能.改性沥青的微观结构研究表明,改性机理是相容性改性、溶胀网络改性、胶体结构变化改性和增强改性等.     

SBS改性脱油沥青宏观性能与微观形态的关系研究

以脱油沥青(DOA)制备针入度30号和50号的调和硬质沥青,并掺量2%到6%的星型SBS在170℃下经剪切、搅拌工艺制备SBS改性硬质沥青,对产物进行常规指标分析及荧光显微检测。常规指标分析表明SBS可以提高沥青的高温稳定性、低温抗裂性能和感温性能;存储稳定性分析表明稳定剂的加入可以明显的改善沥青的稳定性和抗老化性能;荧光显微镜图像表明改性沥青宏观性能与微观结构之间存在相关性,改性沥青要达到较好的宏观性能需要其微观结构中改性剂和沥青呈现均匀连续分散的状态。利用SBS和稳定剂制备优质改性硬质沥青合适配方为:SBS添加量为3.0%,稳定剂添加量为0.2%。     

纳米碳酸钙在密封剂中的应用

综述了纳米碳酸钙在密封剂中的应用及研究现状。着重介绍了纳米碳酸钙的制备过程中对生产工艺和原料的要求。通过“裂缝与银纹相互转化”机理解释了纳米碳酸钙对密封剂的增强机理和作用。提出了纳米粒子在有机介质中,由微观的“微海效应”导致的宏观的触变性的设想。介绍了纳米碳酸钙在密封剂中应用前所需的表面化学改性及表面物理包敷改性,应用中的物理机械分散及原位聚合。并阐述了不同的条件下纳米碳酸钙对密封剂的伸长率、拉伸强度、动态力学等性能的影响。     

基于生物质重油的再生沥青特性多尺度研究

为系统研究生物质重油对道路回收沥青的再生效果及其机理,分别采用高低温流变试验、原子力显微镜技术和红外光谱扫描等多尺度方法,比较分析了沥青老化前后以及不同生物质重油掺量下沥青的宏观流变特性、微观形貌特征以及化学结构等变化规律,并对不同尺度指标之间的内在联系进行了讨论分析.结果表明:沥青在服役过程中在吸氧反应、氢键缔合等作用下发生老化,其微观形貌中蜂状结构数量减少但个体变大,在宏观上表现为粘度、复数模量显著增大,高温性能增强而低温抗裂性能明显变差.随着生物质重油掺量的增大,回收沥青在化学组成和微观形貌上产生逆老化的变化,粘度和复数模量逐渐降低,且低温性能得到有效改善,说明生物质重油对道路回收沥青具有较好的再生效果.此外,为确保再生沥青的高低温性能的平衡,本研究中所采用的的生物质重油掺量建议控制在5％ ～21％范围内.     

橡胶改性道路沥青及其微观结构

介绍了橡胶改性道路沥青以达到高性能的改性技术，主要有废橡胶粉改性技术、丁苯橡胶乳液改性技术、ＳＢＳ改性技术等，各类技术都能有效的提高沥青的路用性能。改性沥表的微观结构研究表明，改性机理是相容性改性、溶胀网络改性、胶体结构变化改性和增强改性等。     

黏层用C9石油树脂/SBR复合改性乳化沥青性能研究

采用C₉石油树脂和SBR胶乳制备高性能复合改性乳化沥青,通过三大指标试验、高温和低温流变试验评价了复合改性乳化沥青的宏观服役性能,借助激光粒度分析仪、荧光显微镜和红外光谱仪分析复合改性乳化沥青的储存稳定性和相容性,揭示C₉石油树脂/SBR复合改性剂对乳化沥青的改性机理。结果表明,C₉石油树脂提高了乳化沥青的力学强度和高温抗变形能力,而SBR胶乳明显改善乳化沥青低温抗裂性能,蠕变劲度最大降低30.4%。制备的C₉石油树脂/SBR复合改性乳化沥青储存稳定性良好,C₉石油树脂和SBR胶乳对乳化沥青的复合改性机理为物理混溶,C₉石油树脂的掺量不高于8%。     

纳米二氧化硅含量对沥青混合料性能的影响

为了减少沥青混合料所产生的诸如永久性变形、疲劳和水损等破坏现象,进一步提高沥青混合料性能显得尤为重要。纳米材料因其在力学、热学和电学性能等方面的优势,在沥青改性中得到了广泛的应用。通过分别向PG64-22号沥青中加入0.5%～6.0%不同剂量的纳米二氧化硅,发现纳米二氧化硅添加剂会对沥青混合料性能产生一定的影响。采用差示扫描量热法、热重分析、傅里叶变换红外光谱和原子力显微镜技术研究了纳米二氧化硅对沥青的改性效果,并进行了定量分析,同时依据动态剪切流变学、车辙试验和粘附性分析试验确定了最佳纳米二氧化硅改性剂含量。     

纳米碳酸钙/苯乙烯-丁二烯-苯乙烯嵌段共聚物复合改性沥青的制备及性能

采用纳米CaCO3和苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）作为外加剂制备纳米CaCO3/SBS复合改性沥青。通过测试基本物理性能确定了外加剂的最佳掺量,通过流变性能测试、离析试验、荧光显微镜观察及热重分析等考察了沥青的性能及微观形貌。结果表明,两种外加剂复配的最佳比例为5%（质量分数,下同）的纳米CaCO3和4%的SBS;在纳米CaCO3改性沥青中掺加SBS后,复合改性沥青在不同温度下的黏度增大,高温抗车辙能力增强,低温性能得到明显改善,储存稳定性良好;纳米CaCO3分子、SBS分子和基质沥青分子三者具有良好的相容性,经复合改性后沥青的热稳定性增强。     

新旧沥青融合多尺度评价研究

应用纳米级技术和宏观力学技术展开对RAP料中旧沥青对新沥青结合料结构和性能的影响,并且对新旧沥青之间的融合程度进行评估。对新沥青、RAP料中抽提出的旧沥青及新旧沥青混合而得的复合沥青进行不同的原子力显微镜试验,除此之外,通过再生沥青的DSR试验和动态模量试验评估得到的新旧沥青融合程度与应用原子力显微镜试验得到的结果相比较。结果表明微观和宏观研究结果具有一致性。     

PE-C9石油树脂改性沥青的研制

实验考察了PE对C9石油树脂改性沥青针入度、软化点以及黏度的影响,并对PE-C9石油树脂改性沥青的老化以及储存稳定性进行分析,采用四组分法对改性机理进行探讨,并利用扫描电镜进行表征。结果表明,当PE与C9石油树脂的质量比为2.1时,改性沥青的针入度,软化点以及黏度均满足要求,同时老化性能和高温储存性能变好。通过四组分的分析可知,C9石油树脂可增加改性沥青体系芳香分的含量,促进PE在C9石油树脂改性沥青中的溶胀和吸附作用,通过电镜观察,当PE与C9石油树脂的质量比为2.1时,PE、C9石油树脂、基质沥青三者形成了稳定的网状结构。     

废旧轮胎橡胶灰分改性沥青的性能研究

为了研究废旧轮胎橡胶灰分用于改性沥青的性能,通过高温热分解方法制备橡胶灰分,并以0%~5.0%掺量对2种基质沥青进行改性.采用沥青三大指标、动态剪切流变试验、针入度指数、布氏粘度、弹性恢复、薄膜烘箱试验和离析试验,评价了橡胶灰分对沥青高、低温性能、温度敏感性、粘温性能、弹性恢复、老化性能和储存稳定性的影响.同时借助扫描电镜观察橡胶灰分的微观形貌,利用荧光显微镜分析改性沥青的均匀程度.结果表明:废旧轮胎橡胶灰分可显著提高沥青的高温性能,降低其温度敏感性,改善其粘温性能;当其掺量低于3.0%时,沥青的弹性恢复得到显著改善,而沥青的低温性能、老化性能和储存稳定性无明显影响;微观试验显示橡胶灰分为不规则的蜂窝状多孔结构,可吸附沥青并在其中均匀分布.     

Stress‐induced changes in microstructure of a low‐crystalline polypropylene investigated at uniaxial stretching

Novel asymmetric metallocene catalysts lead to low isotactic polypropylenes (iPP) with randomly distributed stereo irregularities. The polypropylenes are low crystalline and show elastic mechanical behavior due to physical crosslinking. The morphology of such iPP, which is responsible for the observed mechanical properties, is still sparsely resolved. In the present work a low isotactic, low crystalline metallocene iPP containing randomly distributed stereoerrors was investigated. The influence of the chain microstructure in the elastic properties was studied using two complementary investigation methods, X‐ray diffraction and scanning force microscopy (SFM). For a better understanding of the unique mechanical properties, microscopic changes in morphology and strain‐induced variation in chain orientation were monitored during uniaxial stretching using SFM and wide angle X‐ray scattering measurements. For quantitative analysis and discussion the polymer chain orientations were calculated. The correlation between the orientation, the arrangements of the amorphous and crystalline phases observed by SFM, and the mechanical properties of the material at different elongation ratios allowed an interpretation of the macroscopic behavior on the microscopic scale. It was shown that the deformation behavior of low isotactic polypropylene with randomly distributed stereoerrors is in agreement with existing structural models, which proposed that small crystalline domains act as physical crosslinks for the amorphous matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of polyphosphoric acid (PPA), styrene-butadiene-styrene (SBS), or rock asphalt on the performance of desulfurized rubber modified asphalt

To improve the performance of desulfurized rubber modified asphalt (DRMA), especially its high-temperature performance, three modifiers (including polyphosphoric acid [PPA], styrene-butadiene-styrene [SBS], and rock asphalt) were selected to modify DRMA respectively. The conventional performance, rheological properties, chemical composition, and thermal decomposition were characterized to analyze the performance and modification mechanism of DRMA and its composites. Test results show that, the addition of PPA, SBS, and rock asphalt can all improve the high temperature of DRMA, among which the desulfurized rubber/rock asphalt compound modified asphalt (DRMA-ROCK) has the best high-temperature performance; however, its construction workability, storage stability, and low-temperature performance are poor. In contrast, desulfurized rubber/PPA compound modified asphalt (DRMA-PPA) not only has better high-temperature performance, but also has excellent low-temperature performance, storage stability, and fatigue performance. Fourier infrared spectroscopy (FTIR) test confirms that the modification process of DRMA by these modifiers is chemical modification, and the characteristic peak indexes obtained from FTIR also prove that DRMA-ROCK has better high-temperature performance but poor construction workability from the microscopic point of view. Furthermore, thermogravimetric analysis-differential scanning calorimetry test shows that the addition of rock asphalt improves the thermal stability of DRMA, while PPA and SBS decrease its thermal stability. From the above results, it can be concluded that DRMA-PPA has excellent comprehensive properties.     

新型混凝土掺合料——高活性偏高岭土的研究进展

综述了偏高岭土在混凝土领域国内外的应用现状、研究进展。阐述了具有火山灰特性的偏高岭土在混凝土中的应用机理及其对混凝土微观和宏观性能的影响。     

Experimental investigation of related properties of asphalt binders containing various flame retardants

The improved flame retardancy of asphalt binders containing various kinds of flame retardants including antimony trioxide, decabromodiphenyl ether (EBPED), aluminium trihydroxide (ATH) and zinc borate (ZB) under different additive concentrations was investigated by limited oxygen index (LOI) and differential scanning calorimetry (DSC) test. To assess the effects of the type and concentration of the flame retardants on rheological properties of asphalt binders, the softening point, penetration, ductility, storage stability and viscosity were tested. The thin film oven test (TFOT) was used to investigate the effect of short-term oxidation on flame-resistant asphalt binders. Experimental results indicated that all of selected flame retardants had a relatively small effect of rheological properties of the asphalt binders, but a great effect on flame retardancy. Asphalt binder with LOI of 25.9 was obtained by adding 6 wt% mixed flame retardants of EBPED: antimony trioxide: ZB=3:1:1 by mass. Asphalt binder was transformed from inflammable materials into flame retardant materials. Therefore, the asphalt binder with both good flame retardancy and rheological properties is a novel road functional material to meet two respects' demands as flame retardant materials and road materials at the same time.     

中空聚酯纤维沥青胶浆特性及增韧机理研究

为了研究中空聚酯纤维在沥青胶浆中的作用机理,本文通过在沥青中掺加不同类型和掺量的纤维,研究中空聚酯纤维沥青胶浆的抗剪性能、低温抗裂性能、高温流变性能、热物性和微观形貌特点,并对中空聚酯纤维沥青混合料的路用性能及增韧机理进行分析.研究结果表明:当中空聚酯纤维状态为三维、纤维直径为15D时,对沥青的吸附性能较好;当其掺量为2％时,纤维沥青胶浆的抗剪强度为原沥青胶浆的4.19倍,高温流变性能显著提高;中空聚酯纤维的腔体结构,使沥青胶浆的导热系数降低了15％;沥青混合料的残留稳定度、冻融劈裂强度比、动稳定度和最大弯拉应变较未加纤维的沥青混合料提高了3.1％、5.0％、36.8％和29.0％.沥青与纤维之间的侨联作用,使纤维成网状结构,提高了抗裂性能和高温稳定性能.     

基于正交试验的废轮胎胶粉改性沥青微观特性研究

通过4水平4因素正交试验设计方案制备了废轮胎胶粉改性沥青,并对最优组合胶粉改性沥青进行了薄膜烘箱老化试验。通过对沥青基础指标的测试及傅里叶变换红外光谱、四组分及热重的分析,从宏观角度评价了不同沥青的性能变化,微观角度分析了胶粉改性沥青的化学组分及变化规律。研究结果表明,胶粉改性沥青的最优配比组合为胶粉掺量17%（质量分数,下同）、搅拌温度180 ℃、改性剂质量配比1/6和增塑剂掺量4%。用胶粉改性后沥青的红外光谱特征吸收峰的形状及位置未变,但强度发生变化;使化学组分的含量产生了变化,饱和分和芳香分减少、胶质和沥青质增加。胶粉的掺入降低了沥青的热降解速率,提高了初始降解温度及最终残留物含量,改善了沥青的热稳定性。     

Similarity in field electron emission from nanocrystalline diamond and related materials

Results on a complex study of macroscopic and microscopic electronic properties of nanocrystalline diamond and related material (BN, GaN, CN) films are presented. It was found that all the samples studied showed similar dependencies of macroscopic emission parameters (the Fowler–Nordheim work function, the effective emitting area) on the film emissivity. Also, some microscopic properties were found to be common for all the films tested. It was generally observed that field electron emission occurred at nanosized regions on the boundary of high and low resistivity areas, and peaks of the emission intensity were associated with a lowered surface electron potential. Based on the experimental data, a mechanism of field electron emission from the surface of nanocrystalline films is proposed. We suppose that electrons are transported from narrow conducting channels into vacuum through specific low-dimensional regions, the electronic properties of which, due to the quantum size effect, are different from the bulk material. In this case the base material grains play a role of the conductive channel-containing matrix as well as a heat sink. Details of the new low-field emission mechanism including the filling of discrete energy states, and the decrease in the work function under the action of electric field are discussed.