LDHs对SBS改性沥青性能的影响研究

发布时间：2018-07-20 10:58

【摘要】：层状双羟基金属复合氢氧化物(LDHs)是一种具有层状结构的超分子材料,对紫外光线具有反射、散射和吸收作用,能有效降低紫外光对有机材料的破坏,改善SBS改性沥青的耐紫外老化性能。由于LDHs中主板金属元素的组成、层间客体阴离子的种类等因素均会影响着LDHs的抗紫外线的能力,因此研究不同组成结构的LDHs对SBS改性沥青耐老化性能的影响规律,可为制备耐老化性能优良的SBS改性沥青提供实验和理论指导。本文分别选用清洁工艺生产的Mg-Al LDHs,传统共沉淀法与成核/晶化隔离法生产的Mg-Al LDHs,以及不同金属元素组成的Zn-Mg-Al LDHs,采用X-射线荧光光谱(XRF)、傅立叶变换红外光谱(FTIR)、扫描电镜(SEM)、X-射线衍射(XRD)等手段分析表征了不同LDHs的组成与结构,利用紫外-可见光谱(UV-VIS)测试了不同LDHs的紫外反射性能;将不同LDHs掺加到SBS改性沥青中,研究了不同LDHs对SBS改性沥青物理、紫外老化和热氧老化性能的影响。主要研究结论如下:(1)传统工艺制备的Mg-Al LDHs与清洁生产工艺制备的Mg-Al LDHs层间距相同,但粒径差异较大,前者粒径为50~100nm,后者粒径为300~400nm。紫外-可见光谱分析表明,LDHs对紫外光线的屏蔽阻隔效果与LDHs的粒径大小以及层板金属元素的组成有关:LDHs的粒径与紫外光线的波长相差越小,紫外阻隔能力越好;在Mg-Al LDHs金属层板中引入Zn元素,可明显提高LDHs对紫外光线UVC段的吸收效果。(2)不同种类LDHs对SBS改性沥青的软化点和低温柔度的影响均较小,随着LDHs掺量增加,SBS改性沥青的低温柔度也基本不变,而软化点略微增大。(3)LDHs可显著的提升SBS改性沥青的耐紫外光老化能力,其改善效果主要与LDHs的粒径大小有关:LDHs的粒径与紫外光线的波长越接近,SBS改性沥青耐紫外光老化的能力越好。所以使用粒径范围为200~400nm的LDHs,可大大降低太阳光中UVB与UVA波段的紫外线对沥青的老化作用。LDHs层板金属元素的变化对SBS改性沥青耐紫外光老化能力的影响较小,LDHs板层引入Zn元素并没有明显提高改性沥青耐紫外光老化的能力。(4)LDHs可有效降低热氧老化后沥青软化点与低温柔度的变化,改善SBS改性沥青耐热氧老化的能力。这可能是因为LDHs的片层结构能阻隔氧气进入SBS改性沥青内部,减少沥青在热与氧作用下的老化反应。(5)对于使用不同基质沥青制备的不同SBS改性沥青,LDHs对它们物理性能的影响均很小,但对它们耐紫外光老化性能影响则有较大差异:沥青所含饱和分、芳香分等轻组分较少时,耐老化性更为优异。
[Abstract]:Layered double hydroxyl metal hydroxide (LDHs) is a kind of supramolecular material with layered structure, which can reflect, scatter and absorb ultraviolet rays, which can effectively reduce the destruction of organic materials by ultraviolet light. The UV aging resistance of SBS modified asphalt was improved. Because the composition of main board metal elements and the kinds of guest anions in LDHs affect the UV resistance of LDHs, the effects of LDHs with different composition on the aging resistance of SBS modified asphalt are studied. It can provide experimental and theoretical guidance for the preparation of SBS modified asphalt with excellent aging resistance. In this paper, Mg-Al LDHs produced by clean process, Mg-Al LDHs produced by conventional co-precipitation and nucleation / crystallization isolation method, and Zn-Mg-Al LDHs made of different metal elements were selected. X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FTIR) and scanning were used. The composition and structure of different LDHs were characterized by means of electron microscopy (SEM) and X-ray diffraction (XRD). The UV reflectance of different LDHs was measured by UV-VIS, and the effects of LDHs on physical, ultraviolet aging and thermal oxygen aging properties of SBS modified asphalt were studied by adding different LDHs into SBS modified asphalt. The main conclusions are as follows: (1) the interlayer spacing of Mg-Al LDHs prepared by traditional process is the same as that of Mg-Al LDHs prepared by cleaner production process, but the particle size of the former is 50 ~ 100nm, while the latter is 300 ~ 400nm. The UV-Vis spectrum analysis shows that the shielding barrier effect of LDHs on UV lines is related to the size of LDHs and the composition of metal elements in laminate. The smaller the difference between the diameter of LDHs and the wavelength of UV lines is, the better the UV barrier ability is. When Zn element was introduced into Mg-Al LDHs metal laminates, the absorption effect of LDHs on UV UVC segment could be improved obviously. (2) the effects of different LDHs on softening point and low softness of SBS modified asphalt were small. With the increase of LDHs content, the low softness of SBS modified asphalt is almost unchanged, while the softening point is slightly increased. (3) LDHs can significantly improve the UV aging resistance of SBS modified asphalt. The improvement effect is mainly related to the particle size of LDHs. The closer the diameter of w LDHs to the wavelength of UV ray is, the better the resistance to UV aging of SBS modified asphalt is. So using LDHs with particle size range of 200~400nm can greatly reduce the aging effect of UVB and UVA-band ultraviolet rays on asphalt. The effect of metal elements on the UV aging resistance of 200~400nm modified asphalt is smaller than that of LDHs. (4) LDHs can effectively reduce the change of softening point and low tenderness of modified asphalt after thermal oxygen aging. Improve the heat and oxygen aging ability of SBS modified asphalt. This may be because the lamellar structure of LDHs prevents oxygen from entering the SBS modified asphalt. Reduce the aging reaction of asphalt under the action of heat and oxygen. (5) the effect of LDHs on the physical properties of different SBS modified asphalt prepared from different base asphalt is very small. However, the effect on their UV aging resistance is quite different: when the asphalt contains saturated fraction and less light component, such as aromatics, the aging resistance of asphalt is better.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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