The research for high‐elastic modified asphalt

High‐elastic modified (HEM) asphalt was prepared by the addition of styrene‐butadiene‐styrene (SBS), plasticizer, and crosslinker to base asphalt. The effect and proportion of each modifier in asphalt were studied using physical and rheological tests. It was found that SBS determined the high‐temperature performance of HEM asphalt mainly. Plasticizer (dioctyl phthalate) is very helpful in improving the low‐temperature flexibility and elastic recovery. Crosslinker (sulfur) is necessary in maintaining high‐temperature stability. In this study, Fourier transform infrared, hydrogen nuclear magnetic resonance analysis, and microscopy observation were used to investigate the structural characteristics of modified asphalts further before and after ageing. The research showed the structural characteristics of modified asphalt were influenced evidently by ageing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42132.     

Fundamental characterization of SBS‐modified asphalt mixed with sulfur

The purpose of this study was to characterize the mechanical behavior of asphalt modified by styrene–butadiene–styrene (SBS) and sulfur. Viscosity, microscopy, and rheological tests were conducted to understand the engineering properties of the polymer‐modified asphalt (PMA). Without the addition of sulfur, the polymer‐modified asphalt was microheterogeneous and was made up of two distinct finely interlocked phases, especially at high SBS concentrations. After the addition of sulfur, the PMA was observed to have smaller asphalt domains and a fairly homogeneous dispersion of the asphalt in the SBS matrix. The compatibility between polymer and asphalt produced an elastic network into the asphalt. The addition of sulfur resulted in an excellent elastic system and substantially increased the rheological properties of the PMA. Because of the colloidal nature of asphalt cements, their engineering properties were greatly improved because of the reinforcement of the SBS polymer and the physical‐chemical interaction between SBS and asphalt. The difference in the softening point between the top and bottom layers decreased significantly, and elastic recovery increased when was sulfur was present. A viscoelastic model was examined and shown to be appropriate for predicting the rheological properties ofthe asphalt–SBS blend mixed with sulfur. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2817–2825, 2007     

Physical and rheological properties of crumb rubber/styrene–butadiene–styrene compound modified asphalts

In order to improve the storage stability and tenacity of crumb rubber modified (CRM) asphalt, CRM compound modified asphalt was prepared by the addition of styrene–butadiene–styrene (SBS) and sulfur. The addition of SBS improved the tenacity of CRM asphalt, due to the formation of a dense polymer network. The storage stability of crumb rubber (CR)/SBS‐modified (CRSM) asphalt was improved by the addition of sulfur. The rheological tests confirmed the effect of SBS and sulfur on the physical properties of CRM asphalt to some extent and showed the susceptibility of CR/SBS/sulfur‐modified (CRSSM) asphalt to dynamic shearing. The morphology observation showed the compatibility of CRSM asphalt was improved greatly by vulcanization. POLYM. COMPOS., 38:1918–1927, 2017. © 2015 Society of Plastics Engineers     

The composition and ageing of high‐viscosity and elasticity asphalts

Different kinds of plasticizers and crosslinkers were used to prepare high‐viscosity modified (HVM) asphalt and high‐elastic modified (HEM) asphalt and the major physical properties were studied and compared. The kinds of plasticizers were optimized and the difference in composition between HVM and HEM asphalts was clarified. The plasticizers with different thickness and flexibility were available for HVM or HEM asphalts respectively. The kinds of crosslinkers were also compared and optimized and it was found that the most effective crosslinker was sulfur. The effect of anti‐ageing reagent on HEM asphalt was confirmed and it was found that one of the most effective way to retain the properties of HVM and HEM asphalt before ageing was to increase the SBS content further. POLYM. COMPOS., 38:2509–2517, 2017. © 2015 Society of Plastics Engineers     

Use of rheological compatibility criteria to study SBS modified asphalts

Polymer‐modified asphalts (PMAs) were prepared using Bachaquero asphalt and styrene–butadiene–styrene (SBS) type copolymers. Their rheological behavior was compared to that of unmodified asphalt and of a compatible commercial PMA. Materials were submitted to frequency sweeps between 10^?1 and 10² rad/s from 0 to 50°C. Storage stability tests were performed for 72 h at 160°C. Ring and ball softening points from the top and the bottom of the blends were compared and were used along with fluorescence microscopy to evaluate stability. Samples prepared with styrene–ethylene–butylene–styrene (SEBS) showed improved compatibility and stability as compared with SBS‐modified asphalts, probably because of a higher stability to thermal degradation from the absence of double bonds. An additional improvement in stability and compatibility was observed for SEBS functionalized with maleic anhydride (SEBS‐g‐MAH)–modified blends. Better compatibility, however, did not improve rheological behavior at low temperatures. The systems studied are so complex from a chemical point of view that the rheological criteria normally used to predict compatibility of polyblends did not give enough information regarding the compatibility of the modified asphalts. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1772–1782, 2003     

Comparative study of the effect of sulfur on the morphology and rheological properties of SB‐ and SBS‐modified asphalt

The modification of asphalt with styrene‐ butadiene block copolymers and sulfur was studied to elucidate the effect of the molecular characteristics of the polymer, polymer content, and sulfur/polymer ratio on the physical properties of modified asphalts. Two types of styrene‐butadiene copolymers were used (SB and SBS), which differed considerably in terms of their chain architecture, average molecular weights, and size and distribution of their polybutadiene and polystyrene blocks, as shown by gel permeation chromatography, infrared spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. Sulfur/polymer/asphalt blends were prepared by a hot mixing process and characterized by conventional tests, fluorescence microscopy, and rheology. The results revealed that the morphology of the blends is strongly dependent on polymer concentration and sulfur/polymer ratio. In‐depth rheological characterization showed that the thermomechanical properties changed considerably upon addition of small amounts of sulfur. Collectively, these results suggest that sulfur increases the compatibility between polymer and asphalt by crosslinking polymer chains. Interestingly, the rheological behavior of blends prepared with a combination of SB and sulfur was similar to that exhibited by blends prepared with SBS either in the presence or absence of sulfur. This is explained by assuming that the addition of small amounts of sulfur to SB‐modified asphalt facilitates the formation of an elastomeric network that resembles the one found in SBS‐modified asphalt, effectively contributing to asphalt reinforcement. Nonetheless, the exact dosage of sulfur must be carefully controlled to prevent gel formation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚烯烃弹性体/苯乙烯-丁二烯-苯乙烯嵌段共聚物改性沥青混合料的抗老化性能

采用聚烯烃弹性体（POE）对苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）改性沥青进行复配改性,制备了POE/SBS改性沥青混合料。考察了POE用量对SBS改性沥青抗老化性能的影响。结果表明,POE/SBS复配改性能提升沥青混合料的高温抗老化性能,且对低温性能有一定的改善效果。POE改善了SBS改性沥青混合料的抗车辙和抗老化性能,但会在一定程度上降低其低温韧性。当在沥青中加入质量分数分别为4%和3%的SBS和POE,POE/SBS改性沥青混合料的综合性能较佳。     

SBS对沥青性能的影响

通过测试软化点、针入度和延度对SBS改性沥青的性能进行表征.结果表明:使用线型或星型SBS作为沥青改性剂可以显著提高沥青性能.当硫黄稳定剂质量分数为0.2％,SBS质量分数为4％时,改性沥青的软化点、针入度和延度趋于稳定.此外,相较于线型SBS改性,星型SBS改性沥青的软化点稍高,针入度和延度相对更小.     

苯乙烯-丁二烯-苯乙烯嵌段共聚物改性沥青的老化性能

考察了苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)和加入含硫稳定剂的SBS改性沥青老化后的动态力学性能、黏度变化和低温物理性能。结果表明,SBS与含硫稳定剂的加入改善了老化后沥青的高温性能;老化后的改性沥青表现出更好的高温刚性,蠕变劲度降低,蠕变速率增大,老化后沥青的低温性能提高,且长期使用性能良好。     

Evaluation of high temperature performance of SBS + Gilsonite modified binder

SBS is a widely used polymer modifier for asphalt binders to improve the performance properties of hot mix asphalt. SBS is nearly indispensable when the binder properties do not satisfy the specification requirements under hot service temperatures. One of the concerns in using such additives, however, is the increased cost especially for large-sized construction projects. If a natural modifier can be used to replace some portion of industrial modifier products, such as SBS, it would significantly help reduce the cost of pavement construction. In this study, Gilsonite, a natural asphalt, is used as a binder modifier to reduce the SBS content based on a series of rheological testing. While studies on various properties of binder that is modified only by Gilsonite are common, we investigate the effect of combining SBS and Gilsonte in the same base binder. In the first phase, the binders modified individually with SBS and Gilsonite are evaluated in terms of based on the outcomes of dynamic shear rheometer and rotational viscosimeter tests. Then, the asphalt binders including both SBS and Gilsonite at different contents are subjected to the same rheological testing. The results show that around 3-4% times more Gilsonite is needed to replace 1% of SBS when the two modifiers are mixed in the same binder depending on the Gilsonite/SBS ratio selected. Besides, the viscosity of modified binders with a percent of SBS replaced with Gilsonite is always lower than that of SBS-only modified binder. It is suggested that Gilsonite can be used as an alternative modifier to reduce the cost of asphalt mixture production and compaction in the field.     

Improved properties of SBS‐modified asphalt with dynamic vulcanization

Storage‐stable styrene‐butadiene‐styrene triblock copolymer (SBS)‐modified asphalt was prepared by dynamic vulcanization. The vulcanization characteristics of the asphalt/SBS/sulfur blend were studied using a strain‐controlled rheometer. The vulcanization of SBS in the asphalt resulted in a marked increase in the torque of the blend. In addition, the vulcanization of a butadiene rubber (BR)/sulfur blend was significantly influenced by the addition of asphalt through a curemeter. The existence of asphalt can accelerate the vulcanization of BR/sulfur blend and reduce its reversion. The preparation process of storage‐stable SBS‐modified asphalt by dynamic vulcanization was identified by a plot of the electric current versus time. The addition of sulfur to the SBS‐modified asphalts resulted in the formation of chemically vulcanized network structures in the modified binders. The physical properties of the SBS‐modified asphalt containing sulfur were compared to those of the modified binders without sulfur. The storage stability of the SBS‐modified asphalt was effectively improved by the addition of sulfur. The rheological properties of the SBS‐modified asphalts before and after adding sulfur were characterized by using dynamic shear rheometry and a rotational viscometer. As indicated by the monitored morphology, the compatibility and high‐temperature storage stability of SBS‐modified asphalts were improved by the addition of sulfur.     

微藻油改性沥青耐老化性能研究

为缓解石油沥青短缺局势,探索微藻油用于沥青改性可行性及改性沥青长期性能,将微藻液经降解、离心、萃取得到微藻油并制备改性沥青。通过不同微藻油掺量下改性沥青延度、软化点和黏度确定微藻油最佳掺量,通过高低温流变试验、混合料路用性能试验分析微藻油改性沥青经旋转薄膜烘箱(RTFOT)短期老化、压力老化容器(PAV)长期老化和紫外老化后性能变化并与SBS改性沥青对比,借助红外光谱分析微藻油改性沥青分子结构组成。结果表明:微藻油掺量为30%(外掺质量分数)时,改性沥青延度达到最大值,软化点和黏度满足改性沥青要求;微藻油改性沥青和苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性沥青经RTFOT短期老化后性能差异不显著,微藻油改性沥青耐PAV长期老化和耐紫外老化性能优于SBS改性沥青,尤其是耐紫外老化性能更优。红外分析表明两种改性沥青均含有乙烯基双键、芳香族C—H、甲基和亚甲基等类似成分,但芳香族C—H、伸缩C—C成分含量存在差异。微藻油改性沥青比SBS改性沥青增加的酰胺不饱和基团和羧基利于改性沥青形成网络分子结构。     

基于正交试验的多聚磷酸复配SBS改性沥青粘弹性研究

为了探究多聚磷酸(PPA)复配SBS改性沥青组成材料对其粘弹性的影响,本文以SK90#基质沥青、SBS改性剂、抽出油、稳定剂、PPA、邻苯二甲酸二丁酯(DBP)为原材料,在正交试验设计的基础上,用高速剪切机制备了PPA复配SBS改性沥青,利用动态剪切流变仪分析了其粘弹特性.结果表明:(1)随着温度的升高,PPA复配SBS改性沥青的抗车辙因子随之降低、弹性减弱、抗永久变形能力降低,而其相位角增大、粘性增强、不可恢复变形能力提高.(2)当多聚磷酸的掺量为0.5％,复配改性沥青的其他组分选择最大掺量(均为3号水平)时提高了其粘弹性能,达到最优流变性能.(3)当PPA掺量为0.5％,SBS掺量为4％,抽出油掺量为2％,DBP为2％时,其复配改性沥青的性能最佳.     

基于储存稳定性的橡胶改性沥青制备工艺

为了制备储存稳定性良好的橡胶改性沥青,基于高温混炼工艺,使用聚苯乙烯-聚丁二烯-聚苯乙烯嵌段聚合物(SBS)、芳烃油、辛烯聚合物橡胶反应剂(TOR)、稳定剂与橡胶粉对基质沥青进行复合改性。提出了橡胶改性沥青的制备方法,分析了改性剂对沥青常规性能和流变特性的影响,并通过荧光试验观察改性剂在沥青中的分散效果。研究结果表明:添加质量分数为25%的40目(380 μm)胶粉可以明显提高沥青的高温性能;180 ℃下剪切60~90 min后溶胀发育60 min可以得到稳定性良好的橡胶改性沥青;加入相容剂和稳定剂可以提高胶粉的溶胀与分散程度,改性剂之间对沥青性能的影响存在协同作用;复合改性沥青具有良好的弹性恢复能力和高温抗变形性能;橡胶粉、SBS在沥青中的溶胀程度和分散均匀性是影响沥青常规性能和储存稳定性的直接因素。     

Artificial aging of polymer modified bitumens

This paper presents an investigation of artificial aging of polymer modified binders, prepared from three base bitumens and six polymers. Aging of the binders was performed using the Thin Film Oven Test (TFOT), the Rolling Thin Film Oven Test (RTFOT), and modified RTFOT (MRTFOT). The binders were characterized by means of infrared spectroscopy, different types of chromatography, and dynamic mechanical analysis. It was found that the effect of aging on the chemistry and rheology of the modified binders was influenced by the nature of the base bitumens and was strongly dependent on the characteristics of the polymers. For styrene–butadiene–styrene (SBS) and styrene–ethylene–butylene–styrene (SEBS) modified binders, aging decreased the complex modulus and increased the phase angle. Aging also increased the temperature susceptibility of these modified binders. The rheological changes of SBS modified bitumens were attributed to polymer degradation and bitumen oxidation. However, for SEBS modified bitumens, the mechanisms of aging are unclear. In the case of ethylene vinyl acetate (EVA) and ethylene butyl acrylate (EBA) modified binders, the process of aging increased the complex modulus and elastic response (decreased phase angle), and reduced temperature susceptibility. These changes were mainly due to the oxidative hardening of the base bitumens. The study also showed statistically significant correlation between TFOT, RTFOT, and MRTFOT. However, no definite conclusions could be drawn regarding the difference in severity of aging between these methods. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1811–1824, 2000     

Evaluation of polyphosphoric acid on the performance of polymer modified asphalt binders

The aim of this research is to evaluate the effect of polyphosphoric acid (PPA) on the mechanical performance of styrene–butadiene–styrene (SBS) and styrene–butadiene–rubber (SBR) modified asphalt. Conventional properties, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) tests were conducted to evaluate the performance characteristics of asphalt at different PPA inclusions. Gel-permeation chromatography (GPC), saturates, aromatics, resins, and asphaltenes (SARA), and Fourier transform infrared (FTIR) were carried to reveal the molecular weight, component and infrared spectra of asphalt. Results showed that PPA hardened the asphalt, improved the rutting and fatigue performances of polymer modified asphalt (PMA) binder, but weakened the anti-cracking performances. Besides, storage stability had a significant improvement as the addition of PPA. The addition of PPA brought more macromolecules into asphalt and led to more high-average molecular weight compounds. Furthermore, PPA changed four component ratios of asphalt. Both PMA with or without PPA have similar absorption peaks. This may be due to absorption peak of PMA covered the changes in PPA modification process as the low content of PPA. 0.8% dosage of PPA may be considered optimum for composite modified binder combining the above experimental results for this binder source.     

接枝SBS的研究进展及其在改性沥青中的应用

苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）作为一种性能优异的热塑性弹性体,已成为目前应用最广泛的聚合物沥青改性剂。本文针对SBS与沥青物化性质差异较大、相容性不足、制备的改性沥青易离析的应用缺陷,在阐释接枝SBS接枝原理的基础上,总结了以引发剂法和辐射接枝聚合法为代表的接枝方法,综述了不同单体接枝SBS作为沥青改性剂的研究现状,通过分析评价提出了今后的研究重点,即选择极性合适、不影响沥青性能的单体,综合研究物料用量、温度、时间等因素来严格控制接枝SBS合成过程,全面准确地表征接枝物结构及接枝率等参数,并深入研究其改性沥青机理,建立整套指标体系。     

Performance of biomimetic coating modified fiber incorporated styrene butadiene styrene modified asphalt

This study reports the effect of polydopamine bionic coating and γ-methacryloxypropyltrimethoxysilane (KH570) composite modified polyacrylonitrile (PAN) fiber as a secondary modifier on the performance of styrene-butadiene-styrene (SBS) modified asphalt. Dynamic shear rheometer test indicated the complex shear modulu, storage modulus, and loss modulus of modified PAN (KD-PAN) incorporated SBS modified asphalt was increased by 12.4, 20.5, and 11.2%, respectively compared with PAN/SBS modified asphalt. The master curve of G^* of fiber/SBS composite modified asphalt shows that the deformation resistance of KD-PAN/SBS modified asphalt is greater than that of PAN/SBS modified asphalt in the entire loading frequency range. The cone penetration test showed significantly enhanced shear strength of KD-PAN/SBS modified asphalt. The adhesion work test results and SEM images of interface between fiber and SBS modified asphalt revealed that the adhesion effect of KD-PAN and SBS modified asphalt is better than that of PAN and SBS modified asphalt. SEM and AFM images of fiber further showed that the fiber surface becomes rough after modification. The increased surface roughness of KD-PAN facilitated the adherence of SBS modified asphalt to it, which in turn led to the enhanced performance of KD-PAN/SBS composite modified asphalt at the same fiber content and temperature.     

Preparation and properties of high viscosity and elasticity asphalt by styrene–butadiene–styrene/polyurethane prepolymer composite modification

The porous asphalt pavements is often used in important occasion for its special properties and performance which can be to a great extent attributed to the binder—high viscosity and elasticity asphalt (HVEA). To prepare high demanding binder for porous asphalt pavements, the polyurethane prepolymer (PUP) and styrene–butadiene–styrene (SBS) were used to modify the matrix asphalt compositely. First, based on a series of physical tests, the effects of binder composition on performance of SBS/PUP HVEA binder (SBS/PUP-HVEA) were investigated. Then the Fourier transform infrared (FTIR) test was conducted to investigate the reaction mechanism of SBS/PUP-HVEA binder. Last, the fluorescence microscopy, stability tests, multiple stress creep recovery test, and differential scanning calorimetry test were carried out to evaluate and compare the phase structure, storage, high-temperature performance, thermostability characteristics of several HVEA binders. It is found that the composite modification of SBS and PUP can produce high quality binder which possesses high viscosity and high elasticity. And the composition of SBS/PUP-HVEA were recommended as follows: Shell-70# can be chosen as matrix asphalt, the contents of SBS modifier (SBS1301:SBS4303 = 1:2), H2122A PUP, chain extender M-OEA, and crosslinker sulfur were suggested 4%, 5%, 0.5%, and 1‰, respectively. The new functional groups observed in FTIR confirmed the existence of physical and chemical reactions in the modification process, which were beneficial to improve the high temperature performance and storage stability of the binder. SBS/PUP-HVEA had good phase structure, storage stability, high temperature performance, and thermostability compared to other HVEA binders. This study demonstrated that the SBS/PUP compositely modified asphalt possessed high viscosity and high elasticity, which can be used in the porous asphalt mixture and other highly demanding working environment as well.     

Improving the aging resistance of styrene‐butadiene‐styrene tri‐block copolymer and application in polymer‐modified asphalt

Thermal oxidation process of styrene‐butadiene‐styrene (SBS) copolymer was studied by using a variety of analytical and spectroscopic methods including thermal analysis, dynamic mechanical analysis and FTIR spectroscopy. The experimental results indicate that the thermal oxidation process of SBS is a free radical self‐catalyzed reaction containing four steps (initiation, growth, transfer, and termination of the chain) with both crosslinking and scission and the latter is confirmed to be the main process. The antioxidants 1010 as scavenger of free radicals and 168 acting decomposition of hydroperoxides were used to improve the oxidation aging resistance of SBS copolymer. It has been found that synergic effect of 1010 and 168 may be the best in practice and 0.2 wt % 1010 + 0.4 wt % 168 can effectively prevent SBS from the thermal oxidation at certain temperature. Furthermore, the aging resistance of the SBS‐modified asphalt was improved by addition of complex antioxidants. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010