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     

Improvement of bitumen performance with epoxy resin

This paper studies the modification of petroleum bitumen with epoxy resin. Different amounts of epoxy were doped into bitumen with 50/70 penetration grade and variations in viscosity as a function of temperature and additive concentration were determined. The effects of the epoxy additive were examined by rheometer, penetration, softening point, DSR (dynamic shear rheometer), DSC (differential scanning calorimeter), RTFOT (rolling thin film oven test), PAV (pressure aging vessel), BBR (bending beam rheometer) and surface tension tests. Adhesion and stability of bitumen aggregate mixtures prepared using original and modified bitumen were compared using Nicholson stripping and Marshall tests. The optimum dosage of the additive yielding the best rheological and performance properties was found to be 2% (w/w). Appreciable decrease in the formation of rutting, bleeding, stripping and cracking of modified bitumen may be obtained through epoxy addition.     

Rheological properties of bitumen modified with ethylene butylacrylate glycidylmethacrylate

This article presents experimental results related to rheological viscoelastic properties of polymer modified bitumens, PmBs. Experiments were performed by a dynamical shear rheometer before and after thermo‐oxidative aging. Two types of bitumens with different asphaltene contents were modified by the addition of two types of reactive ethylene terpolymers, Elvaloy AM, and Elvaloy 4170, with a different percentage of reactive functional group, glycidylmethacrylate, GMA. Results of the investigation indicate that the degree of reactive polymer modification is a function of bitumen type, bitumen‐polymer compatibility, and polymer concentration. Polymer modification improves the following physical properties of the base bitumen: penetration, softening point, temperature susceptibility, and elastic recovery. Reactive polymers are effective binder modifiers that improve the susceptibility to high temperature of asphalt mixes, and also their rutting resistance, contribute to their good storage stability and make them less sensitive to aging. This is a result of the formation of a chemical bond between the polymer and molecules of asphaltenes. POLYM. ENG. SCI., 54:1056–1065, 2014. © 2013 Society of Plastics Engineers     

Evaluation of rheological and image properties of styrene‐butadiene‐styrene and ethylene‐vinyl acetate polymer modified bitumens

This article presents a laboratory evaluation of conventional, fundamental, rheological, and morphological characteristics of styrene‐butadiene‐styrene (SBS) and ethylene vinyl acetate (EVA) polymer modified bitumens. Polymer modified bitumen (PMB) samples have been produced by mixing a 50/70 penetration grade unmodified (base) bitumen with SBS and EVA copolymer at different polymer contents. The fundamental viscoelastic properties of the PMBs were determined using dynamic (oscillatory) mechanical analysis and presented in the form of temperature and frequency‐dependent rheological parameters. The morphology of the samples as well as the percent area distribution of polymers throughout the base bitumen have been characterized and determined by means of fluorescent light optic microscopy and Qwin Plus image analysis software, respectively. The results indicated that polymer modification improved the conventional and rheological properties of the base bitumen. It was also concluded that the temperature and frequency had a significant effect on complex modulus of PMBs. The behavior of EVA and SBS PMBs had exhibited quite difference at 50°C. Moreover, it was found out that at low polymer contents, the samples revealed the existence of dispersed polymer particles in a continuous bitumen phase, whereas at high polymer contents a continuous polymer phase has been observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Enhancement of rheological and mechanical properties of bitumen using styrene acrylonitrile copolymer

In this research, styrene acrylonitrile copolymer as a novel additive is used to modify rheological, mechanical and thermal properties of the base bitumen 70 penetration grade. Styrene acrylonitrile copolymer combines the rigidity of polystyrene with the hardness and thermal resistance of polyacrylonitrile to enhance viscoelastic property of the bitumen. To investigate the performance of the proposed mixture, shear complex module, phase angle, penetration, softening point, and reversibility of prepared samples are measured at different additive content and compared with the base bitumen. The results show that softening point of the base and modified samples are 49–86°C, respectively. The rheological properties of the base bitumen and modified samples are measured by a dynamic shear rheometer (DSR). The phase angle as elasticity measure decreases from 55° to 35° in the modified bitumen compared to the base bitumen. Generally, the experimental results showed that styrene acrylonitrile copolymer makes bitumen to be more stable at high temperatures and more flexible at low temperatures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41875.     

The influence of UV aging of a Styrene/Butadiene/Styrene modified bitumen: Comparison between laboratory and on site aging

During the service life in a pavement, neat bitumen and modified bitumen age as the result of the mixing with aggregates, the process of laying, the climatic conditions and the traffic. Laboratory methods for simulating the short-term and long-term ageing (RTFOT and PAV, respectively) are standardized. None of them takes into account the influence of UV radiations. In the particular case of a pavement located in south France, a comparison is drawn through Fourier Transformed InfraRed (FTIR) analysis. Three types of ageing are compared: the standard simulated ageings, the actual on site ageing after 12 and 26 months of road service and the ageing when UV exposure in a weathering oven follows RTFOT simulation. According to carbonyle function evolution by FTIR spectroscopy, this work shows that for all tested binders, the same ageing level as the one simulated by PAV is reached in a few hours when a thin film of binder is submitted to UV exposure after RTFOT. It is also to be noted that the level of the on site ageing of a SBS Polymer modified Bitumen (PmB) reaches the simulated PAV ageing after 12 months of pavement life.     

Rheological characterization of polypropylene/poly(ethylene-<Emphasis Type="Italic">co</Emphasis>-propylene) in-reactor blends synthesized under different polymerization conditions

In-reactor blends of polypropylene/poly(ethylene-co-propylene) with complex microstructure, synthesized through different polymerization procedures; two-step (one homopolymerization and one copolymerization under high ethylene concentration) and three-step (with an additional copolymerization step under low ethylene concentration), were characterized by rheological measurements. The effects of a change in the polymerization process on the types and amounts of block copolymers in the blends were evaluated using small amplitude oscillation rheometry in the linear viscoelastic region. The Palierne model in its complete form was employed to model the rheological behavior of the blends. For this analysis the reactor products were separated into xylene cold insoluble (XCI) and xylene cold soluble fractions. Besides, another two copolymer fractions at 80 and 100 °C, which are crystallizable copolymer fractions and contain block copolymers rich in polyethylene and polypropylene, respectively, were separated from XCI fraction by xylene using temperature gradient elution fractionation method. Considering all copolymer fractions as dispersed and the remained fraction (mostly polypropylene) as matrix phase, it was shown that the rheological properties of the blends could not be predicted by Palierne model. It was found that only by considering part of block copolymer fractions having long polypropylene sequences along with polypropylene homopolymer as one phase, the rheological properties of the blends could be predicted by Palierne model. By rheological modeling, it was confirmed that the amounts of copolymers with long polypropylene sequences which are miscible with the matrix are higher in the case of three-step blends and also the elasticity of three-step polymerized blends is higher than two-step polymerized blends.     

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。     

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。     

Blends of bitumen with polymers having a styrene component

The properties of a 100 penetration grade bitumen are modified considerably, and in a number of ways by the addition of 10 to 40 parts per hundred (pph) of a homopolystyrene and graft, block and random copolymers of styrene with butadiene and acrylonitrile. At low temperatures some blends have a similar stiffness to or even lower stiffness than the bitumen, but generally the blends are more than one order of magnitude stiffer, even when a rubber is added. The contrasting behavior is displayed by a polystyrene and a high impact polystyrene, ～3% to 4% of grafted rubber on the latter being sufficient to cause the enhancement, even at the 10 pph level, by two different random styrene‐butadiene copolymers, and also by blends consisting of different amounts of SBS block copolymer. Some polymers apparently trigger a Hartley inversion of the micellar structure of the asphaltene micelles. High low temperature stiffness correlates roughly with a lower Tg' as measured by the peak maximum in the E″ plots of the dynamic mechanical thermal analysis (DMTA) and by the steps in the differential scanning calorimetry (DSC) curves at temperatures below O°C. Tan δ maxima and DSC traces detected the glass transition in the continuous phase and in the dispersed phases, but none of these amorphous polymers formed a crystalline phase, though the DSC traces of the polystyrene and the SBS blends suggested that the polymer‐rich phases underwent an aging/ordering process on cooling. Our SBS blends differ in phase inversion behavior and the pattern of loss processes from others that had a smaller asphaltene component.     

TFOT与RTFOT对不同油源石油沥青老化效果相关性分析

对两种不同油源的道路石油沥青进行了在不同时间下的沥青旋转薄膜加热试验(RTFOT)老化试验,检测了残留物的软化点、针入度、延度、135℃运动粘度及车辙因子,并同时检测了163℃下5h的沥青薄膜加热试验(TFOT)老化残留物样品的相应指标,分析了RTFOT与TFOT老化效果的相关性。探讨了RT-FOT与TFOT在不同油源的石油沥青老化试验中的可互相替代条件。     

Bitumen modification with a low-molecular-weight reactive isocyanate-terminated polymer

A low-molecular-weight polyethyleneglycol functionalized with a polymeric MDI (4,4′-diphenylmethane diisocynate) was used as a modifying agent for a 60/70 penetration grade bitumen. The rheological properties of the resulting modified binder, at both low and intermediate temperatures, before and after curing at room temperature were studied and compared with those corresponding to a SBS modified bitumen. The analysis showed that the addition of a small quantity of this reactive polymer leads to enhanced rheological properties mainly at high in-service temperature (50 °C). However, modification was found to be rather slow during binder curing at room temperature. Moreover, storage stability analysis showed that phase separation did not take place after bitumen storage at 163 °C, though storage at high temperature affects the modification capability of the reactive polymer. Atomic force microscopy measurements showed that the reactive polymer addition leads to asphaltene-rich regions with lower thermal susceptibility, which are present even at high temperature, yielding an improved bitumen viscosity in this range of in-service temperatures.     

Relationship between chemical and rheological properties of two asphalts of different origins

The chemical and rheological properties of two asphalts selected from different sources (Urals, Russia; Cold Lake, Canada) were investigated. Analyses of chemical (elemental composition, fractional composition, molecular weights) and physical properties (complex viscosity, loss tangent, shear compliance) were performed on all original and aged (rolling thin film oven test, RTFOT; pressurized aging vessel, PAV) samples. The analyses of the chemical properties of both asphalts revealed higher asphaltene content, higher heteroatom content, and lower aging susceptibility of the Cold Lake asphalt (less significant changes in group composition). Based on its chemical composition, the Cold Lake asphalt was expected to perform better in the rheological tests than the Urals asphalt. The rheological tests confirmed this hypothesis and revealed better low- and high-temperature properties of the Cold Lake asphalt and a slower deterioration of its physical properties upon oxidative aging.     

Effect of center block structure on the physical and rheological properties of ABA block copolymers. Part II. Rheological properties

The effect of the chemical structure of the center block on the rheological properties of ABA block copolymers with polystyrene end blocks has been investigated. The chemical structure of the center blocks investigated in the present paper are polybutadiene, polyisoprene, ethylene/butene copolymer, ethylene/propylene copolymer and polydimethyl-siloxane. The chemical structure of the center block was found to have a pronounced effect on the rheological properties of the ABA block copolymer melts. The long range relaxation times of these block copolymer melts increases with increasing incompatibility between the styrene block and the center block. However, the rheological properties of the block copolymers are not influenced significantly by the glass transition or the entanglement molecular weight of the center block.     

Toughening of polystyrene and poly(phenylene oxide) matrices with elastomeric styrene-based block copolymers: Role of molecular architecture

The effects of the molecular architecture of elastomeric styrene-based block copolymers on efficiency of toughening a brittle (polystyrene) and a ductile [a miscible blend of 80% phenylene oxide copolymer and 20% polystyrene (80PEC)] polymer were explored experimentally. Toughening appears to be mainly controlled by the blend morphology, which is determined by the rheological characteristics of the block copolymer relative to that of the matrix. The formation of dispersed particles during melt blending in a Brabender Plasticorder is strongly influenced by the ratio of the matrix and block copolymer viscosities (estimated here by Brabender torque). The size of the dispersed particles was found to be proportional to the 1.77 power of the torque ratio when this ratio is greater than unity. Thus, to a first approximation the effect of block copolymer architecture on toughening efficiency is related to how this structure affects the rheological behavior of the copolymer. Excellent toughness of polystyrene was achieved when the particle size was larger than 1–2 μm. The 80PEC resin is best toughened by block copolymers that form a cocontinuous phase morphology. The extent of toughening of this matrix appears to be a strong function of the styrene block molecular weight, whereas this structural feature seems to have no significant effect in toughening polystyrene.     

Rheological properties of styrene butadiene styrene polymer modified road bitumens

The use of polymers for the modification of bitumen in road paving applications has been growing rapidly over the last decade as government authorities and paving contractors seek to improve road life in the face of increased traffic. Currently, the most commonly used polymer for bitumen modification is the elastomer styrene butadiene styrene (SBS) followed by other polymers such as styrene butadiene rubber, ethylene vinyl acetate and polyethylene. This paper describes the polymer modification of two penetration grade bitumens with SBS. Six polymer modified bitumens (PMBs) were produced by mixing the bitumens from two crude oil sources with a linear SBS copolymer at three polymer contents. The rheological characteristics of the SBS PMBs were analysed by means of conventional as well as dynamic mechanical analysis using a dynamic shear rheometer (DSR). The results of the investigation indicate that the degree of SBS modification is a function of bitumen source, bitumen-polymer compatibility and polymer concentration, with the higher polymer concentrations in a high aromatic content bitumen producing a highly elastic network which increases the viscosity, complex modulus and elastic response of the PMB, particularly at high service temperatures. However, ageing of the SBS PMBs tends to result in a reduction of the molecular size of the SBS copolymer with a decrease in the elastic response of the modified road bitumen.     

RTFOT与TFOT试验对SBS改性沥青老化效果相关性分析

对两种不同SBS掺量的SBS改性沥青进行了在不同温度和时间下的RTFOT老化试验,检测了残留物的软化点、针入度、延度1、35℃运动粘度及车辙因子,并同时检测了163℃下5 h的TFOT老化残留物样品的相应指标,分析了RTFOT与TFOT老化效果的相关性。探讨了RTFOT与TFOT在SBS改性沥青老化试验中的可互相替代条件。     

Evolution of phase morphology in compatibilized polymer blends at constant quench depths: Complementary studies by light scattering and transmission electron microscopy

The effect of added block copolymer on the phase separation and morphology evolution in a partially miscible blend of polystyrene and polybutadiene near the critical composition is studied by temperature jump light scattering (TJLS) and transmission electron microscopy (TEM). As block copolymer is added, the phase boundary is shifted to lower temperatures and the phase separation process is slowed dramatically. Since the quench depth greatly affects the rate of phase separation in any blend system, we have used equivalent quench depths by adjusting for the shift in the phase boundary as block copolymer is added. The morphology evolution of these ternary blends was studied by preparing TEM specimens at equivalent shallow quench depths (ΔT = 1.6°C) and allowing each blend mixture to coarsen for the time required to reach a specific constant size, or q-value, using the TJLS data on the kinetics of phase separation. The q-range selected was q ～ 0.003–0.005 nm^?1, which corresponds to a spacing of 1–2 μm in real space. The combination of light scattering and microscopy techniques more rigorously describes the compatibilization process in these complex ternary systems.     

Preparation and properties of bitumen modified with the maleic anhydride grafted styrene‐butadiene‐styrene triblock copolymer

A procedure to improve the properties of styrene‐butadiene‐styrene (SBS) copolymer modified bitumen by grafting of maleic anhydride (MAH) onto SBS in the presence of benzoyl peroxide (BPO) as initiator was proposed. The effects of the grafting degree (GD) on the properties of modified bitumen were investigated. FTIR spectroscopy was employed to verify the grafting of MAH onto SBS. The GD of MAH onto SBS was determined by a back titration procedure. To assess the effects of the GD of grafted SBS on properties of modified bitumen, the softening point, penetration, ductility, elastic recovery, penetration index, viscosity, storage stability, and dynamic shear properties were tested. Experimental results indicated that the SBS grafted with maleic anhydride (SBS‐g‐MAH) copolymer was successfully synthesized by solvothermal method, and different GD of the SBS‐g‐MAH was obtained by control the MAH concentration. The GD of the MAH onto SBS has great effect on the rheological properties of the modified bitumen, and the high temperature performance and storage stability of modified bitumen were improved with the GD of the MAH onto SBS increasing. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Effect of sequence distribution of PES/PEES random,block, and alternative copolymers on excimer formation in solution

Three copolymers of poly(ether sulfone) and poly(ether ether sulfone) with the same composition but different sequence distribution were synthesized by three kinds of methods. Their molecular aggregation in dichloromethane was studied by fluorescence spectrophotometer and electron microscope. The experimental results revealed that the formation of intermolecular excimers in alternative copolymer (A50) dichloromethane solution were observed at a A50 concentration about 1.6 × 10^?2 g/mL by the fluorescence analysis, but the formation of intermolecular excimers in dichloromethane were not found for random copolymer (R50) and block copolymer (B50). The electron micrograph of three copolymer films, heat‐treated at 200°C for 7 days, presented a diffraction micrograph, which suggest that three copolymer molecular aggregation is changed from a randomly coiled amorphous phase to an ordered one, and the order structure of alternative copolymer (A50) was the most distinct in three copolymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007