排序方式: 共有27条查询结果,搜索用时 15 毫秒
1.
Most adhesives and binders, including bitumen for asphalt mixture production, are presently produced from petrochemicals after
the refining of crude oil. The fact that crude oil reserves are a finite resource means that in the future, it may become
necessary to produce these materials from alternative and probably renewable sources. Suitable resources of this kind may
include polysaccharides, plant oils and proteins. This paper deals with the synthesis of polymer binders from monomers that
could, in future, be derived from renewable resources. These binders consist of polyethyl acrylate (PEA) of different molecular
weight, polymethyl acrylate (PMA) and polybutyl acrylate (PBA), which were synthesised from ethyl acrylate, methyl acrylate
and butyl acrylate, respectively, by atom transfer radical polymerisation. The rheological properties of these binders were
determined by means of oscillatory testing using a dynamic shear rheometer and combinations of stress/strain, temperature
and frequency sweeps. The results indicate that PEA can be produced to have rheological properties similar to that of ‘soft’
100/150 penetration grade bitumen, PMA with similar rheological properties to that of ‘hard’ 10/20 penetration grade bitumen,
while PBA, due to its highly viscous nature and low dynamic moduli, cannot be used on its own as a binder. The synthetic polymers
were found to be thermo-rheologically simple, and the shift factors, used to produce the dynamic moduli master curves, were
found to fit an Arrhenius function. 相似文献
2.
The increasing accumulation of poly(ethylene terephthalate) polymer and poor recycle/disposal practices have made them omnipresent and a major culprit for environmental pollution. Currently global research efforts are focused on primary and secondary recycling of PET waste or through landfills. Chemical recycling of PET through hydrolytic or aminolytic route has been attempted by many researchers however with limited end applications. In our investigations we have used PET waste as a synthon and chemically converted it through a new non-catalytic route into several benzamide derivatives. We have successfully tested them for antistripping performance in bitumen. Our results as elaborated in the paper indicate a comparable performance of the new chemistry products based on PET, to commercially used antistripping chemicals. Our research work thus opens a new route for the recycling of used PET in bituminous concrete roads which may help in alleviating a major environmental problem and disposal of waste PET polymer in large scale. 相似文献
3.
热和空气对我国几种道路沥青粘度的影响 总被引:1,自引:0,他引:1
采用几种国产道路沥青在薄膜烘箱中经受不同温度和时间,分别测定其试验前后,温度为60℃时的粘度,以此粘度的比值作为老化指数的变化趋势,并与国产沥青铺路试验性能进行对照。其粘度比值从小到大为:大庆丙脱 100号、兰炼100号、单家寺100号、大港氧化100号、胜利直馏100号、高升100号、胜利氧化100号、任邱100号、独山子氧化100号。上述结果与我国沥青试验路铺筑试验抗开裂性能的三年总结的结果基本上是吻合的。为此建立预测沥青老化性能的评价方法。 相似文献
4.
Summary Bitumen is modified after a treatment with 2% sulfur, at 160°C. It is more plastic consecutive to a variation of the nature of the interactions between asphaltene molecules.Composites prepared with this bitumen and silica present dynamic viscoelastic properties obeying the time-temperature-interfacial parameter equivalence principles, evidenced previously. However, the domains of applicability of these principles are more restricted.With 11 figures 相似文献
5.
Colloidal forces between bitumen surfaces in aqueous solutions measured with atomic force microscope
Jianjun Liu Zhenghe Xu Jacob Masliyah 《Colloids and surfaces. A, Physicochemical and engineering aspects》2005,260(1-3):217-228
Colloidal forces between bitumen surfaces in aqueous solutions were measured with an atomic force microscope (AFM). The results showed a significant impact of solution pH, salinity, calcium and montmorillonite clay addition on both long-range (non-contact) and adhesion (pull-off) forces. Weaker long-range repulsive forces were observed under conditions of lower solution pH, higher salinity and higher calcium concentration. Lower solution pH, salinity and calcium concentration resulted in a stronger adhesion forces. The addition of montmorillonite clays increased long-range repulsive forces and decreased adhesion forces, particularly when co-added with calcium ions. The measured force profiles were fitted with extended DLVO theory to show the repulsive electrostatic double layer and attractive hydrophobic forces being the dominant components in the long-range forces between the bitumen surfaces. At a very short separation distance (less than 4–6 nm), a strong repulsion of steric origin was observed. The findings provide a fundamental understanding of bitumen emulsion stability and a mechanism of bitumen “aeration” in bitumen recovery processes from oil sands. 相似文献
6.
Identification of viscoelastic properties by means of nanoindentation taking the real tip geometry into account 总被引:1,自引:0,他引:1
Motivated by recent progress in viscoelastic indentation analysis, the identification of viscoelastic properties from nanoindentation
test data taking the real tip geometry into account is presented in this paper. Based on the elastic solution of the indentation
problem, the corresponding viscoelastic solution is obtained by the application of the method of functional equations. This
general solution, which accounts for the real geometric properties of the indenter tip, is specialized for the case of a trapezoidal
load history, commonly employed in nanoindentation testing. Three deviatoric creep models, the single dash-pot, the Maxwell,
and the three-parameter model are considered. The so-obtained expressions allow us to determine viscoelastic model parameters
via back calculation from the measured load–penetration history. The presented approach is illustrated by the identification
of short-term viscoelastic properties of bitumen. Hereby, the influence of loading rate, maximum load, and temperature on
the model parameters is investigated. 相似文献
7.
Heavy oil (bitumen) is characterized by its high viscosity and density, which is a major obstacle to both well logging and recovery. Due to the lost information of T2 relaxation time shorter than echo spacing (TE) and interference of water signal, estimation of heavy oil properties from NMR T2 measurements is usually problematic. In this work, a new method has been developed to overcome the echo spacing restriction of NMR spectrometer during the application to heavy oil (bitumen). A FID measurement supplemented the start of CPMG. Constrained by its initial magnetization (M0) estimated from the FID and assuming log normal distribution for bitumen, the corrected T2 relaxation time of bitumen sample can be obtained from the interpretation of CPMG data. This new method successfully overcomes the TE restriction of the NMR spectrometer and is nearly independent on the TE applied in the measurement. This method was applied to the measurement at elevated temperatures (8-90 degrees C). Due to the significant signal-loss within the dead time of FID, the directly extrapolated M0 of bitumen at relatively lower temperatures (<60 degrees C) was found to be underestimated. However, resulting from the remarkably lowered viscosity, the extrapolated M0 of bitumen at over 60 degrees C can be reasonably assumed to be the real value. In this manner, based on the extrapolation at higher temperatures (> or = 60 degrees C), the M0 value of bitumen at lower temperatures (<60 degrees C) can be corrected by Curie's Law. Consequently, some important petrophysical properties of bitumen, such as hydrogen index (HI), fluid content and viscosity were evaluated by using corrected T2. 相似文献
8.
9.
Naphthenic and paraffinic oils were analyzed by modulated differential scanning calorimetry (MDSC). The results showed several improvements in the analysis of thermal properties when compared with standard DSC. The glass transition temperature (Tg), the enthalpy relaxation at Tg, and the melting endotherms could be deconvoluted, and reversible melting could be identified. This allowed for an easier interpretation of the thermal properties of the oils. With MDSC, the Tgs in mineral oils were found to coincide with endothermic enthalpy relaxation, which is generally regarded as a melting endotherm with standard DSC. A decrease in heat capacity after Tg was attributed to the existence of rigid amorphous material. From Δcp at Tg and the oil molecular weight, the number of repeat units in the oil chains was estimated at less than 20. The Tg of a hypothetical pure aromatic oil was found to be similar to that for petroleum asphaltenes, and that for a naphthenic oil of infinite molecular weight to be similar to that of petroleum resins. 相似文献
10.
Francisco Martínez-Boza Pedro Partal Francisco J. Navarro Críspulo Gallegos 《Rheologica Acta》2001,40(2):135-141
The viscous and linear viscoelastic properties of different asphalt binders have been analyzed in this paper. Thus, an unmodified
bitumen, a polymer-modified (SBS) bitumen, a commercial synthetic binder, and two model synthetic binders with different polymer
(SBS) concentrations have been studied. The mechanical spectra of these binders are quite different, mainly influenced by
SBS concentration. Thus, up to three regions may be observed for a synthetic binder with high polymer concentration. The temperature
dependence of the zero-shear-rate-limiting viscosity is described by an Arrhenius-like equation, in a temperature range that
depends on binder composition. These results have been discussed taking into account the development of a polymer-rich phase
in SBS-modified bitumen and model synthetic binders.
Received: 6 February 2000 Accepted: 8 August 2000 相似文献