Time-Dependent Microstructure of Bitumen and Its Fractions by Modulated Differential Scanning Calorimetry

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1021/ef010233r Energy & Fuels, 16, 2, pp. 470-476, 2002-04-01 Time dependent microstructure of bitumen and its fractions by modulated differential scanning calorimetry Masson, J-F.; Polomark, G. M.; Collins, P. Bitumen fractions were analyzed by modulated differential scanning calorimetry (MDSC) before and after annealing at room temperature. MDSC allowed for separating glass transitions (T g 's) from order-disorder transitions. All fractions showed at least two T g 's and different states of order. Saturates were semicrystalline, aromatics were amorphous, resins, and asphaltenes were mesophasic. In bitumen, the fractions order in four stages upon cooling from the melt. In the first stage, all fractions order rapidly into a weakly organized phase. In the second stage, low molecular weight saturated segments crystallize. In the third stage, high molecular weight saturated segments crystallize. In the fourth stage, resins and asphaltenes order into a mesophase. The third and fourth stages are responsible for the room-temperature (steric) hardening of bitumen.

Processing of bitumens modified by a bio-oil-derived polyurethane

“…With this regard, bitumen is well known to be a multiphase system mainly composed of two fractions: maltenes (which include three different families of compounds: saturates, aromatics and resins) and asphaltenes. According to Masson and co-workers [32,33], they order in four stages upon cooling from melt, yielding four specific thermal events in the non-reversing heat flow curve. The analysis of the fourth thermal event may provide an approximate idea on changes occurred at a microstructural level.…”

Steric Hardening and the Ordering of Asphaltenes in Bitumen

“…6,7 The segregation being time dependent, it was suggested that the formation of the mesophase was responsible for the steric hardening of bitumen. This communication provides evidence of this relationship.…”

Enhancing the viscoelastic properties of bituminous binders via thiourea-modification

“…Hence, above the frozen state defined by T > Tg, molecular mobility increases and those saturates segments order into crystalline domains [22,23,25]. Table 2, which displays second event temperatures (T2nd) confirms a decrease after addition of 9 wt.% Th and 60 days of curing, as the frozen state threshold was shifted to lower temperatures.…”

“…8B presents two welldefined peaks (with peak maximum, Tg1 and Tg2, located at -30.5 and 3.0 ºC, respectively) which, according to Masson et al [22,23], derive from two overlapped glass transitions corresponding to saturates and aromatics. Tg2 values were also determined for the modified binders studied, and compare with neat bitumen's.…”

“…Figures 8A and 8B show the non-reversing thermograms and derivate heat capacity (dCp/dT), respectively, for neat bitumen and its corresponding 9 wt.% Th-binders at different curing times. According to Masson and co-workers [22,23] non-reversing heat flow curves for a neat bitumen presents four clearly marked thermal events: i) a broad endothermic background which approximately extends from -40 up to 80 ºC; ii) and iii) two exotherms located at about -9 and 40 ºC; iv) an endothermic peak, at around 50 ºC, being related to the diffusion of relatively large structures, as those typically found in asphaltenic micelles. Enthalpy associated to this fourth event can be ascertained by mere integration of the corresponding peaks (see Fig.…”