Effect of Graphene Nanoplatelets (GNPs) on Fatigue Properties of Asphalt Mastics

To investigate the effect of graphene on the fatigue properties of base asphalt mastics, graphene nanoplatelets (GNPs)-modified asphalt mastics and base asphalt mastics were prepared. A dynamic shear rheometer (DSR) was used to conduct the tests in the stress-controlled mode of a time-sweep test. The results showed that GNPs can improve the fatigue life of asphalt mastic. Under a stress of 0.15 MPa, the average fatigue life growth rate (ω¯) was 17.7% at a filler-asphalt ratio of 0.8, 35.4% at 1.0, and 45.2% at 1.2; under a stress of 0.2 MPa, the average fatigue life growth rate (ω¯) was 17.9% at a filler-asphalt ratio of 0.8, 25.6% at 1.0, and 38.2% at 1.2. The growth value (ΔT) of fatigue life of GNPs-modified asphalt mastics increased correspondingly with the increase of filler–asphalt ratio, the correlation coefficient R2 was greater than 0.95, and the growth amount showed a good linear relationship with the filler–asphalt ratio. In the range of 0.8~1.2 filler–asphalt ratio, the increase of mineral powder can improve the fatigue life of asphalt mastics, and there is a good linear correlation between filler–asphalt ratio and fatigue life. The anti-fatigue mechanism of GNPs lies in the interaction between GNPs and asphalt, as well as its own lubricity and thermal conductivity.

Preparation and characterization of oleogels with tallow and partially hydrolyzed tallow as organogelators

The aim of this study was to evaluate the organogelation potential of tallow fat (TF) and partially hydrolyzed tallow fat (HTF) against saturated monoglyceride (MG) and a saturated monoglyceride + diglyceride mixture (MDG) as the organogelators. TF itself created oleogel at a 30% addition level, while HTF, MG and MDG oleogels were prepared at 10% addition levels. Fatty acid composition data showed that the oleogel of HTF (HTFO) was quite similar to those of MG and MDG oleogels. Solid fat content, free fatty acidity and peroxide values were found to be in acceptable ranges for HTFO. Thermal properties, crystal morphology and X-ray diffraction patterns were also evaluated. Rheological analyses indicated that all oleogels had higher storage modulus (G´) than loss modulus (G´´). The time-sweep test showed that after applying higher shear rates, the gels re-formed at rest. Further, all oleogels maintained their gelled consistency until around 54 °C. The results suggest that HTF could be a cheap, efficient, fast melting, safe and readily available organogelator.

Improved Repeatability of Oscillatory Rheological Measurements for Polycarbosilane Melt

Dynamic Time Sweep of Rotational Rheometer has been Used to Study the Variation in Rheological Properties of Polymers with Time. Polycarbosilane (PCS) is a Solid Oligomer at Room Temperature and Becomes Melt at its Softening Temperature. Bubbles are Unavoidably Produced by Gasification of Low Molecular Weight Part of PCS, which Significantly Disturbs the Subsequent Rheological Measurement. however, the Rheological Data of PCS Melt Cannot Be Repeated on Conventional Dynamic Time Sweep Test even after Reducing the Bubble. in this Work, a Series of Oscillatory Rheological Measurements were Carried out by Temperature Control to Improve the Data Reliability. the Axial Force Data of PCS Melt were Manually Recorded and Compared before and during the Test, which Reflected the Response of PCS Melt to Temperature Change. the Results Confirmed that the Shear Stress of PCS Melt was Readily Affected by Temperature Alteration. the Data Repeatability of the Rheological Test was Evidently Improved for PCS Melt with the Temperature Control.

Evaluation of flow-induced nanoclay orientation and microstructural stability in polyethylene/clay nanocomposites via melt rheological and thermal analysis

The effects of shear rate upon the flow-induced nanoclay orientation and morphological stability in film blown polyethylene clay nanocomposites were studied by means of linear and nonlinear rheological characterization parallel with differential scanning calorimetry and X-ray diffraction (XRD) analyses. Nanocomposite samples were prepared using a modular twin screw extruder followed by film processing technique. XRD analysis performed on film samples showed that the samples exhibited intercalated/exfoliated microstructure. The 3D physical networks were formed by the clay nanolayers in the structures of undrawn samples. However, the breakdown of the clay physical networks during film processing as a result of the imposed shear field within the die area and also an elongational flow field was evidenced. Time sweep test performed at various shear rates and shearing times using a rheometric mechanical spectrometer showed that, in all samples, the time required for the restructurization of the clay nanolayers during relaxation of the melt was found to be higher than 3600 s.

Research on the Fatigue Properties of Organo-Montmorillonite Modified Bitumen Mortar

This study investigated the fatigue properties of organo-montmorillonite modified bitumen mortar. Organo-modified montmorillonite（OMMT）with a content of 5 wt% was used to modified one base bitumen mortar which consist of filler and bitumen at a weight ratio of 0.8:1. The fatigue properties of these bitumen mortars have been determined using a dynamic shear rheometer（DSR）through time sweep test. Result indicated that, due to the addition of the OMMT, the fatigue properties of modified bitumen mortar was superior to those of pristine mortar. Therefore, the OMMT would be an alternative to modifiers used in the bitumen to improve the lifetime of asphalt pavement. Meanwhile, some fatigue equations were estabilished.