Papers by Author: Xin De Tang

Abstract: Colored binder was prepared by mixing aromatic oil with petroleum resin and functional polymers. Then the colored binder combined with pigment, aggregates, and additives resulted in colored asphalt mixture. Futher modification by nano-montmorillonite or coupling agent, higher pavement performance was chieved. The paving technical indexes of the mixture such as physical properties, moisture susceptibility, and high temperature stability were tested. The results demonstrate that the high temperature stability and moisture susceptibility can be satisfied with the requirements of hardscape projects including asphalt driveways, asphalt walkways, asphalt streets, asphalt bike paths, and asphalt walking paths.

Abstract: Polyethylene (PE) has found widespread use as a packaging material. Plastics waste disposal, as one of the serious environmental issues, has caused much criticism. The environmental oxidative- and bio- dual degradable linear low-density polyethylene (LLDPE) samples containing Eco-Benign Plastics (EBP) pro-oxidant additives were submitted to an investigation aimed at evaluating their preliminary oxidative degradation in natural environment or accelerated oven aging and their ultimate biodegradation in solid incubation substrate or soil composting conditions. Original and test samples submitted to abiotic oxidation including photo degradation and thermal degradation were characterized by means of FT-IR and GPC. Biodegradation test simulating soil burial and composting conditions reveals that the biodegradation degree exceeded 30%. The degradation process is accompanied by a dramatic change in the structural characteristics of the test samples. It is clear that LLDPE-EBP formulations are effective in promoting the oxidation and subsequent biodegradation of polyethylene in natural and soil environment.

Abstract: Organic/inorganic hybrid materials based upon stimuli-responsive copolymers have attracted an inceasing attention. Compared with the polymeric materials, these hybrid materials can form aggregates in aqueous solution with much more stable shape-persistance due to the inorganic structure, which facilitate the mass delivery and long-term life. A novel hybrid material based on a new reactive block copolymer, poly(ethylene oxide)-block-poly{3-(trimethoxysilyl)propyl methacrylate-co-N-isopropylacrylamide-co-6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate} [PEO-P(TMSPMA-NIPAM-AzoMA)] was synthesized via atom transfer radical polymerization (ATRP). The vesicles were obtained by self-assembly of the resulting block copolymer in a selective solvent, and then the PTMSPMA block was subjected to hydrolysis and polycondensation reaction to fix vesicle wall in the presence of triethylamine as a catalyst. The photo- and thermo- dual-responsive properties of the vesicles were investigated.

Abstract: Mesoporous silica nanoparticles (MSNs) have been employed as a versatile solid support for constructing a variety of hybrid materials for controlled drug delivery. Controlled release systems that integrate external stimuli with nanocarriers have attracted much attention for sensors and drug delivery applications. Mesoporous silica nanoparticles grafted with thermo-sensitive polymers on the surface were fabricated via “grafting to” approach through chemical coupling reaction. The encapsulation and release of drug based on the thermo-sensitive nanogated system were investigated. The thermo-sensitive nanogated system can be expected as one of the promising candidates for drug delivery and controlled release.

Abstract: Montmorillonite/SBS composite modifed asphalts were prepared by mixing montmorillonite with SBS-modified asphalt, further the corresponding asphalt mixtures were obtained. The paving technical indexes of the mixture such as physical properties, moisture suscepyibility, and high temperature stability were tested, and compared with that of the corresponding SBS-modifed asphalt mixture and base asphalt mixture. The results demonstrate that the montmorillonite/SBS composite modifed asphalt mixture exhibites enhanced stability, improved flow value and moisture susceptibility, and increased high temperature stability.

Abstract: Composite modified asphalts with nano calcium carbonate (nano CaCO3)/ SBS and nano montmorillonite (nano MMT)/SBS were prepared respectively by melt blending. Rolling thin film oven test (RTFOT) was carried out to study the aging properties. The results demonstrate that CaCO3/SBS and MMT/SBS homogeneously disperse in the base asphalt, which lead to an improvement in terms of toughness, strength, and thermal stability. Effects of the nano CaCO3 and nano MMT on the properties of SBS modified asphalt appear as a decreasing penetration, an increasing softening point, and a decreasing ductility. The anti-aging property of the nano MMT/SBS modified asphalt was better than that of the CaCO3/SBS modified asphalt and SBS modified asphalt.

Abstract: Vertically oriented, highly ordered TiO2 nanotube arrays were fabricated via electrochemical anodization of high purity Ti sheet and Ti foil, which is increasing importance due to their impressing properties in a variety of applications including dye-sensitized solar cells, hydrogen generation by water photoelectrolysis, potocatalysis, and gas sensor. The well aligned TiO2 nanotube arrays by potentiostatic anodization of Ti foil (with 0.3mm thickness) were constructed. We have achieved the self-aligned high ordered nanotube arrays in aqueous electrolyte containing HF and ethylene glycol electrolyte containing NH4F. Depending on the fluoride ion mobile velocity, the resulting nanotubes arrays exhibit the different morphology. The elaborated electrolyte on the morphology of the self-organized nanotubes arrays was investigated. Thermal annealing on the anodized Ti induced crystalline formation, which is confirmed by Raman spectroscopy measurement.

Abstract: Composite modified asphalts with nanoscale calcium carbonate (CaCO₃) and SBS were prepared by melt blending. Rolling thin film oven test (RTFOT) was carried out to study the aging property. The results demonstrate that both nano CaCO₃ and SBS show homogeneous dispersion in the base asphalt, which lead to an improvement in terms of toughness, strength, and thermal stability. Influence of nano CaCO₃ on the properties of SBS modified asphalts appears as a decreasing penetration, an increasing softening point, and a decreasing ductility. The anti-deformation ability under low temperature of nano CaCO₃/SBS modified asphalts improved significantly. The softening point of nano CaCO₃/SBS modified asphalt decreases after aging, in contrast to that of the base asphalt, which can be ascribed to the different rheological peoperties between nano CaCO₃/SBS modified asphalt and the base asphalt. Compared with that of SBS modified asphalt, the anti-ageing property of nano CaCO₃/SBS modified asphalts improved significantly. This indicates that nano structure of CaCO₃ in modified asphalt can prevent oxygen from diffusing and permeating in matrix and the thermo-oxidative ageing of base asphalt and SBS slows down.

Abstract: To provide the valuable references for pavement materials applied in various climatic zones, a series of asphalts paving mixtures including common asphalt mixture, SBS modified asphalt mixture and nano-montmorillonite (NMMT)/SBS composite modified asphalt mixture were designed. Marshall tests were carried out to evaluate the effect of different modifiers on the property of these asphalt paving mixtures. Compared with the other two mixtures, NMMT/SBS composite modified asphalt shows fine mechanical performance and moisture susceptibility. These results indicate that NMMT/SBS as a composite modifier can result in excellent properties for asphalt paving mixture.

Abstract: Nano-montmorillonite (Nano-MMT)/SBS composite modified asphalts were prepared by melt blending, the aging property of which was detected by rolling thin film oven test (RTFOT) method. The microstructure of Nano-MMT/SBS modified asphalts was characterized by X-ray diffraction (XRD). The results demonstrated that nano-composite structures formed by the intercalation effect of SBS and asphalt into the MMT lamellae, which led to improvement in terms of toughness, strength, and thermal stability. In comparison with SBS modified asphalt, Nano-MMT impact on the properties of the modified asphalt appeared as a decreasing penetration, an increasing softening point, and a decreasing ductility. The anti-deformation ability under high temperature of Nano-MMT/SBS modified asphalt improved significantly. The softening point of the Nano-MMT/SBS modified asphalt decreased after aging, in contrast with that of the base asphalt, which could be attributed to the different rheological properties between the Nano-MMT/SBS modified asphalt and the base asphalt. Compared with that of SBS modified asphalt, the anti-aging property of Nano-MMT/SBS modified asphalt improved dramatically. This indicated that the lamellar structure of montomorillonite in modified asphalt could prevent oxygen from diffusing and permeating in matrix and the thermo-oxidative aging of base asphalt and SBS weakens.