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ABSTRACT:The intumescent fire retardant polypropylene (IFP/PP) filled with ammonium polyphosphate (APP), melamine (M), and PA6 (charring agent) is discussed. Intumescing degree (ID) and the char yield were determined. Only when the three main components of IFR coexist at appropriate proportions, it has optimal ID and higher char yield. The appropriate proportion is PA6 : APP : M ϭ 10 : 10 : 5. A new compatibilizer, carboxylated polypropylene (EPP), was added to PP/PA-6 blend. Flow tests indicated that the apparent viscosity increased with the addition of EPP, thermal characterization suggested that EPP has reacted with PA6, PA6-g-EPP cocrystallized with PA6, and EPP-g-PA6 cocrystallized with PP; SEM micrographs illustrated that the presence of EPP improved the compatibility of PP and PA6. All the investigations showed that EPP was an excellent compatibilizer, and it was a true coupling agent for PP/PA6 blends. Using PA6 as a charring agent resulted in the IFR/PP dripping, which deteriorated the flammability properties. The addition of nano-montmorillonite (nano-MMT) as a synergistic agent of IFR enabled to overcome the shortcoming. The tensile test testified that the addition of nano-MMT enhanced the mechanical strength by 44.3%. SEM showed that nano-MMT improved the compatibility of the composites. It was concluded that the intumescent system with nano-MMT was an effective flame retardant in improving combustion properties of polypropylene.

With the rapid development of economic construction, styrene-butadiene-styrene (SBS)-modified asphalt is being more and more widely used in highway engineering, but there are still many deficiencies in the process of its use. In order to further improve its performance for use, nano-organic palygorskite (A-Pal) and star-shaped SBS were compounded to obtain modified asphalt in this study. The high-temperature stability of SBS-modified asphalt was enhanced after incorporation with A-Pal for the high-temperature stability test by a dynamic shear rheometer. The A-Pal should improve the surface free energy and adhesion of SBS-modified asphalt by the water stability test analysis. The aging test shows that A-Pal can reduce the thermal oxygen decomposition of SBS and improve the anti-aging performance and the fatigue resistance of SBS-modified asphalt. A-Pal has a certain improvement effect on the low temperature performance of SBS-modified asphalt as shown by a low temperature crack resistance test. A-Pal-compounded SBS-modified asphalt features good storage stability in normal temperatures with the lowest critical compatibility temperature.

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An airport serves as an interface between ground and air transportation; the efficient processing of ground transportation arrivals and departures is, therefore, an important part of airport operations. At many airports, the current pickup and dropoff locations for taxis and other passenger cars are along the terminal curb or in existing parking facilities, and many of these pickup and dropoff facilities suffer from excessive congestion. In addition, in recent years there has been growth in the use of on-demand ground transportation to and from airports, with the increased adoption of ride-hailing services, resulting in increased congestion. Since most airports are severely space constrained, there is a need to consider pickup and dropoff facilities that are more efficient (in vehicle throughput per unit space) than terminal curbs. In this paper we compare the throughput capacities of different pickup and dropoff facility layouts. We take into account the effect of the facility layout and operational rules on conflicts between the movements of different vehicles, the resulting delays in the movements of vehicles, as well as the spatial requirements of different layouts. We demonstrate the impact of mean service times, variability in service times and vehicle movement times, and operational rules on the relative throughput capacities of different facility layouts.