W Polycyclic aromatic hydrocarbon (PAH) vapor penetration through thin sections of polyurethane foam (PUF) was studied to determine the relationships between sample breakthrough, PAH vapor pressure, and total air volume. Frontal chromatographic movement of fluorene, phenanthrene, anthracene, and pyrene vapors through a PUF bed at high volume airflow was examined. From these fronts, the thickness of foam corresponding to 50% breakthrough was obtained for each compound. This breakthrough point was related to total air volume, and breakthrough volumes (VB) were determined for a 7.5-cm PUF thickness (equivalent to a single field sampling plug). A log-log plot of VB vs. PAH solid phase vapor pressure showed only a rough relationship between the two parameters, but the correlation was much improved (r2 = 0.988) when the subcooled liquid vapor pressure was used. From the frontal chromatograms the number of theoretical plates (N) in the absorbent bed was determined. When V, and N were known, the maximum safe sampling volume at a required collection efficiency was calculated.
We report an insitu thermal reduction of graphene oxide (GO) in a styrene-ethylene/butylene-styrene (SEBS) triblock copolymer matrix during a melt-blending process. A relatively high degree of reduction was achieved by melt-blending premixed GO/SEBS nanocomposites in a Haake mixer for 25 min at 225 • C. Infrared spectral results revealed the successful thermal reduction of, and the strong adsorption of SEBS on, the graphene sheets. The glass transition temperature of polystyrene (PS) segments in SEBS was enhanced by the incorporation of thermally reduced graphene oxide (TRGO). The resultant TRGO/SEBS nanocomposites were used as a masterbatch to improve the mechanical properties of PS. Both the elongation at break and the flexural strength of PS/SEBS blends were enhanced with the addition of the TRGO. Our demonstration of the in situ thermal reduction of GO via melt blending is a simple, efficient strategy for preparing nanocomposites with well-dispersed TRGO in the polymer matrix, which could be an important route for large-scale fabrication of high-performance graphene/polymer nanocomposites.
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