Biobased carbon content of resin extracted from polyethylene composite by carbon-14 concentration measurements using accelerator mass spectrometry
An estimation procedure for biobased carbon content of polyethylene composite was studied using carbon-14 (14C) concentration ratios as measured by accelerated mass spectrometry (AMS). Prior to the measurement, additives and fillers in composites should be removed because they often contain a large amount of biobased carbon and may shift the estimation. Samples of resin with purity suitable for measurement were isolated from composites with a Soxhlet extractor using heated cyclohexanone. After cooling of extraction solutions, the resin was recovered as a fine semi-crystalline precipitate, which was easily filtered. Recovery rates were almost identical (99%), even for low-density polyethylene and linear low-density polyethylene, which may have lower crystallinity. This procedure could provide a suitable approach for estimation of biobased carbon content by AMS on the basis of the standard ASTM D 6866. The biobased carbon content for resin extracted from polyethylene composites allow for the calculation of biosynthetic polymer content, which is an indicator of mass percentage of the biobased plastic resin in the composite.
Structure characterization of copolymers of ethylene and 1-octadecene
Four ethylene-1-octadecene copolymers and the corresponding polyethylene homopolymer, synthesized with a metallocene catalyst, have been analyzed by using three characterization techniques in the solid state: differential scanning calorimetry, wide-angle X-ray diffraction, and Raman spectroscopy. Very important annealing effects are observed in the copolymers with higher comonomer content while standing at room temperature, in such a way that the enthalpies of melting derived from the first and second melting are different. The X-ray diffractograms have been analyzed in terms of amorphous and crystalline components, determining both the crystallinity and the position of the different reflections. The variation of the unit cell parameters has been calculated from those reflections. No indication of a possible participation of the relatively long 1-octadecene branches in the crystallization can be deduced from the X-ray data. The degree of crystallinity has also been determined from the Raman spectra, following two procedures. The results indicate that the crystallinities deduced from the band at 1416 cm−1 are much lower than those derived from the other two characterization techniques. On the contrary, the data from the 1060 cm−1 band are practically coincident with the X-ray determinations. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1440–1448, 2000
Composite monolayer fabrication by an arc-spray process
A single layer (monotape) technique for fabricating complex high-temperature tungsten-fiber-reinforced superalloy composites is proposed. The fabrication of sheets of arc-sprayed monotape 38 cm wide and 122 cm long has been demonstrated. Composites fabricated using the method are shown to have equal tensile strength and a cleaner matrix than composites fabricated from powder metal cloth monotapes, and the present technique is less expensive than the powder metal fabrication techniques.