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.
Sucrose: A prospering and sustainable organic raw material.
Sucrose (alpha-D-glucopyranosyl-(1-->2)-beta-D-fructofuranoside) is an inexpensive chemical produced by sugar cane and sugar beet cultivation. Chemical and/or biochemical transformations convert it into highly valuable synthetic intermediates such as 5-hydroxymethylfurfural (HMF), bioethylene, 1,2-propylene glycol and levulinic acid. Sucrose can also be converted into biodegradable polymers such as polyesters and polyurethanes, as well as into novel carbohydrates such as isomaltulose, trehalulose, inulin, levan, Neo-amylose, and dextran, highly valuable additives for food and cosmetics and materials for separation and purification technologies.
Radiocarbon blank correction: Methodologies and limitations in a major urban study of carbonaceous aerosols
The Northern Front Range Air Quality Study (NFRAQS) was the latest and most ambitious of a series of efforts to apportion sources of carbonaceous aerosol “soot” in the Denver, Colorado metropolitan area. The study was mandated by the Colorado State Legislature as a result of the continuing impact of aerosol carbon on visibility in the region. Apportionment of fossil and biomass carbon was based on blank-corrected values of carbon mass concentrations (μg/m3) and 14C data (fM, fraction of modern carbon) of a selected subset of the samples collected in conjunction with this program. Over 100 14C measurements were made on size segregated (⩽2.5 μm diameter) atmospheric aerosol samples collected during the summer of 1996 and the winter of 1996–1997. The reported fM values required correction for both the mass and fM of the overall carbon blank. Lack of direct fM data for the field blanks had a substantial effect on the estimated uncertainty of the final results, and in a few of the most extreme cases blank-corrected fM data had to be designated as “indeterminate”. Blank correction procedures and limitations will be illustrated with quantitative data from the NFRAQS study.