Carbodiimide-Assisted Synthesis of High Purity Bis(cyclic carbonate) Under Atmospheric Conditions for Preparation of Non-Isocyanate Polyurethane

Journal of Polymers and the Environment - The cyclic carbonates as non-isocyanate polyurethane (NIPU) precursors are usually prepared via CO2 fixation under harsh conditions for a satisfactory...     

Carbon isotopic and biochemical fingerprints of sedimentary organic matter in lower Narmada and Tapi rivers,north-west coast of India

Sources of organic matter (OM) in lower Narmada and Tapi river-estuaries were examined using organic carbon to nitrogen ratio (C_org/N), stable carbon isotope ratio (δ¹³C_org) and lignin phenol biomarkers. The signature of lower C_org (av. 0.50%) and higher δ¹³C_org (av. –20.3‰) in Narmada and, higher C_org (av. 0.85%) and lower δ¹³C_org (av. –22.8‰) in Tapi highlight the difference in OM characteristics of both systems, nevertheless they flow adjacent to each other. The OM in Tapi was predominated by fresh plant tissues, as indicated by higher Λ8?=?1.2–3.2?mg/100?mg C_org, lower Ad/Al_v?=?0.22–0.46 and lower LPVI?=?17–23. The plant OM present in the sediments of Narmada was previously degraded and mixed with soil. The OM contribution from algae was restricted to estuarine stations in both the rivers, which was ～50% in Narmada and ～35% in Tapi. The contribution of OM from fresh vascular plant was higher (20% to 63%) in Tapi than Narmada (2% to 35%). This study illustrated the benefits of using lignin phenols along with C_org/N and δ¹³C_org to identify the potential OM sources in two large river–estuary systems of India, which highlighted the complex interaction of natural and anthropogenic processes acted on the terrestrial OM compositions.     

Bio-Based Non-Isocyanate Urethane Derived from Plant Oil

A new bio-based non-isocyanate urethane was obtained by the reaction of a cyclic carbonate synthesized from a modified linseed oil and an alkylated phenolic polyamine (Phenalkamine) from cashew nut shell liquid. The incorporation of functional cyclic carbonate groups to the triglyceride units of the oil was done by reacting epoxidized linseed oil with carbon dioxide in the presence of a catalyst. Structural changes and changes in molar mass during the carbonation reaction were characterized using infrared spectrometry (FTIR) and chromatography. The aminolysis reaction of the cyclic carbonate with phenalkamine was monitored using real-time FTIR at 80 and 100?°C, respectively. The decay of the carbonate groups and the appearance of the newly built C=O groups of the urethane linkages were measured in situ through real-time FTIR spectra in dependence on the reaction time. Oscillatory time sweep measurements were used to monitor the viscoelastic properties of the system at 80 and 100?°C. The time of gelation was determined from rheometric measurements. Changes of the apparent activation energy with respect to the conversion of the reaction were calculated from isothermal measurements using Vyazovkin??s free kinetic model.     

Seasonal Changes in Soil Atmospheric Co2 Concentrations in Two Upland Catchments and Associated Changes in River Water Chemistry

Seasonal changes in river water chemistry and in soil atmospheric CO₂ concentrations at two depths and drainage water solute composition at two upland peaty podzol sites in north east Scotland were monitored over 12 months. the CO₂ concentrations were controlled by changes in soil temperature and moisture status. Highest CO₂ concentrations were observed in late summer 1988 when both soil temperatures and the moisture status of the soils were high. Then maximum CO₂ concentrations of 4% (v/v) were recorded for one of the sites. No significant correlations between seasonal changes in soil CO₂ concentrations and river water solute composition were observed. Nevertheless the field results and laboratory experiments indicated that in upland areas, where soils with acid surface horizons are common, soil CO₂ substantially influences river water chemistry at baseflow, increasing the pH and cation concentration of the soil water draining into the river. the results suggest that transfer of carbon as dissolved CO₂ in drainage water is a significant pathway for CO₂ transfer to the atmosphere.     

Naturwissenschaften aktuell

Naturwissenschaften aktuell     

Simultaneous sampling of PCDD/PCDF inside the combustion chamber and on four boiler levels of a waste incineration plant

At a MSWI (municipal solid waste incinerator) plant PCDD/PCDF samples (gasphase and particulates) were taken simultaneously be a shock-freezing method in the incinerator combustion chamber at approx. 800°C and in four sampling sections in the boiler at about 490°C, 370°C, 330°C and 270°C. In this way PCDD/PCDF-formation in the flow through the boiler was determined. Two data sets were evaluated. A considerable PCDD/PCDF-formation had occurred already at boiler temperatures of about 490°C; the highest concentration, however, was found at the end of the boiler at about 300°C. The accompanying measuring program of plant parameters made the calculation of the PCDD/PCDF mass flows possible, which allowed the inclusion of the PCDD/PCDF-content in the ESP dust in the mass flow calculations.