Castor oil-based biopolyurethane reinforced with wood microfibers derived from mechanical pulp

Wood fibers with high lignin content show promise to function in numerous applications with advantageous properties if the fiber features are appropriately exploited. The present study introduces a new approach to disintegrate and disperse wood fibers from groundwood pulp (GWP) directly to polyol without additional solvent exchanges or chemical modifications. In comparison bleached chemical pulp with low lignin content was ground in the polyol, but only low consistency (1 wt%) operation was possible, whereas up to 5 wt% consistency with GWP was carried out with ease. The micron sized fibers in polyol were reacted with polymeric diphenylmethane diisocyanate to produce fiber reinforced biopolyurethane (bioPU) composites. The mechanical properties of the composites improved compared to reference bioPU showing 14.6% increase in Young’s modulus, 54.5% in tensile strength and 26.1% in strain at break. The tan δ peaks shifted to higher temperature from 5.5 to 10.4 °C when fibers up to 5.1 wt% were incorporated to bioPU. Overall, the bulk microfibers from GWP with low degree of processing were cost-effective reinforcements for bioPUs, which improved the qualities of the fabricated composites and showed good compatibility with polyurethane.     

Analysis of Chlorinated Phenols,Phenoxyphenols and Dibenzofurans Around Wood Preserving Facilities

Abstract

Until presently chlorophenol containing wood preservative has been widely used in Finland to protect timber, lumber, plywood and fiberboard against rot and bluestaining fungi at saw mills. We analysed soil, ground water, runoff and workers' urine at several saw mills for the presence of the various chemical components of the commercial wood preservative.

We found serious local contamination of soil with chlorophenols and also with the minor, potentially very toxic minor constituents of the commercial product, namely polychlorinated phenoxyphenols and dibenzofurans. Chlorophenols were observed to contaminate soil at great depth. Ground water, surface water and also workers' urine was found contaminated by chlorophenols. Polychlorinated phenoxyphenols and dibenzofurans were found in great quantity (equal or close to that of chlorophenols) in the topmost 5cm of soil at the sawmill area, but these compounds had not penetrated into the soil at such great depth as did chlorophenols.     

Volume phase transition and structure of poly(N-isopropylacrylamide) microgels studied with 1H-NMR spectroscopy in D2O

Thermoresponsive colloidal microgels were prepared by polymerisation of N-isopropylacrylamide (NIPAM) with varying concentration of a cross-linking monomer, N,N-methylenebisacrylamide (MBA), in water with either 0.4 or 6.7 mM concentration of an anionic surfactant, sodium dodecylsulphate (SDS). Volume phase transitions of the prepared microgels were studied in D₂O by ¹H-NMR spectroscopy including the measurements of spin–lattice (T1) and spin–spin (T2) relaxation times for the protons of poly(N-isopropylacrylamide) (PNIPAM) at temperature range 22–50 °C. In addition, microcalorimetry, turbidometry, dynamic light scattering and electrophoretic mobility measurements were used to characterise the aqueous microgels. The results from the different characterisation methods indicated that PNIPAM microgels prepared in 6.7 mM SDS concentration are structurally different compared to their correspondences prepared in 0.4 mM concentration. Increasing MBA concentration in the microgel synthesis appears to increase the structural heterogeneity in both cases of SDS concentration. PNIPAM structures with significantly higher molecular mobilities at temperatures above 35 °C were observed in the microgels prepared in 0.4 mM SDS concentration, as indicated by the ¹H NMR relaxation times of different PNIPAM protons. We conclude that the high mobilities measured with NMR at elevated temperatures and also the clearly negative values of zeta potential are in connection to a fairly mobile surface layer with polyelectrolyte nature and a consequent high local lower critical solution temperature.     

Experiments on the spreading of silicone oil droplets on horizontal rotating plates

The spreading of liquid films is involved in many coating processes, e.g. in the spin-coating process. To achieve a high quality of the coating, the spreading liquid layer should be thin and homogeneous. Instabilities at the wetting front may lead to an inhomogeneous thickness of the coating layer and to uncoated areas. In this article the spreading of perfectly-wetting silicone oil droplets with viscosity of 100 mPa s on rotating glass plates is discussed. A Schlieren system is set up to observe the wetted area and a traversed chromatic confocal distance sensor is used to measure the contour of the droplet. The experimental data are presented and compared to an analytical model which is derived from lubrication theory and valid for thin liquid layers. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)