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Abstract: Thermal degradation of lignocellulosic materials has been studied widely because of its importance in several applications. While a variety of thermal treatment setups has been proposed, this paper introduces a thermal treatment method where high temperature is combined with presence of water vapor in an atmospheric oven chamber. The performance of the device was evaluated at temperature and volume fraction of water vapor ranges of 175–300 °C and 1–98%, respectively. The impact of the treatment was assessed by observing the changes in paper sheets, specifically brightness, light absorption coefficient, burst strength, ultraviolet resonance Raman spectra and the degree of polymerization of cellulose. The results demonstrated that the adapted thermal treatment device functions within the tested ranges of temperature and volume fraction of water vapor. In this study water vapor was found to accelerate hydrolytic thermal degradation of fully bleached paper sheets in terms of thermal yellowing and strength deterioration. In contrast, the empirical findings with lignin-containing paper provided new information on how the residual lignin increases its resistance towards water vapor introduced thermal degradation. This was demonstrated by the results of ultraviolet resonance Raman spectra and light absorption coefficient, which suggested that the thermal degradation of lignin is substantially enhanced in the presence of oxygen. [Copyright &y& Elsevier]

There is interest in replacing inorganic fillers in paper, coatings and plastics with renewable organic fillers to improve the economics, performance and environmental aspects of such products. Starch microcellular foam (SMCF) particles are promising materials in this regard. This research was undertaken to produce SMCF particles and characterize their morphology, optical properties and interaction with water. SMCF particles were produced using corn starch; which was solubilized in water. The foam structure was created by precipitating the starch using ethanol in a solvent exchange technique. The starch was also reacted with alkyl ketene dimer (AKD) wax at different levels in order to understand if the AKD could impart water resistance to the particles. Two methods were used to incorporate AKD: (1) the AKD was coated onto foam particles after foam formation, and (2) the AKD was blended with the starch before foam particle formation. Hexane extraction was used to purify a portion of each of the samples to determine if unreacted AKD existed with the starch matrix. Particles with porous structure and high brightness were developed for all combinations of starch and AKD. The brightness of the particles was significantly higher than that of the uncooked starch, presumably due to the development of a porous structure. For the AKD coated particles a minimum amount of AKD charged was needed to develop a high contact angle, low solubility, and low water retention value, higher levels of AKD in AKD coated particles did not further alter these properties. This indicates that the changes in properties with AKD level with coated particles is a surface phenomena. Starch AKD blends did not show any increased resistance to water relative to the particles with no AKD blended. This is due to the ethanol used in the precipitation process extracting the AKD, which was confirmed by elemental analysis. The particles, even with the 10% AKD coated or blended, lost their porous structure upon rewetting. Further work needs to be performed to more effectively hydrophobize the starch foams with AKD. [Copyright &y& Elsevier]

This paper investigates the utilisation of nanofiltration (NF), agitation (by pump or sonication), freezing and acetone extraction methods to purify paper machine o-water. The results were judged by regained pulp brightness and reduction of various components. In the NF experiments the brightness was almost totally regained. Also the reduction of most measured components like lignin and carbon were retained well by the membrane (PES). The metal ions (Si, Al, Mg, Na, K, Mn, Ca, Fe and Cu) were reduced in the permeate (retained by the membrane) to the level found in the clear filtrate. This indicated that the metal ions (Si, Al, Mg, Na, K, Mn, Ca, Fe and Cu) were not brightness-reducing components. The flux was rather low for a commercial application because the membrane was a low-flux membrane. The reduction of sugar, colour and lignin residuals was quite high (>80%), and it was considered that these were possibly brightness-reducing components. It was found that by treating the fines with acetone and then returning them to the original water, the colour was reduced to a high enough degree that approximately 50% of the brightness reduction was recovered. It was considered that coloured contaminants that were absorbed on the fines were removed or destroyed. The brightness recovery was >50% for both the TMP and PK4 o-water. The brightness recovery was greater using NF, but in that case so many substances were reduced in the permeate that it was difficult to determine which were the brightness-reducing substances. However, in the case of acetone washing, the only component that was reduced was the colour. For both o-water PK4 and TMP the colour was reduced by 50% and the brightness recovery was 50%, suggesting a direct correlation. Agitation of the water samples by the means of a pump and sonication showed no change in the water, which included no changes in the brightness. The same was also found for water samples that were frozen. These experiments also showed that temperature changes did not affect water composition. [Copyright &y& Elsevier]