Zum Einfluss des Holzes sowie des Holzaufschlussverfahrens auf das Benetzungsverhalten von Kiefern- und Fichten-Faserstoffen

Abstract

The main objective of this research work was to study the wettability of thermomechanical pulps (TMP) prepared from heart- and sapwood of Scots pine (Pinus sylvestris [L.]). The TMP were prepared at different pulping temperatures (150 °C, 180 °C). Furthermore, thermomechanical (TMP) and chemo-thermomechanical pulps (CTMP) from Norway spruce (Picea abies [Karst.]) were also investigated. In this case both TMP and CTMP were prepared at 140 °C and 180 °C. Sheets of all pulps were prepared according to a method developed by Roffael et al. (2002). Sheets of TMP pulps from pine sapwood showed much better wettability compared with their counterparts from heartwoods. Pulps from heartwood experienced a dramatic decrease in their wettability when increasing the pulping temperature from 150 °C to 180 °C. In contrast increasing the temperature from 150° to 180 °C seems to have no deleterious effect on the wettability of pulps prepared from sapwood. This phenomenon has been explained by the higher extractive content in pine wood. Comparing TMP and CTMP pulps from Norway spruce leads to the result that in general CTMP pulps are of higher wettability. This can be attributed to the high hydrophobic extractive content in TMP pulps on the one hand and to the higher alkalinity of CTMP pulps on the other hand

Online Pre-Treatment of Thermomechanical Pulp with Emulsified Maleated Polypropylene for Processing of Extruded Thermoplastic Composites

“…This is in line with our initial hypothesis that the lignin-rich surfaces of high-temperature TMP would lead to better compatibility with the hydrophobic PP matrix and to composites with higher strength. It was shown by Roffael et al [46] and Schneider et al [47] that the higher the temperature during thermomechanical pulping, the lower the wettability and the higher the hydrophobicity of the fibres.…”

“…This can be attributed to the hydrophobation effect during high-temperature refining. It has been shown that the higher the temperature during thermomechanical refining, the lower the wettability of the fibres, i.e., the higher the hydrophobicity [46,47]. The more hydrophobic fibres may bond better with polypropylene, which in turn will reduce water uptake of the WPC.…”

“…The presence of lignin on the fibres has a strong effect on water absorption and swelling of the composites, which are processed either with or without the coupling agent. hydrophobicity [46,47]. The more hydrophobic fibres may bond better with polypropylene, which in turn will reduce water uptake of the WPC.…”

Benetzung von TMP und CTMP aus Holz sowie gebrauchten mitteldichten Faserplatten (MDF)

“…Daraus wird ersichtlich, dass die Prüfblätter mit TMP eine wesentlich schlechtere Benetzung als Prüfblätter mit CTMP aufweisen. Dies steht inÜbereinstimmung mit den Ergebnissen von Schneider et al (2007), wonach CTMP sich schneller benetzen lassen als TMP. Dies ist vermutlich zum einen auf den vergleichsweise höheren Gehalt an hydrophoben Extraktstoffen der TMP zurückzuführen und zum anderen auf das den CTMP anhaftende Alkali, das Extraktstoffe auflöst und die generelle Benetzbarkeit der Fasern mit wässrigen Lösungen verbessert.…”