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3 results on '"DEFIBRATION TEMPERATURE"'

1. Surface characteristics of thermomechanical pulps; the influence of defibration temperature and refining

Author

Gustafsson, Johanna, Lehto, Jouko H., Tienvieri, Taisto, Ciovica, Laura, and Peltonen, Jouko

Subjects
*METALS, *THERMOMECHANICAL treatment, *ATOMIC force microscopy, *PHOTOELECTRON spectroscopy
Abstract

The surface properties of thermomechanical pulps (TMP) were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Finnish and French spruce samples representing two different defibration temperatures as well as two different stages of refining were studied. In addition, samples from an RTS process were studied. The XPS results showed that the surface content of non-cellulosic components was higher for Finnish spruce compared with the French pulp samples. Different wood fibre cell wall structures and transition lamellae within the cell walls with characteristic microfibril orientation were identified by AFM. Besides the morphological features, the homogeneity of the surfaces was studied with AFM with respect to adhesion and stiffness. The refining was concluded to result in a cleavage taking place either within the secondary cell wall or at primary/secondary cell wall interface. No randomly oriented microfibrillar network structures typical for the primary cell wall were observed. The RTS process resulted in most homogeneous samples whereas heterogeneous structures with even damaged microfibrils were observed for e.g. the stage-2 refined TMP. [Copyright &y& Elsevier]

Published
2003
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2. Composites of High-Temperature Thermomechanical Pulps and Polylactic Acid

Subjects
Wood fiber composites, Thermal properties, Hydrophobic fibers, POLYPROPYLENE COMPOSITES, Mechanical properties, WOOD, Polylactic acid, High-temperature thermomechanical pulp, FIBER MORPHOLOGY, DEFIBRATION TEMPERATURE, CELL-WALL, LENGTH, BARRIER PROPERTIES, PLA, POLYMER COMPOSITES, ta216, CRYSTALLINITY
Published
2016

3. Composites of High-Temperature Thermomechanical Pulps and Polylactic Acid

Author

Antti E. Koistinen, Sanna Siljander, Iina Solala, Jyrki Vuorinen, Tapani Vuorinen, Department of Forest Products Technology, Tampere University of Technology, Aalto-yliopisto, and Aalto University

Subjects
Thermal properties, Environmental Engineering, Absorption of water, Materials science, lcsh:Biotechnology, Hydrophobic fibers, POLYPROPYLENE COMPOSITES, Mechanical properties, Bioengineering, WOOD, urologic and male genital diseases, Polylactic acid, law.invention, High-temperature thermomechanical pulp, FIBER MORPHOLOGY, chemistry.chemical_compound, Differential scanning calorimetry, DEFIBRATION TEMPERATURE, law, lcsh:TP248.13-248.65, CELL-WALL, Ultimate tensile strength, LENGTH, BARRIER PROPERTIES, heterocyclic compounds, POLYMER COMPOSITES, Fiber, Crystallization, Composite material, Waste Management and Disposal, Wood fiber composites, Izod impact strength test, bacterial infections and mycoses, female genital diseases and pregnancy complications, chemistry, Compounding, PLA, human activities, CRYSTALLINITY
Abstract

High-temperature thermomechanical pulps (HT-TMP, defibrated at 150 to 170 degrees C) were compared to a reference TMP (defibrated at 130 degrees C) as a reinforcement for polylactic acid (PLA). Composites were prepared by melt compounding, followed by injection molding, gradually increasing the used fiber content from 0 to 20 wt.%. The injection-molded specimens were characterized by tensile and impact strength tests, scanning electron microscopy, water absorption tests, and differential scanning calorimetry. The TMP fiber damage was also characterized before and after melt compounding by optical analysis. At 20% fiber content, the Young's modulus increased significantly, while the tensile strength remained unchanged and the impact strength decreased slightly. All fibers suffered damage during melt compounding, but the tensile strength remained about the same as in pure PLA. All types of TMP were able to increase the PLA rate of crystallization. The HT-TMP fibers were dispersed more evenly in PLA than the 130degrees C TMP. The 170 degrees C TMP produced composites of lower water absorption than the other two TMP types, probably because of its lower hemicellulose content and its higher surface coverage by lignin.

Published
2015

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