Einfluss der thermischen Modifizierung von Holz auf das Wasserrückhaltevermögen (WRV-Wert)

Roffael, E.; Kraft, R.

doi:10.1007/s00107-011-0540-4

Cited by 9 publications

(4 citation statements)

References 5 publications

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“…The existence of lignin decreases the water‐holding properties, while hemicellulose increases the WRV of fibers. The beating of fibers during mechanical treatment creates modifies fibers structures by breaking intra and intermolecular bonds, which also improves water absorption properties [17] . Cellulose has amorphous and crystalline regions.…”

Section: Resultsmentioning

confidence: 99%

Effects of Phosphorylation Duration on the Jute Extracted Cellulose Nanofibrils Using Ultra‐sonication

et al. 2020

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The pretreatment process for the extraction of cellulose nanofibrils (CNFs) has been attracting the awareness of researchers. However, toxicity, complicated multistep procedures, and the use of costly chemicals are still some problems for chemical modification of cellulose fibers during the CNFs production. In this work, the phosphorylation reaction is introduced to pretreat jute fibers to extract CNFs with tiny diameter, and then the physicochemical properties of the obtained CNFs are analyzed. Experimental results exhibit that the phosphorylation process can affect the overall defibrillation process and the structure as well as properties of the involved products. This study also reports that the phosphorylation efficiency can be influenced by the existence of water, absence of urea, high temperature, and reaction duration. Even at a low degree of substitution, the phosphorylated CNFs exhibit better thermal stability and higher residual char compared to raw jute at 700 °C.

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Section: Resultsmentioning

confidence: 99%

Effects of Phosphorylation Duration on the Jute Extracted Cellulose Nanofibrils Using Ultra‐sonication

et al. 2020

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“…Similarly, in particles thermally modified at 180 °C for 1.5 hours, Weigl et al (2013) reported a decrease of 28.0 % and 46.0 % of the water retention capacity, which is related to the reduction of polarity. Coincidentally, Roffael and Kraft (2012) indicate that the thermal modification of the wood leads to a marked decrease of the water retention capacity. After subjecting particles to heat treatment, these authors reported a decrease in water retention values (after 72 hours in water) of 27.0 % for Fagus sylvatica, 19.4 % for Fraxinus excelsior and 30.0 % for Picea abies.…”

Section: Water Retention Capacity 32 Kapacitet Zadržavanja Vodementioning

confidence: 94%

“…The wettability of heat treated wood particles decreases in treated fibers (Poblete, 1983;Crespo et al, 2013) as well as water retention capacity (Roffael and Kraft, 2012;Weigl et al, 2013). The higher the temperature and the exposure time of heat treatment, the lower the amount of water absorbed by the wood (Poblete, 1983; Kartal et al, 2007.…”

Section: Uvodmentioning

confidence: 99%

Hygrothermal Treatment of Tepa (Laureliopsis philippiana Looser) Fibers

2020

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The present study consisted in determining the effects of a hygrothermal treatment on wood fibers from the Laureliopsis philippiana Looser species. The fibers were treated in autoclave at 150 °C for 90 minutes at a pressure of 430 kPa, which was generated during the evaporation process of the water in autoclave. Physical properties, color, and water retention capacity of hygrothermically treated and untreated fibers were analyzed. The chemical properties determined were the extractable amount in sodium hydroxide, toluene ethanol, hot and cold water, the cellulose, holocellulose and lignin contents, the pH value, the percentage of volatile and washable acids, and the buffer capacity. In hygrothermically treated fibers, a change of color was detected as well as a reduction in the water retention capacity and an increase in the percentage of extractable, cellulose, lignin and a decrease of holocellulose. Also an increase in acidity, amount of volatile and washable acids and buffer capacity were determined. Due to the chemical changes observed in the treated fibers, these would present advantages in the manufacture of fiberboards, facilitating the setting of the amino resins.

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“…However, it is not effective against thermites [19,20]. Thermal modification reduces the equilibrium moisture content (EMC) of ash [3,21,22] and decreases its water retention value [23], enhancing its dimensional stability [22,24,25]. It also alters the natural colour of wood, making it darker with the increasing severity of the treatment [3,21,26] as well as improves its resistance to weathering factors as regards colour stability, surface quality, and the reduction rate for strength properties [21,27,28].…”

Section: Introductionmentioning

confidence: 99%

Moisture-Dependent Strength Properties of Thermally-Modified Fraxinus excelsior Wood in Compression

et al. 2020

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European ash (Fraxinus excelsior L.) is one of the species commonly used for wood thermal modification that improves its performance. The presented research aimed to investigate a moisture-dependent strength anisotropy of thermally-modified European ash in compression. Wood samples were modified at 180 °C and 200 °C. Their mechanical parameters were determined in the principal anatomical directions under dry (moisture content of 3%) and wet (moisture content above fibre saturation point) conditions. Effect of heat treatment temperature and moisture content on the ash wood mechanical parameters concerning each anatomical direction were determined. The results show that thermal treatment kept the intrinsic anisotropy of wood mechanical properties. It decreased wood hygroscopicity, which resulted in improved strength and elasticity measured for wet wood when compared to untreated and treated samples. Higher treatment temperature (200 °C) increased wood elasticity in compression in all the anatomical directions despite wood moisture content during the measurements. Multivariate analysis revealed that the modification temperature significantly affected the modulus of elasticity perpendicular to the grain, while in the case of compression strength, the statistically significant effect was observed only parallel to the grain. The results obtained can be useful from an industrial perspective and can serve as part of a database for further modelling purposes.

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Einfluss der thermischen Modifizierung von Holz auf das Wasserrückhaltevermögen (WRV-Wert)

Cited by 9 publications

References 5 publications

Effects of Phosphorylation Duration on the Jute Extracted Cellulose Nanofibrils Using Ultra‐sonication

Effects of Phosphorylation Duration on the Jute Extracted Cellulose Nanofibrils Using Ultra‐sonication

Hygrothermal Treatment of Tepa (Laureliopsis philippiana Looser) Fibers

Moisture-Dependent Strength Properties of Thermally-Modified Fraxinus excelsior Wood in Compression

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