Effects of an innovative densification process on mechanical and physical properties of beech and Norway spruce veneers

Cencin, Alex; Zanetti, Michela; Urso, Tiziana; Crivellaro, Alan

doi:10.1186/s10086-021-01948-w

Cited by 8 publications

(6 citation statements)

References 42 publications

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“…The combination of chemical and physical processes (e.g., delignification and pressing processes of wooden materials) leads to the formation of natural materials with higher densities and mechanical properties than the starting materials. As demonstrated in the literature, the final densities of the materials that underwent these treatments showed an increase that fluctuated between +23% and +135% [13].…”

Section: Introductionsupporting

confidence: 54%

“…The results obtained after the densification process led to a greater increase in density than the values found up to now in the literature [13]. Increased density values are shown in Table 2.…”

Section: Discussionmentioning

confidence: 46%

“…Table 2 shows the average increase values of the two different woods after the densification processes. The values found in the available literature are in the range of +25% and +135% [13,15,16]. During the delignification and densification processes, the wood sample colors increasingly turned towards darker shades.…”

Section: Wood Densificationmentioning

confidence: 95%

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From Natural Woods to High Density Materials: An Ecofriendly Approach

et al. 2023

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Recently, different methods have been proposed to develop wood materials, termed “densified woods”, with density increment and improvement in mechanical proprieties. Almost all the proposed methods involve the use of reducing agents and strong bases. In this work, a new method has been developed involving the use of less polluting agents. The formation of densified woods is divided into two steps: delignification involves the removal of lignin, hemicelluloses, and shorter chains of cellulose, whereas densification involves the plastering of the delignified woods. The obtained materials showed a density increase of two to four times. The obtained densified woods were characterized by spectroscopic, microscopic, and thermogravimetric techniques and mechanical tests. The characterizations aimed at determining the variations of chemical and structural compositions of the samples after delignification and densification processes, showing, respectively, a decrease in lignin and a significant increase in the density and force necessary to bring the materials to yield. The final density of wood was two to three times higher and the force necessary to reach the yield point reached more than three times the initial one for some of the studied samples. These characterizations showed how different woods, with different properties, reach comparable densities and final mechanical properties after delignification and densification process. The increased mechanical properties of the materials allow their application in place of other composite woody materials.

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Section: Introductionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 46%

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From Natural Woods to High Density Materials: An Ecofriendly Approach

et al. 2023

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“…On the other hand, finer lignin particles have fewer prominent irregularities, leading to reduced mechanical interlocking and potentially lower internal bonding strength [107]. Additionally, finer lignin particles may have difficulty penetrating the pores and voids between the larger wood particles, resulting in weak bonding and a decrease in internal bonding strength [108]. Furthermore, finer lignin particles can create more void spaces between particles, reducing the effective contact area for bonding and weakening adhesion [109].…”

Section: Mechanical Properties Of Bark Particleboard With Various Par...mentioning

confidence: 99%

Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from <i>Leucaena leucocephala</i> Bark

Salim,

Asik,

Sarjadi

2024

JRM

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Lignin extraction from bark can maximize the utilization of biomass waste, offer cost-effectiveness, and promote environmental friendliness when employed as an adhesive material in bark particleboard production. Particles of fine (0.2 to 1.0 mm), medium (1.0 to 2.5 mm), and coarse (2.5 to 12.0 mm) sizes, derived from the bark of Leucaena leucocephala, were hot-pressed using a heating plate at 175°C for 7 min to create single-layer particleboards measuring 320 mm × 320 mm × 10 mm, targeting a density of 700 kg/m 3 . Subsequently, the samples were trimmed and conditioned at 20°C and 65% relative humidity. In this study, we compared bark particleboard bonded with urea formaldehyde (UF) adhesive to fine-sized particleboard bonded with demethylated lignin adhesive. The results indicated that bark particleboards utilizing demethylated lignin and UF adhesives exhibited similar qualities. Coarse particleboard showed differences in modulus of elasticity (MOE) and modulus of rupture (MOR), while medium-sized particles exhibited significant variations in moisture content (MC) and water absorption (WA). Furthermore, the thickness swelling of coarse and medium-sized particles under wet and oven-dried conditions exhibited notable distinctions. Overall, the demethylated lignin adhesive extracted from L. leucocephala bark demonstrated similar quality to UF adhesive, with particle size correlating inversely to the strength of the bark particleboard. KEYWORDSBark particleboard properties; demethylated lignin; lignin adhesives; Leucaena leucocephala; bark particles Nomenclature UF Urea formaldehyde MOE Modulus of elasticity MOR Modulus of rupture MC Moisture content TS Thickness swelling TS-Wet Thickness swelling from wet to oven dry conditions. TS-AD Thickness swelling from air-dry to oven dry conditions. IB Internal bonding

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“…Some precious wood posse high strength and beautiful pattern, while other ordinary woods are not. Because of the limited availability of precious wood, people on one hand modify the ordinary wood materials to improve the strength and appearance to increase their utilization value [1][2][3], and on the other hand, carry out artificial cultivation of precious tree species (Phoebe bournei, Cyclobalanopsis glauca, etc.) to increase the yield of precious wood.…”

Section: Introductionmentioning

confidence: 99%

Study on the Structural Characteristics and Physical and Mechanical Properties of Phoebe bournei Thinning Wood

Wu¹,

Liu²,

Chen³

et al. 2022

Journal of Renewable Materials

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The artificial afforestation of precious Phoebe bournei has been carried out in China. During the cultivation process, thinning wood will be produced. The properties of thinning wood might vary greatly with matured wood and require evaluation for better utilization. The objective of the present study aims to determine the wood structure, fiber morphology, and physical and mechanical properties of the Phoebe bournei thinning wood to help us understand the wood properties and improve its utility value. Three 14-year-old Phoebe bournei were cut from Jindong Forestry Farm of Hunan Province, China. The wood structure and fiber morphology were observed and analyzed with a light microscope and scanning electron microscope. The physical and mechanical properties were tested according to the Chinese national standards. The results showed as follows: (1) The Phoebe bournei thinning wood has a beautiful wood figure and fine texture, whereas the heartwood has not yet formed. ( 2) It is a diffuse-porous hardwood with small and less pores as well as fine wood rays. (3) The wood fiber is medium length and extremely thin wall thickness. (4) It is low in density and has excellent dimensionally stability. (5) The wood mechanical properties belong to the low to medium class and the comprehensive strength of wood belongs to the medium-strength class. It is concluded that Phoebe bournei thinning wood is suitable for wood carving, handicraft, high-end furniture, and decorative furniture parts.

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Effects of an innovative densification process on mechanical and physical properties of beech and Norway spruce veneers

Cited by 8 publications

References 42 publications

From Natural Woods to High Density Materials: An Ecofriendly Approach

From Natural Woods to High Density Materials: An Ecofriendly Approach

Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from <i>Leucaena leucocephala</i> Bark

Study on the Structural Characteristics and Physical and Mechanical Properties of Phoebe bournei Thinning Wood

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