Mechanical Properties of Cellulose and Flax Fiber Unidirectional Reinforced Plywood

Jorda, Johannes; Kain, Günther; Barbu, Marius Cătălin; Köll, Berndt; Petutschnigg, Alexander; Král, Pavel

doi:10.3390/polym14040843

Cited by 12 publications

(7 citation statements)

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“…The mean density of the tested groups range between 0.768 g/cm 3 (press temperature 140 °C; press time 10 min) and 0.810 g/cm 3 (press temperature 125 °C; press time 20 min) ( Figure 4 a). The gained results are within the range compared to the values mentioned in the literature for identical five-layered beech plywood set-ups [ 42 , 43 ]. Testing of the density specimen for 110 °C press temperature and 10 min press time was not possible due to delamination after pressing and conditioning.…”

Section: Resultssupporting

confidence: 76%

Quebracho Tannin Bio-Based Adhesives for Plywood

et al. 2022

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Wood-based products are traditionally bonded with synthetic adhesives. Resources availability and ecological concerns have drawn attention to bio-based sources. The use of tannin-based adhesives for engineered wood products has been known for decades, however, these formulations were hardly used for the gluing of solid wood because their rigidity involved low performance. In this work, a completely bio-based formulation consisting of Quebracho (Schinopsis balancae) extract and furfural is characterized in terms of viscosity, gel time, and FT-IR spectroscopy. Further, the usability as an adhesive for beech (Fagus sylvatica) plywood with regard to press parameters (time and temperature) and its influence on physical (density and thickness) and mechanical properties (modulus of elasticity, modulus of rupture and tensile shear strength) were determined. These polyphenolic adhesives presented non-Newtonian behavior but still good spreading at room temperature as well as evident signs of crosslinking when exposed to 100 °C. Within the press temperature, a range of 125 °C to 140 °C gained suitable results with regard to mechanical properties. The modulus of elasticity of five layered 10 mm beech plywood ranged between 9600 N/mm2 and 11,600 N/mm2, respectively, with 66 N/mm2 to 100 N/mm2 for the modulus of rupture. The dry state tensile shear strength of ~2.2 N/mm2 matched with other tannin-based formulations, but showed delamination after 24 h of water storage. The proposed quebracho tannin-furfural formulation can be a bio-based alternative adhesive for industrial applicability for special plywood products in a dry environment, and it offers new possibilities in terms of recyclability.

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Section: Resultssupporting

confidence: 76%

Quebracho Tannin Bio-Based Adhesives for Plywood

et al. 2022

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“…Deformation of the model in the processes of compression and recovery [ 26 ] is described by the following equations. For the material compression process:

and for material recovery process:

where γ is the normalized value of changes in the system linear dimensions, i.e., relative strain:

where

and

are, respectively, the sample thickness before mechanical exposure and the sample thickness at the moment of time variation t (mm).…”

Section: Resultsmentioning

confidence: 99%

“…This causes excessive dot gain of thin strokes and dotted features, such as letters and halftone dots, during printing and high pressure on the printed substrate. The compression pressure increases many times after the penetration of water and dichloroethane into the porous structure of the composite web through the layers of cotton fabric [ 25 , 26 ]. The relaxation time is 0.64 s and the compression time is 0.66 s. These liquids have close values of the dipole moments of the molecules.…”

Section: Resultsmentioning

confidence: 99%

Compression Relaxation of Multi-Structure Polymer Composites in Penetrating Liquid Medium

et al. 2022

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Multi-structural polymer composites are widely used in the mechanical engineering, automotive, aviation and oil refining industries, as well as in the printing industry as a shock-absorbing deckle on the offset cylinders of printing machines. During offset printing, composites come into contact with inks and washing solutions, the components of which penetrate the material and cause the polymers to swell. This process degrades the print quality, and for this reason the study of its features is relevant. The prerequisites for this work are the study of the fundamental laws of diffusion and sorption of liquids by polymers with different micro- and macro-structures in different physical states and in different forms (e.g., films, sheets, fibers and fabrics). The combination of polymer materials in the composition of multi-structural fabric blankets makes it possible to obtain materials with unique mechanical properties and high resistance to liquid penetrating media and to use them in high-tech processes of multi-color printing with high resolution and color rendering. This article reports for the first time the kinetics and thermodynamics results obtained from the swelling of multi-structural polymeric blankets in solvents used in printing, and the effect of sorption of different polar liquids on the viscoelastic strain under compression during the operation of the damping systems of printing machines. Using mathematical models of activated liquid diffusion in polymers and deformation of a viscoelastic body, the swelling rate constants, solvent diffusion coefficients (the kinetic characteristics of the swelling process) and Flory–Huggins parameters (the thermodynamic characteristics of the interaction of the solvent with the composite) for composite–solvent systems with several chemical composition variants were determined. The elastic modulus and the viscosity coefficient of the composite under liquid saturation were calculated based on the experimental cyclic compression data. The range of change in the compression and restoration times of the polymeric blankets (0.09 s ÷ 0.78 s) was determined. It was shown that the composite swelled to a limited extent in all the studied liquids. All solvents used were thermodynamically poor (χ > 0.5). It has been established that rubber–fabric blankets coated with nitrile rubber are the least resistant to the action of dichloroethane, and that blankets with layers of polyolefins are not resistant to ethyl acetate. Water significantly affects the physicochemical properties of rubber–fabric blankets with a large proportion of cotton fabric layers. The data obtained can serve as a basis for optimizing the compositions of inks and cleaning solutions, as well as a theoretical basis for the thermodynamics of composite–solvent systems.

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“…To an extent, the size classifications affect both the physical and mechanical properties of the cellulose fibres. It also influences the mechanical properties of materials, such as Young's modulus, shear modulus, yielding stress, fracture toughness, etc ( Joda et al., 2022 ).…”

Section: Introductionmentioning

confidence: 99%