Tensile strength of handsheets prepared with macerated fibres from solid wood modified with cross-linking agents

Holzforschung ◽  
2015 ◽  
Vol 69 (8) ◽  
pp. 959-966 ◽  
Author(s):  
Stergios Adamopoulos ◽  
Reza Hosseinpourpia ◽  
Carsten Mai
Keyword(s):  
Tensile Strength ◽  
Strength Loss ◽  
Solid Wood ◽  
Cross Linking ◽  
Microscopic Appearance ◽  
Finite Span ◽  
The Stability ◽  
And Control ◽  
Additional Role ◽  
Modified Wood

Abstract This study was conducted to explain the tensile strength loss of wood due to the modification with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and glutaraldehyde (GA). Modified and control wood blocks were macerated to deliberate fibres, and handsheets were produced thereof. The nitrogen content of the fibres indicated that maceration removed the major proportions of DMDHEU. The stability of GA in wood during maceration was not assessed. Tensile strength determined at zero span (z-strength) and finite span (f-strength) was equal for the handsheets from DMDHEU-modified fibres and the control handsheets. The microscopic appearance of the tested finite-span paper strips from DMDHEU-modified fibres mainly indicated interfibre failure and did not differ from the fibre fracture mode of the control handsheets. In contrast, the z-strength of the handsheets from GA-modified fibres was lower than that of controls and decreased with increasing content of GA in the initial modified wood. The f-strength behaviour of the handsheets from GA-modified fibres was the opposite: it was higher than that of controls and increased with increasing GA content. The microscopic appearance of the rapture zones of the finite-span testing mainly indicated intrafibre failure for the GA-modified fibres. It was concluded that cross-linking is likely to be the major reason for tensile strength loss of GA- and DMDHEU-modified wood. In terms of DMDHEU-modified wood, the incrustation of the cell wall by the resin and the reduction in pliability could play an additional role.

scholarly journals Effects of modification with glutaraldehyde on the mechanical properties of wood

Holzforschung ◽  
2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Zefang Xiao ◽  
Yanjun Xie ◽  
Holger Militz ◽  
Carsten Mai
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Scots Pine ◽  
Compression Strength ◽  
Bending Strength ◽  
Weight Percent Gain ◽  
Strength Loss ◽  
Modulus Of Rupture ◽  
Finite Span ◽  
Decreasing Ph

Abstract Scots pine (Pinus sylvestris L.) sapwood was treated with glutaraldehyde (GA) and magnesium chloride (MgCl2) as a catalyst. The effects of treating conditions on the mechanical properties were examined. The weight percent gain (WPG) of thin veneer strips after leaching was highest at pH 4.0–4.5 and tensile strength measured in zero-span strength and finite-span strength decreased with decreasing pH in a range of 3.5–5.5. Sole treatment with MgCl2 also gradually decreased the tensile strength up to 25% with decreasing pH. At a fixed GA concentration (1.2 M), increasing MgCl2 concentration linearly diminished tensile strength. Conversely, increasing GA at a fixed MgCl2 concentration (1.5%) displayed the same effect, whereas in both cases zero-span strength loss was higher than finite span-strength loss. GA treatment of Scots pine sapwood stakes did not affect the modulus of rupture and the modulus of elasticity, but significantly reduced work to maximum load in bending and impact bending strength indicating embrittlement of wood. At the same time, compression strength increased with increasing WPG of GA. It is assumed that embrittlement caused by hydrolysis and crosslinking of cell wall polymers is compensated by enhanced compression strength thereby resulting in unchanged bending strength.

scholarly journals Effect of treatments with 1,3-dimethylol-4,5-dihydroxy-ethyleneurea (DMDHEU) on the tensile properties of wood

Holzforschung ◽  
2007 ◽  
Vol 61 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Yanjun Xie ◽  
Andreas Krause ◽  
Holger Militz ◽  
Hrvoje Turkulin ◽  
Klaus Richter ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Tensile Properties ◽  
Failure Mode ◽  
Magnesium Chloride ◽  
Strength Loss ◽  
Finite Span ◽  
Hemicellulose Degradation ◽  
Thin Veneer

Abstract The thin-veneer strip technique was applied to investigate the modifying effects of 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) on the tensile strength of wood. Pinewood veneers treated with solutions of DMDHEU alone and in combination with magnesium chloride (MgCl2) as a catalyst showed considerable strength losses of up to 50% in zero-span and up to 70% in finite-span testing modes. The higher strength losses in the latter case are due to hemicellulose degradation, which cannot be assessed in zero-span testing. Strength loss observed after treatment with DMDHEU and MgCl2 was approximately as high as the sum of the strength losses determined after individual treatments with MgCl2 or DMDHEU. Micrographs of veneers after finite-span testing revealed that catalysed DMDHEU treatment changed the predominant failure mode from interfibre fracture (in controls) to intrafibre fracture. The mechanism of strength loss resulting from treatment with DMDHEU is discussed.

Wrinkle recovery angle enhancement and tensile strength loss of 1,2,3,4-butanetetracarboxylic acid finished lyocell fabrics

2020 ◽  
Vol 90 (17-18) ◽  
pp. 2097-2108
Author(s):  
Guizhen Ke ◽  
Zhiheng Xiao ◽  
Xinya Jin ◽  
Lixiang Yu ◽  
Jianqiang Li ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Breaking Strength ◽  
Strength Loss ◽  
Curing Temperature ◽  
Cross Linking ◽  
Regression Equations ◽  
Acid Degradation ◽  
Recovery Angle ◽  
Butanetetracarboxylic Acid ◽  
Strength Retention

The formaldehyde-free crease-proof finishing agent 1,2,3,4,-butanetetracarboxylic acid (BTCA) was used to treat lyocell fabrics. The effects of BTCA concentration and curing temperature on the wrinkle recovery angle (WRA) and tensile breaking strength of lyocell fabrics were discussed. The results showed that with the increase of BTCA concentration and curing temperature, the WRA value of lyocell fabrics increased obviously and the maximum WRA reached 147°, but breaking strength decreased gradually and the minimum strength retention was 68%. The WRA was durable against laundering. The fabric whiteness difference was not obvious and the whiteness retention of all samples exceeded 98%. After further alkali treatment, the WRA of the treated lyocell fabrics decreased and the fracture strength retention recovered to varying degrees (0.45–10.8%). The developed regression equations were found to be in good correlation ( r2 > 92%) with the selected variables (tensile strength, BTCA concentration, curing temperature). Fourier transform infrared spectroscopy analysis confirmed that the tensile strength loss of BTCA-treated lyocell fabrics was caused by cross-linking of cellulose molecules and acid degradation. Tensile strength loss that resulted from ester bonding could be restored after hydrolysis in alkaline solution. The recoverable magnitude of tensile strength was related to the curing temperature. A high temperature not only promoted the cross-linking of cellulose macromolecules, but also accelerated the acid degradation of cellulose.

Preparation and Characterization of β-glucosidase Films for Stabilization and Handling in Dry Configurations

2020 ◽  
Vol 21 (8) ◽  
pp. 741-747
Author(s):  
Liguang Zhang ◽  
Yanan Shen ◽  
Wenjing Lu ◽  
Lengqiu Guo ◽  
Min Xiang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Protein Function ◽  
Protein Stabilization ◽  
Functional Protein ◽  
Elongation At Break ◽  
Gelatin Films ◽  
The Stability ◽  
And Function ◽  
General Method

Background: Although the stability of proteins is of significance to maintain protein function for therapeutical applications, this remains a challenge. Herein, a general method of preserving protein stability and function was developed using gelatin films. Method: Enzymes immobilized onto films composed of gelatin and Ethylene Glycol (EG) were developed to study their ability to stabilize proteins. As a model functional protein, β-glucosidase was selected. The tensile properties, microstructure, and crystallization behavior of the gelatin films were assessed. Result: Our results indicated that film configurations can preserve the activity of β-glucosidase under rigorous conditions (75% relative humidity and 37°C for 47 days). In both control films and films containing 1.8 % β-glucosidase, tensile strength increased with increased EG content, whilst the elongation at break increased initially, then decreased over time. The presence of β-glucosidase had a negligible influence on tensile strength and elongation at break. Scanning electron-microscopy (SEM) revealed that with increasing EG content or decreasing enzyme concentrations, a denser microstructure was observed. Conclusion: In conclusion, the dry film is a promising candidate to maintain protein stabilization and handling. The configuration is convenient and cheap, and thus applicable to protein storage and transportation processes in the future.

scholarly journals Data-Driven Stability Assessment of Multilayer Long Short-Term Memory Networks

2021 ◽  
Vol 11 (4) ◽  
pp. 1829
Author(s):  
Davide Grande ◽  
Catherine A. Harris ◽  
Giles Thomas ◽  
Enrico Anderlini
Keyword(s):  
Neural Network ◽  
Network Architecture ◽  
Short Term Memory ◽  
Moving Average ◽  
Machine Learning Algorithms ◽  
Physical Models ◽  
Data Driven ◽  
The Stability ◽  
And Control ◽  
Nonlinear Autoregressive

Recurrent Neural Networks (RNNs) are increasingly being used for model identification, forecasting and control. When identifying physical models with unknown mathematical knowledge of the system, Nonlinear AutoRegressive models with eXogenous inputs (NARX) or Nonlinear AutoRegressive Moving-Average models with eXogenous inputs (NARMAX) methods are typically used. In the context of data-driven control, machine learning algorithms are proven to have comparable performances to advanced control techniques, but lack the properties of the traditional stability theory. This paper illustrates a method to prove a posteriori the stability of a generic neural network, showing its application to the state-of-the-art RNN architecture. The presented method relies on identifying the poles associated with the network designed starting from the input/output data. Providing a framework to guarantee the stability of any neural network architecture combined with the generalisability properties and applicability to different fields can significantly broaden their use in dynamic systems modelling and control.

Tensile properties of finger-jointed lumber under high-temperature and oxygen-free conditions

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kong Yue ◽  
Feng Wang ◽  
Weidong Lu ◽  
Zhongqiu Tang ◽  
Zhangjing Chen ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Tensile Properties ◽  
High Temperatures ◽  
Variable Temperature ◽  
Physical Property ◽  
Solid Wood ◽  
Nitrogen Atmosphere ◽  
Thermal Physical Property ◽  
Electron Microscopy Analysis ◽  
Increasing Temperature

Abstract A model for engineered wood was developed that considers the parallel-to-grain tensile strength of finger-jointed lumber at high temperatures relevant to fire conditions. The finger-jointed lumber was composed of Douglas fir, larch, and poplar wood with phenol-resorcinol-formaldehyde (PRF) as an adhesive. The tensile properties of the finger-jointed lumber were evaluated at high temperatures under oxygen-free conditions, i.e. in a nitrogen atmosphere. A combination of chemical and thermal-physical property analysis of the PRF adhesive and microscopic observations on the glueline was used to discuss the reduction of tensile strength of the parallel-to-grain finger-jointed lumber at variable temperature. The results show that the tensile strength of the finger-jointed lumber decreased linearly with increasing temperature. The parallel-to-grain tensile strength of the PRF finger-jointed samples at 20 and 280 °C were 84 and 5% of the tensile strength of the solid wood at 20 °C, respectively. The thermal-physical properties and scanning electron microscopy analysis revealed that the pyrolysis intensity of the PRF adhesive was lower than that of the wood at 220 °C or higher.

scholarly journals Tensile Strength of Nylon Netting Subjected to Various Concentrations of Disinfecting Chemicals

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Heidi Moe Føre ◽  
Stine Wiborg Dahle ◽  
Rune H. Gaarder
Keyword(s):  
Hydrogen Peroxide ◽  
Tensile Strength ◽  
Fish Farming ◽  
Strength Loss ◽  
Chemical Exposure ◽  
Strength Reduction ◽  
Severe Reduction ◽  
Service Stations ◽  
Trade Names ◽  
Net Cages

This paper presents a study of traditional netting materials subjected to disinfecting chemicals during fish farming and treatment of net cages. A series of tests were performed in order to study the effect of various concentrations of disinfecting chemicals on the tensile strength of Raschel knitted Nylon netting materials. Simulated spill of diluted hydrogen peroxide (HP) to the jump fence during de-lousing did not affect the strength of the applied new and used knotless nylon netting samples. Hydrogen peroxide reacted with biofouling forming gas bubbles, but this did not result in reduced netting strength. The performed tests did not indicate any effect on netting strength from a simulated single, traditional bath disinfection as performed at service stations applying the disinfectant Aqua Des (AD) containing peracetic acid (PAA). However, increasing the AD concentration from 1 to 10% resulted in a strength reduction of 3–6%. Simulated spill of concentrated AD on the jump fence of a net with copper coating residuals resulted in a severe reduction in strength of 45%. This strength loss was probably a consequence of chemical reaction between copper and Aqua Des, and uncoated netting did not experience any loss in strength subjected to the same chemical exposure. These findings from application of AD should also apply to other PAA disinfection chemicals with trade names as, for example, Perfectoxid and Addi Aqua.

The Application of the Amorphous Metal Transformers in Heavy Oil Electric Heating System

2014 ◽  
Vol 532 ◽  
pp. 191-195 ◽  
Author(s):  
Bao Jiang Sun ◽  
Lei Su ◽  
Chao Zhang
Keyword(s):  
Electric Heating ◽  
Heating System ◽  
Intermediate Frequency ◽  
Amorphous Metal ◽  
Technical Performance ◽  
Alloy Material ◽  
Working Principle ◽  
The Stability ◽  
And Control ◽  
Fast Rise

In order to solve the problem that the big loss of no-load and the fast rise of temperature when employ the conventional silicon steel metal transformer (SSMT) in the electric heating system, we choose the amorphous metal transformer (AMMT). In this paper, firstly, we give a brief introduction of the amorphous alloy material properties and compare the no-load characteristic of the AMMT with the SSMT. Secondly, the structure of intermediate frequency heating system working principle and control strategy are introduced. Finally, extensive experiments were conducted to validate the ideas. The experiments show that the AMMT not only improve the efficiency of transformer, solve the heating problem of transformer, but also improve the stability, security and other technical performance of the system, so it is worth recommending and promoting.

scholarly journals An estimation on the mechanical stabilities of SAMs by low energy Ar+ cluster ion collision

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Y. Tong ◽  
G. R. Berdiyorov ◽  
A. Sinopoli ◽  
M. E. Madjet ◽  
V. A. Esaulov ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Crystal Surface ◽  
Depth Profiling ◽  
Low Energy ◽  
Cross Linking ◽  
Xps Spectra ◽  
Self Assembled ◽  
The Stability

AbstractThe stability of the molecular self-assembled monolayers (SAMs) is of vital importance to the performance of the molecular electronics and their integration to the future electronics devices. Here we study the effect of electron irradiation-induced cross-linking on the stability of self-assembled monolayer of aromatic 5,5′-bis(mercaptomethyl)-2,2′-bipyridine [BPD; HS-CH2-(C5H3N)2-CH2-SH] on Au (111) single crystal surface. As a refence, we also study the properties of SAMs of electron saturated 1-dodecanethiol [C12; CH3-(CH2)11-SH] molecules. The stability of the considered SAMs before and after electron-irradiation is studied using low energy Ar+ cluster depth profiling monitored by recording the X-ray photoelectron spectroscopy (XPS) core level spectra and the UV-photoelectron spectroscopy (UPS) in the valance band range. The results indicate a stronger mechanical stability of BPD SAMs than the C12 SAMs. The stability of BPD SAMs enhances further after electron irradiation due to intermolecular cross-linking, whereas the electron irradiation results in deterioration of C12 molecules due to the saturated nature of the molecules. The depth profiling time of the cross-linked BPD SAM is more than 4 and 8 times longer than the profiling time obtained for pristine and BPD and C12 SAMs, respectively. The UPS results are supported by density functional theory calculations, which show qualitative agreement with the experiment and enable us to interpret the features in the XPS spectra during the etching process for structural characterization. The obtained results offer helpful options to estimate the structural stability of SAMs which is a key factor for the fabrication of molecular devices.

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