scholarly journals Effect of lignin and hemicelluloses on the tensile strength of micro-veneers determined at finite span and zero span

Holzforschung ◽  
2012 ◽  
Vol 66 (4) ◽  
Author(s):  
André Klüppel ◽  
Carsten Mai
Keyword(s):  
Tensile Strength ◽  
Combined Treatment ◽  
Sodium Chlorite ◽  
Wet Strength ◽  
Finite Span ◽  
Significant Strength ◽  
Strength Determination ◽  
Dry Conditions ◽  
Water Saturated ◽  
Moisture Conditions

Abstract Scots pine micro-veneers were subjected to hydrolysis with sulphuric acid or delignification with acidic sodium chlorite and a combination of both treatments. The tensile strength of untreated and treated veneers was determined at finite span (f-strength) and zero span (z-strength) under both dry (20°C, 65% relative humidity) and water-saturated conditions. Acidic hydrolysis resulted in significant strength losses in both testing modes and both moisture conditions, with the greatest strength reduction found for f-strength tested dry. After delignification, only f-strength under wet conditions was substantially reduced; dry f-strength and both dry and wet z-strength hardly changed. A combined treatment of prehydrolysis and delignification resulted in disintegration of the veneers, which made strength determination impossible. It was concluded that, in addition to cellulose, the hemicelluloses determine the f-strength under dry conditions, while lignin confers wet strength but appears not to contribute to interfibre adhesion and f-strength under dry conditions.

The Tensile Strength of Glass Yarn in Rubber. II. The Effects of Normal Humidities

1972 ◽  
Vol 45 (1) ◽  
pp. 49-59 ◽  
Author(s):  
R. A. Gregg
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Glass Composite ◽  
Moisture Index ◽  
Permanent Loss ◽  
Dry Conditions ◽  
The Stability ◽  
Moisture Conditions ◽  
High Temperature Drying

Abstract The resinous impregnant in glass yarn influences the stability of the yarn. Some glass yarns suffer tensile degradation on storage and/or vulcanization at high humidities. One type of glass yarn was exposed in atmospheres over the range 0–88% relative humidity at 73° F for times up to 400 days. Tensile losses of 30% or more can occur on storage of the glass yarn at the humidities in the upper end of the range. This loss is permanent as even vigorous drying at high temperatures will not restore the tensile. Under dry conditions the yarn has excellent storage stability. Furthermore, after vulcanization even into thin composites, the glass yarn shows only a small permanent loss of tensile under moisture conditions that would seriously degrade the yarn in a package. An increased degree of vulcanization of the rubber slightly increases the tensile strength of the composite. In addition to its permanent degradative action in long-term exposure, water has a phenomenological effect of reducing glass composite tensile by its presence. A tensile sensitivity to moisture index is suggested and used to characterize the glass yarn. This tensile loss is recoverable by drying but some of the water is bound very tightly. Thin composites do not give up all of the water in 150 days over Drierite® as shown by the fact that more vigorous high temperature drying leads to a further increase in tensile strength. Tensile strength at 300° F is about 25% lower than at 73° F at any moisture content. Higher moisture contents lead to lower absolute tensiles. Tensile values are detailed for conditions that might exist during cure or in a product running at a high temperature. The high temperature incurred tensile reductions from a standard tensile are significant and should be considered in designing products. The detailed observations apply only to this particular glass yarn but the principles and methods are applicable in the evaluation or development of any glass yarn.

scholarly journals Effects of water absorption on the mechanical properties of hybrid natural fibre/phenol formaldehyde composites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sekar Sanjeevi ◽  
Vigneshwaran Shanmugam ◽  
Suresh Kumar ◽  
Velmurugan Ganesan ◽  
Gabriel Sas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Water Absorption ◽  
Hybrid Composites ◽  
Phenol Formaldehyde ◽  
Natural Fibre ◽  
The Other ◽  
Fibre Reinforcement ◽  
Dry Conditions

AbstractThis investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m2) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.

Experimental Study on Mechanical Property of Concrete Based on Seawater and Sea Sand

2013 ◽  
Vol 641-642 ◽  
pp. 574-577 ◽  
Author(s):  
Ying Tao Li ◽  
Ling Zhou ◽  
Mao Jiang ◽  
Yu Zhang ◽  
Jun Shao
Keyword(s):  
Mechanical Property ◽  
Experimental Study ◽  
Fly Ash ◽  
Raw Materials ◽  
Growth Trend ◽  
Sea Sand ◽  
Significant Strength ◽  
Dry Conditions ◽  
Early Strength ◽  
Better Than

In this paper, the mechanical property experiments of concrete based on the seawater and sea sand have been carried in different raw materials preparation and different conservation environments. The results show that the early strength and late strength of concrete based on seawater and sea sand are better than concrete based on freshwater and sand. There is no significant strength decreased for concrete based on seawater and sea sand under accelerated alternating wet and dry conditions. For concrete based on seawater and sea sand mixed with admixture, the downward trend of late strength is significantly delayed, the late strength of concrete based on the seawater and sea sand mixed with slag gets the most obvious growth trend, while the late strength of seawater and sea sand concrete mixed with fly ash gets the largest increment.

Flexible cellulose nanopaper with high wet tensile strength, high toughness and tunable ultraviolet blocking ability fabricated from tobacco stalk via a sustainable method

2018 ◽  
Vol 6 (27) ◽  
pp. 13021-13030 ◽  
Author(s):  
Qingbo Wang ◽  
Haishun Du ◽  
Fang Zhang ◽  
Yuedong Zhang ◽  
Meiyan Wu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Mechanical Performance ◽  
Residual Lignin ◽  
Wet Strength ◽  
High Toughness ◽  
Uv Blocking ◽  
Cellulose Nanopaper ◽  
Tobacco Stalk

Retaining residual lignin in nanopaper leads to UV-blocking ability and significantly improves mechanical performance, especially the toughness and wet strength.

scholarly journals Environmentally friendly and breathable wet-laid hydroentangled nonwovens for personal hygiene care with excellent water absorbency and flushability

2018 ◽  
Vol 5 (4) ◽  
pp. 171486 ◽  
Author(s):  
Chao Deng ◽  
Wanjun Liu ◽  
Yinjiang Zhang ◽  
Chen Huang ◽  
Yi Zhao ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Environmentally Friendly ◽  
Air Permeability ◽  
Personal Hygiene ◽  
Water Absorbency ◽  
Excellent Performance ◽  
Wet Strength ◽  
Abrasion Test ◽  
Mechanical Bonding ◽  
Bonding Technique

Developing wet-laid papers with a good wet strength remains a longstanding challenge in the papermaking industry. In this study, hydroentanglement, a mechanical bonding technique is developed to consolidate the wet-laid fibre web. The results indicate that wet tensile strength, ductile stretching property, softness, air permeability and water absorbency of the wet-laid fibre web are significantly improved by hydroentanglement. In addition, the abrasion test shows that the dusting off rate of wet-laid fibre web can be effectively reduced through hydroentanglement. Moreover, the disintegration experiment proves that wet-laid hydroentangled nonwovens could be easily dispersed when compared with conventional carded hydroentangled nonwovens. Therefore, the new wet-laid hydroentangled nonwovens can maintain excellent performance in a wet state, showing a great potential for personal hygiene applications.

scholarly journals Tensile Strength and Dispersibility of Pulp/Danufil Wet-Laid Hydroentangled Nonwovens

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3931
Author(s):  
Chao Deng ◽  
R. Hugh Gong ◽  
Chen Huang ◽  
Xing Zhang ◽  
Xiang-Yu Jin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fiber Length ◽  
Water Jet ◽  
Pulp Fibers ◽  
Wet Strength ◽  
Blend Ratio ◽  
Sewage Systems

Wet-laid hydroentangled nonwovens are widely used for disposable products, but these products generally do not have good dispersibility and can block sewage systems after being discarded into toilets. In this study, both pulp fibers and Danufil fibers are selected as we hypothesize that the high wet strength and striated surface of Danufil fibers would allow us to produce nonwovens with better dispersibility while having enough mechanical properties. The wet strength and dispersibility of nonwovens are systematically studied by investigating the influence of the fiber blend ratio, fiber length, and water jet pressure. The results indicate that the percent dispersion could be as high as 81.3% when the wet strength is higher than 4.8 N, which has been improved greatly comparing the percent dispersion of 67.6% reported before.

Bio-adhesives from unfolded soy protein reinforced by nano-chitosan for sustainable textile industry

2019 ◽  
Vol 90 (9-10) ◽  
pp. 1094-1101 ◽  
Author(s):  
Xiaoyun Xu ◽  
Wenfeng Hu ◽  
Qinfei Ke ◽  
Honggang Liu ◽  
Juan Li ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Environmental Pollution ◽  
Soy Protein ◽  
Textile Industry ◽  
Sodium Dodecyl ◽  
Water Stability ◽  
Protein Films ◽  
Sodium Dodecyl Sulfonate ◽  
Wet Strength ◽  
Protein Adhesives

Biodegradable adhesives from nano-chitosan-reinforced unfolded soy protein have been fabricated to potentially reduce environmental pollution and drive a sustainable textile industry. The weak adhesion strength and poor water stability of soy protein films limit their use in the textile industry. In this work, the influence of sodium-dodecyl-sulfonate on unfolding of soy protein, and the reinforcement effects of nano-chitosan on the tensile properties of unfolded soy protein adhesives were investigated. The results demonstrate that the bio-adhesives developed had 157% and 85% increments on tensile strength and water stability compared with unmodified soy protein. Also, dry and wet strength of the pulp/viscose wet-laid nonwovens were increased 43% and over 100% after adhesion, indicating that modified soy protein shows promise for use as a textile bio-adhesive for sustainable industry.

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.

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

2015 ◽  
Vol 60 (4) ◽  
pp. 985-996 ◽  
Author(s):  
Xiangyu Wang
Keyword(s):  
Tensile Strength ◽  
Failure Mode ◽  
Coal Mine ◽  
Transversely Isotropic ◽  
Failure Criteria ◽  
Ground Control ◽  
Brazilian Tensile Strength ◽  
Splitting Strength ◽  
Water Saturated ◽  
Brazilian Splitting

Abstract For coal mine ground control issues, it is necessary to propose a failure criteria accounting for the transversely isotropic behaviors of rocks. Hence, it is very helpful to provide experimental data for the validation of the failure criteria. In this paper, the method for preparing transversely isotropic specimens and the scheme of the Brazilian tensile strength test are presented. Results obtained from Brazilian split tests under dry and water-saturated conditions reflect the effect of the development direction β of the structural plane, such as the bedding fissure, on the tensile strength, ultimate displacement, failure mode, and the whole splitting process. The results show that the tensile strength decreases linearly with increasing β. The softening coefficient of the tensile strength shows a sinusoidal function. The values of the slope and inflection point for the curve vary at the different stages of the Brazilian test. The failure mode of the rock specimen presented in this paper generally coincides with the standard Brazilian splitting failure mode. Based on the test results, the major influencing factors for the Brazilian splitting strength are analyzed and a mathematical model for solving the Brazilian splitting strength is proposed. The findings in this paper would greatly benefit the coal mine ground control studies when the surrounding rocks of interest show severe transversely isotropic behaviors.

The Study of Sodium Alginate Adsorption with PAE as Environmental Friendly Additive for Paper Strength

2012 ◽  
Vol 476-478 ◽  
pp. 1855-1861
Author(s):  
Xiao Lei Song ◽  
Chun Li Yao ◽  
Xiao Juan Jin
Keyword(s):  
Tensile Strength ◽  
Electron Microscope ◽  
Binary System ◽  
Scanning Electron Microscope ◽  
Paper Strength ◽  
Wet Strength ◽  
Environmental Friendly ◽  
Film Forming ◽  
Scanning Electron ◽  
Sem Analyses

This study shows a optimization usage of SA and PAE on enhancing both wet and dry strength of paper. The influence of the dosage of PAE and the viscosity of SA on the binary system for strengthening of paper have been studied and compared with paper which use PAE alone as a wet strength additive. A optimization ratio of PAE/SA was obtained, and with this ratio unchanged the amount of PAE/SA and initial of pH of the pulp has been tested. Scanning electron microscope (SEM) was used as a assistant method to observe those influence. The results showes that PAE/SA binary strengthening system for paper has a better property than that of PAE alone as a wet strength additive. The optimal viscosity of SA is about 350 mPa•S and the optimal ratio of PAE and SA is 3:2 and the addition of PAE and SA are 0.75% and 0.5% respectively. SEM analyses confirm that the film-forming property of PAE is accelerated by SA and it is also noticeable that the PAE/SA film can stick to the suface of fibres uniformly in the aqueous pulp slurry environment. The reaserch on the effects of the slurries at different pH to the wet and dry tensile strength prove that PAE/SA strength system is more suitable for neutral and alkaline papermaking conditions.

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