scholarly journals Comparison of Bonding Performance Between Plywood and Laminated Veneer Lumber Induced by High Voltage Electrostatic Field.

2019 ◽  
Vol 275 ◽  
pp. 01013
Author(s):  
Qian He ◽  
Tianyi Zhan ◽  
Haiyang Zhang ◽  
Zehui Ju ◽  
Lu Hong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Voltage ◽  
Electrostatic Field ◽  
Wood Surface ◽  
Bonding Strength ◽  
Surface Characteristics ◽  
Wood Failure ◽  
Photoelectron Spectra ◽  
Masson Pine ◽  
Laminated Veneer Lumber

High voltage electrostatic field (HVEF) was applied in order to improve wood surface characteristics, bonding and mechanical properties of wood composites. Masson pine (Pinus massoniana Lamp.) plywood and laminated veneer lumber (LVL) were selected in this study. Surface characteristics were conducted by the electron spin resonance (ESR) and X-ray photoelectron spectra (XPS). Bonding interphase and mechanical properties were investigated by fluorescence microscopy and vertical density profile (VDP), bonding strength, wood failure ratio, MOE and MOR. The results indicated that more increments were obtained in free radicals, O/C ratios and C2-C4 components. This is because electrons broke more wood chemical groups and new ions occurred among wood surface under HVEF. Significantly decreased PF adhesive penetration depth (PD) and increased density at bonding interphase was achieved in HVEF treated composites. More decrease of PD and increment of density were observed in plywood than that of LVL. This was attributed to cross linked wood fibers among bonding interphase in plywood. Mechanical properties of bonding strength, wood failure ratio, MOE and MOR were significantly increased under HVEF treatment both for two composites. Higher bonding strength, MOE and MOR were obtained in plywood and their increments were as 98.53%, 33.33%, 18.55% and 12.72%.

scholarly journals Highly Mechanical Performance of Laminated Veneer Lumber Induced by High Voltage Electrostatic Field

2019 ◽  
pp. 67-75
Author(s):  
Qian He ◽  
Tianyi Zhan ◽  
Zehui Ju ◽  
Haiyang Zhang ◽  
Lu Hong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
High Voltage ◽  
Electrostatic Field ◽  
Shear Failure ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Contact Angles ◽  
Bonding Interface ◽  
Laminated Veneer Lumber

The high voltage electrostatic field (HVEF), as a novel technology, was applied in the study to obtain a highly mechanical performance of LVL (laminated veneer lumber) by increasing limiting value of shear failure strength directly affected by bonding strength. The surface property of wood, polymerization extent of PF, bonding interface of wood-to-PF and mechanical properties of LVL were investigated under the HVEF treatment. The results showed that increased free radicals and total surface energy were acquired under the HVEF treatment resulting from more polar groups (?OH, ?CHO) and ions were triggered leading to decreased contact angles identified both for Poplar and Masson specimens. The HVEF provided more reactions among wood-to-UF and more cross linking reaction of PF occurred in the treating step. The tendency of vertical density profile was more extremely steep than the control with max density increased by 24.93% and 30.24% for Poplar and Masson LVL respectively since adhesive aggregated continuously and orderly along bonding interface and permeation depth reduced to around 200 ?m, accounting for improved bonding shear strength, which eventually brought an enhancement on mechanical properties of LVL with horizon shear strength (?and?), modulus of elasticity and static bending strength significantly enhanced by 14.65%, 10.68%, 20.67% and 12.34% for Poplar LVL and that of Masson LVL enhanced by 17.30%, 13.93%, 18.55% and 12.72%. Besides, the delamination ratio was decreased by 49.57% and 58.32% respectively both for Poplar and Masson specimens.

Variation of surface and bonding properties among four wood species induced by a high voltage electrostatic field (HVEF)

Holzforschung ◽  
2019 ◽  
Vol 73 (10) ◽  
pp. 957-965 ◽  
Author(s):  
Qian He ◽  
Tianyi Zhan ◽  
Haiyang Zhang ◽  
Zehui Ju ◽  
Lu Hong ◽  
...  
Keyword(s):  
High Voltage ◽  
Electrostatic Field ◽  
Wood Species ◽  
Phenol Formaldehyde ◽  
Lignin Content ◽  
Chemical Properties ◽  
Pinus Massoniana ◽  
Populus Tomentosa ◽  
Chinese Fir ◽  
Masson Pine

Abstract A high voltage electrostatic field (HVEF) was applied to enhance the bonding performance of wood composites prepared with phenol-formaldehyde (PF) adhesive and different wood species and radial cut combinations. Four wood species including Masson pine (Pinus massoniana), Chinese fir (Cunninghamia lanceolata), poplar (Populus tomentosa) and ayous (Triplochiton scleroxylon) were studied. The results of HVEF-treatment turn out to be species-dependent, and are related to the anatomical and chemical properties of wood. It was demonstrated by a statistical approach that the lignin content is the most significant parameter with a good correlation coefficient (R2 > 0.8). High lignin content leads to high free radical concentration at the wood surface and the HVEF enhanced the adhesive penetration depth, the maximal density and the bonding strength (Bst) at the interphase. On the contrary, high extract contents and large lumina diameters negatively impacted the surface modification by HVEF. The magnitude of the effects was in the following order: ayous < poplar < Masson pine < Chinese fir.

Addition of Boron Based Compound in the LVL Glueline: Effect on the Mechanical Properties and the Leaching of Boron

Holzforschung ◽  
2001 ◽  
Vol 55 (5) ◽  
pp. 559-562 ◽  
Author(s):  
V. Bridaux ◽  
B. Charrier ◽  
N. Fauroux ◽  
F. Charrier ◽  
J. Goncalez
Keyword(s):  
Mechanical Properties ◽  
Boric Acid ◽  
Bonding Strength ◽  
Urea Formaldehyde ◽  
Strength Properties ◽  
Water Leaching ◽  
Laminated Veneer Lumber ◽  
Cielab System

Summary This study aims at the optimization of the durability of Laminated Veneer Lumber (LVL) panels by adding borates to the gluing formulation. Poplar veneers measuring 2.6 mm thickness were used for the manufacture of LVL by Isoroy, a French company located in Lisieux. The melamine-urea-formaldehyde (M.U.F.) glue formulations were mixed with various concentrations of boric acid. A 0.8% retention of boron was measured in the LVL panel after intensive water leaching. The mechanical properties of finished LVL panels and their bonding strength properties were evaluated. The influence of the glue bonding on leaching was also evaluated. The amount of boron in LVL was measured by spectrocolorimetry using the CIELAB system. Results demonstrated that the incorporation of boron in the glueline may improve LVL durability.

The effect of high voltage electrostatic field (HVEF) treatment on bonding interphase characteristics among different wood sections of Masson pine (Pinus massoniana Lamb.)

Holzforschung ◽  
2018 ◽  
Vol 72 (7) ◽  
pp. 557-565 ◽  
Author(s):  
Qian He ◽  
Tianyi Zhan ◽  
Haiyang Zhang ◽  
Zehui Ju ◽  
Chunping Dai ◽  
...  
Keyword(s):  
Pore Size ◽  
High Voltage ◽  
Electrostatic Field ◽  
Phenol Formaldehyde ◽  
Dynamic Contact Angle ◽  
Treated Wood ◽  
Polarization Degree ◽  
Tangential Section ◽  
Masson Pine ◽  
Wood Surfaces

AbstractHigh voltage electrostatic field (HVEF) treatment has been investigated as an optimization method for enhancing the bonding performance of wood via increasing its polarization degree and improvement of the penetration of phenol formaldehyde (PF) adhesive. As the wood surfaces from cross cut (C), radial cut (R) and tangential cut (T) behave differently, five cut combinations formed the samples to be tested, namely C-C, R-R, R-T, T-T (always parallel to grain) and T-T⊥, where the grains were perpendicular to each other. The gluing and HVEF treatments were performed simultaneously. The sample surfaces were characterized by electron spin resonance (ESR) spectroscopy, dynamic contact angle (CAdyn) measurements, X-ray densitometry, fluorescence microscopy, Fourier-transform infrared (FTIR) spectroscopy and measurements of compression shear bonding strength (CSBS). An increased surface energy led to decreased CAdynS in the following order: cross section<tangential section<radial section. Obviously, the triggered free electrons of the HVEF treatments changed the wood surfaces. The penetration depth of PF into wood cell decreased significantly and the maximal density increased after the HVEF treatment. The lower CAdyns also contributed to the better reaction of the wood surface with the PF resin. The CSBS of the five sample combinations was enhanced owing to a better performance of adhesive aggregation, which was increased by 18% (C-C), 24% (T-T), 26% (T-T⊥), 31% (R-T) and 42% (R-R), respectively. Pore size and pore size distribution contributed a lot to the bonding properties of HVEF-treated wood sections.

scholarly journals Incorporation of Hybrid Nanomaterial in Dental Porcelains: Antimicrobial, Chemical, and Mechanical Properties

Antibiotics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 98
Author(s):  
Carla L. Vidal ◽  
Izabela Ferreira ◽  
Paulo S. Ferreira ◽  
Mariana L. C. Valente ◽  
Ana B. V. Teixeira ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Antimicrobial Activity ◽  
Biofilm Formation ◽  
Silver Ions ◽  
Surface Characteristics ◽  
Streptococcus Sobrinus ◽  
Hybrid Nanomaterial ◽  
Antimicrobial Substances ◽  
Health Area

Biofilm formation on biomaterials is a challenge in the health area. Antimicrobial substances based on nanomaterials have been proposed to solve this problem. The aim was to incorporate nanostructured silver vanadate decorated with silver nanoparticles (β-AgVO3) into dental porcelains (IPS Inline and Ex-3 Noritake), at concentrations of 2.5% and 5%, and evaluate the surface characteristics (by SEM/EDS), antimicrobial activity (against Streptococcus mutans, Streptococcus sobrinus, Aggregatibacter actinomycetemcomitans, and Pseudomonas aeruginosa), silver (Ag+) and vanadium (V4+/V5+) ions release, and mechanical properties (microhardness, roughness, and fracture toughness). The β-AgVO3 incorporation did not alter the porcelain’s components, reduced the S. mutans, S. sobrinus and A. actinomycetemcomitans viability, increased the fracture toughness of IPS Inline, the roughness for all groups, and did not affect the microhardness of the 5% group. Among all groups, IPS Inline 5% released more Ag+, and Ex-3 Noritake 2.5% released more V4+/V5+. It was concluded that the incorporation of β-AgVO3 into dental porcelains promoted antimicrobial activity against S. mutans, S. sobrinus, and A. actinomycetemcomitans (preventing biofilm formation), caused a higher release of vanadium than silver ions, and an adequate mechanical behavior was observed. However, the incorporation of β-AgVO3 did not reduce P. aeruginosa viability and increased the surface roughness of dental porcelains.

Research on the Break Impact Test of Ultra High Voltage Composite Strain Insulator String

2013 ◽  
Vol 706-708 ◽  
pp. 1689-1692
Author(s):  
Cao Lan Liu ◽  
Bin Liu ◽  
Sheng Chun Liu ◽  
Zhen Liu ◽  
Kuan Jun Zhu
Keyword(s):  
Mechanical Properties ◽  
High Voltage ◽  
Impact Test ◽  
Test System ◽  
Dynamic Impact ◽  
Composite Insulator ◽  
Composite Strain ◽  
High Voltage Engineering ◽  
Dynamic Impact Factor ◽  
Ultra High Voltage

To guarantee the security of composite insulators as tension strings applied to ultra-high voltage engineering, it is necessary to study the mechanical properties of composite insulator regarding break impact. The test system was designed and the implementation plan was developed. Test was done to two insulator strings broken and the dynamic impact factor under different broken conditions at different tension was obtained accordingly, which provides reference and evidence for further study on mechanical properties of composite insulator and development of applicable design specifications.

Investigating the Effect of Thermoelectric Processing on Ionic Aggregation in Thermoplastic Ionomers

2017 ◽  
Author(s):  
Prasant Vijayaraghavan ◽  
Vishnu-Baba Sundaresan
Keyword(s):  
Mechanical Properties ◽  
Electrostatic Field ◽  
Thermal Studies ◽  
Effect Of Temperature ◽  
Self Healing ◽  
Polymer Backbone ◽  
Ionic Dissociation ◽  
Dissociation Temperature ◽  
Aggregate Morphology ◽  
Poly Ethylene

Ionomers are a class of polymers which contain a small fraction of charged groups in the polymer backbone. These ionic groups aggregate (termed ionic aggregates) to form temporary cross-links that break apart over the ionic dissociation temperature and re-aggregate on cooling, influencing the mechanical properties of these polymers. In addition to enhanced mechanical properties, some ionomers also exhibit self-healing behavior. The self-healing behavior is a consequence of weakly bonded ionic aggregates breaking apart and re-aggregating after puncture or a ballistic impact. The structure and properties of ionomers have been studied over the last several decades; however, there is a lack of understanding of the influence of an electrostatic field on ionic aggregate morphology. Characterizing the effect of temperature and electric field on the formation and structure of these ionic aggregates will lead to preparation of ionomers with enhanced structural properties. This work focuses on Surlyn 8940 which a poly-ethylene methacryclic acid co-polymer in which a fraction of the carboxylic acid is terminated by sodium. In this work, Surlyn is thermoelectrically processed over its ionic dissociation temperature in the presence of a strong electrostatic field. Thermal studies are performed on the ionomer to study the effect of the thermoelectric processing. It is shown that the application of a thermoelectric field leads to increase in the ionic aggregate order in these materials and reduction in crystal size distribution. Thermal Analysis is performed using a Differential Scanning Calorimeter and the resulting thermogram analysis shows that thermoelectric processing increases the peak temperature and onset temperature of melting by 4 C and 20 C respectively. The peak width at half maximum of the melting endotherm is reduced by 10 C due to thermoelectric processing. This serves as a measure of the increased crystallinity. A parametric study on the effect of field duration and field strength is also performed.

Size Effect on Mechanical Properties of LVL

2014 ◽  
Vol 887-888 ◽  
pp. 824-829
Author(s):  
Qing Fang Lv ◽  
Ji Hong Qin ◽  
Ran Zhu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Size Effect ◽  
Tensile Test ◽  
Compression Test ◽  
Test Results ◽  
Laminated Veneer Lumber ◽  
Object Of Study ◽  
The Relationship

Laminated veneer lumber is taken as an object of study, and use LVL specimens of different sizes for compression test and tensile test. The goal of the experiment is to investigate the size effect on compressive strength and tensile strength as well as the influence of the secondary glued laminated face, which appears in the secondary molding processes. The results show that both compressive strength and tensile strength have the size effect apparently and the existence of the secondary glued laminated face lower the compressive strength of LVL specimens. Afterwards, the relationship between compressive strength and volume along with tensile strength and area are obtained by the test results.

Effect of Fiber’s Surface Pretreatment on the Interfacial Bonding Strength between Steel Fiber and Resin

2014 ◽  
Vol 989-994 ◽  
pp. 177-180
Author(s):  
Hao Yang ◽  
Jian Hua Zhang ◽  
Guo Yan Sun ◽  
Yi Zhang
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Bonding Strength ◽  
Steel Fiber ◽  
Resin Composite ◽  
Interfacial Bonding ◽  
Steel Fibers ◽  
Surface Pretreatment ◽  
Interfacial Bonding Strength ◽  
Coupling Treatment

For the characteristic that the mechanical properties of resin composite are lower than cast iron, steel fibers are used to improve its properties in this paper. A weak interfacial bonding strength between steel fibers and resin indicates that steel fibers’ property cannot perform well in the polymer. In order to improve the interfacial bonding strength, four methods of surface treatment, phosphating, acid pickling, oxidation, and coupling are applied to steel fibers, and the corresponding pull-off tests are carried out to compare with untreated steel fibers. Research results show that the maximum interfacial bonding strength is increased by 45.1% after coupling treatment.

Controlled ice nucleation under high voltage DC electrostatic field conditions

2009 ◽  
Vol 42 (7) ◽  
pp. 879-884 ◽  
Author(s):  
Marta Orlowska ◽  
Michel Havet ◽  
Alain Le-Bail
Keyword(s):  
High Voltage ◽  
Electrostatic Field ◽  
Ice Nucleation ◽  
Field Conditions
Sign in / Sign up

Export Citation Format

Share Document