scholarly journals Discharge Plasma Treatment as an Efficient Tool for Improved Poly(lactide) Adhesive–Wood Interactions

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3672
Author(s):  
Mariusz Ł. Mamiński ◽  
Igor Novák ◽  
Matej Mičušík ◽  
Artur Małolepszy ◽  
Renata Toczyłowska-Mamińska
Keyword(s):  
Failure Mode ◽  
Discharge Plasma ◽  
Carbonyl Oxygen ◽  
Surface Barrier ◽  
Air Plasma ◽  
Cohesive Failure ◽  
Efficient Tool ◽  
Water Contact ◽  
Lap Shear ◽  
Adhesive Interactions

Poly(lactide) (PLA) films obtained by thermoforming or solution-casting were modified by diffuse coplanar surface barrier discharge plasma (300 W and 60 s). PLA films were used as hot-melt adhesive in joints in oak wood. It was demonstrated that lap shear strength increased from 3.4 to 8.2 MPa, respectively, for the untreated and plasma-treated series. Pull-off tests performed on particleboard for the untreated and treated PLA films showed 100% cohesive failure. Pull-off strength tests on solid oak demonstrated adhesion enhancement from 3.3 MPa with the adhesion failure mode to 6.6 MPa with the cohesion failure mode for untreated and treated PLA. XPS revealed that carbonyl oxygen content increased by two-to-three-fold, which was confirmed in the Fourier-transform infrared spectroscopy experiments of the treated PLA. The water contact angle decreased from 66.4° for the pristine PLA to 49.8° after treatment. Subsequently, the surface free energy increased from 47.9 to 61.05 mJ/m2. Thus, it was clearly proven that discharge air plasma can be an efficient tool to change surface properties and to strengthen adhesive interactions between PLA and woody substrates.

scholarly journals A study of laser surface treatment in bonded repair of composite aircraft structures

2018 ◽  
Vol 5 (3) ◽  
pp. 171272 ◽  
Author(s):  
Shaolong Li ◽  
Ting Sun ◽  
Chang Liu ◽  
Wenfeng Yang ◽  
Qingru Tang
Keyword(s):  
Surface Treatment ◽  
Failure Mode ◽  
Photoelectron Spectroscopy ◽  
Laser Scanning ◽  
Chemical Properties ◽  
Laser Scanning Confocal Microscopy ◽  
Cohesive Failure ◽  
Laser Etching ◽  
Bonded Repair ◽  
Lap Shear

Surface pre-treatment is one of the key processes in bonded repair of aircraft carbon fibre reinforced polymer composites. This paper investigates the surface modification of physical and chemical properties by laser ablation and conventional polish treatment techniques. Surface morphology analysed by laser scanning confocal microscopy and scanning electron microscopy showed that a laser-treated surface displayed higher roughness than that of a polish-treated specimen. The laser-treated laminate exhibited more functional groups in the form of O 1 s/C 1 s atomic ratio of 30.89% for laser-treated and 20.14% for polish-treated as evidenced by X-ray photoelectron spectroscopy observation. Contact angle goniometry demonstrated that laser treatment can provide increased surface free energy and wettability. In the light of mechanical interlocking, molecular bonding and thermodynamics theories on adhesion, laser etching process displayed enhanced bonding performance relative to the polishing surface treatment. These properties resulted in an increased single lap shear strength and a cohesive failure mode for laser etching while an adhesive failure mode occurred in polish-treated specimen.

scholarly journals Enhancing the surface properties of linen by non-thermal atmospheric air-plasma treatment

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Orsolya Erzsébet Szabó ◽  
Emília Csiszár ◽  
András Tóth
Keyword(s):  
Plasma Treatment ◽  
Plasma Reactor ◽  
Fiber Surface ◽  
Surface Barrier ◽  
Air Plasma ◽  
Water Contact ◽  
Atmospheric Air ◽  
Polar Groups ◽  
Surface Barrier Discharge ◽  
Air Plasma Treatment

AbstractIn this research, a diffuse coplanar surface barrier discharge (DCSBD) type plasma reactor was used for the surface modification of raw linen fabric. Changes in physical properties and chemical composition of the fiber surface as well as color of the fabric were measured as a function of time of the atmospheric air plasma treatment. Furthermore, ageing of the effects created on the fiber surface by plasma treatment was also characterized in a period of 0-14 days elapsed after the plasma treatment. Significant differences were found between the properties of the raw and plasma treated linen fabrics, including increase of wettability, wickability, surface energy and O/C ratio, and decrease of water contact angle and deterioration of the waxy outer layer of the fibers. Most of the parameters depended on the time of plasma treatment (0–180 s). O/C ratio increased steadily with the increase of duration of the plasma treatment, which was explained by destruction of the waxy surface layer, creation of polar groups and exposure of cellulosic components. Most of the properties tested were found to be stable during two weeks of storage after the plasma treatment, indicating that the surface ‘topography’ created by plasma remained almost unaltered and the recovery of the etched waxy coverage of the fiber did not occur.

scholarly journals Determining Interface Fracture Toughness in Multi Layered Environmental Barrier Coatings with Laser Textured Silicon Bond Coat

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 55
Author(s):  
Markus Wolf ◽  
Hideki Kakisawa ◽  
Fabia Süß ◽  
Daniel Emil Mack ◽  
Robert Vaßen
Keyword(s):  
Bond Coat ◽  
Ceramic Matrix Composites ◽  
Interface Fracture ◽  
Matrix Composites ◽  
Air Plasma ◽  
Cohesive Failure ◽  
Corrosive Media ◽  
Environmental Barrier ◽  
Interface Toughness ◽  
Plasma Sprayed

In the high temperature combustion atmosphere inside of aircraft turbines, the currently used ceramic matrix composites require a protective environmental barrier coating (EBC) to mitigate corrosion of the turbine parts. Besides thermomechanical and thermochemical properties like matching thermal expansion coefficient (CTE) and a high resistance against corrosive media, mechanical properties like a high adhesion strength are also necessary for a long lifetime of the EBC. In the present work, the adhesion between an air plasma sprayed silicon bond coat and a vacuum plasma sprayed ytterbium disilicate topcoat was aimed to be enhanced by a laser surface structuring of the Si bond coat. An increase in interface toughness was assumed, since the introduction of structures would lead to an increased mechanical interlocking at the rougher bond coat interface. The interface toughness was measured by a new testing method, which allows the testing of specific interfaces. The results demonstrate a clear increase of the toughness from an original bond coat/topcoat interface (8.6 J/m2) compared to a laser structured interface (14.7 J/m2). Observations in the crack propagation indicates that the laser structuring may have led to a strengthening of the upper bond coat area by sintering. Furthermore, in addition to cohesive failure components, adhesive components can also be observed, which could have influenced the determined toughness.

scholarly journals An open-source surface barrier discharge plasma pretreatment for reduced cracking of outdoor wood coatings

Cellulose ◽  
2021 ◽  
Author(s):  
Sebastian Dahle ◽  
Megi Pilko ◽  
Jure Žigon ◽  
Rok Zaplotnik ◽  
Marko Petrič ◽  
...  
Keyword(s):  
Discharge Plasma ◽  
Barrier Discharge ◽  
Protective Coatings ◽  
Surface Barrier ◽  
Source Surface ◽  
Plasma Pretreatment ◽  
Plasma Device ◽  
Surface Barrier Discharge ◽  
Barrier Discharge Plasma ◽  
Outdoor Weathering

AbstractThe development of a simple surface barrier discharge plasma device is presented to enable more widespread access to and utilization of plasma technology. The application of the plasma device was demonstrated for pretreatment of wood prior to application of protective coatings for outdoor usage. The coatings' overall performance was increased, showing a reduction or absence of cracking due to weathering on plasma-pretreated specimens. Moreover, after ten months of outdoor weathering, the plasma-pretreated specimens showed fewer infections with biotic factors and improved adhesion performance in cross-cut tests, while the surface gloss performed independently from plasma pretreatment. In contrast to that, plasma-pretreated specimens were slightly more prone to discoloration due to outdoor weathering, whereas the plasma pretreatment did not impact the initial color after coating application. Graphic abstract

scholarly journals Microstructure and mechanical properties of an ultrasonic spot welded aluminum alloy: the effect of welding energy

2021 ◽  
Author(s):  
He Peng ◽  
Daolun Chen ◽  
Xianquan Jiang
Keyword(s):  
Shear Strength ◽  
Aluminum Alloy ◽  
Cyclic Loading ◽  
Crack Growth ◽  
Failure Mode ◽  
Spot Welding ◽  
Energy Levels ◽  
Lap Shear Strength ◽  
Pull Out ◽  
Lap Shear

The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique–ultrasonic spot welding (USW)–at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT) crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with “river-flow” patterns and characteristic fatigue striations. Keywords: aluminum alloy; ultrasonic spot welding; EBSD; microstructure; tensile strength; fatigue

scholarly journals Hydrophobic Waxes in Ivory Nuts Affect Surface Modification by Atmospheric Air Plasma Jet

2020 ◽  
Vol 2 (2) ◽  
pp. 48-49
Keyword(s):  
Contact Angle ◽  
Surface Modification ◽  
Water Contact Angle ◽  
Plasma Jet ◽  
Raman Imaging ◽  
Wall Material ◽  
Air Plasma ◽  
Water Contact ◽  
Atmospheric Air ◽  
Imaging Results

Ivory nuts, produced by palms from the genus Phytelephas, possess a hard and microporous endosperm with a strong resemblance to elephant ivory. The nuts sustainable appeal made them popular as eco-friendly substitutes to ivory since they promote the development of forest communities without contributing to deforestation and animal poaching. In addition, they have been commercialized as microbeads to replace microplastics in cosmetic applications. However, this material is vulnerable to deterioration by micro-organisms and insects, as they are predominantly constituted by β-1,4-mannan, a hydrophilic polysaccharide similar to cellulose. In this context, seed endosperm was treated for 80 s by an atmospheric air plasma jet so as to modify its wettability, as plasma has been widely studied recently for seed disinfection and surface modification. Plasma treated samples were characterized by the water contact angle, AFM, and Raman imaging. Water contact angle results showed an increase from (31.5 ± 8.7)º to (78.9 ± 5.4)º, indicating incorporation of hydrophobic moieties to the sample surface. In turn, AFM images demonstrate the formation of a rough and heterogeneous coating that resembles epicuticular wax layers. Furthermore, principal component analysis of Raman imaging results evidenced contributions from wax (1156, 1170 and 1410 cm-1), carbohydrates (1020, 1080 and 1106 cm-1), and lignin (1573, 1635 and 1662 cm-1). These results indicate that plasma treatment promoted the migration of hydrophobic waxes to the surface and their crosslinking with fragmented cell wall material such as mannan, xylan, and lignin, promoting seed hydrophobization with no need for additional precursors or generation of side products.

scholarly journals Anticoagulant Polyethylene Terephthalate Surface by Plasma-Mediated Fucoidan Immobilization

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 750 ◽  
Author(s):  
Kadir Ozaltin ◽  
Marian Lehocky ◽  
Petr Humpolicek ◽  
Jana Pelkova ◽  
Antonio Di Martino ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Photoelectron Spectroscopy ◽  
Anticoagulant Activity ◽  
Blood Clot ◽  
Clot Formation ◽  
Thrombin Time ◽  
Air Plasma ◽  
Water Contact ◽  
Polymeric Biomaterials ◽  
Performance Surface

Biomaterial-based blood clot formation is one of the biggest drawbacks of blood-contacting devices. To avoid blood clot formation, their surface must be tailored to increase hemocompatibility. Most synthetic polymeric biomaterials are inert and lack bonding sites for chemical agents to bond or tailor to the surface. In this study, polyethylene terephthalate was subjected to direct current air plasma treatment to enhance its surface energy and to bring oxidative functional binding sites. Marine-sourced anticoagulant sulphated polysaccharide fucoidan from Fucus vesiculosus was then immobilized onto the treated polyethylene terephthalate (PET) surface at different pH values to optimize chemical bonding behavior and therefore anticoagulant performance. Surface properties of samples were monitored using the water contact angle; chemical analyses were performed by FTIR and X-ray photoelectron spectroscopy (XPS) and their anticoagulant activity was tested by means of prothrombin time, activated partial thromboplastin time and thrombin time. On each of the fucoidan-immobilized surfaces, anticoagulation activity was performed by extending the thrombin time threshold and their pH 5 counterpart performed the best result compared to others.

scholarly journals A Study on the Effect of Ambient Air Plasma Treatment on the Properties of Methylammonium Lead Halide Perovskite Films

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 991 ◽  
Author(s):  
Masoud Shekargoftar ◽  
Jana Jurmanová ◽  
Tomáš Homola
Keyword(s):  
Plasma Treatment ◽  
Band Gap ◽  
Treatment Time ◽  
Perovskite Solar Cells ◽  
Ambient Air ◽  
Surface Barrier ◽  
Air Plasma ◽  
Plasma Treatment Time ◽  
Halide Perovskite ◽  
Air Plasma Treatment

Organic-inorganic halide perovskite materials are considered excellent active layers in the fabrication of highly efficient and low-cost photovoltaic devices. This contribution demonstrates that rapid and low-temperature air-plasma treatment of mixed organic-inorganic halide perovskite film is a promising technique, controlling its opto-electrical surface properties by changing the ratio of organic-to-inorganic components. Plasma treatment of perovskite films was performed with high power-density (25 kW/m2 and 100 W/cm3) diffuse coplanar surface barrier discharge (DCSBD) at 70 °C in ambient air. The results show that short plasma treatment time (1 s, 2 s, and 5 s) led to a relatively enlargement of grain size, however, longer plasma treatment time (10 s and 20 s) led to an etching of the surface. The band-gap energy of the perovskite films was related to the duration of plasma treatment; short periods (≤5 s) led to a widening of the band gap from ~1.66 to 1.73 eV, while longer exposure (>5 s) led to a narrowing of the band gap to approx. 1.63 eV and fast degradation of the film due to etching. Surface analysis demonstrated that the film became homogeneous, with highly oriented crystals, after short plasma treatment; however, prolonging the plasma treatment led to morphological disorders and partial etching of the surface. The plasma treatment approach presented herein addresses important challenges in current perovskite solar cells: tuning the optoelectronic properties and manufacturing homogeneous perovskite films.

Bond Behaviour of FRCM Composites: Effects of High Temperature

2019 ◽  
Vol 817 ◽  
pp. 161-166
Author(s):  
Antonio Iorfida ◽  
Sebastiano Candamano ◽  
Fortunato Crea ◽  
Luciano Ombres ◽  
Salvatore Verre ◽  
...  
Keyword(s):  
High Temperature ◽  
Failure Mode ◽  
Failure Modes ◽  
Construction Materials ◽  
Mechanical Damage ◽  
High Density ◽  
Bond Behaviour ◽  
Bond Slip ◽  
Masonry Construction ◽  
Lap Shear

The fire remains one of the serious potential risks to most buildings and structures, as recently it’s been witnessed in Paris’ historic Notre Dame Cathedral and London’s Grenfell Tower. Concrete and masonry construction materials suffer physiochemical changes and mechanical damage caused by heating that is usually confined to the outer surface but can eventually compromise their load-bearing capacity. FRCM systems could provide when applied, supplemental fire insulation on pre-existing structural members, but there is a lack of knowledge about their properties in those conditions. This experimental work, thus, aims to evaluate the mechanical behaviour of carbon-FRCM and basalt-FRCM composites bonded to masonry substrate after high temperature exposure. Temperatures of 100 °C, 300 °C and 500 °C over a period of three hours were used to investigate the degradation of their mechanical properties. Single lap shear bond tests were carried out to evaluate the bond-slip response and failure modes. For all the tested temperatures higher peak stresses were measured for carbon-FRCM composite than basalt ones. Furthermore, low-density basalt-FRCM composite showed higher peak stresses and lower global slips up to 300 °C than high-density one. Carbon-FRCM composite failure mode was not effected by temperature. High-density basalt-FRCM composite showed a change in failure mode between 300 °C and 500 °C.

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