scholarly journals Mechanical performance of timber connections made of thick flexible polyurethane adhesives

2021 ◽  
Vol 247 ◽  
pp. 113125
Author(s):  
Jaka Gašper Pečnik ◽  
Igor Gavrić ◽  
Václav Sebera ◽  
Meta Kržan ◽  
Arkadiusz Kwiecień ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Polyurethane Adhesives ◽  
Timber Connections ◽  
Flexible Polyurethane

scholarly journals Structural Changes and Their Implications in Foamed Flexible Polyurethane Composites Filled with Rapeseed Oil-Treated Ground Tire Rubber

2021 ◽  
Vol 5 (3) ◽  
pp. 90
Author(s):  
Paulina Kosmela ◽  
Adam Olszewski ◽  
Łukasz Zedler ◽  
Paulina Burger ◽  
Krzysztof Formela ◽  
...  
Keyword(s):  
Rapeseed Oil ◽  
Structural Changes ◽  
Mechanical Performance ◽  
Reactive Extrusion ◽  
Solid Particles ◽  
Tire Rubber ◽  
Average Cell ◽  
Economic Point ◽  
Ground Tire Rubber ◽  
Flexible Polyurethane

The utilization of post-consumer car tires is an essential issue from an ecological and economic point of view. One of the simplest and the least harmful methods is their material recycling resulting in ground tire rubber (GTR), which can be further applied as fillers for polymer-based composites. Nevertheless, insufficient interfacial interactions implicate the necessity of GTR modification before introduction into polymer matrices. In this study, we investigated the influence of rapeseed oil-assisted thermo-mechanical treatment of GTR using a reactive extrusion process on the processing, structure, and performance of flexible polyurethane/GTR composite foams. Applied modifications affected the processing of polyurethane systems. They caused a noticeable reduction in the average cell size of foams, which was attributed to the potential nucleating activity of solid particles and changes in surface tension caused by the presence of oil. Such an effect was especially pronounced for the waste rapeseed oil, which resulted in the highest content of closed cells. Structural changes caused by GTR modification implicated the enhancement of foams’ strength. Mechanical performance was significantly affected by the applied modifications due to the changes in glass transition temperature. Moreover, the incorporation of waste GTR particles into the polyurethane matrix noticeably improved its thermal stability.

scholarly journals The Impact of Ground Tire Rubber Oxidation with H2O2 and KMnO4 on the Structure and Performance of Flexible Polyurethane/Ground Tire Rubber Composite Foams

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 499
Author(s):  
Aleksander Hejna ◽  
Adam Olszewski ◽  
Łukasz Zedler ◽  
Paulina Kosmela ◽  
Krzysztof Formela
Keyword(s):  
Mechanical Performance ◽  
Hydroxyl Groups ◽  
Tire Rubber ◽  
Economic Implications ◽  
Ground Tire Rubber ◽  
Polyurethane Composite ◽  
Composite Foams ◽  
And Performance ◽  
Flexible Polyurethane ◽  
The Impact

The use of waste tires is a very critical issue, considering their environmental and economic implications. One of the simplest and the least harmful methods is conversion of tires into ground tire rubber (GTR), which can be introduced into different polymer matrices as a filler. However, these applications often require proper modifications to provide compatibility with the polymer matrix. In this study, we examined the impact of GTR oxidation with hydrogen peroxide and potassium permanganate on the processing and properties of flexible polyurethane/GTR composite foams. Applied treatments caused oxidation and introduction of hydroxyl groups onto the surface of rubber particles, expressed by the broad range of their hydroxyl numbers. It resulted in noticeable differences in the processing of the polyurethane system and affected the structure of flexible composite foams. Treatment with H2O2 resulted in a 31% rise of apparent density, while the catalytic activity of potassium ions enhanced foaming of system decreased density by 25% and increased the open cell content. Better mechanical performance was noted for H2O2 modifications (even by 100% higher normalized compressive strength), because of the voids in cell walls and incompletely developed structure during polymerization, accelerated by KMnO4 treatment. This paper shows that modification of ground tire rubber is a very promising approach, and when properly performed may be applied to engineer the structure and performance of polyurethane composite foams.

Preparation and properties of polyurethane film with photothermal conversion and energy storage capability

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lihong Bao ◽  
Suyi Cao ◽  
Lin Tu
Keyword(s):  
Molecular Weight ◽  
Energy Storage ◽  
Visible Light ◽  
Mechanical Performance ◽  
Low Cost ◽  
Light Trapping ◽  
Surface Finishing ◽  
Content Type ◽  
Photothermal Conversion ◽  
Flexible Polyurethane

Purpose This paper aims to provide a flexible polyurethane (PU) film with visible light trapping ability, photothermal conversion and energy storage performance by covalently bonded a visible light absorbing dye into the polymer through copolymerization. Design/methodology/approach For this target solution copolymerization of diphenyl-methane-diisocyanate (MDI), poly(1,4-butylene adipate) (PBA2000), polyethylene glycol (PEG) of different molecular weight, self-made dye, 1,4-butanediol (BuOH) was carried out in a flame-dried flask under an inert nitrogen (N2) atmosphere. First, an isocyanate-terminated prepolymer of dried PEG, MDI and PBA2000 was prepared in dimethylformamide and stirred for 1 h at 35°C. Then, self-made dye and 1, 4-butanediol (BuOH) were added and heated at 85°C for 3 h to get photothermal conversion polyurethane (PTPU) solution. Allowed the solution to dry at room temperature for seven days and then at 65°C for 12 h to get PTPU films. Findings The flexible PU films with photothermal conversion and energy storage performances were successfully synthesized and the functional films presented both excellent energy storage and mechanical property when the molecular weight of PEG was in the range of 6,000∼10,000. Research limitations/implications The materials that were used in this research paper had a reasonably low cost. Also, the procedures for the synthesis of dye and polymers were extremely easy because there was no need for high pressure or temperature and no dangerous solvents were used. Practical implications The photothermal conversion property and mechanical performance of the synthesized flexible PU films were characterized. The results have proved that these films were soft and elastic, and have certain photothermal conversion and energy storage ability, thus can be used in the surface finishing of special fabric and leather. Originality/value Visible light trapping photothermal conversion PU flexible film with energy storage capability was prepared for the first time.

Experimental investigation on the effect of accelerated ageing conditions on the pull-out capacity of compressed wood and hardwood dowel type fasteners

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sameer Mehra ◽  
Annette M. Harte ◽  
Adeayo Sotayo ◽  
Zhongwei Guan ◽  
Conan O’Ceallaigh
Keyword(s):  
Shape Recovery ◽  
Mechanical Performance ◽  
Accelerated Ageing ◽  
Recovery Effect ◽  
Climate Conditions ◽  
Robotic Fabrication ◽  
Pull Out ◽  
Timber Construction ◽  
Timber Connections ◽  
Compressed Wood

Abstract The widespread use of adhesives in timber construction has negative implications for the end-of-life disposal or re-use of the structural timber components. To promote the circular bioeconomy, it is preferable to substitute adhesives with more sustainable alternatives such as wood-based connectors. Today, robotic fabrication technologies facilitate the development of dowel-laminated timber (DLT) products whereby hardwood dowels are used to connect timber laminates as a substitute to adhesives. In recent years, thermo-mechanical densification of wood has resulted in significant improvements in the mechanical performance of the wood. This modified product often termed compressed wood (CW) has a shape-recovery effect which may be beneficial for the development of DLT products and timber-timber connections with improved friction fit with time. To test the hypothesis, accelerated ageing tests were carried out on CW-timber and hardwood-timber dowel type connections subjected to variable climate conditions. Finally, the capacity of the connections or friction fit was assessed using pull-out tests. Results show that the shape-recovery effect leads to the continuous expansion of the CW dowels and facilitates a friction fit with the timber substrate yielding higher pull-out loads when compared to hardwood dowels.

scholarly journals Mechanical Properties Of 3D-Structure Composites Based On Warp-Knitted Spacer Fabrics

2015 ◽  
Vol 15 (2) ◽  
pp. 127-137 ◽  
Author(s):  
Si Chen ◽  
Hai-ru Long ◽  
Ying-hao Liu ◽  
Feng-chao Hu
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Layer Structure ◽  
Structural Parameters ◽  
3D Structure ◽  
Three Dimension ◽  
Different Types ◽  
Spacer Fabrics ◽  
Flexible Polyurethane ◽  
The Impact

Abstract In this paper, the mechanical properties (compression and impact behaviours) of three-dimension structure (3D-structure) composites based on warp-knitted spacer fabrics have been thoroughly investigated. In order to discuss the effect of fabric structural parameters on the mechanical performance of composites, six different types of warp-knitted spacer fabrics having different structural parameters (such as outer layer structure, diameter of spacer yarn, spacer yarn inclination angle and thickness) were involved for comparison study. The 3D-structure composites were fabricated based on a flexible polyurethane foam. The produced composites were characterised for compression and impact properties. The findings obtained indicate that the fabric structural parameters have strong influence on the compression and impact responses of 3D-structure composites. Additionally, the impact test carried out on the 3D-structure composites shows that the impact loads do not affect the integrity of composite structure. All the results reveal that the product exhibits promising mechanical performance and its service life can be sustained.

scholarly journals Ground Tire Rubber Filled Flexible Polyurethane Foam—Effect of Waste Rubber Treatment on Composite Performance

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3807
Author(s):  
Paulina Kosmela ◽  
Adam Olszewski ◽  
Łukasz Zedler ◽  
Paulina Burger ◽  
Adam Piasecki ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Mechanical Performance ◽  
Raw Materials ◽  
Reactive Extrusion ◽  
Waste Oil ◽  
Tire Rubber ◽  
Average Cell ◽  
Ground Tire Rubber ◽  
Application Range ◽  
Flexible Polyurethane

The application range of flexible polyurethane (PU) foams is comprehensive because of their versatility and flexibility in adjusting structure and performance. In addition to the investigations associated with further broadening of their potential properties, researchers are looking for new raw materials, beneficially originated from renewable resources or recycling. A great example of such a material is ground tire rubber (GTR)—the product of the material recycling of post-consumer car tires. To fully exploit the benefits of this material, it should be modified to enhance the interfacial interactions between PU and GTR. In the presented work, GTR particles were thermo-mechanically modified with the addition of fresh and waste rapeseed oil in the reactive extrusion process. The introduction of modified GTR particles into a flexible PU matrix caused a beneficial 17–28% decrease in average cell diameters. Such an effect caused an even 5% drop in thermal conductivity coefficient values, enhancing thermal insulation performance. The application of waste oil resulted in the superior mechanical performance of composites compared to the fresh one and thermo-mechanical modification without oils. The compressive and tensile performance of composites filled with waste oil-modified GTR was almost the same as for the unfilled foam. Moreover, the introduction of ground tire rubber particles enhanced the thermal stability of neat polyurethane foam.

The Mechanical Performance of Carbon Fibres- Addressing the Role of Microstructure

2019 ◽  
Author(s):  
Peter Peter ◽  
Claudia Creighton ◽  
David Fox ◽  
Pablo Mota Santiago ◽  
Adrian Hawley ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Carbon Fibres

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

NUMERICAL STUDY ON THE MECHANICAL PERFORMANCE OF GRAPHENE BRIDGES ON SILLICON THIN FILM TRANSISTORS

2011 ◽  
Author(s):  
Byung-Jae Kim ◽  
Hyeon-Seok Seo ◽  
Won-Ho Lee ◽  
Jong-Hyun Ahn ◽  
Youn-Jea Kim
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Mechanical Performance ◽  
Numerical Study
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