Mechanical performance of timber connections made of thick flexible polyurethane adhesives

Pečnik, Jaka Gašper; Gavrić, Igor; Sebera, Václav; Kržan, Mojca; Kwiecień, Arkadiusz; Zając, Bogusław; Azinović, Boris

doi:10.1016/j.engstruct.2021.113125

Cited by 20 publications

(8 citation statements)

References 30 publications

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“…The joining of wooden components is traditionally carried out using mechanical fasteners such as nails, bolts, and screws [ 88 , 89 , 90 ]. However, these joining methods rely on the introduction of a hole to the substrates to be bonded.…”

Section: Wood/bio-adhesive Jointsmentioning

confidence: 99%

Sustainable Development Approaches through Wooden Adhesive Joints Design

et al. 2022

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Over recent decades, the need to comply with environmental standards has become a concern in many industrial sectors. As a result, manufacturers have increased their use of eco-friendly, recycled, recyclable, and, overall, more sustainable materials and industrial techniques. One technique highly dependent on petroleum-based products, and at the edge of a paradigm change, is adhesive bonding. Adhesive bonding is often used to join composite materials and depends upon an adhesive to achieve the connection. However, the matrices of the composite materials and the adhesives used, as well as, in some cases, the composite fibres, are manufactured from petrochemical products. Efforts to use natural composites and adhesives are therefore ongoing. One composite that has proven to be promising is wood due to its high strength and stiffness (particularly when it is densified), formability, and durability. However, wood must be very carefully characterised since its properties can be variable, depending on the slope of the grains, irregularities (such as knots, shakes, or splits), and on the location and climate of each individual tree. Therefore, in addition to neat wood, wood composites may also be a promising option to increase sustainability, with more predictable properties. To bond wood or wooden composite substrates, bio-adhesives can be considered. These adhesives are now formulated with increasingly enhanced mechanical properties and are becoming promising alternatives at the structural application level. In this paper, wooden adhesive joints are surveyed considering bio-adhesives and wood-based substrates, taking into consideration the recent approaches to improve these base materials, accurately characterise them, and implement them in adhesive joints.

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Section: Wood/bio-adhesive Jointsmentioning

confidence: 99%

Sustainable Development Approaches through Wooden Adhesive Joints Design

et al. 2022

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“…A separate area is attempts to describe the influence of non-linear material characteristic of flexible adhesive on the performance of lap joints [5], as well as attempts to determine the parameters of the Mooney Rivlin model [6] or to use of the Darijani -Naghdabadi Strain Tensors and Kirchhoff -de Saint-Venant Elastic Potential to model of flexible adhesives in simple mechanical states [7]. On the basis of experimental tests, analytical models of connection behaviour description were developed [8] and numerical models were made for flexible adhesive connections [9].…”

Section: Introductionmentioning

confidence: 99%

PUFJ (PolyUrethane Flexible Joints) as an innovative polyurethane system for structural and non-structural bonding of timber elements

Śliwa-Wieczorek

Zając

2023

J. Phys.: Conf. Ser.

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PolyUrethane Flexible Joints (PUFJ) as an innovative adhesive system has been developed by a team of researchers from the Cracow University of Technology (CUT) for several years. Initially, the research focused mainly on joining masonry and reinforced concrete elements. Due to environmental concerns and climate changes, further advancement of the PUFJ system was focused on the technology development based on connecting natural materials such as wood and wood-based materials. In 2019, the cooperation of the CUT with a private company resulted in the implementation of the PUFJ system for the construction of innovative connections in a prefabricated timber frame construction of a family house near Cracow. Currently, further research are carried out focused on the complex understanding of behaviour of adhesive bond used in structural and non-structural timber bonding, taking into account different species of wood (pine, spruce, beech, douglas fir) and a different thickness of the flexible adhesive layer (from 1 mm to 30 mm). The article contains the properties of the PUFJ system, describes variants of the available applications (wet application in form of liquid substance curing in time or dry application as a prefabricated bonding layers glued to the elements with a thin adhesive layer). Examples of double-lap shear connections and laminated beams made of douglas fir wood of C24 class and Sika®PS polyurethane flexible layer are presented. All specimens were constructed with three various flexible adhesive thicknesses of 1, 2 and 4 mm. The influence of elevated temperature on the load capacity of the connection and on the final deflection was tested. The tests were conducted at four temperature levels (20, 40, 60 and 80°C).

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“…Polyurethane (PU) adhesives have strong polarity and chemical activity because of their urethane and isocyanate groups, so they can form strong bonding with substrates containing active hydrogen and a variety of pores, such as wood, leather, paper, fabric, ceramics, etc. − Meanwhile, they can also have good chemical adhesion with some substrates with a smooth surface, such as metals, plastics, rubber, glass, etc. , Although traditional solvent-based PU adhesives play an important role in many fields, they cause serious pollution to the environment but also they will increase the full utilization of petroleum resources. − In contrast, waterborne polyurethane (WPU) adhesive is characterized by non-toxicity, environmental protection, as well as safe storage and transportation. WPU adhesive is used in shoe-making, packaging, construction, automobile, medical and health care, aerospace, and a wide range of general bonding. − However, the introduction of hydrophilic groups leads to the deterioration of water resistance, mechanical properties, and thermal stability of the WPU film; as a result, its application in some fields is limited. , …”

Section: Introductionmentioning

confidence: 99%

Triethoxysilane End-Functional Branched Waterborne Polyurethane Adhesives for Leather Substrates

Long-fang

Niu

et al. 2023

ACS Appl. Polym. Mater.

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In order to improve the adhesion and water resistance of waterborne polyurethane (WPU) adhesive, a kind of amino-terminated hyperbranched organosilicon (HPSi-NH2) was first synthesized by using trimethylchlorosilane, diethoxydimethylsilane, and γ-aminopropyltriethoxysilane (KH550) as raw materials. Then, HPSi-NH2, as the cross-linking agent, was used to modify the polyurethane prepolymer to obtain HPSi-NH2-modified WPU (HSiPU). The single-factor experiment results showed that when the amount of HPSi-NH2 was 2.0 wt %, the adhesion properties of HSiPU-2 were the best. Compared with the HSiPU-0 film, the water absorption rate of the HSiPU-2 film decreased by 10.9%, the water contact angle increased by 26.3°, the tensile strength increased by 10.1 MPa, and the elongation at break increased from 630.7 to 813.0%. HSiPU adhesive was used in the bonding of the goat leather substrate, and the results showed that the peel strength of leather bonded by HSiPU-2 was increased from 1.38 to 3.15 N/mm, and the maximum peel force was increased from 1.67 to 5.51 N/mm, which indicated that the bond strength of HSiPU adhesive with different contents of HPSi-NH2 can be used for bonding substrates with different cohesion strengths.

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Mechanical performance of timber connections made of thick flexible polyurethane adhesives

Cited by 20 publications

References 30 publications

Sustainable Development Approaches through Wooden Adhesive Joints Design

Sustainable Development Approaches through Wooden Adhesive Joints Design

PUFJ (PolyUrethane Flexible Joints) as an innovative polyurethane system for structural and non-structural bonding of timber elements

Triethoxysilane End-Functional Branched Waterborne Polyurethane Adhesives for Leather Substrates

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