Tag Archives: SEM

1062–1070 V. Kolář, M. Tichý, M. Müller, P. Valášek and A. Rudawska
Research on influence of cyclic degradation process on changes of structural adhesive bonds mechanical properties
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Research on influence of cyclic degradation process on changes of structural adhesive bonds mechanical properties

V. Kolář¹*, M. Tichý¹, M. Müller¹, P. Valášek¹ and A. Rudawska²

¹Czech University of Life Sciences, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Faculty of Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
²Lublin University of Technology, Department of Production Engineering, Mechanical Engineering Faculty, Nadbystrzycka 36, PL20 618 Lublin, Poland
*Correspondence: vkolar@tf.czu.cz

Abstract:

The paper deals with an influence of a cyclic degradation process on changes of a shear tensile strength of single lap-shear adhesive bonds and their elongation according to ČSN EN ISO 9142. Five one-component structural adhesives used in a construction of car body works were used within the research. The degradation of adhesive bonds is a significant factor which influences a quality and a service life of adhesive bonds exposed to environment. A main requirement in production companies is not only reaching satisfactory initial mechanical properties but namely ensuring a reliability and a safety of adhesive bonds during their usage.
These reasons show a great importance of adhesive bonds tests either directly in the operating environment or by a simulation of operating conditions in laboratories. The degradation process of adhesive bonds worsens mechanical properties of not only the bond itself but also of the bonded material. This process is progressing and it is usually permanent and irreversible. It is a change of mechanical and physical properties which can endanger a safety and a reliability of parts, prospectively of the whole equipment. It can leads up to a complete failure of its function in the extreme case. A temperature, a moisture, a direct contact with water and chemicals or an atmospheric corrosion belong among the most serious degradation agents. It is important to take into regard time of the processes influence at the same time which can act either independently or concurrently when their effects grow stronger.
From that reason the adhesive bonds were exposed to the cyclic degradation process according to the standard ČSN EN ISO 9142. Subsequently, the adhesive bonds mechanical properties were tested on universal testing machine and by means of SEM analysis (TESCAN MIRA 3).
Results of mechanical tests proved a fall of the shear tensile strength of single lap-shear adhesive bonds after 42 cycles of the degradation process of 12.8 to 21.7%. The bond strength fall was gradual and it showed a linear trend at some adhesives. Other adhesives showed a significant fall after the exposition to the degradation process after which the strength fall stabilized.

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1257-1265 M. Tichý, M. Müller, P. Valášek and I. Miturska
Effect of rubber powder from waste tyre rubbers on mechanical properties of one-component polyurethane putty
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Effect of rubber powder from waste tyre rubbers on mechanical properties of one-component polyurethane putty

M. Tichý¹*, M. Müller¹, P. Valášek¹ and I. Miturska²

¹Czech University of Life Sciences, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Faculty of Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
²Lublin University of Technology, Department of Production Engineering, Mechanical Engineering Faculty, Nadbystrzycka 36, PL20 618 Lublin, Poland
*Correspondence: xticm001@studenti.czu.cz

Abstract:

The utilization of adhesives in technical practice is varied. Adhesives serve for a creation of strength bonds on the one hand, and on the other hand e.g. for cementing. The aim of the research is a modification of one-component polyurethane putty RPS 45 used in automotive industry to increase strength properties in an adhesive bond. An interaction between a filler in the form of rubber powder micro-particles and one-component polyurethane adhesive was investigated by means of SEM analysis. Sealing is a primary property of this putty. Sealing putties usually reach very small strength which can be increased by an admixture of the filler. In order to keep elastic properties, micro-particles of the rubber powder gained from tyre recycling process were used as the filler. An aspect of a loading speed of the adhesive bond is essential at the practical application at which the adhesive bond can be failed in adhesive or cohesive layers. The adhesive bond can be perceived in terms of its function as a complex of three layers, i.e. an adhesive bonded material, the interaction between the adhesive and the adhesive bonded material and the adhesive layer itself. There are often states in the practices when the adhesive bonds are exposed to the loading which can be either a static or a dynamic one. That is why the research is focused not only on the evaluation of the influence of the modification of the one-component polyurethane adhesive, but also on the influence of the loading speed of the adhesive bond. Tested speeds set on a universal testing machine Zwick/Roell Z150 were 2, 50 and 100 mm min-1. The results of mechanical tests proved a positive influence of the filler on the strength σm higher by 42.68 ± 6.96% and the elongation at break εb higher by 12.2 ± 20.95%. On the contrary, the stress at yield σy was decreased.

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1107–1118 M. Müller
Mechanical properties of resin reinforced with glass beads
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Mechanical properties of resin reinforced with glass beads

M. Müller

Department of Material Science and Manufacturing Technology, Faculty of Engineering, Czech University of Life Sciences, Kamýcká 129, CZ165 21 Prague, Czech Republic
Correspondence: muller@tf.czu.cz

Abstract:

The research was focused on the evaluation of a loading speed and a size of the particle filler in a form of glass beads B159 and B112 on resultant behaviour of a composite material and during its application in a structural adhesive bond. A fall of the tensile strength of the composite material of ca. 60% is obvious from the experiment results when adding both fillers (B159 as well as B112). This composite material showed in the positive way as the adhesive at the adhesive bonds. The experiment results proved the positive influence of adding the particle filler of the spherical shape – glass beads B159 (the fraction size 85.23 ± 31.23 μm) on the adhesive bond strength. The adhesive bond strength was increased up of 14% at the filler glass beads B159. However, adding the filler into the resin proved that this filler eliminated the influence of various loading speeds. Adding the filler into the resin changed a fracture surface. An analysis of a scanning electron microscopy (SEM) proved a good wettability of the filler, the resin and the adhesive bonded material (a structural carbon steel S235J0). A crack propagation was concentrated around the filler B112 (151.59 ± 53.04 μm), namely at higher value of the loading speed, i.e. 10 mm min-1. The crack propagation is a consequence of this. Higher particles show in a negative way namely at an initiation of the fracture surface.

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1170–1181 S. Petrásek and M. Müller
Mechanical qualities of adhesive bonds reinforced with biological fabric treated by plasma
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Mechanical qualities of adhesive bonds reinforced with biological fabric treated by plasma

S. Petrásek and M. Müller

Department of Material Science and Manufacturing Technology, Faculty of Engineering, Czech University of Life Sciences in Prague, Kamýcká 129, CZ165 21, Prague, Czech Republic
*Correspondence: petrasek@tf.czu.cz

Abstract:

The paper deals with the utilization of a biological reinforcement in the area of an adhesive layer at structural adhesive bonds. A significant disadvantage of adhesive bonds is uneven layer of an adhesive, which can be eliminated by various technological procedures. One possibility is to use a reinforcing even layer. The primary aim of this paper was to experimentally investigate an influence of the surface plasma treatment of natural fabrics (flax, cotton) at different intervals of plasma affecting (0 to 90 seconds and power 350 W) on mechanical properties of the adhesive bond. There were positive results from reinforcing the adhesive bond by a layer of linen and cotton. Strength characteristics of reinforced adhesive bond were increased compared to non–reinforced adhesive bonds. When the linen was used, the strength was increased by 43.2% and when the cotton then 15.5% strength increase could be seen. When modifying the surface by plasma, next adhesive bond’s strength increase was seen. Using the linen there was approx. 47% strength increase, using the cotton the strength increase was approx. 38% compared to non–reinforced adhesive bonds (without reinforcing phase). It is obvious from the results that plasma modifying showed better results when the cotton was used as the reinforcing material. SEM analysis proved that adhesion was improved with plasma surface modification of biological fibres. In other words the distance between the warp and the resin was significantly decreased for 87.1% when using the cotton and by 46.5% when the linen was used.

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