Zdenka Prochazkova; Vlastimil Kralik; Jiri Nemecek; Michal Sejnoha
Abstract
Introduction of recycled plastic materials in structural applications such as bridges, retaining walls or railway sleepers requires a proper identification of necessary material properties. Given similarities in the microstructure of various structural elements we limit our attention to beams having ...
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Introduction of recycled plastic materials in structural applications such as bridges, retaining walls or railway sleepers requires a proper identification of necessary material properties. Given similarities in the microstructure of various structural elements we limit our attention to beams having a rectangular cross-section. Owing to the manufacturing process the cross-section is represented by a porous-core (inner section) surrounded by a homogeneous material (outer section). The influence of microstructural details on material parameters is examined here with a reference to the elastic Young’s modulus derived from nanoindentation measurements. To identify a gradual evolution of the stiffness of plastic material from the outer section into the core the grid indentation method based on the statistical evaluation of a large number of indentations was adopted. These tests were accompanied by standard static indentation measurements to address also the effect of temperature in the range of 20–40°C. When dealing with these types of recycled plastics, even a 5°C temperature variation leads to a significant change in the material stiffness. In addition, standard macroscopic material properties were measured by tensile tests of samples with and without the porous core and compared with microscopic parameters. The elastic modulus obtained from nanoindentation was found to be ~20 % higher than that provided by the tensile tests.
Jagrati Kandpal; Samar B. Yadaw; Arun K. Nagpal
Abstract
In the present paper effect of thermoplastic on various mechanical and thermal properties of multifunctional epoxy resin have been studied. Epoxy phenol novolac resin has been cured with hardner diamino, diphenyl sulfone. Changes in mechanical and thermal properties of epoxy phenol novolac resin with ...
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In the present paper effect of thermoplastic on various mechanical and thermal properties of multifunctional epoxy resin have been studied. Epoxy phenol novolac resin has been cured with hardner diamino, diphenyl sulfone. Changes in mechanical and thermal properties of epoxy phenol novolac resin with engineering thermoplastic poly (ether imide) have been investigated. Specimens were prepared using different mixing orders for multifunctional epoxy resin with poly (ether imide). Effect on glass transition temperature (Tg) were observed by using DSC measurements. Variation in mechanical properties viz. Tensile strength, flexural strength, flexural modulus, interlaminar shear strength and impact strength have been observed. With the thermoplastic modification of thermoset matrix material, improvement in mechanical properties of epoxy-glass fiber reinforced composites have been expected. Changes in storage modulus and loss modulus of all specimens were also evaluated by dynamic mechanical analysis (DMA). Scanning electron microscopy (SEM) was used to investigate the relationship between the morphological study of the fractured epoxy resins and mechanical properties of the modified epoxy resins and glass fiber reinforced composites. If the polymer matrix is fairly brittle (unmodified epoxy), there may be a corresponding reduction in mechanical properties. Incorporation of engineering thermoplastic Poly (ether-imide) has resulted in improvement of above stated mechanical properties. All results indicated that thermoplastic modified multifunctional epoxy resin proved to be a good matrix material which enhances the mechanical properties of glass fiber reinforced composites.