Mechanical behaviour law for thermoplastic polymers was established on the basis of phenomenological models. This work is intended to examine whether a constitutive equation used for thermoplastic polymers could be applied in case of their composites. G’Sell-Jonas model gave good results when used for the prediction of stress-strain characteristics at high strain rate, for semi-crystalline polymers subjected to mechanical tests. Data obtained through compressive test of polyphenylene sulphide (PPS) composites were processed by a numerical algorithm based on G’Sell-Jonas constitutive equations. Besides, a comparative analysis of experimental results and numerical model was done. The study showed clearly a good agreement between experimental and numerical results.
Dry sliding friction and wear behavior of single-wall (SW) and multi-wall (MW) carbon nanotubes (CNTs)/ vinylester composite have been investigated, under several loads and sliding speeds. Three different contents (0.1, 0.15 and 0.2 wt. %) of SWCNT and MWCNTs have been dispersed into the vinylester resin in order to obtain polymer nanocomposites. The present study discusses the coefficient of friction, specific wear rate and friction stability of vinylester composites with different CNTs content, using a pin-on-disc test. The friction and wear experiments were carried out following 3 loads�3 speeds, as test parameters. The best combination of friction and wear properties was found with the nanocomposite containing 0.2 wt.% MWCNT.
Performance evaluation of the polyester composites with added carbon nanotubes is presented herein, based on the results of compressive tests. Composites were obtained from polyester resin mixed with three types of carbon nanotubes: singlewall, multiwall and functionalized. The contents of carbon nanotubes were 0.1, 0.15 and 0.2 wt%. Cylindrical specimens with a diameter of 6 mm and a height of 9 mm were designed and prepared in conformity with the standards. Compressive tests were performed according to ISO 604, at the speeds of 1, 5, 10, 25 and 50 mm/min. Morfological study of the samples was carried out using SEM analysis. Dispersive X-ray spectrum in energy, associated with SEM micrograph, enabled to notice the elements existing in the composite. Stress-strain characteristics of polyester composite were determined through the compressive tests. The results revealed improved mechanical behavior of polyester composite, for test speed under 10 mm/min.
Single walled carbon nanotubes (SWCNT) and multi walled carbon nanotubes (MWCNT)/ vinyl ester nanocomposites with three different contents of carbon nanotubes (CNTs) have been prepared by the simple melt-compounding method. A fine and homogeneous dispersion of CNTs throughout vinyl ester resin has been noticed by SEM images. Two mechanical tests (compression and three point bending test) show that, compared to neat vinyl ester resin, compression modulus and compression strength of the nanocomposites have been significantly improved by about 9% and 14%, respectively, when incorporating only 0.15 wt.% MWCNTs. Furthermore, thermal behavior of SWCNT and MWCNT/ vinyl ester nanocomposites has been investigated and discussed based on differential scanning calorimetry (DSC) and thermo- mechanical analysis (TMA). Glass transition temperature (Tg) and coefficient of thermal expansion (CTE) have been increased and decreased, respectively, with increasing of CNTs content.
Phenomenological constitutive equations are applied successfully to predict stress-strain relationship for semi-crystalline polymers at high strain rates encountered in mechanical tests. The parameters of mechanical behaviour law for polymer composites with nanoscopic additives and carbon fibres can be identified by applying a known law over a lot of data obtained from compressive tests. The objective of this study is to investigate the applicability of the model G'Sell - Jonas in the case of poly (ether-ether-ketone) composites with carbon nanotubes and carbon fibres.
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