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2 2022

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Hierarchical Carbon Fiber-Carbon Nanotubes by Using Electrospray Deposition Method with Preserved Tensile Properties

Zakaria Muhammad Razlan, Akil Hazizan Md, Omar Mohd Firdaus, Al Bakri Abdullah Mohd Mustafa, Rahim Shayfull Zamree Abd, Nabiałek Marcin, Wysłocki Jerzy J.

Archives of Metallurgy and Materials

2022

Vol. 67, iss. 4

1299--1304

In this study, the electrospray deposition (ESD) method was used to deposit carbon nanotubes (CNT) onto the surfaces of carbon fibers (CF) in order to produce hybrid carbon fiber-carbon nanotubes (CF-CNT) which is rarely reported in the past. Extreme high-resolution field emission scanning electron microscopy (XHR-FESEM), high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS) were used to analyse the hybrid carbon fiber-carbon nanotube (CF-CNT). The results demonstrated that CNT was successfully and homogenously distributed on the CF surface. Hybrid CF-CNT was then prepared and compared with CF without CNT deposition in terms of their tensile properties. Statistically, the tensile strength and the tensile modulus of the hybrid CF-CNT were increased by up to 3% and 25%, respectively, as compared to the CF without CNT deposition. The results indicated that the ESD method did not cause any reduction of tensile properties of hybrid CF-CNT. Based on this finding, it can be prominently identified some new and significant information of interest to researchers and industrialists working on CF based products.

Crumb rubber geopolymer mortar at elevated temperature exposure

Azmi Ahmad Azrem, Abdullah Mohd Mustafa Al Bakri, Ghazali Che Mohd Ruzaidi, Ahmad Romisuhani, Jaya Ramadhansyah Putra, Rahim Shayfull Zamree Abd, Almadani Mohammad A., Wysłocki Jerzy J., Śliwa Agata, Sandu Andrei Victor

Archives of Civil Engineering

2022

Vol. 68, nr 3

87--105

Low calcium fly ash is used as the main material in the mixture and the crumb rubber was used in replacing fine aggregates in geopolymer mortar. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) which were high alkaline solution were incorporated as the alkaline solution. The fly ash reacted with the alkaline solution forming alumino-silicate gel that binds the aggregate to produce a geopolymer mortar. The loading of crumb rubber in the fly ash based geopolymer mortar was set at 0% (CRGM-0), 5% (CRGM-5), 10% (CRGM-10), 15% (CRGM-15), and 20% (CRGM-20), respectively. NaOH solution (12M) and Na2SiO3 solution ratio is set constant at 2.5 for all geopolymer mixture and the fly ash to alkali activator ratio was kept at 2.0. The CRGM at 28 days of curing time was exposed to elevated temperature at 200ºC, 400ºC, 600ºC and 800ºC. The weight loss of the CRGM increases with increasing temperature at all elevated temperatures. However, the density and compressive strength of CRGM decrease with an increase of crumb rubber loading for all elevated temperature exposure. The compressive strength of CRGM reduced due to the fact that rubber decomposes between 200ºC and 600ºC thereby creating voids. CRGM-15 and CRGM-20 showed cracks developed with rough surface at 800ºC. Image obtained from scanning electron microscope (SEM) showed that, the CRGM changed significantly due to the decomposition of crumb rubber and evaporation of the free water at 400ºC, 600ºC and 800ºC.