Mechanical and frictional properties of coconut husk powder reinforced polymer immersed in a simulated acidic medium for oil/gas applications.

Polymeric materials are constantly exposed to aggressive environments, negatively impacting their mechanical and chemical properties. In salt, acid, or alkaline solutions, polymer materials degrade due to surface flaws, microcracks, or other irregularities. For the first time, this study considers the behaviour of coconut powder/coir-reinforced synthetic LDPE hybrid composite immersed in an aggressive (acidic) medium for 15, 30 and 45 days. The structural, mechanical, and frictional behaviour of the developed coir/coconut husk powder/LDPE hybrid composites were measured after ageing in hydrochloric acid (HCl) as potential materials for oil and gas applications. From the XRD patterns, the prominent reflections in the control samples increased with the acid ageing days, while less prominent reflections characterized the hybrid composites. The hardness of the reinforced samples immersed for 30 and 45 days (30B and 45A) showed the highest values of 0.28 Hv, while the control samples immersed for 15 days had the least hardness. The reinforced samples immersed for 15 and 30 days (15B and 30B) showed the lowest and highest fracture toughness, respectively. The control samples were observed to absorb little water after immersion for 144 h. The result showed that although the reinforced hybrid composites showed better mechanical properties, with an increase in the days of immersion in an aggressive medium, the properties became compromised compared to the un-reinforced samples. Hence, the applications of the produced reinforced polymers in the oil and gas industries may be limited.

Datasets on the elastic and mechanical properties of hydroxyapatite: A first principle investigation, experiments, and pedagogical perspective.

The purpose of this data article is to report the quantum mechanical analysis by generalized gradient approximation (GGA) exchange-correlation functional using density functional theory (DFT). The predictions were based on the elastic constants and mechanical properties of stoichiometric hydroxyapatite (HAp) crystal. The elastic stiffness constants in hexagonal symmetry were obtained by fitting the Hookes' law for the energy-strain and stress-stain relations. Some of the theoretical datasets were compared to measured mechanical properties of produced HAp pellets obtained through micro and nanoindentation experiments. The datasets show considerable anisotropy in the stress-strain behaviour and are discussed in the context of the mechanical properties of HAp which are useful for tissue engineering. We also provide a pedagogical snapshot on the use of the datasets herein to teach and interpret DFT based atomistic simulations in a typical blended online teaching set-up for engineering students using a new pedagogy, CACPLA (Communicate, Active, Collaborate, Practice, Learning and Assessment).