Previous strengthening mechanisms described in literature for high density polyethylene (HDPE) carbon nanotubes composites are typical of those observed in fibre reinforced polymeric micro composites. Here, we present a new molecular level strengthening mechanism based on HDPE carbon nanotubes composite, which has not been reported before to the best of authors' knowledge. The HDPE nanocomposite was produced by melt intercalation technique via twin-screw extrusion. Thereafter, the samples were subjected to mechanical tensile tests and scanning electron microscope (SEM) examination. Carbon nanotubes (CNTs) were found to be disentangled from the polymer molecules after yielding and prior to breaking. SEM and optical microscopic observations revealed visible black agglomerate bands at 45 appeared after yielding and prior to the breaking of the ductile HDPE. It was observed that CNTs were pushed out from the intricate mechanical interlocking with the thermoplastic polymeric chains of HDPE during strain hardening. ARTICLE HISTORY

A novel tweakable nanocomposite was prepared by spark plasma sintering followed by systematic oxidation of carbon nanotube (CNT) molecules to produce alumina/carbon nanotube nanocomposites with surface porosities. The mechanical properties (flexural strength and fracture toughness), surface area, and electrical conductivities were characterized and compared. The nanocomposites were extensively analyzed by field emission scanning electron microscopy (FE-SEM) for 2D qualitative surface morphological analysis. Adding CNTs in ceramic matrices and then systematically oxidizing them, without substantial reduction in densification, induces significant capability to achieve desirable/application oriented balance between mechanical, electrical, and catalytic properties of these ceramic nanocomposites. This novel strategy, upon further development, opens new level of opportunities for real-world/industrial applications of these relatively novel engineering materials.

Multiwall carbon nanotube (CNT)-filled high density polyethylene (HDPE) nanocomposites were prepared by extrusion and considered for their suitability in the offshore sheathing applications. Transmission electron microscopy was conducted to analyse dispersion after bulk extrusion. Monolithic and nanocomposite samples were subjected to accelerated weathering and photodegradation (carbonyl and vinyl indices) characterisations, which consisted of heat, moisture (seawater) and UV light, intended to imitate the offshore conditions. The effects of accelerated weathering on mechanical properties (tensile strength and elastic modulus) of the nanocomposites were analysed. CNT addition in HDPE produced environmentally resilient nanocomposites with improved mechanical properties. The energy utilised to extrude nanocomposites was also less than the energy used to extrude monolithic HDPE samples. The results support the mass substitution of CNT-filled HDPE nanocomposites in high-end offshore applications.

In this research, solution casting technique was applied to produce four types of nanocomposites. Different ethanol dosages; 0g, 1g, 3g, and 5g were used to disperse graphene in the epoxy matrix. It was observed that 1g dosage of ethanol was the most effective concentration to disperse 1wt% graphene in the epoxy matrix. At 1 g dosage of ethanol used, the Young’s modulus, tensile strength, and toughness were increased by 130%, 76%, and 187% respectively. SEM images illustrated that the graphene was able to inhibit the advancing cracks and detoured cracks propagation. It is observed that the ethanol needs to be removed completely during processing to ensure its effectiveness, otherwise, the remaining ethanol can cause porosity which is undesirable to the tensile properties of the nanocomposites.

Commercial applications of polymer nanocomposites for materials used in offshore settings is continuously touted as a potential solution to expand the material property envelope of polymers used in high pressure and temperature environments. In this regard, polyurethane urea (PUU) has been successfully used in such environments, however, they are limited in terms of their ability to offer multifunctional behavior i.e., thermal conductive behavior with mechanical properties. This gap offers the opportunity for their properties to be enhanced as an advanced multi-functional polymer. Hence, in this study, polyurethane urea/graphene nanocomposites were synthesized using commercial Polyurethane urea (Task 12), and graphene nanoplatelets (GnP). The graphene nanoplatelets were dispersed in one part of the polyurethane urea component using facile dispersion methods. The properties of the new PUU nanocomposite materials were studied using SEM, mechanical and thermal analysis techniques (DMA and Hot Disk), to examine the development of the multifunctional properties in the PUU nanocomposite. Our analysis describes the influence of graphene nanoplatelets at ultra-low concentrations on multi-functional properties of the PUU nanocomposites. The developed nanocomposites recorded a 16% increase in the tensile strength and an 8% increase in the thermal conductive values. The property improvements are credited generally to the high aspect ratio of graphene nanoplatelets, dispersion and filler-polyurethane interactions at the interface. The impartation of multi-functional behavior, in enhancing the thermal conductivity whilst maintaining the mechanical properties makes it a potentially valuable for subsea applications.

Granite Powder (GP) is industrial byproducts generated from the granite polishing and milling industry in powder form. The byproduct is left largely unused and is hazardous materials to human health because they are airborne and can be easily inhaled. GP was used as an additive to the concrete to explore the possibility of increasing the mechanical properties (compressive strength) of the concrete. The slump, compressive strength and water absorption test were performed on fresh and hardened concrete. The addition of GP to concrete to serve as an additive shows an improvement in the compressive strength of the concrete. The highest 3-day compressive strength (23.03 N/mm2) was recorded at 10% GP addition level while the lowest 3-day compressive strength (20.47 N/mm2) was recorded at 2.5% GP addition level.  The highest 28-day compressive strength (28.29 N/mm2) was recorded at 10% GP addition level while the lowest 28 days compressive strength (27.40 N/mm2) was recorded at 2.5% GP addition level. Peak compressive strength of 33.40 N/mm2 was obtained at 56 days when 10% GP was added in the concrete production. The workability of the concrete decreased with increase in GP replacements. Therefore a higher water to cement ratio will be required to maintain a certain level of workability. In conclusion, employing GP as an additive in concrete helped in boosting the mechanical properties of concrete. The GP at 10% addition is the best choice among other concrete mixtures as it is equivalent to grade 30 concrete suitable for producing post tensioned concrete.