Chinyere Okolo
Northumbria University
Okolo is currently a Subsea engineering research associate at Northumbria University, Newcastle Upon Tyne.
Prior to this she studied at Newcastle University where she gained her Masters degree in Subsea Engineering and Management. Her undergraduate degree was in Mechanical Engineering with a specialist focus on metallurgy and mechanical properties of materials. She also has professional experience as an analyst in an engineering consulting and design firm.
Her most recent research efforts have been devoted towards the commercial development of advanced materials and nanomaterials (including graphene, boron nitride and carbon nanotubes) for the petroleum and manufacturing sectors.
INTRODUCTION: The search for novel materials has continued to dominate industries like automotive, power, aerospace and energy where maintaining a competitive edge is necessary for increasing industry market share. For subsea applications, where high pressures and temperatures are the norm, using reinforced composites have potential as the next generation solution.
This presentation investigates the influence of micro/nano fillers on mechanical properties of lightweight polymeric materials employed in thermoplastic risers and hoses for subsea applications and the challenge of incorporating such novel materials for potential up-scaling.
To obtain commercially viable microstructures, a two-step processing routes was selected and its influence on final polymer nanocomposite morphology has been studied.
METHODOLOGY: The polymer nanocomposite used in this study consists of carbon nanotubes and HDPE purchased from Nanocyl SA. The pellets were fed into a Brabender single screw laboratory extruder with conditions selected to optimize dispersion and distribution. Filler orientation by shear flow extrusion was achieved by using a rectangular shaped die with unique design and area.
Tensile samples were prepared by punching out dog-shaped dumbbells with die cutter sized-ISO 527-2 5A. Morphology of the fractured surfaces were obtained from the tensile samples examined via FE-SEM (TESCAN MIRA 3; 5KV) after sputter coating (Q150T Turbo-Pumped Sputter Coater) with platinum.
RESULTS: Figure 1 attached compares the Tensile Strength and Young's Moduli of the different concentrations (0%-3%) of carbon nano-tubes in HDPE.
Figure 2 attached shows the micro-graphs of well dispersed 1 wt% CNT in HDPE.
DISCUSSION: By adding approximately 1% by weight (wt%) of carbon nano-tubes, we found the nano-composite to have a Young’s modulus of 1.462±0.263GPa, an increase of about 15% compared to the pure matrix.
Increasing the filler loading to 2% resulted in improved modulus and tensile strength properties without good dispersion. The CNTs can be seen to be bridging cracks in the matrix.The degree of improved dispersion at 1% wt which is demonstrated in FE-SEM images, translated into an improved composite reinforcement.
In summary, the study showed improvements in mechanical properties can be achieved using a two-step processing route. Further studies to develop practical quality control methods are being considered.
