Composites in the growing field of carbon nanotubes and other carbon nano-forms

Achieved mechanical properties did not differ from the original system which was seen as the advantageous aspect compared to graphene particles which reduce the property of epoxy modified systems by a significant percentage with each added layer, levelling at 30% loss in mechanical properties, However, the increased electrical conductivity of CFRP modified with 1% CNT was tenfold.

Vahid Nekouie, The University of Sheffield

© 2015 The University Of Sheffield

Funded by AFOSR 2011-2014, and US Army & AFOSR in 2015

Yi Zhang and Richard Grainger, The University of Sheffield

Note: error bar represents standard deviation, n = 5

Heating cycle: 177℃ for 2 hours, (harshest conditions)
Purpose: to investigate any potential reduction of the ILSS, due to the presence of printed surface. ILLS values of all groups are enhanced after heat treatment, which indicated the existence of post curing.

© 2015 The University Of Sheffield

Yi Zhang and Richard Grainger, The University of Sheffield

Note: error bar represents standard deviation, n = 5

Yi Zhang and Richard Grainger, The University of Sheffield

Printed surface ratio between the plies:
30 ~ 40%

© 2015 The University Of Sheffield

Optical images of epoxy coated glass substrates with printed PMMA droplets:
5, 10 and 20% PMMA deposits before and after the heating cycle.

Yi Zhang and Jonathan Stringer, The University of Sheffield

PMMA film is comparable to inkjet printed area that is double the percentage of concentration of the film pattern. 10% film pattern is comparable to 20% PMMA droplets due to the volume fraction of PMMA in those two systems.

Yi Zhang and Jonathan Stringer, The University of Sheffield

GIc values of printed areas are comparatively higher than unprinted areas, which means inkjet printing can be applied to delicate material design work, and manufacture property graded multifunctional materials.

A

B

Crack propagation way

Yi Zhang, Patrick Smith and Jonathan Stringer, The University of Sheffield

PMMA droplets act as plastic zones that can absorb energy by plastic deformation. Due to the viscoelastic nature of PMMA, those well dispersed microphases by inkjet printing provide an energy-absorption path by thermoplastic deformation, which can decelerate crack growth as the crack tips are shielded by those plastic zones.
Crack propagation is arrested by the combination of crack-diverting discretely deposited droplets and the higher fracture toughness of PMMA. The second option can be further evidenced by the lower standard deviation in the system with hexagonally printed 20% PMMA system.

© 2015 The University Of Sheffield

Indented areas on (a) the non-aged specimen and the specimens aged at (b) 200 C and (c) 350 C, in MTM44-1 CF0300. MTM44-1 resin is a toughened phenol–formaldehyde (PF)-based aerospace grade resin, CF0300 is a 2/2-twill carbon fabric, (HS) carbon fibre reinforcement.

Julian Marino-Perez, The University of Sheffield

© 2015 The University Of Sheffield

Julian Marino-Perez, The University of Sheffield

Maximum temperatures developed in the drilling of selected CFRP systems:
(a) MTM44-1 CF0300, (b) MTM44-1 CF2216 and (c) MTM28B CF0300 at different distances away from the hole edge, measured using thermocouples and thermal imaging (IR camera).

Julian Marino-Perez, The University of Sheffield

Left to right: SEM images at the hole exit corresponding to 49.8 m/min, 99.6 m/min, 149.4 m/min and 199.2 m/min cutting speeds. Above: fibres at 90° (perpendicular to the machining direction), below: fibres at 0° and 90°.