Q2. What is the effect of graphene on the initiation area?
at low graphene layers contents (i.e., 0.04 wt%) the initiation area quickly propagates, the presence of graphene prohibiting the reorientation of polymer chains and leading to a premature break of the polymer chains.
Q3. What is the effect of the dispersion of graphene on the tensile?
The dispersion of only 0.07 wt% exfoliated graphene nanosheets in PET led to materialswith better mechanical properties than previous melt-processed PET/graphene nanocomposites [30, 31].
Q4. How did the graphene layer increase the semi-minor axis?
In summary, polymer/graphene nanocomposites with superior mechanical properties were manufactured via melt processing using an extremely low loading level of exfoliated graphene layers (i.e., less than 0.1 wt%) and by carefully choosing a polymer matrix.
Q5. What is the degree of dispersion of graphene flakes in the polymer matrix?
The fact that the graphene flakes remain well-exfoliated and highly dispersed within thepolymer matrix suggests these composites to potentially display mechanical reinforcement.
Q6. What is the reason for the occurrence of fibrils?
The occurrence of fibrils may suggest that the break was due to crazing either in the amorphous area (short fibrils) or in the semi-crystalline area (long fibrils) [48].
Q7. What is the common aims of graphene research?
such research has progressed in many directions, two of the most common aims are either to produce high-performance composites such as high-strength, polymer-graphene fibers or to achieve modest levels of reinforcement but at very low graphene loading levels.
Q8. What is the effect of graphene on the semi-minor axis?
As the graphene content was increased above 0.04 wt% and the stress and strain-at-break began to increase (Figure 3B-C), the sample presented pronounced fibrillation (Figure 3G) and the semi-minor axis decreased to 15 μm for PET with0.08 wt% exfoliated graphene layers.
Q9. How does the paper describe the fabrication of graphene nanocomposites?
In this paper, the authors report the fabrication of polymer/graphene nanocomposites via melt compounding, using pristine graphene layers at weight fractions lower than 0.1 wt%.
Q10. What did the graphene layer add to the semi-minor axis?
This suggested that the stress was transferred from the polymer to the graphene layers, which delaminated creating more surfaces and allowing the material to withstand higher loads.
Q11. How long does the rule of mixtures predict a modulus increase?
assuming that the composite is filled with graphene flakes which are aligned in plane and are long enough for stress to transfer effectively from the polymer matrix to the graphene layers, the rule of mixtures would predict a modulus increase of 0.5 GPa for Vf=0.05% [29].
Q12. How much graphene did the initiation area have?
increasingthe amount of graphene to 0.07 wt%, had a significant effect on the local structure in the initiation area with considerably larger fibrils observed (Figure 3G).
Q13. What is the effect of graphene on the strain at break?
While the authors observe this decrease at low volume fractions, as the graphene content was increased above 0.04 wt% the strain at break improved significantly.
Q14. What is the strength of the PET composite?
While this strength enhancement is lower than previous observations of a 2-3 fold enhancement of both modulus and strength for PET loaded with ~0.5% graphene and functionalized graphene oxide [9, 15], it also occurs at a much lower loading level.
Q15. What is the disadvantage of few-layer graphene?
this is not a disadvantage: previous work has shown few-layer graphene to be a more effective reinforcing material than monolayer graphene [21].