Abstract:
Electrospinning is a commercially viable technique to mass produce nanofibres. Different levels of adhesion strength is desired, depending on the application of the finished nanofibre products. Nanofibre membrane is a type of non-woven substrate. Currently, adhesion of nanofibre membrane is usually measured using traditional testing methods for films and coatings. However, the traditional methods sometimes are not suitable for testing nanofibres. This is because morphology of nanofibre membrane is different to traditional films and coatings. Furthermore, nanofibre membrane is extremely fragile and weak to be used in conventional adhesion testing equipment. Adhesion between the nanofibre membrane and its substrate is first achieved at the first layer of the nanofibre within the membrane. This research study will identify, investigate and develop suitable methods to quantitatively test adhesion force of a single nanofibre on its adhering substrate using nanoindentation technique. A single PA6, 6 nanofibre membrane layer was fabricated using Revolution Fibres’ electrospinning machine. Using Hysitron’s TI950 Triboindenter, nano-scratch was performed to effectively “push” a single nanofibre on two types of flat substrates (PA6, 6 and PP) with different chemical structure and surface energy. This was conducted to observe the effect of substrates on the adhesion of nanofibre membrane. Scanning probe microscopy (SPM) was also done in conjunction with nano-scratch tests as part of adhesion force analysis and visual representative evidence that the nanofibre has been “pushed” by the conical indenter probe. Prior to nano-scratch method development study, hardness and reduced modulus of nanofibres and substrates were tested and recorded using Berkovich indenter tip. Interestingly, difference in adhesion force of a single PA6, 6 nanofibre on the two substrates was qualitatively identifiable using nanoindentation method. All the tested data were further supported with multiple statistical analysis to find any evidence for correlation between tested variables.
