Hello everyone
I am studying fiber-reinforced composites. I have found that the modulus of Meso-fiber-based composites is between the matrix and fiber while the modulus of Nano-fiber-based composites is higher than the fiber. the main difference between the nano-fiber and Nano-fiber is their dimension which leads to different specific areas and different aspect ratios. these parameters could affect the shear stress between the fiber and matrix but I can't understand how it increases the modulus ratio of composite compare to fiber.
Dear Milad Razbin , probably you have to take into account the rule of mixtures:
https://en.wikipedia.org/wiki/Rule_of_mixtures
A description of how a fiber composite works could be this:
Tensile strength is provided by the fibers while the shear strength is furnishided by the matrix (usally a resin or polymer). Furthermore, since fibers are embedded in the matrix, it -the matrix- prevents fibers from buckling in compression. It also enhances the compressive and bending strength of the object fabricated with the composite.
Fine diameter fibers have a lot of surface area exposed to the matrix, so the matrix material can bind them. More adhesion points between matrix and fiber is key to obatain the benefits of composites, since it enhances the strength of the object fabricated.
With thick fibers the area of contact is smaller and therefore the modulus.
Examples abound in nature and human constructions. A common example is wood, where cellulose is the fiber and lignin is the matrix.
Hope it helps.
The modulus of mesofiber can be measured without huge challenge, whereas measuring the modulus of nano fiber is not easy. Therefore, it is likely that the data you used for the nano fiber is not the true value. Maybe the modulus value of the nano fiber is underestimated. This can lead to the false predicted value having the composite modulus to be greater than the rule of mixture predicts using this underestimated nano fiber data.
Dear Manuel Gómez
Thanks a lot for your insight. I have considered the rule of mixture for meso-fiber and it was true but according to the below article, in the case of nano-fiber it is not.
Professor Hatsuo Ishida
I appreciate your insight. its been a question for me too how to determine the mechanical properties of nano-fiber properly. as you said, " it is likely that the data you used for the nano-fiber is not the true value ". the thing I learned from testing of meso and micro textile was that the aspect ratio could affect tensile properties (at a lower aspect ratio you obtain higher values for modulus and etc). according to papers, the nanofiber has a high aspect ratio but subjecting a single nano fiber to tensile loading is almost impossible due to the limitations of instruments. I think there should be reconsideration about measuring the tensile properties of nano-fiber and nano-fiber reinforced composites.
Dear Milad
Composites in meso scale and micro scale can be considered as continuum medium, so you are allowed to use continuum-based theories (like Rule Of Mixture, GMC, SUC, ...) to obtain the effective properties of these composites.
But about nanocomposites, they can not be considered as continuum medium and in order to obtain effective properties of nanocomposites you are not allowed to use continuum-based theories. You should obtain the effective properties of nanocomposites by using theoris for discrete medium like as Mulcular Dynamic and nonlocal theories.
Dear Milad, for the modulus of nanofiber you can try using AFM based three-point bending test.
Dear Mohsen Maleki
Thanks a lot for your insight. I will study that subject.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nano