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A cohesive law for carbon nanotube/polymer interfaces based on the van der Waals force

Liying Jiang's picture

A cohesive law for carbon nanotube/polymer interfaces based on the van der Waals force (JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 54 (11): 2436-2452 NOV 2006)

Authors: Jiang, L.Y., Huang, Y., Jiang, H., Ravichandran, G., Gao, H., Hwang, K.C. and Liu, B. 

We have established the cohesive law for interfaces between a carbon nanotube (CNT) and polymer that are not well bonded and are characterized by the van der Waals force. The tensile cohesive strength and cohesive energy are given in terms of the area density of carbon nanotube and volume density of polymer, as well as the parameters in the van der Waals force.

For a CNT in an infinite polymer, the shear cohesive stress vanishes, and the tensile cohesive stress depends only on the opening displacement. For a CNT in a finite polymer matrix, the tensile cohesive stress remains the same, but the shear cohesive stress depends on both opening and sliding displacements, i.e., the tension/shear coupling. The simple, analytical expressions of the cohesive law are useful to study the interaction between CNT and polymer, such as in CNT-reinforced composites. The effect of polymer surface roughness on the cohesive law is also studied.

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Comments

Liying Jiang's picture

Carbon nanotube composites; Cohesive law; Carbon nanotube/polymer interface; van der Waals force

Henry Tan's picture

Nice papaer that I have cited in my blog before.

Can the van der Waals law be applied to get the relation between shear and sliding on the nanotube/polymer interface?

Liying Jiang's picture

Hi Henry,

 

Thank you for your citing my paper. Here is the reply to your question:

 

For CNTs in infinite polymer matrix, the shear stress vanishes. The vanishing shear cohesive stress is the consequence of average van der Waals interactions at the interface.  For CNT composites with interfacial functionalization and/or mechanical interlocking, the shear cohesive stress may not vanish any more, just as in fiber-reinforced composites.For CNTs in finite polymer matrix, the shear cohesive stress depends on both the opening and sliding displacements, i.e., the tension/shear coupling. The polymer surface is assumed to be flat in the above mentioned situations. If the waviness of the polymer surface is accounted for, the average shear cohesive stress also vanishes. This represents shear stress averaged over the period of wavy polymer surface.  However, the local shear stress may not be zero. 

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