Novel method to measure the shear strength of exfoliated montmorillonite/polymer nanocomposite films

Abstract

Shear fracture of exfoliated montmorillonite/poly(methyl acrylate-co-methyl methacrylate) (MMT/P(MA-co-MMA)) nanocomposite films fabricated via soap-free emulsion polymerization was studied using a unique test fixture that is capable of controlling the inclined angle between the loading axis and the shear fracture plane. It was found that fracture of the films depended on both shear and normal stresses and could be described by the Mohr-Coulomb criterion. The effects of MMT content on the intrinsic shear strength (i.e. the shear strength at zero normal stress) τ s were also examined. The obtained τ s increased from 1.66 to 2.78 MPa as 1 wt% MMT was incorporated into P(MA-co-MMA) and then increased almost linearly to 5.32 MPa when the content of MMT increased to 15 wt%. Also, the fracture-surface morphology of the composite film depended on both the MMT content and the inclined angle (and hence the normal-to-shear stress ratio). For low MMT contents and low normal-to-shear stress ratios, striations normal to the shear direction appeared on the fracture surface. As the MMT content or the stress ratio increased, the fracture surface became rough accompanied by the presence of interfacial micro-cracking between MMT nanoplatelets and the matrix. With further increase in MMT content and high stress ratio, the MMT nanoplatelets were compressed into large flakes on the fracture surface.

Swelling, mechanical and mucoadhesion properties of Mt/starch-g-PMAA nanocomposite hydrogels

“…Note that, when using different amounts of Mt, such as 1-10 mass% for the preparation of the starch based CPN hydrogel, Mt/S-g-PMAA products with different mechanical properties can be obtained. These results were in good correlation with the other earlier studies performed with Mt containing natural and synthetic polymer based CPN hydrogels (Lee and Chen, 2004;Xu et al, 2006;Depan et al, 2009;Lin et al, 2010;Lin et al, 2012).…”

Mechanical and barrier properties of copolyester-nanoclay composites

“…during loading in the form of increased deformation, crack arresting, high modulus of nanoclay, load bearing, etc. [36,37]. However, the rate of increase of these tensile parameters was lower at higher clay content ( > 2 wt%), possibly due to the formation of an intercalated nanocomposite structure.…”

Nanoscale dispersion of delaminated sheets of layered double hydroxides in polyvinyl acetate

“…In recent years, organic polymers blended with inorganic nanofillers have attracted considerable interest. One kind of the inorganic components widely investigated was the layered materials, including montmorillonite-type clays [1][2][3][4][5][6][7][8][9][10], layered silicate [11,12], molybdenum sulphides [13][14][15], titanates [16,17] and layered double hydroxides (LDHs) [18][19][20][21][22][23][24][25][26][27]. Benefiting from their nanosized thickness, the clay layers can form homogeneous dispersion at the content of 3-5% in the polymer matrix, and improve the mechanical and thermal properties of the polymer matrix to the same extent as the 30-50% of microscale fillers [5].…”