10/29/2010
The effects of molecular weight and polymorphism on the fracture and thermo-mechanical properties of a carbon-fibre composite modified by electrospun poly (vinylidene fluoride) membranes  
(Pages 2585-2596) Polymer 51 #12 (2010)
Magniez et al prepared the composites by electrospinning the nanofibres directly onto commercial pre-impregnated carbon fibre materials.  Under these optimised conditions, PVDF primarily crystallised in its β phase polymorphic form.  The improved plastic deformation at the crack tip after inclusion of the nanofibres was directly translated to a 57% increase in the mode II interlaminar fracture toughness (in-plane shear failure). Conversely, the fracture toughness in mode I (opening failure) was slightly lower than the reference by approximately 20%, and the results were interpreted from the complex micromechanisms of failure arising from the changes in polymorphism and molecular weight of the PVDF.  (RDC 12/22/2010)

10/29/2010
Suppression of AC conductivity by crystalline transformation in poly(vinylidene fluoride)/carbon nanofiber composites 
(3230-3237) Polymer 51 #14 (2010)
Sun et al found that the transformation from α-phase to β-phase in PVDF, induced by the addition of CNFs, had a surprisingly suppressive effect on the AC conductivity of the nanocomposites. These unexpected results indicate that the decline in conductivity occurs after re-crystallization treatment (annealing) of the nanocomposites, and the reduction levels increase with increasing amounts of CNFs. Interestingly, the AC conductivity of annealed 5 wt% CNF/PVDF composites becomes even lower than that of re-crystallized nanocomposites with 3 wt% CNFs.  (RDC 12/22/2010)