Toughening mechanisms of blends of poly(acrylonitrile-butadiene-styrene) copolymer and BPA polycarbonate

Insights into the cavitation morphology of rubber reinforced with a nano-filler

Notwithstanding the various uses of rubber, the fracture mechanism of filler-reinforced rubber remains unclear. This study used four-dimensional computed tomography (4D-CT) involving monochromatic synchrotron X-rays to examine the cavitation within silica-reinforced rubber quantitatively and systematically. The results suggested a threshold value of silica content for the cavitation morphology. Macroscopic fractures, such as those developed by void formation, occurred below the threshold value of silica content. Above this threshold, the density of rubber decreased but macroscopic voids rarely occurred. The lower-density rubber area in the high-silica-content rubber was reversible at the effective pixel size for 4D-CT. These results suggest that the growth of the damage points to macrosized voids could be stopped by the formation of a network of rigid polymer layers. This study allows the elucidation of the reinforcing mechanism and the cavitation morphology of filler-reinforced rubber.

Microscopic observation of the effects of elongation on the polymer chain dynamics of crosslinked polybutadiene using quasi-elastic γ-ray scattering

A synchrotron-radiation-based quasi-elastic γ-ray scattering system has been developed that uses time-domain interferometry to observe microscopic polymer dynamics under uniaxial deformation. The stress-producing mechanism of crosslinked polybutadiene has been studied from a microscopic viewpoint. It was found that the mean relaxation time ⟨τ⟩ of the microscopic polymer motion observed over a relatively high temperature (T) range (i.e. T^-1 < 0.0045 K^-1) increased with elongation on both the intra- and intermolecular scales. Following an extensive strain dependence study, it was found that the strain dependences of both the intra- and intermolecular ⟨τ⟩ changed with the stress dependence. It was therefore suggested that ⟨τ⟩ increased due to the constraint of the local polymer chain motion caused by elongation. The local molecular dynamics of polymer chains under uniaxial deformation could be evaluated at intra- and intermolecular scales separately for the first time using our method.

High-speed rotating device for X-ray tomography with 10 ms temporal resolution

The temporal resolution of X-ray tomography, using a synchrotron radiation X-ray source, has been improved to millisecond order in recent years. However, the sample must be rotated at a speed of more than a few thousand revolutions per minute, which makes it difficult to control the environment around the sample. In this study, a high-speed rotation device has been developed, comprising two synchronized coaxial motors movable along the direction of the axis, which can stretch or compress the rotating sample. Using this device, tomograms of breaking rubber were successfully obtained at a temporal resolution of 10 ms.

Excellent impact strength of ethylene-methyl acrylate copolymer toughened polycarbonate

The notched izod impact strength of PC/EMA blends showed a positive blending effect and increased 381% with incorporation of a very little amount of EMA (5%) with a marginal decrease in tensile strength of PC.

Effect of the glass fiber length on the mechanical properties of long glass fiber reinforced polyphenylene sulfide

The effects of the length of glass fibers on the toughness of long glass fiber reinforced polyphenylene sulfide (PPS) composites (PPS-LFT), made by the pulltrusion process, were studied with regards to both the molding V notched specimen and the cutting V notched specimen. Toughness was excellent on the molding V notched specimen. By observing the fracture morphology of the molded V notched specimen, it was found that a crack was formed, due to a slip or debonding at the fiber surface. The crack was propagated along the fiber, due to the pulling out of fibers from the matrix polymer. Both the maximum load and the fracture energy increased with increasing length of the glass fiber, because the resistance created by pulling out the fibers increased with increasing fiber length. In the case of PPS-LFT, it is understood that toughness improved because the slip between the fiber and the resin occurs before the excessive elastic strain energy is stored.