One of the critical characteristic of natural rubber is strain-induced crystallization associated with exceptional physical properties such as cut, tear and heat resistance, resilience, high tensile stress and large hysteresis loss for tire application. Recently, the relation between physical properties and the structure for vulcanized natural rubber has been considerably studied. Especially, by the use of synchrotron X-rays, interesting results of strain-induced crystallization and structural deformation of natural rubber during the stretching were reported. It demonstrated that highly stretched network chains act as nuclei and strain-induced crystals can be initiated from them. Amorphous chains surrounding the nuclei participate in the crystal growth. Even though extensive studies on the strain-induced crystallization of vulcanized natural rubbers were carried out, crystal growth and crystallization mechanism are still not clear.<br/>The traditional study of strain-induced crystallization of rubber by the real time X-ray diffraction is under the continuous stretching. This methods lead to somewhat complicating crystallization behavior due to the continuous change of strain during crystal growth. Strain-induced crystallization was simplified by using a specially designed strain jumping device which enables one to examine strain-induced crystal growth with a time at a given fixed strain. In the presentation, we will discuss the mechanism of strain-induced crystallization of crosslinked natural rubber based on our new device and the results obtained.

Strain-induced crystallization of natural rubber as studied by utilizing strain jumping device

251st National Meeting (2016)

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