English Abstract

Strain-Induced Crystallization and Mechanical Properties of Rubber.
2. SIC of Vulcanized and Un-Vulcanized Rubber, Reinforcement Filled Rubber, Thermoplastic Elastomer.

Shigeyuki TOKI
retired from Mahidol University, State University of New York at Stony Brook, Tonen Chemical and Bridgestone.
Nippon Gomu Kyokaishi,(2017),90(11),531-538 General Review in Japanese

Strain-induced crystallization (SIC) of rubber is a common phenomenon of highly stretched rubber. SIC is one of crystallization processes of polymer.
1. Un-vulcanized rubber, vulcanized rubber, reinforcement filled rubber, and thermoplastic elastomer perform SIC.
2. Un-vulcanized NR performs SIC with 1/2 amount of crystal fraction of vulcanized NR at smaller strain than vulcanized NR. It suggests that crosslinking is not vital for SIC rather than entanglement.
3. Reinforcement filler and nano-filler increase crystalline fraction of SIC at smaller strain than pure vulcanized NR. Fillers do not interfere SIC of rubber.
4. Thermoplastic elastomers perform SIC with breakdown of existing crystals which are created during processing. Crystalline part play the role of a network point like the chemical network of vulcanized rubber during deformation.
5. SIC of NR and IR transforms oriented amorphous fraction into crystalline fraction with increase of strain. On the other hand, BR and IIR increase oriented amorphous and crystalline fraction independently with increase of strain.
6. Flow induced crystallization (FIC) of semi-crystalline plastics is similar to SIC of rubber. Un-vulcanized rubber is semi-crystalline Polymer at melt state. Both crystallization processes need entanglements as pivot points to align and stretch polymer chains.

Keywords: Crystallization, Mechanical Properties, Rubber