Sulfur

NR (Standard Vietnamese Rubber SVR-10, dirty content = 0.1 wt%, Astlett Rubber Inc., Oakville, ON, Canada), ENR-25, and ENR-50 (Epoxyprene 25, Epoxyprene 50, Muang Mai Guthrie Public Co., Ltd., Muang, Phucket, Thailand) were used as base rubbers. Silica (Ultrasil 7000 GR, Evonik Industries AG, Essen, Germany) with a Brunauer–Emmett–Teller (BET) surface area of 160 to 175 m²/g was used as a filler. Bis-[3-(triethoxysilyl)propyl]-tetrasulfide (TESPT, Si-69, Evonik Korea Ltd., Seoul, Korea) was used as the silane coupling agent. ZnO and stearic acid (Sigma-Aldrich Corp., Seoul, Korea) were used as activators, and N-(1,3-dimethyl butyl)-N-phenyl-p-phenylenediamine (6PPD, Kumho Petrochemical Co., Daejeon, Korea) was used as the antioxidant. Sulfur (Daejung Chemicals and Metals Co., Siheung, Korea) was used as the crosslinking agent. N-cyclohexyl benzothiazyl-2-sulfenamide (CBS, 98%, Tokyo Chemical Industry Co., Ltd., Tokyo, Japan) and 1,3-diphenylguanidine (DPG, 98%, Tokyo Chemical Industry Co., Ltd., Tokyo, Japan) were used as cure accelerators. N-cyclohexylthio phthalimide (PVI, Shandong Yanggu Huatai Chemical Co., Ltd., Liaocheng, China) was used as the pre-vulcanization inhibitor.

SSBR (SOL-5220M, Kumho Petrochemical Co. Daejeon, Korea, styrene content: 26.5 wt%, vinyl content: 26 wt%, non-oil extended) was used as the base polymer. Silica (Ultrasil 7000 GR, Evonik Industries AG, Essen, Germany, Brunauer–Emmett–Teller (BET) surface area: 160–175 m²/g) was used as a filler; and bis-[3-(triethoxysilyl)propyl]tetrasulfide (TESPT, Si-69, Evonik Korea Ltd., Seoul, Korea) was used as a silane coupling agent. Moreover, TDAE oil (Kukdong Oil & Chemicals Co., Yangsan, Korea) was used as a processing aid for mixing. ZnO and stearic acid (both from Sigma-Aldrich Corp., Seoul, Korea) were used as activators, and N-(1,3-dimethylbutyl)-N-phenyl-p-phenylenediamine (6PPD, Kumho Petrochemical Co., Daejeon, Korea) was used as an antioxidant in the compound. Additionally, sulfur (Daejung Chemicals & Metals Co., Siheung, Korea) was used as a crosslinking agent. N-cyclohexyl benzothiazole-2-sulfenamide (CBS, 98%, Tokyo Chemical Industry Co. Ltd., Tokyo, Japan) and 1,3-diphenylguanidine (DPG, 98%, Tokyo Chemical Industry Co. Ltd., Tokyo, Japan) were used as cure accelerators.

Natural rubber (NR, Standard Vietnamese Rubber SVR-10, dirty contents 0.1 wt %, Astlett Rubber Inc., Oakville, ON, Canada) was used as the base rubber, and carbon black (N134, iodine adsorption (IA): 142 g/kg, N₂SA adsorption specific surface area: 143 m²/g, OCI Company Ltd., Seoul, Korea) was used as the filler. Zinc oxide and stearic acid used as crosslinking activators were purchased from Sigma Aldrich (Seoul, Korea). N-(1,3-dimethybutyl)-N′-phenyl-phenylenediamine (6PPD, Kumho Petrochemical Co., Daejeon, Korea) and 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ, Sinopec Corp., Beijing, China) were used as antioxidants. Sulfur (Daejung Chemicals & Metals Co., Siheung, Korea) was used as the crosslinking agent, and N-tert-butyl-2-benzothiazyl sulfenamide (TBBS, Shandong Yanggu Huatai Chemical Co., Ltd., Liaocheng, China) was used as the vulcanization accelerator. N-cyclohexylthio phthalimide (PVI, Shandong Yanggu Huatai Chemical Co., Ltd., Liaocheng, China) was used as the prevulcanization inhibitor. For processing aids, three different substances were used: TDAE oil (Kukdong Oil & Chemicals Co., Yangsan, Korea), which is commercially available, and N-LqBR and amino-LqBR, which were synthesized. Details on the synthesis method of LqBR are presented in Section 2.3.