First, the tearing strength of various rubber (vulcanized rubber) :
NR>TPC>IR>PUR>CO>NBR>IBR>CR>CSM>SBS>BR>SBR>EPDM>FKM> Silicone rubber>ACM
Second, the relationship between tearing strength and vulcanization system:
The relationship between tear strength and crosslinking density has a maximum value. Generally, with the increase of crosslinking density, tear strength increases, and a maximum value appears. Then, with the increase of crosslinking density, the tear strength decreases sharply, similar to the tensile strength, but the crosslinking density of the optimal tear strength is lower than the crosslinking density of the optimal tensile strength. The traditional sulfur-accelerator vulcanization system with 2.0-3.0 parts of sulfur should be used. Medium activity and good flatness are selected as promoters, such as DM,CZ, etc., which have great influence on excessive sulfur. In natural rubber, if the effective vulcanization system is used instead of the ordinary vulcanization system, the tearing strength is significantly reduced, but the effect of oversulfur is little.
Third, the relationship between tear strength and filling system:
The tear strength increases with the decrease of carbon black particle size. Carbon black with low structure is beneficial to the improvement of tear strength. The tear strength can be increased by increasing the amount of high wear-resistant carbon black in natural rubber. The amount of highly wear-resistant carbon black (60-70 parts) is increased in styrene butadiene rubber, the maximum value appears, and then gradually decreases. In general, synthetic rubber, especially butyl rubber, can significantly improve the tearing strength when carbon black is used. The use of isotropic reinforcing fillers, such as carbon black, white carbon black, white brilliant, Litho powder and zinc oxide, etc., can obtain higher tearing strength. The use of anisotropic reinforcing fillers, such as clay, magnesium carbonate, etc.,can not obtain higher tearing strength. Some coupling agent modified inorganic fillers, such as carboxylated polybutadiene CPB modified calcium carbonate, aluminum hydroxide, can also improve the tear strength of styrene butadiene rubber.
Forth, influence of softening system on tear strength:
Usually the addition of softener will reduce the tear strength of vulcanized rubber, especially the paraffin oil is very unfavorable to the tear strength of styrene butadiene rubber vulcanized rubber. The aryl-hydrogen oil can ensure the tearing strength of the styrene butadiene rubber vulcanizate. When using petroleum softener as the softener of butadiene rubber and neoprene rubber, high aryl hydrogen oil with aryl hydrogen content higher than 50-60% should be used, and paraffin oil should not be used.
