The parabutyl rubber, we should know more about the common properties I will briefly explain, followed by BR9000 as an example of the interpretation of the characteristics of BR9000
First, the nature of BR and processing behaviour
1, chemical structure
Cis poly 1,4-butadiene rubber
BR has a certain degree of tensile crystalline properties, but the tensile crystalline properties are much lower than IR, poor self-reinforcement, the need to apply a separate reinforcing agent
2、Physical properties
① low heat generation, low rolling resistance
② general rubber in the best wear resistance
③Excellent cold resistance, TG of BR can reach -110℃.
④Good elasticity, the best in general-purpose rubber
⑤Low mechanical strength, low tear strength, not resistant to cutting
3、Processing performance
①BR rubber processing performance is poor:
Opening process: easy to occur off-axis and other phenomena (you can add a little tackifier)
Refining process: difficult to form a group, easy to powder state, in general, the refining of BR in the refining room to fill more than NR10-15%
often with a little SBR, NR to improve processing performance
② rubber storage process cold flow phenomenon is obvious
Second, BR9000 index research
The study of a dry glue mainly includes the following indicators: microstructure, molecular weight and molecular weight distribution, gel content, vulcanisation speed, physical properties of vulcanised rubber
1、Microstructure of BR9000
According to SH/T1727-2017 standard, the cis-1,4 structure of BR9000 is 97.5%, the trans-1,4 structure is 1.3% and the 1,2-structure is 1.3%.
2、Relative molecular weight and molecular weight distribution
The number average molecular weight of BR9000 is 50000-70000, the weight average molecular weight is 270000-350000, the polydispersity coefficient is 4-6, it can be seen that the molecular weight distribution of BR9000 is relatively wide, and the processing performance and cold flow performance are better.
3、Properties of raw gel
Gel content: 0.2%; ash content: 0.02%.
4、Curing speed
It can be used (MH-ML)/(full vulcanisation time – start vulcanisation time)
Post time: Apr-26-2024