Butyl Rubber typically contains about 98% polyisobutylene with 2% isoprene distributed randomly in the polymer chain. To achieve high molecular weight, the reaction must be controlled at low temperatures (-90 to -100 degC).The reaction is highly exothermic.utyl Rubber typically contains about 98% polyisobutylene with 2% isoprene distributed randomly in the polymer chain. To achieve high molecular weight, the reaction must be controlled at low temperatures (-90 to -100 degC).
There may be no single cause of bipolar disorder (aka manic depression). Instead, research indicates the causes of bipolar disorder are probably a combination of biochemical, genetic and environmental factors that may trigger and perpetuate the chemical imbalances in the brain.
Researchers have discovered that some people with bipolar disorder have: 1  biochemical imbalances of hormones and certain neurotransmitters in the brain; especially dopamine, serotonin, norepinephrine, and acetylcholine. 2  1. 3  an over-secretion of cortisol, a stress hormone.