Butyl rubber is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for isobutylene isoprene rubber. Polyisobutylene, also known as PIB or polyisobutene, (C 4 H 8) n, is the homopolymer of isobutylene, or 2-methyl-1-propene, on which butyl rubber is based.Butyl rubber is produced by polymerization of about 98% of isobutylene with about 2% of isoprene.Structurally, polyisobutylene resembles polypropylene, having two methyl groups substituted on every other carbon atom.utyl rubber has excellent impermeability, and the long polyisobutylene segments of its polymer chains give it good flex properties. The formula for PIB is: â(âCH 2 âC(CH 3) 2 â) n â. The formula for IIR is:
Biot wrote two main articles on breathing patterns. One large exploratory work focused on his observations on CheyneâStokes breathing.3 4 In each paper, he described patients who were admitted to the Hotel Dieu Hospital with CheyneâStokes Ë respiration, his major interest.
In the endogenous respiration concept the biodegradable fraction of X OHO is regarded as a homogenous substrate that undergoes self-destruction in the absence of external substrate. The degradation process of X OHO is modelled with Eq. (4) and Eq.xperimental evidence for the validity of the endogenous respiration model comes from Marais and Ekama (1976) . Using the OUR method, the value of b OHO was found to be 0.24 d â1 and independent from SRT in the range of 2.5â30 days. Similar results were obtained by van Haandel et al.