Polyurethane chemistry

J. H. Saunders and K. C. Frisch, Polyurethanes, Chemistry andPechnology, Vol. I, Wiley-Interscience, New York, 1963. 

PHILLIPS, L. N., and PARKER, D. B. V., Polyurethanes—Chemistry Technology and Properties, Iliffe, London (1964)... 

A new ionic polymeric polycarbamate was synthesized after steps of polyurethane chemistry using 3-iso-cyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate, 2,5-dimethyl-2,5-dihydroperoxyhexane, 1,6-butanediol, 2,4-tolylenediisocyanate, and N,N -bis(j3-Hydroxy-ethyOpiperazine [27]. Modification of the nitrogen of the piperazine ring into quaternary ammonium salt by treatment with methyliodide gave the MPI high electroconductivity. 

Saunders J.H. and Frisch K.C., Polyurethanes Chemistry and Technology, Part I, Chemistry High Polymer Series, Vol. 16, Wiley, New York, 1962. 

Saunders, J.H. Frisch, K.C. Polyurethane Chemistry and Technology Interscience Publ., New York, 1962 and 1963, part I. Thiele, L. Acta Polymerica 1979, 30, 323-342. 

We have already been introduced to polyurethane chemistry in Chapter 10, Section 2, where we used toluene diisocyanate (TDI) reacting with a diol to give a polyurethane. Polyurethanes derived from MDI are more rigid than those from TDI. New applications for these rigid foams are in home insulation and exterior autobody parts. The intermediate MDA is now on the Reasonably Anticipated to Be Human Carcinogens list and the effect of this action on the market for MDI remains to be seen. The TLV-TWA values for MDA and MDI are some of the lowest of the chemicals we have discussed, being 0.1 and 0.005 ppm respectively. 

Isocyanate chemistry is of itself a very complex field of chemistry, and even a brief description of the extent is outside the scope of this article. For a comprehensive description of isocyanate chemistry and its applications to polyurethane polymers, readers are directed to a handbook that is the standard in the industry [1]. A brief description follows for the purpose of introducing the role of isocyanates in polyurethane chemistry. 

Isocyanates that are produced fi om aliphatic amines are utilized in a limited range of polyurethane products, mainly in weatherable coatings and specialty applications where the yellowing and photodegradation of the aromatic polyurethanes are undesirable [5]. The aliphatic isocyanates are not used more widely in the industry due to the remarkably slow reaction kinetics of aliphatic isocyanates compared to their aromatic counterparts [6]. Due to the slow reactivity of aliphatic isocyanates, it is not practical to use them in the preparation of flexible or rigid foams, which are the main commercial applications for polyurethane chemistry. 

Recently a solvent-free dual-cure laminating adhesive based on the combination of polyurethane chemistry and EB cure was developed that exhibits improved properties compared to laminates prepared by either method alone. ... 

In addition to providing the properties of polyurethane chemistry, the authors reported that HNIPUs also exhibit the chemical resistance of epoxy binders. Potential uses of HNIPUs include commercial application in paints, varnishes, adhesives, caulking compounds, flooring/industrial coatings, foams, and composite materials. 

Our approach to the chemistry of the polyurethanes has no such limitations, and we use it to some advantage. While we take advantage of the physical properties of PURs, our focus is on what happens to a fluid (gas or liquid) when it passes through or otherwise comes in contact with a polyurethane chemistry. It has been part of the polyurethane tradition to consider the material inert. By removing the traditional restraints of conventional raw materials and a limited range of end uses, we allow the chemistry to affect the fluid or components of the fluid. 

Saunders, J., Frisch. K.. Polyurethanes Chemistry and Technology, Parts I, page 5, Interscience Publishers NY. 1967. 

While this book covers the full range of polyurethane chemistries to one degree or another, our perspective has been on the chemical nature of the molecule. Unlike most polyurethane chemists, we have worked almost exclusively on hydrophilic polyurethanes. This specialty grade of polymer (which we will describe at length) is valued for its chemical properties (ability to absorb water, for instance) almost to the exclusion of its physical properties. 

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