| Abstract: | Polyurethanes and polyureas containing long methylene chain units have been prepared from the following six series of monomer combinations; aliphatic diisocyanates with aliphatic glycols or diamines, methylene bis(4-phenyl isocyanate) with aliphatic glycols or diamines, and p-xylylene diisocyanate with aliphatic glycols or diamines. A good linear relationship was noted between the polymer melting points of each series against the concentration of functional groups. Both polyurethanes and polyureas from p-xylylene diisocyanate showed higher melting points than those from methylene bis(4-phenyl isocyanate) with corresponding aliphatic monomers. The relations between the melting points of these polymers with long methylene chains, including polyamides which were previously reported, and the chain components were discussed. The higher melting points of polymers containing p-xylylene group are attributed to the high rigidity of this group. |
