nuclei in the sample methods for ensuring this proportionality are known in the art and involve allowance for sufficient time for relaxation after a pulse the use of gated decoupling techniques relaxation agents and the like the relative intensity of a peak or group of peaks is obtained in practice from its computer generated integral after obtaining the spectrum and integrating the peaks those peaks associated with the comonomer are assigned this assignment can be made by reference to known spectra or literature or by synthesis and analysis of model compounds or by the use of isotopically labeled comonomer the mole comonomer can be determined by the ratio of the integrals corresponding to the number of moles of comonomer to the integrals corresponding to the number of moles of all of the monomers in the interpolymer as described in randall for example the reactivity ratios of single site catalysts in general are obtained by known methods for example as described in u201c linear method for determining monomer reactivity ratios in copolymerization u201d m fineman and s d ross j polymer science 5 259 1950 or u201c copolymerization u201d f r mayo and c walling chem rev 46 191 1950 incorporated herein in their entirety by reference for example to determine reactivity ratios the most widely used copolymerization model is based on the following equations where m i refers to a monomer molecule which is arbitrarily designated as u201c i u201d.