i u03c9 is the intensity of the raman spectrum at frequency u03c9 l arbitrary units plots of the ordered sequence length distribution function f l derived from the raman lam 1 spectra for three polyethylene samples to be described below are shown in fig2 a 2 b and 2 c preferably a polyethylene yarn of the invention is comprised of filaments for which the peak value of f l is at a straight chain segment length l of at least 45 nanometers as determined at 23 u00b0 c from the low frequency raman band associated with the longitudinal acoustic mode lam 1 the peak value of f l preferably is at a straight chain segment length l of at least 50 nanometers more preferably at least 55 nanometers and most preferably 50 u2013 150 nanometers it is well known that dsc measurements of uhmwpe are subject to systematic errors cause by thermal lags and inefficient heat transfer to overcome the potential effect of such problems for the purposes of the invention the dsc measurements are carried out in the following manner a filament segment of about 0 03 mg mass is cut into pieces of about 5 mm length the cut pieces are arranged in parallel array and wrapped in a thin wood 39 s metal foil and placed in an open sample pan dsc measurements of such samples are made for at least three different heating rates at or below 2 u00b0 k min and the resulting measurements of the peak temperature of the first polyethylene melting endotherm are extrapolated to a heating rate of 0 u00b0 k min a u201c parameter of intrachain cooperativity of the melting.