Wide-angle X-ray scattering of random metallocene-ethylene copolymers withdifferent types and concentration of comonomer

The WAXS diffractograms of random ethylene copolymers were analyzed for sam ples rapidly quenched, annealed, or isothermally crystallized. Comonomers s tudied include 1-decene, 1-hexene, 4-methylpentene, norbornene, and dicyclo pentadiene in a range of concentration that includes semicrystalline and am orphous copolymers at ambient temperature. Only crystalline reflections cor responding to the orthorhombic structure were identified in these copolymer s. Focus is given to analyze the contribution of the concentration of comon omer as well as the comonomer type in the angular position of the amorphous halo. For samples quenched to 23 degreesC the peak value scales linearly a nd in inverse proportion with the concentration of comonomer in the copolym er reflecting the increase of the average backbone carboncarbon intermolecu lar distance associated with the interlamellar region. With increasing temp erature, a progressive melting of crystallites changes the comonomer compos ition of the amorphous region and leads to a temperature coefficient of the peak position of the halo that is a function of the concentration of comon omer in the chain.