Lamellar structure in melt crystallized low density polyethylene

The investigation of representative details in the lamellar microstructure of LDPE observed after controlled chlorosulfonation using both EM and SAXD is reported. For this purpose melt crystallized PE with two branch contents (=0.28 and 2.53 branches per 10²CH²) has been prepared using Kanig's technique over a range of temperatures and treatment times. During the first treatment hours the selective incorporation of electron-dense atoms at the lamellar surface produces a macroscopic weight increase, swelling of the sample and a concurrent decrease of the SAXS intensity. The main result, however, is that the thickness of the lamellar structure does not vary with treatment time. After long chlorosulfonation times a saturation of electron-dense atoms within the surface layer and a reduction in the lateral dimensions of the lamellae take place. Optimum conditions for revealing the representative morphology are such as to lead to a weight increase of 50% for PE with=0.28 of branches and only to an increase of 10% for material of branch content represented by an value of 2.53.On leave from Inst. Estructura de la Materia, Madrid-6. Spain