The paper presents some examples of the surface gradient, generally existing in polymer materials and concerning both : their chemical composition and physical structure.

Experimental data on the surface segregation in polymer blends are focused on the elastomer/plastomer systems. Plastomer components (polyethylenes) varied according to molecular weight and its distribution, degree of  crystallization  or macromolecular branching. Elastomer component-ethylene-propylene-diene rubber (EPDM) varied according to its macromolecular structure.  An influence of physical characteristics of the both: the elastomer matrix and the  plastomer modifier on morphology of their blends and the surface segregation of the latter, were studied. Some practical aspects of the phenomenon are demonstrated and discussed form the point of view of possibility to increase ageing resistance of styrene butadiene rubber (SBR).

Modification of supermolecular structure of high density polyethylene  (HDPE) produced by the so-called “rolling with side constraints” is presented  and micro mechanical and micro-tribological data, confirming changes to the material provided. The results presented point on influence of material history and processing on its exploitation characteristics , what has not been normalized so far.

Another example of modification concerns the surface gradient of crosslink density and structure, being produced in rubber subjected to conventional vulcanisaton in a steel mould. Influence of temperature gradient, polarity of the mould surface and a migration of low molecular weight components of a crosslinking system are discussed. Susceptibility of various crosslinking systems to creation of the surface gradient in vulcanisates of cis-, 4-polyisoprene (IR) is compared. A profile or hardness was also detected for photocured polyester resin (PES) The effect, which was correlated with a degree of curing, is opposite to that observed for IR samples.

Mechanisms behind the changes detected have been proposed and discussed, based on FTIR, DSC and XPS spectroscopies, contact angle, micro-indentation and micro-friction measurements, AFM and SEM studies. Composition or structural profile of the surface layer have been described in terms of their possible influence on exploitation characteristics of polymer materials, represented e.g. by such parameters as ageing resistance, polarity, mechanical moduli, hardness friction and wear.