During processing of molten polymers the thermal and mechanical stress acting on the melt in presence of oxygen can induce degradation with a modification of the chemical structure of the polymers. This picture can become even more relevant if the melt is a multiphasic polymer system. In this last case, the effects of the degradation depend also on the presence of a second phase and on the interactions between the two phases.

In this work, the effect of the processing conditions, temperature and time, have been considered in order to investigate the thermo-mechanical and thermo-oxidative degradation of nanocomposites made by polypropylene and different contents of graphene nanoplatelets. Graphene nanoplatelets improve the stability of the polymer matrix and the sample with the lower content of nanofiller shows a lower level of degradation. The better resistance of the filled samples has been interpreted with a barrier effect to the oxygen of the nanofiller that hinders the transport of oxygen necessary for the oxidation of the polypropylene. The unexpected effect of the concentration of graphene nanoplatelets has been correlated with the agglomeration of the nanoplatelets that reduces the surface area of the filler and then the barrier effect to the oxygen.

在熔融聚合物的加工过程中，在氧气存在下作用于熔体的热应力和机械应力会导致降解，同时改变聚合物的化学结构。如果熔体是多相聚合物体系，那么这张图片可能会变得更加相关。在后一种情况下，降解的影响还取决于第二相的存在以及这两个相之间的相互作用。

在这项工作中，考虑了加工条件，温度和时间的影响，以便研究聚丙烯制得的纳米复合材料以及不同含量的石墨烯纳米片的热机械降解和热氧化降解。石墨烯纳米片提高了聚合物基质的稳定性，而纳米填料含量较低的样品则降解程度较低。已经解释了填充样品的更好的电阻对纳米填料的氧气具有阻挡作用，这阻碍了聚丙烯氧化所需的氧气的运输。石墨烯纳米片的浓度的出乎意料的影响已经与纳米片的附聚相关，该附聚减少了填料的表面积，然后降低了对氧的阻挡作用。