This work focuses on the physico-chemical analysis of a silane-grafted polyethylene stabilised with an excess of Irganox 1076® as phenolic antioxidant before and after surface cleaning using acetone as a polar solvent. The non-uniform distribution of Irganox 1076® in this polymer matrix was investigated with several complementary characterisation techniques including FTIR spectroscopy (in both ATR and transmission modes), DSC analysis, OIT measurements, and optical microscopy. Initially, the presence of antioxidant crystals at the polymer surface was confirmed. Surface cleaning showed to be effective to remove all antioxidant crystals present at the polymer surface, as confirmed by FTIR spectroscopy in ATR mode, DSC analysis, and optical microscopy. The remaining concentration of antioxidant in the polymer matrix was estimated by FTIR spectroscopy in transmission mode and OIT measurements using preliminary established OIT and FTIR calibration curves. It was found that this concentration corresponds to the solubility threshold at 25 °C of about 0.9 wt% (i.e. ≈ 1.6 × 10⁻² mol.L⁻¹) determined in a previous publication. Hence, all experimental results suggest that antioxidant crystals would only be present at the polymer surface, and not within the polymer bulk, which finally allows proposing a simplified microstructural model for this heterogeneously stabilised polymer. It was also found that antioxidant crystals efficiently participate to the stabilisation process of the polymer matrix during oxidation, thus significantly increasing the OIT. This important result might constitute an interesting stabilisation route for industry, still unexplored to date, obviously depending on the intended final application of the polymer.

这项工作的重点是在使用丙酮作为极性溶剂进行表面清洁之前和之后，用过量的Irganox1076®作为酚类抗氧化剂稳定化的硅烷接枝聚乙烯的物理化学分析。用几种互补的表征技术研究了Irganox1076®在该聚合物基质中的不均匀分布，这些技术包括FTIR光谱（在ATR和透射模式下），DSC分析，OIT测量和光学显微镜。最初，确认在聚合物表面存在抗氧化剂晶体。经ATR模式的FTIR光谱，DSC分析和光学显微镜证实，表面清洁可有效去除聚合物表面存在的所有抗氧化剂晶体。聚合物基体中抗氧化剂的剩余浓度通过透射光谱的FTIR光谱和使用初步建立的OIT和FTIR校准曲线的OIT测量进行估算。发现该浓度对应于25°C时约0.9 wt％（即≈1.6×10）的溶解度阈值。在先前出版物中确定的^-2 mol.L ^-1）。因此，所有实验结果表明，抗氧化剂晶体仅存在于聚合物表面，而不存在于聚合物本体中，这最终允许为这种非均相稳定的聚合物提出简化的微观结构模型。还发现抗氧化剂晶体在氧化过程中有效地参与了聚合物基质的稳定化过程，从而显着增加了OIT。该重要结果可能构成工业上令人感兴趣的稳定化途径，至今仍未开发，显然取决于聚合物的最终用途。