Rose Alyssa M, McLauchlin Andrew R, Wilson George, McDonald Tom O, Blanc Frédéric
Department of Chemistry, Crown Street, University of Liverpool L69 7ZD UK
Henry Royce Institute, Department of Materials and Department of Chemistry, University of Manchester M13 9PL UK.
Polym Chem. 2024 Mar 6;15(15):1511-1521. doi: 10.1039/d4py00010b. eCollection 2024 Apr 16.
High-density poly(ethylene) (HDPE) is an important class of polymer used extensively in plastic packaging as well as numerous other applications. HDPE has a structure that consists of crystalline (monoclinic and orthorhombic) and amorphous domains. Here, we exploit a range of approaches focusing on magic angle spinning (MAS) nuclear magnetic resonance (NMR) aimed at comparing the effect of the HDPE sample formulation (cutting, shaving and cryomilling), from the commercially available manufactured pellets, into these domains and their quantification. C cross polarisation (CP) experiments reveal that these formulated HDPEs are qualitatively different and C CP build-up curves and C direct excitation experiments enable the content of each domain to be obtained, pointing to an increase of monoclinic domain at the expense of the orthorhombic one upon increased processing. The crystallinity contents obtained compared, in some cases, favourably with those obtained by differential scanning calorimetry (DSC) data. These results provide evidence that the manner of preparation of HDPE pellets modifies the concentration of the various domains and suggest that care should be taken during processing.
高密度聚乙烯（HDPE）是一类重要的聚合物，广泛应用于塑料包装以及许多其他领域。HDPE具有由结晶（单斜晶和正交晶）和非晶域组成的结构。在此，我们采用了一系列以魔角旋转（MAS）核磁共振（NMR）为重点的方法，旨在比较HDPE样品配方（切割、刨削和低温研磨）对从市售制造颗粒形成这些域及其定量的影响。碳交叉极化（CP）实验表明，这些配方的HDPE在性质上有所不同，并且碳CP累积曲线和碳直接激发实验能够获得每个域的含量，表明随着加工增加，单斜晶域增加，正交晶域减少。在某些情况下，所获得的结晶度含量与通过差示扫描量热法（DSC）数据获得的结果相比具有优势。这些结果证明了HDPE颗粒的制备方式会改变各个域的浓度，并表明在加工过程中应谨慎操作。
