Studying banded spherulites in HDPE by electron microscopy

HDPE is a semi-crystalline thermoplastic polymer, with remarkable physical properties such as high chemical resistivity, high impact strength, and high modulus. Compared to the other semi-crystalline polymers, HDPE mostly possesses a high crystallinity, due to which, it exhibits a unique combination of mechanical and chemical resistance properties. In the present work, we have characterized the crystalline spherulites of neat and formulated HDPE compositions thoroughly characterized by different electron microscopy techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). One of the critical steps to obtaining well-resolved SEM images is the sample preparation that typically involves the etching process to elucidate the crystalline spherulites. Though such traditional methodology can effectively be used for neat HDPE, it leads to the creation of undesirable experimental artifacts when used to investigate formulated HDPE compositions. An alternate TEM-based method provides clear images without any artifacts, apart from being a direct and green method and taking relatively a lesser measurement time. •The paper summarizes a novel, simple and green method for imaging the spherulitic structures in HDPE.•While the lamellae are ubiquitous in the HDPE, they cannot differentiate between monomodal, bi-modal or multimodal HDPE.•In the TEM method, we are able to clearly elucidate the crystalline spherulites of neat and blended HPDE.•The TEM method avoids the use of acids for etching, heavy metal stains and takes less time.•This method can be used to study the effect (on crystalline morphology) of incorporating new additives, monomers or comonomers to HDPE.