Conventional poly(ethylene terephthalate) (PET) and polycarbonate (PC) blends exhibit insufficient heat resistance, restricting their use in demanding applications such as new energy vehicles and portable consumer electronics. Poly(ethylene 2,6-naphthalate) (PEN) offers superior thermal stability, strength and chemical resistance, making PEN/PC blends promising alternatives. In this study, we investigated the relationships between the composition, structure and properties of PEN/PC blends through non-catalyzed melt blending. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectra (¹H NMR) confirm transesterification between PEN and PC, with the extent of exchange (X) increasing with PC content. Non-isothermal differential scanning calorimetry (DSC) and X-ray diffraction (XRD) show that moderate PC content promotes crystallization, while high PC content suppresses it. Thermogravimetric analysis (TGA) shows enhanced thermal stability in PEN-rich blends. Compared to PET/PC, PEN/PC blends maintain similar tensile strength but exhibit 53% higher elongation and 1–2.5% lower density. This study demonstrates the potential of PEN/PC blends for high-performance, thin-walled applications in the new energy vehicle and electronics industries.

This is an editorial article. It has no abstract.

This is an editorial article. It has no abstract.

This study examines the combined effects of molecular modalities (unimodal, bimodal, trimodal) and biaxial stretching modes (sequential and simultaneous) on the yielding, stiffness, and necking behaviour of stretched high-density polyethylene (HDPE). Yield strength and stiffness were examined in relation to oriented material produced by drawing at linear strain rates 5.4·10^–3, 2.2·10^–2, and 8.6·10^–2 s^–1 under both stretching modes. Simultaneous stretching outperformed sequential stretching, with yield strength increasing with draw rate. Unimodal HDPE showed higher yield strength and stiffness than bimodal and trimodal grades, while trimodal HDPE had the lowest necking tendency from greater flexibility and uniformity. The highest necking tendency was observed in unimodal HDPE in strain localization analysis using the maximum strain/average strain ratio, while trimodal HDPE deformed more uniformly due to improved molecular weight distribution and strain hardening. Increasing the draw rate reduced strain localization, improving mechanical performance. Insights for optimising polyethylene materials in industry are provided by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) spectroscopy, and mechanical analyses, establishing the correlation between HDPE structure, processing, and properties.

The use of rheo-optical techniques to evaluate crystallization in polymer processing has many advantages; however, it is still little seen. Shear-induced crystallization of polyamide 6 (PA6) was here proposed and studied with these techniques. Mixtures of PA6 in a polypropylene (PP) matrix were also studied. A polarized light optical microscope, with an AxioVision system attached to its top allowing the acquisition of photos at any time during the measurement and a Linkam hot stage device to control shear and temperature, was modified to receive a specially built quantitative rheo-optical detector. Temperature was variable, characterizing non-isothermal analysis. The experiments consisted of varying the shear rate on the polymer system while collecting the respective cross-polarized transmitted light intensity response by LabVIEW software. Shear rates of 1, 10, 100 and 180 s^–1 were applied to all samples. Differential scanning calorimetry (DSC) analysis was also performed to predict crystallization behavior. PA6’s crystallization increased with the increase of shear rate; however, for the PP/PA6 mixtures under the highest rates, crystallization intensity falls from a specific temperature in which the polymer’s viscosity is not enough to maintain the structural integrity. Data related to PP/PA6 mixtures showed that shear increases crystallization if the polymer has time to organize itself.