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Reported herein is a continuous one-step melt extrusion approach for highdensity polyethylene (HDPE) vitrimers. A grafting agent and a coagent were used to produce high-performing vitrimers. Maleic anhydride (MA) served as a reactive agent to facilitate crosslinking, while dimethyl maleate (DM) acted as a grafting enhancer by reducing the surface energy of HDPE grafted with MA. For comparison, MA alone was also tested as a grafting agent. The vitrimers obtained displayed superior mechanical properties compared with HDPE. The storage modulus, as well as crystallinity, were determined for the HDPE vitrimers. These vitrimers are reprocessable, thus supporting recycling efforts despite their crosslinked nature, owing to very fast relaxation due to low activation energy for the transesterification reaction. Consequently, these vitrimers are not only recyclable but also exhibit enhanced thermal and mechanical properties compared with conventional HDPE. 

In this presenation, I will discuss a continuous melt extrusion approach in one go for the synthesis of high-density polyethylene (HDPE)-based vitrimers. Vitrimers are produced with two grafting two agents, with maleic anhydride serving as a reactive agent to facilitate crosslinking while dimethyl maleate helped to lower the surface energy for better maleation. This improved property is reflected in the 2 wt% system, where the crosslinking density had doubled and enhanced the stiffness of the material. Overall, these vitrimers had enhanced tensile stress at break and impact resistance as compared to that of HDPE, while yet having a similar melting temperature and tensile stress at yield. The crystallinity of the polymers decreased and thus these materials may be strong candidates for 3D printing applications as they are less susceptible to the warping issues that are encountered with unmodifed HDPE. These vitrimers are reprocessable with torque pf ~ 30 Nm, and thus they can be readily recycled despite the crosslinking of layers which imparts them with better mechanical and thermal properties. 

Abstract Reported herein is a continuous one‐step melt extrusion approach for high‐density polyethylene (HDPE) vitrimers. A grafting agent and a coagent were used to produce high‐performing vitrimers. Maleic anhydride (MA) served as a reactive agent to facilitate crosslinking, while dimethyl maleate (DM) acted as a grafting enhancer by reducing the surface energy of HDPE grafted with MA. For comparison, MA alone was also tested as a grafting agent. The vitrimers obtained displayed superior mechanical properties compared with HDPE. The storage modulus, as well as crystallinity, were determined for the HDPE vitrimers. These vitrimers are reprocessable, thus supporting recycling efforts despite their crosslinked nature, owing to very fast relaxation due to low activation energy for the transesterification reaction. Consequently, these vitrimers are not only recyclable but also exhibit enhanced thermal and mechanical properties compared with conventional HDPE. 

Abstract Demand for water‐ and oil‐repellent‐coated paper as an alternative to plastics is growing, but the challenge is that coated paper lacks concurrent recyclability and biodegradability. Reported herein is a novel carboxylic acid‐functionalized poly(butylene adipate‐co‐terephthalate) (CPBAT) copolymer investigated for recyclable and repulpable water‐borne paper coatings. The CPBAT synthesized here is characterized by spectroscopic methods. Paper coated with waterborne CPBAT exhibited excellent water, oil, moisture, and gas barrier properties suitable for packaging applications. The recyclability and repulpability of the CPBAT‐coated paper are successfully validated via certified TAPPI methods. This work demonstrates the first successful preparation of coated paper that is per‐ and polyfluoroalkyl substances (PFAS)‐free, recyclable, and biodegradable, with significant benefits for the environment and human health.