Search

A lignin-based PU coating was prepared for paper-based green packaging. Two representative diisocyanate were used to prepare the coatings. Due to the rigid aromatic, the physical properties of the TDI system reached the maximum below the lignin content of 40%. The HDI that contains flexible aliphatic chains alleviated the brittleness of coating, and it showed physical advantages when the lignin content was more than 50%. Owing to the high lignin content, the coating presented enhanced thermal stability. After coated with the lignin-based PU coatings, the dry tensile strength of coated paper was improved by 126%. Amazingly, the wet strength was increased from 0.31 to 12.6 MPa with an improvement nearly 40 times. Based on the coordination of lignin, Ag+ was introduced into the PU matrix, which imparted the coating with excellent antibacterial ability. The colony forming units of E. coli and S. aureus were both less than 1. However, no inhibition halo was observed, which indicated that the Ag was firmly anchored on the coating and the antibacterial ability is only available when the bacterial contact the coating surface. The lignin-based PU coating with favorable sustainability and properties shows great potential in paper-based green packaging fields. The prepared PU coating with high lignin content and firmly anchored Ag+ exhibits outstanding physical properties, thermal stability, and antibacterial property, which makes it an ideal candidate to be used in paper-based green packaging. [Display omitted] [ABSTRACT FROM AUTHOR]

An anisotropic aerogel hot-extrusion strategy is designed to convert polyimide aerogels into aerogel-based paper. The multilayer interconnected aerogel-based paper exhibits excellent thermal stability and mechanical properties, and the mechanical properties remain great at high temperatures. This aerogel-based paper has huge application potential in the aerospace field. [Display omitted] • Multi-layer interconnected aerogel based paper was successfully prepared by anisotropic aerogel hot extrusion strategy. • Aerogel-based papers exhibit excellent thermal stability and stable mechanical properties (PI-1: 216.28 MPa at 25 °C). • The tensile strength of PI-1 was 3 times that of commercial polyimide paper and 24 times that of aramid paper at 400 °C. • Aerogel-based paper maintain stable mechanical property after 5000 cycles. The continuous improvement of papermaking technology has attracted widespread attention. However, the prevention of high-temperature decomposition and a subsequent decline in mechanical strength is still a significant challenge with current papermaking technology. Herein, a newly developed multilayer interconnected polyimide aerogel-based paper was successfully prepared via an anisotropic aerogel hot-extrusion strategy. Precursor solutions of highly rigid benzimidazole units containing intermolecular hydrogen bonds and linear rod-like benzimide units were first prepared. Anisotropic precursor polyimide (PAAS) aerogels with a thickness of 3 mm were then manufactured by unidirectional freeze-drying. Then, aerogel-based papers with a thickness of 40 μm and microstructure multilayer interconnected properties were obtained by a hot extrusion strategy and a thermal imidization process. This polyimide structural paper exhibited excellent thermal and mechanical properties. Through the design of micro and macro structures, the tensile strength of the aerogel-based paper was much higher than that of commercial paper at both room temperature and 400 ℃. This aerogel-based paper also exhibited high-temperature cycle stability, high flexibility, and good stretchable bending properties. The successful preparation of this aerogel-based paper demonstrates the feasibility of the hot extrusion strategy. This work provides a new papermaking technology method and broadens the application field of paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel dimer acid-based waterborne polyurethanes (DWPUs) were designed and prepared. • DWPUs were first used as multifunctional coatings for paper substrates. • Papers coated by DWPUs exhibited excellent water- and oil-resistances. • Alkyl and uniform membrane of DWPUs are critical to improve papers' properties. Paper derived from lignocellulose has great advantages over plastics as packaging material, nevertheless, the poor water- and oil-resistances of paper-derived products limited their application in high-end field. Herein, novel dimer acid-based waterborne polyurethanes (DWPUs) with different content of dimer acid-based polyester polyol (DG) were prepared and used as water- and oil-resistant coating for paper substrate. The effects of DG contents on water- and oil-resistances, mechanical properties and thermal stability of DWPUs coated papers were systematically investigated. When the content of DG reached up to 7 wt% (based on polyester glycol), the paper coated by DWPU exhibited 88.06% decrease in Cobb 60 value, 8.7 times increase in kit rating compared with uncoated paper. Meanwhile, DWPUs coated papers showed good mechanical properties and thermal stability. These improvements are attributed to the flexible long-alkyl chain, and six-ring structure of DWPUs as well as the continuous and homogeneous DWPU-derived membrane on the surface of paper. This study provides a new framework for the preparation of high quality, multifunctional, environmentally friendly water- and oil-resistant coatings for paper substrates. [ABSTRACT FROM AUTHOR]