Preparation of zinc oxide loaded polyurethane/polysulfone composite nanofiber membrane and study on its waterproof and moisture permeability properties

Polylactic Acid/Calcium Stearate Hydrocharging Melt-Blown Nonwoven Fabrics for Respirator Applications

Non-biodegradable polypropylene, which poses a serious threat to the environment, is the most utilized material in air filtration systems. Moreover, under conditions of high temperature and high humidity, the electrostatic charge in melt-blown nonwoven fabrics treated with traditional corona electrets will quickly dissipate. Here, biodegradable polylactic acid, calcium stearate, and an innovative hydrocharging technique are reported to develop environmentally friendly polylactic acid/calcium stearate hydrocharging melt-blown nonwoven fabrics with high charge stability. Compared with polylactic acid melt-blown nonwoven fabrics, the crystallization structure and charge storage of polylactic acid/calcium stearate melt-blown nonwoven fabrics have been greatly improved due to the presence of calcium stearate. In PM0.3, it exhibited a high filtration efficiency (96.78%), a low pressure drop (65.20 Pa), and a good quality factor (0.053 Pa-1), which can meet the N95 respirator standard. Furthermore, it is worth mentioning that the filtration performance remained at a high level (>95.00%) after 2 months. Importantly, based on the test and analysis of surface electrostatic potential, crystallization, and charge storage and distribution, we proposed plausible charge generation and stable storage mechanisms. It demonstrated more potential for electret air filtration and smart respirators as the further possible step of research in the field.

Enhancing the Mechanical Properties of Waterborne Polyurethane Paint by Graphene Oxide for Wood Products

Water-based polyurethane paint is widely used for wood furniture by virtue of the eco-friendliness, rich gloss, and flexible tailorability of its mechanical properties. However, its low solution (water or alcohol) resistance and poor hardness and wear resistance limit its application. The emerging graphene oxide has a high specific surface area and abundant functional groups with excellent mechanical properties, endowing it with great potential to modify waterborne polyurethane as a nanofiller. In this study, graphene oxide prepared by Hummers' method is introduced in the chemosynthetic waterborne polyurethane through physical blending. The testing results demonstrate that the appropriate usage of graphene oxide at 0.1 wt% could obviously improve water absorption resistance and alcohol resistance, significantly enhancing the mechanical properties of waterborne polyurethane paint. The corresponding tensile strength, abrasion resistance, and pendulum hardness of the graphene oxide-modified paint film increase by 62.23%, 14.76%, and 12.7%, respectively, compared with the pristine paint film. Meanwhile, the composite paint film containing graphene oxide possesses superiority, including gloss, abrasion resistance, pendulum hardness, and tensile strength in contrast with the commercial paint. The use of graphene oxide to enhance the waterborne polyurethane possesses strong operability and practical value, and could provide useful reference for the modification of waterborne wood paint.

Fabrication of Durable Superhydrophobic Surface for Versatile Oil/Water Separation Based on HDTMS Modified PPy/ZnO

Superhydrophobic materials have been widely applied in rapid removal and collection of oils from oil/water mixtures for increasing damage to environment and human beings caused by oil-contaminated wastewater and oil spills. Herein, superhydrophobic materials were fabricated by a novel polypyrrole (PPy)/ZnO coating followed by hexadecyltrimethoxysilane (HDTMS) modification for versatile oil/water separation with high environmental and excellent reusability. The prepared superhydrophobic surfaces exhibited water contact angle (WCA) greater than 150° and SA less than 5°. The superhydrophobic fabric could be applied for separation of heavy oil or light oil/water mixtures and emulsions with the separation efficiencies above 98%. The coated fabric also realized highly efficient separation with harsh environmental solutions, such as acid, alkali, salt, and hot water. The superhydrophobic fabric still remained, even after 80 cycles of separation and 12 months of storage in air, proving excellent durability. These novel superhydrophobic materials have indicated great development potentials for oil/water separation in practical applications.