Abstract: An electromagnetically absorbing composition and a manufacturing method thereof are provided. The manufacturing method includes steps of: a) 40 wt %-80 wt % of a fluid resin and 20 wt %-60 wt % of coffee grounds; b) mixing the fluid resin and the coffee grounds into homogeneous slurry through a mixing process; c) placing the slurry into a mold assembly; d) after curing and cooling, removing from the mold assembly the composition of a thickness of 0.5 mm-5.0 mm, with a reflection loss above 10 dB from 2 to 18 GHz.

Abstract: An electromagnetically absorbing composition and a manufacturing method thereof are provided. The manufacturing method includes steps of: a) 40 wt %-80 wt % of a fluid resin and 20 wt %-60 wt % of coffee grounds; b) mixing the fluid resin and the coffee grounds into homogeneous slurry through a mixing process; c) placing the slurry into a mold assembly; d) after curing and cooling, removing from the mold assembly the composition of a thickness of 0.5 mm-5.0 mm, with a reflection loss above 10 dB from 2 to 18 GHz.

Abstract: A catalyst for esterification and polyesterification is proposed. The catalyst is an iron acetylacetonate complex having a formula of Fe(RCOCH2COR)3, where R is methyl or a substituent other than methyl. A method for making an esterified product or a polyesterified product by using the iron acetylacetonate complex through esterification and polyesterification is also disclosed so as to improve the existing processes where hydrochloric acid or sulfuric acid used as the catalyst causes yellowed products, danger operation and environmental pollution.