Hemp as Bio Fiber Material for Paper Applications: Fiber Processing

Abstract

Hemp known as Cannabis Sativa, has been cultivated as an agricultural crop centuries before the Common Area and has been used extensively during colonial times as a cash crop in Europe and America. During industrialization the agricultural production of hemp declined and came to an end in the U.S. with the 1937 Marijuana Tax Act. In the 1990s Hemp production was reauthorized throughout the European Union and in the U.S. in 2014 with the Farm Bill. Today hemp has been rediscovered as a new sustainable environmentally friendly fiber source for many products including paper making. During this research project hemp fiber for paper manufacturing was produced from agricultural waste products with a KRK pressurized refiner at 60°C and processing the hemp stems of 0.75-inch (19.0 mm) with a refiner plates gap of 0.5 mm at 1800 rpm. To eliminate the hemp fibers stringing tendency fibers are screened using a Valley type screen with a 150 µm screen plate and a screen box with a 150 mesh (105 µm) for collecting the fibers. Final refining to adjust the dewatering properties of the hemp fibers was done with a Valley beater type machine. The manufactured handsheets had a basis weight of 71.31 g/m² and a caliper of 255.6 μm. Mechanical properties measured yielded for the Short Compression Strength Index, Burst Index and Tensile Index 0.45 kNm/g, 0.58 kPa*m³/g and 3.61 mNm³/g respectively. Elongation was measured at 3.46% and a Tensile Energy Adsorption at 61.20 kJ/m². Air permeance 108.00 cfm and smoothness was at 3070.00 cfm for the top surface and 3002.00 cfm for the bottom surface. Air resistance was measured at 62.80 seconds. Optical properties of the handsheets were measured for Color at a value of 77.34 for the L*, 0.08 for a*, and 17.57 for the b* properties. Whiteness was at -63.17% and brightness at 28.73%. Applying hemp at present time as a valid fiber source for paper production requires more research and development on laboratory and pilot scale installations to determine the full potential of the hemp fiber material and its industrial application potential.