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The Impact of Enzyme Application on Strength Properties of Recycled Corrugating Board Papers

Recycling cardboard production increases continuously in Turkey. The recycled fibers are used for corrugated medium in corrugated board in years instead of primary fibers. High quality products must be obtained from low quality raw materials in order to meet the growing demands for raw materials in our country, as is all over the world, as well as to fulfill the customers demand on better quality raw materials.

As well known, the physical strength properties of fiber decrease with recycling. The aim of this study is to investigate the positive impact of using commercial cellulase enzymes on the physical strength properties of corrugated medium. The long fiber fraction is the most appropriate application point of cellulase enzyme. Therefore, the paper pulp used in this research has been obtained at fractionation screens level of Modern Karton Paper Mill Tekirdağ. The retention aid additive used in experiments have been obtained from the same mill. The enzymes, Roglyr Bio 1537, Maximyze 2520 and Benstone / Bensoft Plus have been obtained from Mavi Jeans mill, Buckman Laboratory, and Bengü Kimya respectively.

Before proceeding the beating experiment for the pulp treated with enzyme, the optimum amount of retention aid to be used has been determined. Similarly, the optimum conditions of the enzyme treatments have been determined separately for each enzyme. After the enzymatic treatment, the long fiber fraction has been beaten with 150 and 250 kWh/t specific beating energy.

Handmade papers have been made by blending 70 % short fibers and 30 % long fibers and retention additive according to Rapid Köthen method. Enzyme activity has been determined according to Baily Method (1989), fiber swellability in isopropyl alcohol has been made according to Yiannos (1965).

In laboratory papers that obtained, basis weight, thickness, density, moisture content, short compression strength, concora medium strength, corrugated crush strength, tensile strength and bursting strength have been determined. Physical strength tests have been carried out under the standard conditions of 23 °C temperature and 50 % relative humidity.

The obtained test results have indicated that the enzymes, Roglyr Bio 1537, Maximyze 2520, Benstone and Bensoft plus, have positive effects on the physical properties of the corrugated medium. The best treatment which gives the significant increase in physical strength is the following procedure: Maximyze 2520 enzyme with 0.2 % dose and 30 minutes and followed by beating with 250 kWh/t specific energy. Maximyze 2520 increases SCT index, CCT index, CMT₀ index, CMT₃₀ index, bursting index, tensile index and elasticity module. If treated pulp is beaten with 250 kWh/t specific beating energy, these increases are 20.8 %, 12 %, 30 %, 16.43 %, 16 % , 14 % and 10 % respectively.