tailieunhanh - Average molecular weight and molecular weight distribution of the Vietnamese acacia pulps

The results show that these pulps have an average degree of polymerization (DP) in the range from 842 to 878. Additionally, the fraction of pulps with DP lower than 200 units is about 15 percent. The fractionations have the most percentage in the range from 600 to 1050 units. And, there are differences of MW and MWD of pulps from various brightness. | Vietnam Journal of Chemistry, International Edition, 55(2): 135-138, 2017 DOI: Average molecular weight and molecular weight distribution of the Vietnamese acacia pulps Doan Minh Khai1*, Phan Duc Nhan1, Trinh Dac Hoanh2 1 2 Military Technical Academy Institute of Military Science and Technology Received 4 August 2016; Accepted for publication 11 April 2017 Abstract The average molecular weight (MW) and the molecular weight distribution (MWD) of the several acacia pulps produced from wood of acacia tree in Vietnam were investigated. These chosen pulps had the various brightness were produced by Kraft method and bleaching. The MW was determined by viscosity of the pulps in copper-ammonium complex. The MWD was determined by fractional method which was carried out by dissolving pulp in the various phosphoric acids from to 83 % in weight. The results show that these pulps have an average degree of polymerization (DP) in the range from 842 to 878. Additionally, the fraction of pulps with DP lower than 200 units is about 15 percent. The fractionations have the most percentage in the range from 600 to 1050 units. And, there are differences of MW and MWD of pulps from various brightness. Keywords. Acacia pulp, average molecular weight, molecular weight distribution. 1. INTRODUCTION The MW and the MWD of cellulose are very important characteristics. These characteristics have an effect on physical properties, structure and reactivity of cellulose. The MW and MWD depend strongly on the type of wood, climate conditions, the method of production, etc. [1]. Thus, the various origin of cellulose causes the difference of MW and MWD. Additionally, cellulose difficultly dissolves in the common organic solvents and the water [1, 7]. In the case, there are not much solvent dissolving cellulose for analysis of MW and MWD. There are many researches for MW and MWD of various celluloses [1, 3-9]. Jose M. Perena [3] analyzed MWD of a purified .

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