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Abstract
The kinetics of graft copolymerization reaction of acrylonitrile monomer onto cellulosic paper sheet in the presence of comonomer {Styrene or Acrylic acid or Itaconic acid } 1:1 molar ratio are investigated in dimethyl formamide using benzoyl peroxide (Bz2O2) as free radical initiator under nitrogen atmosphere at different temperatures.
The effect of initiator concentration, monomer concentration and temperature on the graft yield are studied. The graft yield-time curves are plotted and the data are tabulated and graphically represented. from which, the initial reaction rates are calculated and also given in tables.
The orders of the graft copolymerization reactions with respect to the initiator concentration, monomer concentration are determined from the double logarithmic relationship between initial rate (Ri) and the concentration of the investigated parameter.
The effect of temperature (60,65 and 70 °C) on the graft copolymerization rate of each monomer bair is investigated for the paper sheet activated by dipping in ferrous ammonium sulphate for 20 minutes or in H2O2 for 10 minutes. Both of the initial and overall reaction rates are calculated. from the relationship between Log Ri and 1/T using Arrhenius equation, the apparent activation energy (Ea) for each graft copolymerization system is calculated. The thermodynamic activation parameters (ΔH* and ΔS*) are calculated for each system using Eyring equation.
from the above kinetic studies, the reaction rate law for each graft copolymerization system are given.
Reactivity ratio of the binary mixture of monomers calculated according to Finemane - Rớss method and the copolymers structure are suggested . The graft copolymerization mechanism onto a cellulosic paper sheet by different investigated binary mixture is also given .
The polymers produced in solution after 120 minutes for each investigated parameter are isolated and purified , and their viscosity average molecular weights are determined at 30 °C in butanone for AN-S copolymer and in DMF in case of AN-AA , AN-IA copolymer . Also, the molecular weight of copolymers separated from solution at optimum condition were determined by (GPC ).
The grafted paper sheet is isolated and the copolymer is precipitated by suitable non solvent . The paper was characterized by IR spectroscopy, x-ray diffraction, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), chemical & mechanical resistance measurements .
Some physical properties as dimensional stability ,water and moisture resistance and biodegradability properties according to soil burial degradation test were investigated for paper sheet before and after grafting .
The effectiveness of graft copolymerization as a preservation treatments for document paper was studied with estimation of the permanence of grafted paper sheets by detecting color change , mechanical properties after thermal accelerated aging , in which the paper sheet samples before and after grafting were tested for thermal accelerated aging according to ASTM test method D6819-02 (Standard Test Method for Accelerated Temperature Aging of Printing and Writing Paper by Dry Oven Exposure Apparatus),determination of their pH with cold extraction method was according to (ISO 6588). The color change by indication of the color differences (∆E), Yellowness index (YI) as proposed by the ASTM (YI) was determined spectrophotometry with a standard illumination D65 in which the color parameters corresponding to the uniform color space as suggested in the CIEL a b 1931{ international Commission Illumination ) and the tristimulus value colorimetry system (X, Y, Z ) were obtained directly from the spectrophotometer .
Also , graft copolymerization can be consider as a preservation treatments for erasable ink entries on paper in which the color strength ( K/S ) according to Kubelka–Munk equation for blue erasable ink entries of pure ungrafted, grafted paper sheet samples before and after mechanical erasure was determined spectrophotometry in the reflection mode at ( λ max ═ 585 nm ) and the color change by indication of ( b ) coordinate for blue erasable ink entries on paper after thermal accelerated aging was determined. .
The graft copolymerization reaction onto paper sheet enhances the physical, chemical and mechanical properties ,it also enhances the biodegradability resistance of the paper sheet and the order of improvement in each case is mentioned . The graft copolymerization ,improves the permanence of the paper .