Efficiency grafting

Two parameters such as percentage of grafting (%G) and grafting efficiency are usually determined as functions of different variables that influence graft copolymerization. Percent grafting is usually determined from the increase in weight of the backbone polymer after grafting after complete removal of the homopolymer. It is expressed as follows ... 

Grafting efficiency is determined from the total conversion of monomer into homopolymer and graft copolymer and is expressed as ... 

This is the same order of the solubility of the monomer in water. The increase in acrylonitrile concentration increases the percent grafting and grafting efficiency. 

There are a number of important factors that must be considered before applying gamma radiation-induced grafting. These factors include the radiation sensitivity of the polymer/monomer system, radiation dose and dose rate, type and concentration of inhibitor, type of solvent or diluent, and monomer concentration. The effect of such parameters on the grafting efficiency during mutual grafting is given below. 

The graft products are usually characterized by different methods. The first method is the calculation of graft parameters known as the grafting percentage (GP), grafting efficiency (GE), and weight conversion percentage (WC). These parameters can be calculated as follows ... 

Figure 1 Effect of monomer concentration on the total conversion percent and grafting efficiency. LR 30 I, acid concentration l%, initiator concentration 0. l%, grafting time 1 h, and reaction temperature 27°C — = total conversion (%) O—O = grafting efficiency (%).

The effect of acid concentration on the rate of grafting has been studied. It is clear that increasing the acid concentration from 0.5% to 1.0% increases not only the total monomer conversion percent from 60.1% to 61.5%, but also the grafting efficiency from 58.0% to 59.6%. This... 

Figure 4 Effect of monomer pulp ratio on grafting yield and grafting efficiency. = cotton linters O = wood pulp.

Table II. Synergistic Effect of Acid and DVB on the Grafting Efficiency of Styrene to Polyethylene Film Initiated by Ionising Radiation3...

Hydrogen abstraction from -SH is faster than from -OH groups. It is generally of interest to increase both the yield of polymer and the grafting efficiency and decrease the formation of homopolymer. This can be achieved by proper selection of the grafting conditions, e.g. monomer concentration, initiating system and its application, reaction temperature and time. 

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