The kinetics of the early stage of acid catalyzed heterogeneous hydrolysis of different samples of regenerated cellulose at low temperatures (0,20, and 30°C) was studied. The degradation of macromolecules was followed by determining the decrease of the degree of polymerization by measuring the viscosity of cellulose solutions in cadoxen. Interpretation of the experimental results using equations for first order reactions showed that in the studied experimental range first order kinetics cannot be applied. It was found that the rate constant decreases during the course of the hydrolysis at constant temperature. However, the experimental results could be explained by kinetic equations for heterogeneous processes with a solid and a liquid phase in the heterogeneous system. Kinetic parameters calculated from these equations point out that the process could be described as a diffusion controlled process. In 1 ---In 1 --= k . t ( A) ( A)
The kinetics of free radical polymerization in bulk of alkylphenyl methacrylates with ethyl-, isopropyl and tert-butyl groups in the orthoand para-positions of the phenyl ring with dilauroyl peroxide as initiator were investigated. For comparison and completion of the investigation, ortho-and para-tolyl methacrylates were reinvestigated with this particular initiator. Most of the results obtained do not obey classical kinetics of polymerization. The results were treated according to the concept of degradative chain transfer and it was concluded that this mechanism is responsible for the non-ideality. The ortho-substitution with increasing size of the substituents decreases the overall rate of polymerization and strengthens chain transfer to monomer.
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