Kinetics of milling of polymers

Effect of shrimp shells milling on the molar mass of chitosan

“…Although it was not done in this work the milling of chitosan to evaluate the reduction of its molar mass, but the milling of shrimp shells, it is known that chitin is chemically very similar to chitosan, and in this case, any changes made in the chitin structure can potentially be observed in the chitosan, so that the results of molar mass reduction of chitosan are agree with those found in previous studies [9,14] . Thus one can say that the processing stages of chitin to obtain chitosan, subsequent to milling, acted in the same manner over the material which shows que the only variable analyzed actually was the milling time.…”

“…By using experimental data from van der Hoff and Chopra in their deduced equations, the author found that the milling time is the most important parameter that influences the average molar mass of the polymer during this unit operation. Its kinetic study showed that the increase in milling time causes an increase in the number of disruptions in the polymer chains, which is proven by the reduction of the average molar mass [9] .…”

“…The degradation of the polymer chain can be caused by the energy supplied by mechanically milling the material as the primary response of a polymeric material to an external mechanical force is the relaxation of the chain. Another important type of response to mechanical force of the milling is the polymer chain scission [9] , which can also be obtained by means other than mechanical, such as contact with thermal energy, among others [10,11] . When a particulate solid material is milled in a ball mill, for example, there are mainly two types of combined actions that are responsible for the particles' shearing of the material: impact and abrasion.…”