Nowadays, the management of plastic waste represents a major challenge. If recycling is already in place in some sectors, it struggles to gain widespread interest. In the case of PMMA, the use of thermochemical treatment has proven its effectiveness in the depolymerization [1], however, it requires much energy which can limit its industrialization [2]. As PMMA is well know to degraded by radiation treatment through chain scissions mechanisms [3], in this work, PMMA was irradiated in order to optimize these effects and to initiate the depolymerization. The possibility of degrading crosslinked PMMA, which reprocessability is limited, has been explored additionally.

Three grades of PMMA have been used: casted (Mw=3,000,000 g.mol-1); extruded  (Mw=70,000 g.mol-1); casted and crosslinked (Mw=3,000,000 g.mol-1).Irradiations were conducted on the Aerial feerix® plant with 7 MV X-rays and 10 MeV electron beam, as well as on IPHC’s cyclotron Cyrcé with 24 MeV proton beam. Irradiation temperature has also been taken into consideration. Mechanical measurements, HPLC-SEC, DSC and gel fraction analysis were performed to evaluate post irradiation modifications in chemical structure and properties.

PMMA has shown a degradation in chain size and in properties in every irradiation conditions which is consistent with occurring chain scissions. Looking at chain size, it appears that irradiation tends to standardize the polymer molecular mass after exposure, even with different initial chain lengths. Crosslinked PMMA could be degraded by irradiation from 100 % gel fraction down to 0 % at high absorbed dose.

[1] Moens, E.K.C, et al. Polymers 20201 12

[2] Shamsuyeva M. and Endres H.J., Compos. C: Open Access. 2021, 6

[3] Vasile, C. and  Butnaru, E., RADIATION CHEMISTRY OF ORGANIC SOLIDS 26. 2017