Green anionic polymerization of vinyl acetate using Maghnite-Na+ (Algerian MMT): synthesis characterization and reactional mechanism

Abstract

Abstract In this work, the green polymerization of vinyl acetate is carried out by a new method which consists in the use of clay called Maghnite-Na + as an ecological catalyst, non-toxic, inexpensive and recyclable by simple filtration. X-ray diffraction (XRD) showed that Maghnite-Na + is successfully obtained after cationic treatment (sodium) on raw Maghnite. It is an effective alternative to replace toxic catalysts such as benzoyl peroxide (BPO) and Azobisisobutyronitrile (AIBN) which are mostly used during the synthesis of polyvinyl acetate (PVAc) making the polymerization reaction less problematic for the environment. The synthesis reaction is less energetic by the use of recycled polyurethane as container for the reaction mixture and which is considered as a renewable material and a good thermal insulator which maintains the temperature at 0 °C for 6 h. The reaction in bulk is also preferred to avoid the use of a solvent and therefore to stay in the context of green chemistry. In these conditions, the structure of obtained polymer is established by Nuclear Magnetic Resonance Spectroscopy 1 H NMR and 13 C NMR. Infrared spectroscopy (FT-IR) is also used to confirm the structure of PVAc. Thermogravimetric analysis (TGA) showed that it is thermally stable and it starts to degrade from 330 °C while Differential Scanning calorimetry (DSC) shows that this polymer has a glass transition temperature (Tg = 50 °C). The composition in PVAc/Maghnite-Na + (7 wt% of catalyst) is the most tensile resistant with a force of 182 N and a maximum stress of 73.16 MPa, the most flexible (E = 955 MPa) and the most ductile (εr = 768%).