Structure-Thermal Stability Relationships and Pyrolysis Course in Cross-Linked Citronellyl and Geranyl...

Studies on the relationships between structure and thermal stability, as well as on the pyrolysis behavior of cross-linked citronellyl methacrylate/hexyl acrylate and geranyl methacrylate/hexyl acrylate copolymers, are presented. These insoluble and highly chemically resistant polymeric materials exhibited glass transition temperatures (T_g) ranging from -55.2 °C to 7.6 °C, depending on their composition. The thermal stability of the prepared copolymers also depended on their composition and decreased with increasing geranyl methacrylate or citronellyl methacrylate content. The highest thermal stability was achieved for copolymers containing 20 wt% methacrylate and 80 wt% hexyl acrylate. The corresponding decomposition temperatures were 167 °C for citronellyl methacrylate-based copolymers and 190 °C for geranyl methacrylate-based copolymers. The thermal decomposition of the investigated copolymers proceeded in at least three stages, involving simultaneous pyrolysis processes and chemical reactions between the decomposition products. As a result, a mixture of low-molecular-weight saturated and unsaturated volatile compounds, as well as CO, CO₂, and H₂O, evolved. Based on the gaseous FTIR analysis, the pyrolysis pathways of the tested copolymers and the structures of the emitted saturated and unsaturated volatile products were proposed.