The present work reports on the thermal and mechanical properties of composites prepared by mixing hollow glass microspheres (HGM), as such or surface modified by treatment with (3-aminopropyl)triethoxysilane (APTES), with poly(?-caprolactone) (PCL). The silanization treatment implies a good dispersion of filler particles within the matrix and an improved filler-polymer adhesion. The addition of HGM affected the mechanical properties leading to a significant enhancement in material stiffness. In particular, tensile tests showed a high increase of Young's modulus for all investigated composites compared to the neat PCL. This behavior was combined to a decrease of elongation at break with a consequent reduction of material ductility. Nevertheless, the composites filled with the modified HGM, characterized by an enhancement of the tensile strength, pointed out the important role played by the silane coupling agent in improving the filler-matrix adhesion [1]. A crystallization study under isothermal and dynamic conditions revealed the nucleating effect of the HGM. The increase of PCL crystallization rate was observed as a function of the HGM amount in the composites. The functionalization of the microspheres enabled even faster rates and attributed higher nucleation activity as a result of better dispersion and the formation of a strong interface between the filler and the matrix. An in depth kinetic analysis was performed based on the data from crystallization procedures. Polarized optical microscopy images confirmed the effectiveness of both fillers as heterogeneous nucleation agents. The presence of HGM gives rise to an overall increase in the thermal stability of the composites compared to the neat PCL. The barrier effect concerns the diffusion of the oxygen from the external gas phase to the polymer matrix bulk and, at the same time, the opposite out-diffusion of the volatile decomposition products [2]. Conversely, the thermograms of composites filled with functionalized HGM exhibit a shift towards lower temperatures, because of the presence of less stable APTES moieties anchored onto HGM surface. This behavior involves a reduction of thermo-oxidative stability. Finally, rotational molding tests demonstrated the possibility of successfully producing manufactured goods in PCL and PCL-based composites on both laboratory and industrial scale.
THERMAL AND MECHANICAL BEHAVIOR OF LIGHTWEIGHT POLY(?-CAPROLACTONE) COMPOSITES FOR ROTATIONAL MOLDING
Fabio Bertini;Maurizio Canetti;Salvatore Iannace;Paola Stagnaro;Roberto Utzeri;Adriano Vignali
2019
Abstract
The present work reports on the thermal and mechanical properties of composites prepared by mixing hollow glass microspheres (HGM), as such or surface modified by treatment with (3-aminopropyl)triethoxysilane (APTES), with poly(?-caprolactone) (PCL). The silanization treatment implies a good dispersion of filler particles within the matrix and an improved filler-polymer adhesion. The addition of HGM affected the mechanical properties leading to a significant enhancement in material stiffness. In particular, tensile tests showed a high increase of Young's modulus for all investigated composites compared to the neat PCL. This behavior was combined to a decrease of elongation at break with a consequent reduction of material ductility. Nevertheless, the composites filled with the modified HGM, characterized by an enhancement of the tensile strength, pointed out the important role played by the silane coupling agent in improving the filler-matrix adhesion [1]. A crystallization study under isothermal and dynamic conditions revealed the nucleating effect of the HGM. The increase of PCL crystallization rate was observed as a function of the HGM amount in the composites. The functionalization of the microspheres enabled even faster rates and attributed higher nucleation activity as a result of better dispersion and the formation of a strong interface between the filler and the matrix. An in depth kinetic analysis was performed based on the data from crystallization procedures. Polarized optical microscopy images confirmed the effectiveness of both fillers as heterogeneous nucleation agents. The presence of HGM gives rise to an overall increase in the thermal stability of the composites compared to the neat PCL. The barrier effect concerns the diffusion of the oxygen from the external gas phase to the polymer matrix bulk and, at the same time, the opposite out-diffusion of the volatile decomposition products [2]. Conversely, the thermograms of composites filled with functionalized HGM exhibit a shift towards lower temperatures, because of the presence of less stable APTES moieties anchored onto HGM surface. This behavior involves a reduction of thermo-oxidative stability. Finally, rotational molding tests demonstrated the possibility of successfully producing manufactured goods in PCL and PCL-based composites on both laboratory and industrial scale.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
