High-temperature stable piezoelectric PVDF/Nylon 11 powder blend films

A new type of ferroelectric polymer produced by melt blending ~1 micrometers powder particles of poly (vinylidene fluoride) (PVDF) and nylon 11 exhibited several enhanced properties compared to the homopolymers. One of the most significant changes previously observed was in the polarization as a function of composition which exhibited a maximum at the 50/50 level by weight. In this study, we report the enhanced high temperature stability of the polarized PVDF crystals imparted by the presence of ~20% nylon 11 in uniaxially stretched films. This is in contrast to the large loss in polarization and piezoelectric properties observed to occur in uniaxially oriented, Phase I, PVDF films. The powder blend films exhibited almost no loss in piezoelectric response after annealing at 160 degree(s)C for two hours while PVDF films exhibited more than an 80% loss in d31 after the same annealing treatment: similar decreases in e31 were also observed. Both the glass transition temperature and melting point of nylon 11 were observed to decrease with increasing PVDF content, indicating the presence of interactions between these two polar polymers.