Hi, I have some questions regarding Polyvinylidene fluoride. It would be great if anyone could heمp and answer them. 1- I know this material is used in lighters because of its piezoelectricity property. I want to know if this property is stable or like batteries it has a life span? 2- about this property, what really changes in the structure of Polyvinylidene fluoride when it is stretched? If you can even provide me a reference to show what happens when it is stretched, it would be so helpful. 3- is there any other material that has this property and is not toxic with long lasting? Thank you very much.