Abstract
Polyimide films have conventionally been prepared by thermal imidization of poly(amic acid)s (PAAs). Here we report that the improvement of tensile strength while increasing (or maintaining) film flexibility of polyimide films was accomplished by simple microwave (MW) irradiation of the PAAs. This improvement in mechanical properties can be attributed to the increase in molecular weight of the polyimides by MW irradiation. Our results show that the mechanical properties of polyimide films can be improved by MW irradiation, which is a green approach that requires relatively low MW power, very short irradiation time, and no incorporation of any additional inorganic substance.
Highlights
Polyimide films have been widely used as high-performance polymer materials in flexible printed circuit boards, heat-releasing sheets, and organic light-emitting diode displays due to their excellent heat resistance, chemical resistance, electric characteristics, and mechanical strength [1,2,3]
The resulting poly(amic acid)s (PAAs)-PO solution was drop-cast onto slide glasses, and MW irradiation was performed
There was no significant difference between elongations at break values of the MW-treated samples and those of corresponding control samples (p > 0.05). These results indicate that the tensile strength of the polyimide films was enhanced by the MW treatment while film flexibility was maintained
Summary
Polyimide films have been widely used as high-performance polymer materials in flexible printed circuit boards, heat-releasing sheets, and organic light-emitting diode displays due to their excellent heat resistance, chemical resistance, electric characteristics, and mechanical strength [1,2,3]. Most studies have focused on the reinforcement of the polyimide films with inorganic substances such as graphene [4,5], graphene oxides [6,7,8], clays [9,10], silica [11,12,13], and carbon nanotubes [14]. In the majority of cases, by the incorporation of stiff inorganic substances, the tensile strength and modulus were increased, and the elongation at break was reduced. A few studies reported increased strength, modulus, and elongation at break values of the organoclay-reinforced polyimide films [15,16]. Because the modulus and elongation at break properties represent film flexibility [17,18,19,20], reinforcement with inorganic materials generally results in the reduction of film flexibility. Mechanical-property improvement achieved without the addition of any inorganic material is more advantageous. No use of additional inorganic substances leads to a simpler film forming process, less energy consumption, and less use of auxiliary chemicals, and it is considered to be a green approach [21]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
