Smart Thermoplastic Elastomers With High Extensibility From Poly (Vinylidene Fluoride) and Hydrogenated Nitrile Rubber: Processing–structure–property Relationship

Abstract

Novel smart thermoplastic elastomers (TPEs) with very high extensibility were prepared by blending polyvinylidene fluoride (PVDF) with hydrogenated nitrile rubber (HNBR) at an appropriate ratio, and their processing–structure–property relationship was investigated. Although the rubber phase was found to be dispersed in the matrix of PVDF for all compositions, morphology was shear sensitive and changed significantly after each processing step. Dropletlike structure was observed after the mixing in an internal mixer and compression molding, which changed to the lamellar structure after milling and injection molding. The compression molded sample exhibited very high extensibility (∼1600% elongation at break for 30/70 PVDF/HNBR blend) and a tensile strength of ∼6 MPa due to the formation of a strong interface. The elongation at break was much higher than any of the TPEs reported so far. Theoretical calculation of rubber particle size was also in agreement with the experimental observation. Dissipative particle dynamics simulation was run to capture the morphology, where HNBR chains were more sensitive to the shear force than the PVDF chains. The electromechanical sensitivity of the blend was 14.3 MPa−1, much better than the existing reported elastomeric actuator as well as pristine PVDF. Dynamic vulcanization gave further improvement in tensile strength and tension set properties.

Augmentation of performance properties of maleated SEBS/TPU blends through reactive blending

“…The samples were heated from −80 °C to 200 °C with a heating rate of 10 °C/min and then cooled to −80 °C and again heated to 200 °C. The glass transition temperature ( T g ) and the melting behavior of the blends and virgin materials were analyzed from the second heating scans to eliminate the thermal history of the samples . Netzsch Proteus‐61 software was used to accurately determine the glass transitions, melting points, and heat of fusion of the pure components and the blends.…”

Microstructure and relaxation behavior of flexible dielectric PVDF and HNBR blends: An assessment through small‐angle x‐ray scattering and dielectric relaxation spectroscopy

“…The shape of the scattering curves indicated the formation of lamella‐like crystals for both the pristine PVDF and its blends, as the slope of log I versus log q curve was ∼−2 . The intense peak of pristine PVDF indicated its high degree of ordering as well as higher crystallinity (49 and 54% as determined by WAXD and DSC, respectively, observed from our previous study) . The blends showed mild peaks due to its lower percentage of crystallinity (e.g., a 30/70 PVDF/HNBR blend showed 13 and 14% crystallinity as determined by WAXD and DSC, respectively) because they contained amorphous HNBR.…”

“…Li et al discussed the PVDF/acrylate polymer blends which were again miscible in nature . PVDF/HNBR blend which is thermoplastic elastomeric in nature at ambient temperature, on the other hand, was not miscible but it showed a very high elongation at break . In the present work, we have examined the effect of HNBR chains on the crystal structure of PVDF in PVDF/HNBR blends and also observed the effect of crosslinking, which was not studied before.…”

“…Moreover, during crystallization, PMMA segments were incorporated into the interlamellar amorphous region of PVDF as they were miscible in nature and consequently, the crystal long period of PVDF increased . On the other hand, we have observed that PVDF and HNBR formed immiscible blends from our previous study and the effect of the flexible long chains was not also extensively studied so far. Li et al discussed the PVDF/acrylate polymer blends which were again miscible in nature .…”

“…Several combinations were tried. We have successfully prepared novel blends with hydrogenated nitrile rubber (HNBR) which is also electroactive in nature and the blends showed very high elongation at break along with moderate tensile strength . At ambient temperature, these blends behaved like rubber, but unlike rubbers, the properties can be retrieved after the reprocessing.…”