Abstract
Strain hardening has important roles in understanding material structures and polymer processing methods, such as foaming, film forming, and fiber extruding. A common method to improve strain hardening behavior is to chemically branch polymer structures, which is costly, thus preventing users from controlling the degree of behavior. A smart microfiber blending technology, however, would allow cost-efficient tuning of the degree of strain hardening. In this study, we investigated the effects of compounding polymers with microfibers for both shear and extensional rheological behaviors and characteristics and thus for the final foam morphologies formed by batch physical foaming with carbon dioxide. Extensional rheometry showed that compounding of in situ shrinking microfibers significantly enhanced strain hardening compared to compounding of nonshrinking microfibers. Shear rheometry with linear viscoelastic data showed a greater increase in both the loss and storage modulus in composites with shrinking microfibers than in those with nonshrinking microfibers at low frequencies. The batch physical foaming results demonstrated a greater increase in the cell population density and expansion ratio with in situ shrinking microfibers than with nonshrinking microfibers. The enhancement due to the shrinkage of compounded microfibers decreasing with temperature implies that the strain hardening can be tailored by changing processing conditions.
Highlights
The strain hardening behavior of molten polymers has important roles in characterization and manufacturing, which is demonstrated by the tensile stress growth coefficient above the linear curve during extensional flow
During the test, in and the gap ledresulted to a difference in the strain microfiber shrinking during the difference test, and the gap led to difference in the the two straintypes beginning of the continuously test, which led to a tensile stress appearing at a0.1 s between hardening hardening enhancement in theinextensional rheometry ofe-PP/heat-activated shrinking (HAS)
We proved that compounding microfibers that have active-shrinking behavior into thermoplastic polymer is a feasible approach to enhance and control strain hardening and foamability
Summary
The strain hardening behavior of molten polymers has important roles in characterization and manufacturing, which is demonstrated by the tensile stress growth coefficient above the linear (invariant with rate) curve during extensional flow. Control strain hardening by confirming the existence between the matrix and the Extensional of linear polymers by compounding withhardening heat-shrinking fibers to tailor the resulting by rheometry was conducted to show strain due to shrinking microfibers andproperties to study the changing certain operating temperature. We hypothesized that compounding a linear polymer matrix with shrinking “microfibers” would show a more apparent enhancement of strain hardening upon extensional deformation and that such enhancement could be more accurately controlled by changing the operating temperature than in our previous work. To investigate the effect of shrinkage, extensional viscosity measurements were described in terms of strain hardening behaviors in PP composites containing shrinkable or heat-activated shrinking (HAS) microfibers (PP/HAS). Extensional rheometry was conducted to show strain hardening due to shrinking microfibers and to study the possibility of controlling the degree of strain hardening using the processing temperature.
Sign-in/Register to view highlights & summary 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.
