Antioxidant-rich agro-wastes such
as grape pomace waste (GW), turmeric
shavings and waste, coffee grounds, and orange peel waste are used
as-received for the first time as thermo-oxidative stabilizers for
polymer. Relative to neat low density polyethylene (LDPE), a well-dispersed
hybrid made by solid-state shear pulverization with 4 wt % GW results
in 62 and 44 °C increases in temperatures corresponding to 10
and 20% mass loss in air (T
10% and T
20%), respectively. Such enhancements are superior
to those obtained by adding 1 wt % synthetic antioxidant Irganox I1010
to LDPE by melt mixing. Relative to neat LDPE, hybrids with well-dispersed
agro-waste exhibit enhanced Young’s modulus, equal or enhanced
tensile strength, and relatively small reduction in elongation at
break. Reprocessing or recycling sometimes leads to enhanced antioxidant
activity: relative to a hybrid before melt extrusion, 92/8 wt% LDPE/TW
exhibits major increases in T
10% and T
20% after two and six melt extrusion passes,
which is consistent with formation of transformation products with
improved antioxidant activity during multiple high-temperature reprocessing
cycles. Natural antioxidants are effective in suppressing LDPE chain
scission and branching. After ten extrusion passes, neat LDPE exhibits
a 16% increase in zero-shear viscosity and reduction in elongation
at break from 500% to 280%, whereas hybrids with agro-waste have zero-shear
viscosity and elongation at break values close to those of unprocessed
hybrids. Isothermal shear flow measurements also show the effectiveness
of natural antioxidant in stabilizing LDPE: hybrids exhibit no sign
of chain branching during 3000 s of melt flow at 200 °C whereas
neat LDPE branches after ∼500 s.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.