Petrochemical costs,
limited fossil fuel reserves, and
concerns
about greenhouse gas emissions have raised interest in developing
renewable approaches for synthesizing biobased polyurethanes. This
study aims to solve these problems by making nanocrystalline hydroxyapatite
(HA) reinforcement from waste chicken eggshells and adding it to polyurethane
synthesis through in situ polymerization. The novelty of the research
lies in the utilization of HA as a reinforcement material and renewable
resources for polyurethane production. The results confirm that HA
was successfully added to the polyurethane backbone. Fourier transform
infrared (FTIR) analysis confirmed that the NCO groups were changed
to urethane linkages. TGA examination demonstrated that the samples
exhibited thermal stability up to 457 °C with a mass loss of
61%, indicating enhanced thermal stability. DMA measurements showed
improved mechanical properties of the synthesized polyurethanes, with
storage modulus (E′), complex modulus (E*), and compliance complex (D*) values
of 0.177, 22.522, and 0.660 MPa–1, respectively.
SEM analysis confirmed the homogeneous surface and well-dispersed
HA reinforcement. Swelling characteristics revealed an optimum absorption
of 30% H2O, 35% CH3OH, and 45% CCl4. Polyurethane composites exhibited significant chemical resistance
and hydrolytic stability in acidic and basic media. Additionally,
the composites demonstrated efficient adsorption of methyl orange
from wastewater, with the PUHCI series achieving a maximum adsorption
capacity of 85.50 mg/g under optimal conditions of 0.030 g/mL dose,
45 °C temperature, 2.5 h contact time, and pH 6.0..