Optical, thermal, and thermomechanical tailoring of PVA/CMC/CNT nanocomposites via CdS incorporation

Abstract

In this study, polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) nanocomposite films reinforced with carbon nanotubes (CNTs) and 1, 2, and 3 wt% CdS nanoparticles were successfully fabricated via a facile solution-casting method. XRD and FTIR analyses confirmed the preservation of the polymer structure and the formation of strong interfacial physical interactions between the nanofillers and polymer matrix. UV–Vis spectroscopy revealed enhanced and tunable optical absorption following CdS incorporation, with a distinct CdS-related absorption feature emerging around 460 nm at 3 wt% loading. TGA demonstrated improved thermal stability and increased residual char content with increasing nanofiller incorporation. DMA identified 2 wt% CdS as the optimum loading, where the storage modulus increased by 116% from 0.82 to 1.77 GPa, accompanied by an increase in the calculated physical crosslinking density from 2.43 × 10 4 to 4.48 × 10 4  mol m −3 . At 2 wt% CdS, the damping factor decreased from 0.1785 to 0.1699, indicating restricted polymer-chain mobility and enhanced elastic behavior. Further increasing the CdS content to 3 wt% resulted in reduced reinforcement efficiency, consistent with partial nanoparticle agglomeration. Meanwhile, the glass transition temperature exhibited only a slight decrease from approximately 49.6 to 49.0°C. Overall, the 2 wt% CdS nanocomposite provides an optimum balance of stiffness, thermal stability, and optical responsiveness, highlighting its potential for advanced multifunctional polymer applications.