Spectroscopic, Thermal and Electrical Evaluation of CNT-Modified PVC/PMMA Blends

This study presents a systematic evaluation of the spectroscopic, thermal, morphological, and electrical behavior of PVC/PMMA blends reinforced with 0.1–1 wt% carbon nanotubes (CNTs) at three different PVC ratios (40%, 50%, and 80%). A total of twelve nanocomposites were fabricated using a solvent-casting method to investigate how blend composition and CNT loading cooperatively influence structure–property relationships. DSC analyses revealed a single glass-transition temperature (Tg ≈ 60–70 °C) for all samples, confirming complete miscibility between PVC and PMMA. XRD patterns demonstrated the preservation of amorphous character across all formulations, while minor fluctuations in crystallinity were observed depending on CNT concentration. TGA measurements indicated typical multi-step thermal degradation behavior, with initial mass losses near 194 °C and main-chain decomposition occurring above 340 °C, showing that CNT addition did not substantially alter overall thermal stability. SEM micrographs confirmed homogeneous CNT dispersion and revealed composition-dependent morphological arrangements that directly correlated with electrical performance. Electrical conductivity measurements exhibited a clear percolation threshold in the 50:50 blend: PVC50–1 achieved ~10⁻⁶ S/cm, marking the onset of semiconducting behavior, whereas PVC40 and PVC80 required higher CNT connectivity to reach comparable values. Interfacial energy calculations based on the Owens–Wendt model predicted preferential CNT localization within the PVC phase, supporting the experimentally observed conductivity enhancement in PVC-rich domains and explaining why optimal percolation occurs only when CNT localization and phase continuity coincide. Overall, the results demonstrate that modulating the PVC/PMMA ratio is an effective strategy for controlling CNT distribution, percolation network formation, and charge-transport properties. The synergistic influence of blend composition and CNT loading provides valuable insight into designing PVC/PMMA/CNT nanocomposites for antistatic, flexible electronic, and low-cost semiconductive applications.