Enhancing Thermal Stability of PVC Through Organic Acid-Interlayered Hydrotalcite Modification: Experimental and Computational Analysis

This study systematically examines the effects of diphenylphosphinic acid (DPPA) and sarcosine (SAR) intercalation into magnesium aluminum lanthanum hydrotalcite (LDHs) on its structure and thermal stability. Using charge distribution, structural optimization, energy calculations, XRD, FTIR, TEM, and thermal stability tests, the study reveals that DPPA anions, with higher negative charge density, increase the interlayer spacing to 6.08 Å and exhibit a binding energy of −0.7624 eV. SAR anions, with a thinner interlayer spacing of 4.11 Å and a binding energy of −1.603 eV, create a more stable structure. SAR's higher dipole moment (2.827 a.u.) compared to DPPA (2.077 a.u.) enhances electrostatic interactions. Thermal stability tests show SAR-LDHs and DPPA-LDHs extend PVC's stability to 53.67 and 56.67 min, respectively. DPPA anions provide superior stability at high temperatures, while SAR anions excel in moderate temperatures. This study offers insights for designing thermally stable composite materials.