Exploring the Mechanism of Bis‐Maleate Organotin Thermal Stabilizers via Dynamic Raman Spectroscopic Technique

ABSTRACT The molecular design and structural regulation of thermal stabilizers are crucial for the processing stability and mechanical properties of polymer products. Herein, three di‐n‐butyltin di(monobutyl/monohexyl/monooctyl maleate) thermal stabilizers (named MA‐ X ‐Sn, X = 4, 6, and 8) were synthesized and used in poly(vinyl chloride) (named PVC‐ X Sn‐ Y , Y = 0.5–3.5) to clarify their microscopic thermal stability mechanism. According to the Congo red and thermal aging measurements, these thermal stabilizers present a remarkable stabilizing effect, much better than that of commercial dibutyl tin dilaurate (DBtL). Both variable‐temperature and real‐time Raman spectra confirm the thermal stabilizing effect of MA‐ X ‐Sn on PVC macromolecules, that is, by restraining the removal of Cl and the formation of CC bonds to boost the thermal degradation temperature and prolong the degradation time. The initial formation temperature (214°C) and the intensity increasing time (57.5 × 100 ms) of CC bonds in PVC‐6Sn‐2 are both higher than those of PVC‐DBtL‐2 (162°C and 36 × 100 ms), proving the better heat resistance of PVC‐6Sn‐2. During the thermal plasticization process of PVC, MA‐ X ‐Sn acts as a plasticizing accelerator to facilitate the plasticization generally within 150 s. The MA‐ X ‐Sn based PVC resins reveal better mechanical performance, such as the optimal tensile strength and elongation at break up to 51 MPa and 187% for PVC‐4Sn‐3.5, the impact strength of 10–15 kJ m −2 , and the hardness of 78–80. The prepared thermal stabilizers undoubtedly show large applications in transparent and rigid PVC products owing to their remarkable comprehensive properties.