Exploring the Impact of MIL ‐125‐ NH ₂ (Ti) on Considerably Boosting the Storage Modulus of Unsaturated Polyester Nanocomposites: A Study on Curing Kinetics

ABSTRACT This study aimed to elucidate how MIL‐125‐NH ₂ (M125) particles regulate the curing process and network architecture of unsaturated polyester resin (USPR) and, in turn, enhance its dynamic–mechanical properties. M125 was synthesized and characterized by XRD and SEM, then incorporated into USPR at various weight fractions. All samples were prepared under identical curing conditions to isolate the particle effect. Dynamic mechanical analysis (DMA) showed that adding only 0.1 wt% M125 increased the storage modulus (E′) by ~43%, indicative of higher crosslink density and more regular network architecture. Differential scanning calorimetry (DSC) revealed that in the M125‐containing system, the curing shifted earlier toward diffusion‐controlled mechanisms, reflected by reduced kinetic parameters (K and E _D ) in the VSDF‐modified Kamal model. This transition was linked to the ability of Ti centers in M125 to adsorb and gradually release free radicals, promoting styrene–alkyd copolymerization over styrene homopolymerization. The resulting network exhibited improved regularity, restricted mobility of reactive species, and enhanced stress transfer. These findings provide a mechanistic framework for designing high‐performance thermosetting resins through targeted control of curing kinetics and network architecture using MOF‐based additives.