Effects of molecular design parameters on plasticizer performance in poly(vinyl chloride): A comprehensive molecular simulation study

Abstract

Using all-atom molecular simulation, a wide range of plasticizers for poly(vinyl chlorid) (PVC), including ortho-and tere-phthalates, trimellitates, citrates, and various aliphatic dicarboxylates, are systematically studied. We focus on the e ects of plasticizer molecular structure on its performance, as measured by performance metrics including its thermodynamic compatibility with PVC, e ectiveness of reducing the material's Young's modulus, and migration rate in the PVC matrix. The wide variety of plasticizer types covered in the study allows us to investigate the e ects of seven molecular design parameters. Experimental ndings about the e ects of plasticizer molecular design are also compiled from various literature sources and reviewed. Comparison with experiments establishes the reliability of our simulation predictions. The study aims to provide a comprehensive set of guidelines for the selection and design of high-performance plasticizers at the molecular level. Molecular mechanisms for how each design parameter in uences plasticizer performance metrics are also discussed. Moreover, we report a nontrivial dependence of plasticizer migration rate on temperature, which reconciles seemingly con icting experimental reports on the migration tendency of di erent plasticizers.

Understanding the balance between additives’ miscibility and plasticisation effect in polymer composites: a computational study

“…23,24 The results of theoretical and computational studies, including mesoscale and atomistic models of polymerplasticisers systems, have shown a change in the polymer T g due to a microscopic interplay between polymer and plasticisers. [25][26][27][28][29][30][31][32][33][34] A lattice model, called Limited Mobility, has been recently applied to study the influence of additives on the mobility of a matrix and the consequent change in the polymer T g . 26 The authors showed that both additive concentration and their molecular properties, such as stiffness, determine whether the T g of the system is raised or lowered respected to the pure material.…”

Molecular Mechanism of Plasticizer Exudation from Polyvinyl Chloride

“…The MD-predicted density and total HSP values in Table can also be compared to previous work. As noted earlier, Li et al employed the Polymer Consistent Force Field (PCFF) for all-atom MD simulations of plasticized PVC; they report density and solubility parameters at 300 K and 1 atm for homogeneous systems of atactic PVC (ρ: 1.36 g/cm 3 , δ t : 16.50 MPa 1/2 ) and several different plasticizers, including DEHP (ρ: 0.948 g/cm 3 , δ t : 19.46 MPa 1/2 ) and DEHT (ρ: 0.951 g/cm 3 , δ t : 18.74 MPa 1/2 ) . When comparing these selected PCFF-predicted values to the present GAFF-predicted values, the percent difference, (value 1 – value 2 )/average­(value 1 , value 2 ) × 100%, ranges from 1.29 to 2.87% (density) and 2.76 to 32.06% (total HSP).…”

“…In another study, AA-MD was used to systematically investigate the influence of plasticizer chemistry (DEHP and five different di-iso phthalates with 4 to 13 alkyl carbons) on the properties of plasticized atactic PVC, such as density, T g , Hildebrand solubility parameter, enthalpy of mixing, radial density distributions, mobility/diffusivity based on mean-square displacement vs time, and uniaxial tensile modulus . This AA-MD work was later extended by the same researchers to several additional plasticizers, including DEHT, citrates, trimellitates, and aliphatic dicarboxylates, for a total of 14 different plasticizers . In a separate study, AA-MD was used to investigate the influence of 11 different plasticizers, including DEHP, levulinates, succinates, an adipate, and an oleate, on PVC based on glass-transition temperature, Flory–Huggins interaction parameters, and mechanical properties .…”

“…22 This AA-MD work was later extended by the same researchers to several additional plasticizers, including DEHT, citrates, trimellitates, and aliphatic dicarboxylates, for a total of 14 different plasticizers. 23 In a separate study, AA-MD was used to investigate the influence of 11 different plasticizers, including DEHP, levulinates, succinates, an adipate, and an oleate, on PVC based on glass-transition temperature, Flory− Huggins interaction parameters, and mechanical properties. 24 AA-MD, Support Vector Regression (SVR) surrogate models, and Particle Swarm Optimization (PSO) have been employed to develop CG-MD parameters for PVC using AA-MD density and stress−strain response data as targets; the resulting parameters were further assessed with untrained properties including glass-transition temperature, thermal conductivity, and end-to-end distance.…”

Bio‐based glycerol plasticizers for flexible poly(vinyl chloride) blends

“…A similar relationship was observed with linear succinate diester plasticizers as the largest improvement in tensile properties was observed for plasticizers functionalized with alkyl chain lengths between four and seven carbons. 38 The complex relationship between chemical structure and plasticizer efficiency is one which has been studied both practically and computationally by many academic groups, 23,42,43 and highlights the challenge of striking a fine balance between polar and nonpolar functional groups on the plasticizer molecule. The polar functional groups are essential to compatibilize the plasticizer with the polar PVC backbone and serve as hydrogen-bond acceptors, while the nonpolar groups disrupt the PVC chain-chain interactions and increase the free volume of polymer matrix 44 (for a more in-depth discussion on this topic as well as additional theories of plasticization, we direct the readers to the works of Daniels and Mascia).…”