Equilibrium distribution of diethyl phthalate plasticiser in cellulose acetate-based materials: Modelling and parameter estimation of temperature and composition effects

Understanding the transport and fate of semi-volatile organic compounds (SVOCs) such as phthalates in indoor envi-ronments is fundamental for quantifying levels of human exposure and preventing adverse health effects. In this con-text, the partition coefficient of phthalates between indoor built materials and/or consumer goods and the surrounding atmosphere represents a key parameter for determining concentration distributions. Partition coefficients are also of fundamental importance for describing degradation phenomena associated with plasticiser loss from polymeric mate-rials. However, this key parameter has only been determined for a limited number of systems and environmental con-ditions. Here, we assess the partitioning behaviour of the diethyl phthalate (DEP) plasticiser in cellulose acetate (CA) -based materials for the first time, determining the effects of temperature and plasticiser composition on equilibrium distributions at temperatures between 20 and 80 degrees C and using CA samples with DEP contents ranging from 6 to 22 wt%. Additionally, we propose a model to describe and quantify the effect of temperature and plasticiser composi-tion, with model parameters being estimated using non-linear regression and measurements from 130 distinct exper-iments. Finally, we assess the suitability of our developed model to simulate the migration of DEP from CA-based materials.

Automated summary

Understanding the transport and fate of semi-volatile organic compounds like phthalates in indoor environments is crucial for quantifying human exposure levels and preventing adverse health effects. This study evaluates the partitioning behavior of the plasticizer DEP in cellulose acetate-based materials, proposing a model to quantify the effects of temperature and plasticizer composition.