Abstract
Plasticizers are commonly added to poly(vinyl chloride) (PVC) and other brittle polymers to improve their flexibility and processing properties. Phthalate plasticizers such as di(2-ethylhexyl phthalate) (DEHP) are the most common PVC plasticizers and have recently been linked to a wide range of developmental and reproductive toxicities in mammals. Our group has developed several replacement compounds that have good biodegradation kinetics, low toxicity profiles, and comparable plasticizer properties to DEHP. Knowledge of the rheology of PVC–plasticizer blends at elevated temperatures is crucial for understanding and predicting the behavior of the compounds during processing. In this work, the time–temperature profiles of PVC blended with our replacement green plasticizers—succinates, maleates, and dibenzoates, of varying alkyl chain length—are compared to blends prepared with DEHP and a commercially available non-phthalate plasticizer, di(isononyl cyclohexane-1,2-dicarboxylate) (Hexamoll® DINCH®). The relationship between the plasticizer molecular structure and viscoelastic response was examined by applying time–temperature superposition. All compounds except the diethyl esters showed a comparable viscoelastic response to DEHP and Hexamoll® DINCH®, and dihexyl succinate exhibited the most effective reduction of the storage modulus G′. All of the dibenzoate blends exhibited a lower stiffness than the DEHP blends. These experiments help to show that the green plasticizers described herein are viable replacements for DEHP, providing a less toxic alternative with comparable processing and rheological performance.
Highlights
Plasticizers are commonly added to poly(vinyl chloride) (PVC) and other brittle polymers to improve their flexibility and processing properties [1]
Epoxidized soybean oil was purchased from Chemtura Corporation (Philadelphia, PA, USA) as a thermal stabilizer for PVC, and stearic acid was purchased from Fisher Scientific (Montréal, QC, Canada) as a lubricant
It is important that any viable replacement plasticizers display similar rheological behavior to di(2-ethylhexyl) phthalate (DEHP), so that existing industrial equipment can be used without intensive retrofitting or modification
Summary
Plasticizers are commonly added to poly(vinyl chloride) (PVC) and other brittle polymers to improve their flexibility and processing properties [1]. They are typically small organic molecules that are blended with polymers to reduce their glass transition temperature (Tg ), thereby making them more malleable. Most plasticizers are incorporated into the polymer matrix through mechanical mixing and are not chemically bound to the polymer, allowing them to leach out of the blend over time [5] This results in humans’ exposure to plasticizers, and in their entry into the environmentProcesses [6,7].2017, Notably, because of the high volumes of phthalates used annually, they are
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