The strong interaction between poly(vinyl chloride) and a new eco-friendly plasticizer: A combined experiment and calculation study

Environmental-friendly extraction of di(2-ethylhexyl) phthalate from poly(vinyl chloride) using liquefied dimethyl ether

Poly(vinyl chloride) (PVC) is one of the most widely used plastics. However, a major challenge in recycling PVC is that there is no economical method to separate and remove its toxic phthalate plasticizers. This research made a breakthrough by extracting PVC with liquefied dimethyl ether (DME) and successfully separating the plasticizer components. Nearly all (97.1 %) of the di(2-ethylhexyl) phthalate plasticizer was extracted within 30 min by passing liquefied DME (285 g) through PVC at 25 °C. The compatibility of PVC with organic solvents, including liquefied DME, was derived theoretically from their Hansen solubility parameters (HSP), and actual dissolution experiments were conducted to determine the optimal PVC solvents. A liquefied DME mixture was used to dissolve PVC, and the extract was diluted with ethanol to precipitate the dissolved PVC. We demonstrated that liquefied DME is a promising method for producing high quality recycled products and that the process retains the fundamental properties of plasticizers and PVC without inducing degradation or depolymerization. Because of its low boiling point, DME can be easily separated from the solute after extraction, allowing for efficient reuse of the solvent, extracted plasticizer, and PVC. DME does not require heat and produces little harmful wastewater, which significantly reduces the energy consumption of the plasticizer additive separation process.

Terahertz Time-Domain Spectroscopy of Plasticized Poly(vinyl chloride)

Poly(vinyl chloride) (PVC) is today one of the most important commodity polymers. Its broad range of applications is due to the presence of plasticizers whose concentration largely impacts the microscopic and the macroscopic properties. Quantifying the concentration of plasticizer in PVC products is therefore of fundamental importance. Thus, in this paper, the applicability of terahertz (THz) time-domain spectroscopy for the characterization of plasticized PVC is for the first time evaluated in a systematic way. It could be demonstrated that the method is able to distinguish between PVC samples with different types and concentrations of plasticizers. Furthermore, a simple, fast, and efficient method is introduced to quantify the concentration of plasticizer in PVC samples of known plasticizer type but different thermal histories. The presented results are of key importance due to the need of reliable noninvasive and nondestructive analytical methods which can deliver onsite information about the remaining plasticizer concentration inside PVC products. Furthermore, it is expected that the proposed approach can be easily extended to other plasticized polymers.

Nondestructive Quantification of Local Plasticizer Concentration in PVC by (1)H NMR Relaxometry

The properties of plasticized poly(vinyl chloride) (PVC) , one of the most important polymers today, are strongly dictated by the concentration of plasticizer. Yet, it has been impossible to quantify this concentration at different positions inside a PVC product without its destruction because of a lack of suitable analytical methods. Thus, this paper introduces a simple, fast, and efficient way to determine truly nondestructively the concentration of plasticizer in PVC by single-sided nuclear magnetic resonance (NMR). With the help of correlation curves between the concentration of plasticizer inside nonaged PVC samples and the corresponding volume-averaged NMR parameters, single-sided NMR allows the quantification of the local concentration of plasticizer in aged PVC plates at different depths by spatially resolved relaxation measurements. The presented approach represents a fundamental step toward in situ characterization of plasticized PVC.