Standard Test Method for Determination of an Emission Parameter for Phthalate Esters and Other Non-Phthalate Plasticizers from Planar Polyvinyl Chloride Indoor Materials for Use in Mass Transfer Modeling Calculations

Importancia y uso:

5.1 The conventional approach for characterizing VOC emissions from building materials and products (for example, Test Methods D6007 and D8142; Practices D6177, D6330, D6670, D6803, D7143; Guide D5116; and ISO 16000-6 standards) results in modeling VOC emissions in the indoor environment using area-specific emission rates (µg h^-1 m^-2). These approaches work for most chemicals classified as VOCs, because most VOC emissions are controlled by the internal mass transfer processes (diffusion of the chemical through the material) and most VOCs sorb to minimal extent to chamber walls. Hence, chamber area-specific emission rates can be directly applied to models of indoor environments.

5.2 In contrast, chemicals classified as SVOCs will sorb strongly to chamber walls and are controlled by the external mass transfer process (migration through the air boundary layer on the material surface). When used for the equilibrium gas phase concentration of certain SVOCs above source materials, conventional chamber emission characterization approaches are typically time-consuming taking up to several months due to sorption of analytes to chamber walls. Due to SVOC’s external mass transfer limitation, the SVOC area-specific emission rate (µg h^-1 m^-2) measured in a test chamber can be different from that for the same material in a real indoor environment. To accurately model SVOC concentrations in indoor environments, a mass transfer approach to determine gas phase concentrations in equilibrium with the material phase is needed.

5.3 Modeling emissions in a real environment using a mass transfer framework requires knowledge of the convective mass transfer coefficient (h_m), the initial SVOC concentration in the material (C_o), the diffusion coefficient in the material (D), and the concentration in the air immediately above the material surface (y₀). Typically, the convective mass transfer coefficient, h_m, and diffusion coefficient, D, can be estimated. The initial concentration in the material (C_o) can be determined by means of extraction. EPA Method 8270E and Test Method CPSC-CH-C1001-09.4 can be used to determine bulk concentrations of phthalates in materials. The unknown mass transfer emission parameter required for exposure modeling in full-scale environments is the gas-phase concentration of SVOCs in equilibrium with the material phase (y₀). This standard describes procedures for rapidly determining y₀ for phthalates from indoor planar polyvinyl chloride materials.

5.4 This method may be used to provide manufacturers, builders, and end users with some of the input data (y₀) required for models used to evaluating the impact of indoor planar, polyvinyl chloride materials on concentrations of indoor SVOCs as well as for mass transfer exposure models.

5.5 This method assumes that an instantaneous equilibrium exists between gas phase and material surface. This assumption has been made for a variety of SVOC mass transfer emission and exposure models (see Little et al. (2), Liang and Xu (1, 3), and Guo (4)). However, this assumption may be invalid under some environmental conditions.

Subcomité:

D22.05

Referida por:

D8141-22

Volúmen:

11.07

Número ICS:

13.040.20 (Ambient atmospheres), 83.140.99 (Other rubber and plastics products)

Palabras clave:

indoor air quality; plasticizers; small-scale environmental test chamber; SVOCs;