Standards Development

Scope

This document specifies a method for the determination of the contents of residue monomers in ABS by headspace-gas chromatography (HS-GC) equipped with a hydrogen flame ionization detector (FID).These monomers including styrene, acrylonitrile and 4-vinyl-1-cyclohexene (butadiene dimer). It may also be used for the determination of other volatile aromatic hydrocarbons such as toluene, xylene, isopropyl benzene in ABS.

Purpose

ABS is a common thermoplastic used many products such as automotive body parts, musical instruments, house-hold appliances, toys, and food containers. Generally, there are some residual monomers such as styrene, acrylonitrile, and dimer of1,3-butadiene after the synthetic process. These residue monomers and dimers are harmful to human health. Styrene is a skin and mucous membranes irritant and has narcotic effect[1,2]. Acrylonitrile is believed to be a carcinogen[1]. 4-Vinyl-1-cyclohexene is a potential health hazard[3]. Monitoring levels of residue monomers in ABS is important in ABS product quality control and its application.

Currently the determination of different monomers is specified in multiple ISO documents. ISO 2561[4] is used to determine the styrene in PS and Ps-1. ISO 4581[5] is suitable to determine the acrylonitrile content in styrene-acrylonitrile copolymers. The detection limit of the direct liquid injection method is 3 ppm using FID, while using a nitrogen phosphorus detector (NPD) could achieve lower detection limit. However, NPD has no response to hydrocarbon and is not applicable to styrene and 4-vinyl-1-cyclohexene determination. There is no proper method for the simultaneous determination of all potential residual monomers in ABS.

Here we propose a new, individual standard which could be used to determine styrene, acrylonitrile and 4-vinyl-1-cyclohexene in ABS by a headspace-gas chromatography (HS-GC) equipped a common detector FID. It may also be used for the determination of other volatile aromatics such as toluene, xylene, isopropyl benzene in ABS. This new method would help resin producer, product manufacturer, and researcher to better control the residual monomers of ABS, and also reduce test cost.