Chemosphere 2015-09-01

Designing greener plasticizers: Effects of alkyl chain length and branching on the biodegradation of maleate based plasticizers.

Hanno C Erythropel, Tobin Brown, Milan Maric, Jim A Nicell, David G Cooper, Richard L Leask

Index: Chemosphere 134 , 106-12, (2015)

Full Text: HTML

Abstract

The ubiquitous presence of the plasticizer di (2-ethylhexyl) phthalate (DEHP) in the environment is of concern due to negative biological effects associated with it and its metabolites. In particular, the metabolite mono (2-ethylhexyl) phthalate (MEHP) is a potential endocrine disruptor. Earlier work had identified the diester di (2-ethylhexyl) maleate (DEHM) as a potential greener candidate plasticizer to replace DEHP, yet its biodegradation rate was reported to be slow. In this study, we modified the side chains of maleate diesters to be linear (i.e., unbranched) alkyl chains that varied in length from ethyl to n-octyl. The plasticization efficiency of these compounds blended into PVC at 29 wt.% increased with the overall length of the molecule, but all compounds performed as well as or better than comparable samples with DEHP. Tests conducted with the equally long DEHM and dihexyl maleate (DHM) showed that branching has no effect on glass transition temperature (Tg) reduction efficiency. Biodegradation experiments with the common soil bacterium Rhodococcus rhodocrous in the presence of the plasticizer showed acceptable hydrolysis rates of maleates with unbranched side chains, while the branched DEHM showed almost no degradation. The addition of hexadecane as auxiliary carbon source improved hydrolysis rates. Temporary buildup of the respective monoester of the compounds were observed, but only in the case of the longest molecule, dioctyl maleate (DOM), did this buildup lead to growth inhibition of the bacteria. Maleates with linear side chains, if designed and tested properly, show promise as potential candidate plasticizers as replacements for DEHP.Copyright © 2015 Elsevier Ltd. All rights reserved.

Related Compounds

Structure Name/CAS No. Articles
Chloroform Structure Chloroform
CAS:67-66-3
Hydrochloric acid Structure Hydrochloric acid
CAS:7647-01-0
Butanol Structure Butanol
CAS:71-36-3
pentadecane Structure pentadecane
CAS:629-62-9
Maleic anhydride Structure Maleic anhydride
CAS:108-31-6
Monopotassium phosphate Structure Monopotassium phosphate
CAS:7778-77-0
diethylmaleate Structure diethylmaleate
CAS:141-05-9
n-Butyl fumarate Structure n-Butyl fumarate
CAS:105-76-0
stearic acid Structure stearic acid
CAS:57-11-4
diethoxymethane Structure diethoxymethane
CAS:462-95-3