Plasticizers are ubiquitous environmental contaminants. Biodegradation of some of these chemicals, such as di(2-ethylhexyl) phthalate (DEHP or DOP), has been shown to lead to the accumulation of toxic metabolic breakdown products. As a result there is a desire to produce new, fully biodegradable, "green" plasticizers. With this goal in mind, a series of tests were developed to be used to measure the plasticizing efficiency of potential green plasticizers. The base resin selected for the study was poly(vinyl chloride) (PVC). The glass transition temperature (Tg) of the plasticized polymer was measured by temperature-modulated differential scanning calorimetry (TMDSC). Tensile tests were carried out on samples of the material from which the tensile strength and the strain at break of the material were measured. The aforementionned properties were measured for PVC plasticized with the commercial plasticizers DEHP, diethylene glycol dibenzoate (DEGDB) and dipropylene glycol dibenzoate (DPGDB) at several plasticizer concentrations. / 1,5 pentanediol dibenzoate (PDDB) was synthesized and evaluated as a plasticizer by comparing results for this compound with those for the commercial plasticizers using the developed tests. The depression in Tg and tensile properties were comparable at a fixed composition for blends with PDDB relative to blends with DEHP, DEGDB, and DPGDB. PDDB was subjected to biodegradation unsing co-metabolism by the common soil bacterium Rhodococcus rhodocrous (ATCC 13808). After 16 days of growth, nearly all the PDDB was degraded and only small amounts of transient, unidentified, metabolites were observed in the growth medium during the experiment.

M.Sc. (Chemistry) / Please refer to full text to view abstract

No description available.

This project studied the biodegradation of a plasticizer, di-(2-ethylhexyl) adipate (DEHA), by two mammalian cell lines, HepG2 and WIF-B, in vitro . An MTT assay showed that DEHA had a toxic effect on both cell lines. Despite this, both hepatocyte cell lines successfully degraded the plasticizer. Metabolites were identified and quantified by gas chromatography. HepG2 cells showed minimal alcohol dehydrogense activity and this resulted in the accumulation of 2-ethylhexanol. WIF-B cells were able to breakdown the alcohol and produced 2-ethylhexanoic acid. It is important to note that an enzyme was essential for this step in the degradation of the plasticizer, as this proves that it was biodegradation and not physical degradation. By comparing the metabolites formed and the order of their appearance, the degradation pathway in these mammalian cells was found to be similar to the established degradation pathways for bacteria, fungi and yeast.

No description available.