Environmental Degradation Tests

International agreement is close as of 1996 on what an acceptable environmentally degradable polymer should do ia the environment succiacdy put, it must not harm the environment. There has been much progress ia the early 1990s on this issue standard protocols are available to determine degradation ia the environment of disposal, and definitions are understood and accepted ia a broad sense, if not ia detail. Fate and effects issues for these new polymers are being addressed, and these will be resolved and appropriate tests developed. 

ASTM Standards on Environmentally Degradable Plastics, ASTM Pubhcation Code Number (PCN) 03-420093-19, American Society for Testing and Materials, Philadelphia, Pa., 1993. 

To help lessen the complications of product testing, a common approach is to separate mechanical and environmental testing. The mechanical properties can be tested on the product, using a relatively simple product test rig, while environmental degradation is studied on samples of the material. For time dependent mechanical properties, the degree of mechanical deterioration of the product is then increased by a factor reflecting the... 

This overview is an attempt to briefly cover the history and recent developments In environmentally degradable commodity and specialty polymers and plastics. Degradation pathways are mentioned, polymer types, including blends, are reported and the limitations of current testing protocols raised. The chapter concludes with generalizations on structural requirements for degradable polymers. 

Their conclusions were that many pharmaceuticals would degrade to innocuous substances but that degradation testing should take place as part of the portfolio of drug testing and also that analytical methods available at the time were inadequate to measure the expected concentrations of pharmaceuticals in the environmental matrices concerned. 

Despite the wider availability of experimental data in these nations, risk assessments for new substances often demand estimation of environmentally important parameters. For example, degradation and partitioning processes must be considered in environmental exposure assessments, but neither Henry s Law constant nor abiotic degradation processes such as hydrolysis and photolysis are included in the MPD. Only if a substance is not readily biodegradable may requirements for abiotic degradation testing be imposed. 

Due to the different fate of lubricants during their use, e.g. contamination by fuel and combustion products of engine oils, the toxicity of used lubricants may be significantly different than that of fresh oils. Fluids which are considered environmentally friendly must not only be biodegradable, but also relatively nontoxic, in both their initial form and degradation products. Their effects on flora and fauna must be minimal. There are two common tests to evaluate toxicity the Microtox and the Rainbow Trout bioassay. Considerable environmental toxicity testing has been carried out on esters fluids. Esters cause minimal acute toxicity by ingestion and skin absorption. 

For each of the steps in the flow diagram, Figure 1, standards organizations worldwide have developed very similar and entirely appropriate laboratory simulation methods for testing plastics for use in various environments such as compost, soil, water, etc. Developing plastics may, therefore, be tested and approved as environmentally degradable in a particular environment, such as soil, compost, seawater and freshwater. Based on these methods, specifications have been established for what is and what is not disposable in such sites or use environments. 

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