If starch is added to polyolefins, its presence can be vey easily detected by IR spectroscopy. Biodegradability is, however, not guaranteed. I am sure that thermoanalytical techniques (DSC, TGA) would also detect the presence of starch is polyolefins.

Polyolefins should dissolve in polar solvents (like chloroform e.t.c.) while starch will not. This could be a fast method to check the composition. The methods mentioned by Gyorgy are quite fast and very informative too.

In the case you have one or two days you can try applying of extreme acidic conditions for a few hours and then check the composition and molecular weight.

Biodegradability need the complete test however you can test the presence of starch simply by partially dissolve the material in water (you only need traces) and test with iodine or directly on the material

http://www.youtube.com/watch?v=HO_q8GPl3bE&feature=related

you probably mean the difference between biodegradable, bio-based and oxo-degradable.

- Biodegradability means (in terms of plastics), that 90 % of material should be decomposed by microorganism in 90 days. That includes wide range of materials that can origin from renewable or either from fossil source.

- bio-based are some conventional plastics such as PP, PET etc. blended usually with starch to obtain biological decomposition of plastic product into smaller pieces.

- oxo-degradable plastics are fully made of conventional plastic with addition of special plasticiser that degrades after some time (doesn't matter in which environment).

Bioplastics are made from renewable sources but are not all biodegradable! There are plenty of materials on the market as well as bio-based and oxo-degradable.

I recommend you to check European bioplastics at http://en.european-bioplastics.org/

and also to read scientific paper: Biodegradable Plastics from Renewable Sources

by M. FLIEGER, M. KANTOROVÁ, A. PRELL, T. ŘEZANKA, J. VOTRUBA at Folia Microbiol. 48 (1), 27–44 (2003)

Hope I have helped you

Pavel

There is color test for starch. Starch gives a blue color with iodine. Here is the wilipedia link.

http://en.wikipedia.org/wiki/Iodine_test

my group in China is doing the modification of starches. There are two simple ways: 1) IR spectroscopy comparison between normal starch and your bag material, and see the O-H vibration at 3300 cm-1 and C-O in range 1050-1150 cm-1; 2）using DSC or TGA. Since a cheap starch-based polyolifen blend material has minimum one melting range close to that of the polyolifen itself. a 50% wt blend of polyolifen has distinguished polyolifen thermal characteristics.

These tests are generally based on the chemical and physical properties of starch and biodegradable plastics, and can be used to identify the presence of these materials in a sample.

One common test for starch-based plastics is the iodine test, in which a small sample of the plastic is dissolved in a solvent, such as water or alcohol, and then mixed with a solution of iodine. If the plastic is starch based, the iodine solution will turn blue or violet, indicating the presence of starch in the sample.

Another test for biodegradable plastics is the disintegration test, in which a sample of the plastic is placed in a container of water or soil and allowed to degrade over a period of time. If the plastic is biodegradable, it will break down into smaller pieces or fully disintegrate within a certain timeframe, depending on the specific properties of the plastic.

It is important to note that these tests are only indicative of the presence of starch or biodegradability, and cannot provide a definitive determination of these properties. More detailed analytical techniques, such as spectroscopy or chromatography, may be needed to confirm the chemical composition of a plastic material.