As we ran out of EcoStore dishwashing powerde, I had the pleasure of buying the auto dishwasher tablets instead because Pack’n Save didn’t have anything else.

When I opened the cardboard box, I was first shocked about the plastic warpper around each tablett. But they felt we weird. As it turned out, it was made from PVA.

I put one wrapper under water and – how amazing – it dissolved within seconds. My wife asked me what PVA actually is and I said: Polyvinyl something. So what is it really?

From Wikipedia (http://en.wikipedia.org/wiki/Polyvinyl_alcohol):

Polyvinyl alcohol has excellent film forming, emulsifying, and adhesive properties. It is also resistant to oil, grease and solvent. It is odorless and nontoxic. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However these properties are dependent on humidity, in other words, with higher humidity more water is absorbed. The water, which acts as a plasticiser, will then reduce its tensile strength, but increase its elongation and tear strength. PVA is fully degradable and is a quick dissolver. PVA has a melting point of 230°C and 180–190°C for the fully hydrolysed and partially hydrolysed grades, respectively. It decomposes rapidly above 200°C as it can undergo pyrolysis at high temperatures.

[..]

Unlike many vinyl polymers, PVA is not prepared by polymerization of the corresponding monomer. The monomer, vinyl alcohol, almost exclusively exists as the tautomeric form, acetaldehyde. PVA instead is prepared by partial or complete hydrolysis of polyvinyl acetate to remove acetate groups.

So we would in turn have to look at PVAc (polyvinyl acetate) to find out about eco credentials. This in turn seems to be made “from ethyne, acetic acid and a mercury(I) salt.”

Wow, difficult. Any chemistry students around who can tell me how long down the chain I would have to research and whether this is eco or not?

 


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