There are some really bad logic in that blog that your second post referred to there from my point of view, which I consider the meat and core of yoru argument.
1) BioVAL already said BBBMax is made out of resin.
Resin ain't glass.
Case in point, if you were to use
www.matweb.com, and use "resin" with a minimal melting point of 500*C, you would have 21 hits.
To use temperature alone to figure out which material it is IN ABSENCE OF ANY SALIENT MATERIAL FEATURE is a bit like using weight to tell my age, my height, my gender and race etc.
2) The term biodegradable pretty vague too, especially in absence of any data on how it degrades. Remember, biodegrabeable is degradation of a material by natural means, it doesn't just have to be nom-nom-noms for bacteria (e.g. UV degradation, humidity degradation, etc.)
3) Too much room for error in that calculation. 2 things
a) the author ASSUMED that the BB is 6mm. Most BBs advertised as 6mm are in fact more often lower than that. See
this as a good example. Even just by deviation of 0.1mm will compound the final error to 4% (1.6% ^ 3)- and this is without considering the other possible error. Are you willing to go out and call someone a fraud with a possible deviation in your data by a minimum of 4%, possibly more?
b) there is no way of telling how "pure" is the component used to make the 0.27g BBs. It's all fine and well if they are only using 1 material component, but if they are using 2 different componentns with different weight and material specs you start to have a headache. 3 or more and it's starting to become impossible. The way the author did his calculation, he only assumed that it is a 1 component system - when there are good reasons to suspect that the BBBMax is quite possibly a 2 component or more system. (A BB made purely out of pure resin and can be used in high-temperature application isn't likely to be cheap to start with)
What is the lesson learnt here? ASSUME makes ASS out of U and ME. The author in that blog used too much assumptions. Any university undergraduate project supervisor will happily kick you in the butt if you were to write a report using so much assumptions!
4) And lastly:there is this thing called the synergistic effect in material science - you add 2 materials together you can get a better property, i.e 1 + 1 to get 3. The manufacturer may have taken advantage of this to claim that their product is thermal-stable. However, when you mix something together though, you could lose volume etc, which wrecks havoc on specific gravity calculations. Again, without knowing whether the BB is made out of just 1 component or more, using specific gravity to determine a material is a bit fallacious.
The best way to investigate the manufactuere's claim? Get some samples (which should be easily done if you ask nicely and pay for postage), lay them out under the sun, and see what happens after 30 days ("The Composting Test"). This is far more reliable than any armchair calculation done by even the best mathematician armed with the latest version of Perry's Chem Engineering handbook next to him..