Maybe you already know about this, but azodicarbonamide has been used as a blowing agent in some thermoplastic applications, and decomposes just below the temperature range you stated.

Depending on your application, e.g. food due to risk of ethylcarbamate formation, you may look for alternatives. 

https://books.google.nl/books?id=qJwX5gqcbf0C&pg=PA288&lpg=PA288&dq=azodicarbonamide+blowing+agent+alternatives&source=bl&ots=vlG8PG2A7M&sig=ioma7M0ulsQqPuw_6KeSj2GO5oI&hl=en&sa=X&ved=0ahUKEwjZ7Migwp_JAhXEYg8KHSx1AXAQ6AEINzAF#v=onepage&q=azodicarbonamide%20blowing%20agent%20alternatives&f=false

Reports on such risks concerning azodicarbonamide  you may find on ECHA, any a very interesting site for finding information on HSE/registration aspects et al:

http://www.echa.europa.eu/documents/10162/d9e11c88-481a-47a9-8fff-915b48086ddb

This reports also discusses the alternatives.

Searching on ECHA:

http://www.echa.europa.eu/

I was also looking up aluminum hydroxide, as it is used as a flame retardant in some applications (due to release of water and formation of alumina in the process).  I found an interesting article that lists in its Table 1, several potential flame retardants (which also presumably releases water and/or CO2).  The two that were in your range were:

Mineral Chemical # Formula                          # Approx. Decomp. T 

Hydromagnesite  # Mg5(CO3)4(OH)2·4H2O # 220–240 °C

Dawsonite            # NaAl(OH)2CO3               # 240–260 °C

http://www.sciencedirect.com/science/article/pii/S0141391010003526