Thermal decomposition products of polyurea?

Are the thermal decomposition products of polyurea polymers known, especially of the urea group, in the absence of water?


Looking at the formula



```
R-NH-C=O
     |
    HN-R

```

there appears to be no obvious candidate for a decomposition product - not enough oxygen for CO2, not enough hydrogen for Ammonia.


Any ideas or, even better, references?




Here's [one abstract](http://onlinelibrary.wiley.com/doi/10.1002/pol.1982.170200703/abstract):



> 
> The primary fragmentation processes in the thermal decomposition of polymers were studied in detail on a series of structurally related polyureas by direct pyrolysis with a mass spectrometer. Our results indicate that polyureas I–III undergo a quantitative depolycondensation process analogous to that observed for N-monosubstituted polyurethanes. The thermal decomposition of polyureas IV–VI proceeds by intramolecular hydrogen transfer processes that occur at higher temperatures with respect to depolycondensation. Polycarboxypiperazine VI is decomposed by a single-stage decomposition mechanism that leads to fragments with amino end groups and carbon oxide.
> 
> 
> 


I took a look at the article. Depolycondensation is accurate: most of the polyureas examined decomposed to the "parent" isocyanates and amines. The temperature range examined was 150°C to 350°C. 


If you're interested in what happens at higher temperatures, I would guess a decomposition to mixtures of CO, ammonia, water, and possibly methane and/or hydrogen. But I didn't find any references that would support me after a quick look


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