Hi Folks,
I've been trying to make silicone elastomers by reacting the end- groups of functionalized PDMS chains. My aim was to use a short tetrafunctional silanol and a long-chain -OH end capped PDMS to hopefully get an elastomer with high elongation (tensile strength not a huge issue). What I've found by using a variety of MW PDMS molecules (1000-8000g/mol) is that I get sticky gels with a little elongation (about 150%) and virtually no tensile strength (they seem to tear easily). So, I need help - my questions are:
What sort of x-link density does a typical 'soft' silicone elastomer have (or MW between x-links) ?
My results seem to suggest that PDMS forms relatively weak materials but to me this is just counter-intuitive when one considers the typical stretchy silicone elastomer - what is the truth here ? have I just done a crap job at trying to form a PDMS network ?
Should I be looking at other siloxanes rather than PDMS ?
Any help greatly appreciated,
Gill
PS: I know there are easier ways to x-link silicone rubber or just purchase an RTV silicone but I have a specific application that requires a specific approach.