Keywords: low viscosity 107 gum, high viscosity 107 silicone rubber, α,ω-dihydroxy polydimethylsiloxane, hydroxyl-terminated PDMS base polymer, RTV-2 sealant formulation, 107 gum viscosity range

Question 1: It's the same α,ω-dihydroxy PDMS molecule — where is the viscosity line between "low" and "high," and why does it matter?

Answer: One sentence: by industry convention, hydroxyl-terminated PDMS above 2,500 mPa·s is called "107 silicone rubber" (gum); below that it behaves as a fluid-grade diluent or structure control agent — chain length decides role.

MY 2107 spans 25–100,000 mPa·s (customizable) with hydroxyl content 0.5–3%, inversely tied to viscosity; the ≤30 mm²/s, ≥8.5% OH short-chain grade (MY 1203 type) sits at the extreme low end. Low-viscosity members flow, wet fillers, and thin compounds; high-viscosity members carry the chain entanglement needed for tensile and tear strength. Selection rule: workability, penetration, anti-structuring → low viscosity; cured-property ceiling → high viscosity.

Question 2: How does 107 gum viscosity change processing and cured properties — can grades be swapped or blended?

Answer: Let's look scenario by scenario (based on measured parameters of published formulations):

Conclusion: They are one continuous ladder, not two products — and climbing it is never free. Raising viscosity buys cured strength and dimensional firmness but costs flow, filler incorporation speed, and bubble release; dropping viscosity buys workability but lowers the achievable mechanical envelope. Practical guidance: ① if parts come out too hard or stiff, check whether the base-gum viscosity is unnecessarily high before touching the crosslinker dose; ② if compound thickens or structures in storage, the fix is normally adding a low-viscosity high-OH grade like MY 1203, not solvent; ③ when blending grades, re-validate cure speed and working time — total hydroxyl concentration shifts with every ratio change. Confirm your target viscosity window against your own filler and catalyst system, since both move effective working viscosity substantially.

Antistatic precipitated silicone rubber, plz check MY HTV 336 series