I'm trying to use PX30 to make a flexible mold, this resin is very flexible, but his tear resistance is poor, I bend it with my hand, it can bend a lot of angle, but when I twist it, it will easily break and crack.
Is this because of the properties of the resin? I can confirm that my blending ratio is no problem, why does it have such a problem? Or there are no other rubber-like resins, I would like to take to make a flexible resin mold, for casting silicone hand ring.I'm trying to use PX30 to make a flexible mold, this resin is very flexible, but his tear resistance is poor, I bend it with my hand, it can bend a lot of angle, but when I twist it, it will easily break and crack. Is this because of the properties of the resin? I can confirm that my blending ratio is no problem, why does it have such a problem? Or there are no other rubber-like resins, I would like to take to make a flexible resin mold, for casting silicone hand ring.I'm trying to use PX30 to make a flexible mold, this resin is very flexible, but his tear resistance is poor, I bend it with my hand, it can bend a lot of angle, but when I twist it, it will easily break and crack. Is this because of the properties of the resin? I can confirm that my blending ratio is no problem, why does it have such a problem? Or there are no other rubber-like resins, I would like to take to make a flexible resin mold, for casting silicone hand ring.

You are almost certainly just reaching the limit of what the resin is capable of.  Twisting and tearing it putting a lot of force in multiple directions hence you can rip chunks out of it, yet with a simple bending force it bends fine.

If you compare the mechanical data you are looking at  test figures of  tear strength being 3.5 kN/m for the PX30 where as a good quality RTV Silicone is in the 15kN/m ball park.

So what that means is in practice a typical silicone has 4 times the tear strength, so try not to compare the PX30 directly with a silicone and just be a bit more careful during the demoulding process to avoid tearing the rubber.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant