Absolutely not. Cork and all building materials included are actually rated on a scientific term called Thermal Conductivity, not R value. R Value is a false marketing scheme. All building materials change in value as the temperature, humidity and altitudes change.
For example: Thermal conductivity of building materials, is measured in how long it takes a certain material to transfer heat / cold energy through it. The longer it takes, the smaller the decimal. The longer it takes for heat energy to go through a material the more (insulation) energy savings it has.
The thermal conductivity of Cork from Diasen is 0.086
Here is an analogy that everyone can understand and could be a fun test for those so inclined: Picture a full aluminum beer can compared to a full glass beer bottle, sitting in the sun. Put them in a cooler of ice! The beer can will always be cooler to begin with and it will cool off much quicker once placed on the ice. How significant is this difference? The difference would be Aluminum has a thermal conductivity rating of 237.0 The Glass 0.93 (FYI Copper 390.0) The aluminum is able to dissipate the heat even in the sun! Now there is a lot of difference isn’t there? My beer is going to be way colder quicker in the can, and I didn’t melt all the dam ice in my cooler trying to cool off my beer with the aluminum cans. This difference is huge when I want my beer cold and I want the ice to last all day or weekend.