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TPGOA Technical Insights

Styrenic Rubber Triblock Polymers for PP modification

There are many ways to increase the impact strength and elongation of PP Homoplymers. Traditionally, PP Homopolymers are not very impact-resistant. This limits their use in many applications that require good impact strength. They can be modified by blending with impact modifiers.

A commonly-used product is sold under the tradename of Engage. These are butane- and octane-based polyethylene copolymers which are not suitable for higher temperature applications due to their relatively low melting points. Additionally, you do not see a large increase in impact-resistance, even at very high loading levels.

A far better choice for increasing impact-resistance and elevated temperature creep-resistance, is the use of Styrenic Rubber Triblock Polymers. These products contain styrene to rubber ratios from 13 to 26%. The unique modification method is essentially a cross-linked rubber phase, that is resistant to elevated creep temperatures, until a very high temperature of 150 C is reached or exceeded.

These crosslinks disappear at these temperatures and above, allowing the product to be melt-processable. The crosslinked structure also allows for consistent impact values from very low to very high temperatures.

The products tend to be a bit costly, however, in most cases, they can be used at lower loading levels, thus mitigating the premium paid.

TPG makes every effort to insure that the information contained herein is accurate - however, we accept no liability for the content of this piece, or for the consequences of any actions taken on the basis of the information provided.
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