One product - a whole range of characteristics
EVM without vinyl acetate would in effect be polyethylene (PE). And EVM without ethylene would be polyvinyl acetate. Both of these are thermoplastic materials. However, there are a wide range of technical possibilties between these two extremes.
At a glance
- As robust as polyethylene thanks to saturated backbone
- Excellent characteristics typical of rubber from 40 percent vinyl acetate content upwards
- High oil resistance
- Compatible with high levels of polar fillers such as silica
For example, statistical mixing of vinyl acetate (VA) and ethylene components during the Levapren® synthesis process at ARLANXEO results in an extremely flexible chain molecule that is a lot less rigid than of polyethylene or brittle polyvinyl acetate (PVA). With a vinyl acetate content of between around 40 and 70 percent, the material behaves like a perfect elastomer, resulting in a highly resistant rubber material with the robustness of polyethylene.
Integrating vinyl acetate components into the non-polar polyethylene chain results in further adavantages. Each percentage of VA makes the polymer more polar. Pure vinyl acetate is almost as polar as polyvinyl chloride (PVC). For example, the oil resistance of Levapren® increases with the VA content. EVM grades with a high vinyl acetate content hardly even swell in hot oil baths.
The polarity can also be adjusted using the VA content which ensures excellent compatibility with polar fillers such as silica or other polar polymers such as PVC. For this reason, Levapren® is also an ideal polymeric plasticizer (i.e. a plasticizer which cannot be washed out) for this popular plastic.
Moreover, the glass transition temperature of the polymer changes as the VA content increases. With 50 percent vinyl acetate, the glass transition temperature is almost permanently under -30 °C. With higher VA content, this temperature increases to up to 0 °C at 80 percent VA.