ADDITIVES | NUCLEATORS AND CLARIFIERS
Electron micrographs show foam cell size distribution using LNP ColorComp WQ117945 PET compound (right) compared to a traditional nucleation system (left)
Source: SABIC
Crys-Talc will act as a reinforcing additive, increas- ing stiffness almost linearly with talc content. The Imerys nucelation portfolio also includes
Steagreen talc, which is targeted at recycled polymers. It acts as a nucleating and reinforcement agent for the PP fraction in post-consumer recycled resin. And the company’s HAR talc is also frequent- ly used for nucleation of biopolymers such as PLA, PBS and PHA. “Talc is used mainly to enhance crystallisation speed, which is usually quite low for some of those bio-based polyesters,” says Schmidt.
Improving foams For nucleation of polymer foams, Imerys recom- mends its Mistrocell talc grades. “In this application the talc particles act as a seed for growing foam bubbles, in addition to acting as a powerful polymer crystallisation promotor,” Schmidt says. A key role of nucleating agents in plastics foams is to help create a uniform cell structure. “Good foam nucleation allows a cellular structure in the finished good that is a closed structure that is as small and evenly dispersed as possible. The improved use of the gas via foam nucleation helps to attain greater density reduction while retaining key properties like stiffness and strength. Talc, calcium carbonate and chemical nucleation agents are all candidates. Particle size of the nucleator and its ability to disperse will influence nucleation as well,” says Peter Schroeck, President of Reedy Chemical Foam. “Foam bubble nucleation must consider the nucleation (non-foam nucleation) package of the PP itself. We have designed products that consider the effect of foaming agents in PP formulas.” Cristina Arroyo, Manager of New Products and
R&D at Cellmat Technologies in Spain, agrees that polymer, blowing agent, and foaming technology must all be considered when designing a foam nucleating system. She says that while traditional
64 COMPOUNDING WORLD | June 2021
foaming solutions are functional, there is scope for significant improvement to develop nucleating systems based on a deeper understanding of nucleation phenomena, as well as considering dispersion. “We have developed several nucleating systems based on nanoparticles and on organic phases that are extremely efficient in reducing the cell size several times in XPS, PU, PE and PP based foams,” she claims. Meanwhile, the newly-launched LNP ColorComp WQ117945 compound from SABIC is designed to improve control over nucleation and cell growth in PET foams used as core materials in sandwich structures. The resulting decreased cell size and uniform, narrower cell size distribution can reduce the foam’s weight by minimising resin uptake in sandwich structures and can potentially improve shear strength/strain properties for better fatigue performance, the company says. It claims that, compared to conventional talc nucleating agents, the WQ117945 can reduce foam cell size as much as three-fold and decrease cell size disparity by a factor of up to five. PET foams can be used, for example, as cores in wind turbine blades, where lightweighting and strength are key. The company says that the nanotechnology nucleating agent can be used in other polymers as well.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.milliken.com �
www.amfine.com �
www.adeka.co.jp/en �
www.jacobypolymer.com �
www.mayzo.com �
https://constab.com �
www.CAIadditives.com �
www.imerys.com �
www.reedychemicalfoam.com �
www.cellmattechnologies.com �
www.sabic.com
www.compoundingworld.com
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