CLARIFIERS AND NUCLEATORS | ADDITIVES
Whether to improve clarity or to enhance physical properties, application of clarifier and nucleator additives continues to grow. Mark Holmes learns more
Making a clear difference
Clarifiers and nucleating agents improve the performance of plastics and can considerably expand their range of applications. Advanced nucleators can enhance stiffness, providing scope for weight savings and improving physical proper- ties. This can, for example, allow PP to be substi- tuted for heavier and more expensive materials such as PS or PET. Meanwhile, clarifiers, as the name suggests, allow polymers such as PP to be used in applications requiring high clarity in place of amorphous polymers such as PS, PC, PET and PVC, and in some cases glass. This article takes a look at some of the latest developments. Nucleating agents are widely used in PP to
improve both physical and optical properties. “The improved stiffness and strength of nucleated PP and the faster achievable cycle times in moulding and extrusion lead to down-weighting and cost savings. Nucleated PP also exhibits higher heat deflection temperatures allowing it to be used in more demanding, high temperature applications,” says Dr Philip Jacoby, independent consultant and President of Jacoby Polymer Consulting. “In recent years, nucleating agents have been introduced that achieve higher clarity, higher
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stiffness, and a reduction in warpage and shrink- age. Another growing trend has involved the use of special nucleating agents that can induce the formation of a different crystal phase of PP, known as the beta crystal phase. These beta nucleants have been used to further improve certain physical properties and have also led to unique products such as microporous films used in the manufacture of protective clothing and lithium ion batteries,” he says. Nucleators are most commonly employed to
increase the stiffness and tensile strength in moulded parts, with cost reduction a key goal. “High modulus or stiffness is especially important in automotive applications, where PP is the most widely used plastic. Higher modulus allows the part to be down-weighted by reducing the wall thick- ness while still retaining high rigidity. This allows the part weight to be reduced, and lower weight leads to higher automotive fuel efficiency,” Jacoby says. “In addition, the main factors driving new technical developments include the desire to downgauge and reduce cost, substitute PP for more expensive polymers, and reduce the environ- mental impact of the PP part.”
� June 2020 | COMPOUNDING WORLD 45
Main image: Clarifiers such as Milliken’s Millad NX 8000 can enhance the clarity of PP while reducing process energy requirements and speeding cycle times
IMAGE: MILLIKEN
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