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Polymer foams | additives feature


help disperse filler particulates and blowing agents, which helps improve cell size and structure. Coupled filler particulates reduce the tendency of particulates to act as a failure point in bubble formation.


Melt-enhancing additives Good melt strength is necessary for producing and maintaining a foamed cellular structure. Melt strength can be improved with high molecular weight acrylic polymers that act as foam cell stabilizers, such as Dow’s SureCel and Arkema’s Plastistrength. Arkema also offers Biostrength acrylic polymers for PLA. In polyester resins, processing causes chain scission


and CFAs can cause further degradation, leading to reduced melt strength. Melt-enhancing additives counteract chain scission by knitting chains back together. For example, BASF’s Joncryl functional additives contain reactive epoxy functional groups that create chain extension and branching. Clariant Master- batches’ CESA-extend can be used in combination with its CFAs to repair broken polymer chains and improve melt strength. Titanate and zirconate coupling agents also catalyze chain building and branching, notes Salvatore Monte, president of Kenrich Petrochemicals. Material selection trends are driving increased use of melt-enhancing additives for improving foaming. First, the use of post-industrial and post-consumer recyclate is growing, and additive suppliers are seeing more projects looking at increased levels of regrind or recyclate. These reprocessed materials typically have experienced some degradation, causing melt strength loss that is detrimental to the foaming process. Second, in foamed film and sheet extrusion, improved melt strength may be needed to enable downgauging and prevent the thinner web from breaking during extrusion. Clariant Masterbatches’ CESA-extend, for example, is finding use in improving melt strength in thin-gauged, foamed PET sheet. Finally, poor melt strength is an inherent problem in some biobased materials, such as


PLA, and suppliers see increasing interest in melt- enhancing additives for these resins as they grow in use.


More information The proceedings for the Polymer Foam 2012 conference are now on sale at: http://bit.ly/PFoam2012. AMI’s Polymer Foam 2013 conference will be held in Europe in the final quarter of this year. For more information contact Dr Sally Humphreys, sh@amiplastics.com, +44 117 924 9442.


Click on the links for more information: ❙ www.appliedminerals.comwww.arkema.comwww.basf.comwww.clariant.comwww.colormatrix.comwww.dow.comwww.imerys.comwww.interfacialsolutions.comwww.4kenrich.comwww.reedyintl.com


Interfacial Solutions


carried out tests on


nucleating agents using a Leistritz 27 mm twin-screw extruder


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