additives feature | Fire retardants
60 50 40 30 20 10 0
compared to the neat polymer. The decrease was more than 30% for PS. Synergistic effects were noted with nanosilica composites, whereby such composites had more than a 50% reduction in peak heat-release rates. According to the researchers, in a typical application
the polymer is first dry-mixed with PHA or PMeOA at a loading of between 1 and 20%/wt prior to compounding. Further information on the work is available from the Kennedy Innovative Partnerships Office.
reference
dePal (20%)
loI mVr
dePal/ acT 200 Sm
(15/5%) charpy
dePal/ acT 200 Sm
(12/8%)
dePal/ acT 200 Sm
(10/10%) charpy (notched)
NabalTec’S acTIlox 200 Sm gIVeS a good balaNce of ProPerTIeS wheN uSed To ParTIally rePlace dePal IN PbT
70 60 50 40 30 20 10 0
Selecting synergists Nabaltec is expanding the use of its Apryral high- temperature mineral fillers based on aluminium oxide hydrate (AOH), also known as boehmite, for use as FR synergists. They are used in engineering resins, such as nylon and PBT, to create compounds with thermal stability as high as 340o
C. The company recently
introduced Actilox B, a boehmite-type based FR, aimed at substituting as much phosphorus FR as possible in PBT and nylon while retaining mechanical properties. Recent results show that Actilox B can substitute a
loI charpy
certain amount of DEPAL (aluminium salt of diethyl phosphinic acid), which is not only in short supply but also can result in the formation of corrosive by-products during compounding and/or injection moulding, explains Dr. Oliver Toepfer, sales and technical services regional manager for functional fillers. In fact, boehmite has been demonstrated to act as an acid scavenger for these by-products. Nabaltec has also developed surface-treated grades
of Actilox B that have been shown to be very effective in boosting the flame-retardant performance of both PBT and nylon 66 formulations. According to Toepfer, this can provide compounders with added flexibility to reduce the overall FR additive level to either improve the mechanical properties or to fulfil higher flame retardancy requirements for special applications.
NabalTec’S Surface modIfIed acTIlox b 60 aS1 comPared To dePal IN PbT
preventing vaporisation of the polymer, and cooling through the formation of chemical bonds in either the vapour or condensed phase. Under thermal stress, the cyclic hydroxyl/methoxy component forms polybenzoxa- zole (PBO) in a reaction that absorbs heat from its surroundings. PBO under thermal stress cross-links, forming a protective char layer, which thermally insulates the polymer. The researchers report that PMeOA derivative
formulations used as an FR additive in nylon and PS resulted in notable reduction in peak heat-release rates
42 COMPOUNDINg wORLD | December 2011
Key trends in FR compounds Scott Fallon, general manager of global specialty products at Sabic Innovative Plastics cites three key trends that are driving new developments in flame retardant compounds in the diverse industries that the company serves. l Thinner walls/ lighter weight: As the manufacturers of consumer electronics, automobiles and medical devices seek to introduce lighter and more compact products, there is an increasing need for flame retardant materials that will help designers push existing boundaries. SABIC’s Innovative Plastics business will be announcing three new grades of Lexan PC resin which are UL SVA-compliant early in 2012. They are designed to deliver clear, thinner-wall, lighter-
www.compoundingworld.com
PbT gf20 depal 20%
dePal/acT b60//15/5 dePal/acT b60 aS1//15/5
dePal/acT b60//12/8 dePal/acT b60 aS1//12/8
dePal/acT b60//10/10 dePal/acT b60 aS1//10/10
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