Non-Hazardous Flame Retardant Synergists for Polymers Robert Leeuwendal Chemspec 2018, Cologne
Content Polymer Structure and Flammability Char formation- model and mechanism Role of synergists in flame retardant systems Examples of Flamtard synergist solutions Conclusions
Polymer Structure and influence on flammability (LOI) Polyethylene 17 Polypropylene 17 Polymethylmethacrylate 17 Polyetheretherketone 38 n Polystyrene 18 Polycarbonate 26 Polytetrafluoroethylene 95 Polyvinylchloride 45 Polyphenylenesulfide 44
Polymer FR Additives general principles ~Br, ~Cl + Sb 2 O 3 Al (OH) 3 Mg(OH) 2 Phosphate based Increasing regulatory pressure on chemicals management and performance requirements (i.e. SBI, smoke) cause established flame retardant solutions to be abandoned or adapted to meet new criteria
Char Formation mechanism and model Oxidative Combustion Pyrolysis Intra-molecular X-ing T Di Blasi and Branca, 2001 Melting / Softening
Char Formation intumescent system Intumescent Protective Coating (aquaeous) Solution Water (30w%) Binder EVA Copol (14w%) Acidic Source Ammonium polyphosphate (25w%) Carbon Source Penta ehrytritol (15w%) Spumific or blowing agent Melamine (16w%) Ratio and concentration of additives determines: Expansion factor Number of foam cells Strength of foam Percentage charring
Degradation Model Problem with Polymer Char: Keeps burning or smoldering if mass and heat transfer are not eliminated Approach: Build improved char structures and charring mechanisms How: Use of synergists Di Blasi and Branca, 2001
Flamtard Synergists for PVC and halogenfree flame retardant systems Synergist Flamtard H Flamtard S Flamtard V Chemical nature Zinc tin oxide Zinc tin oxide Metal doped silicate Function Promotes X-linking Promotes X-linking High temperature flux Particle size 1-2 micron 1-2 micron 4-6 micron Polymer processing < 220 0 C > 220 0 C. > 220 0 C.. Benefits in PVC Low smoke, (partially) replaces Sb2O3 Low smoke, (partially) replaces Sb2O3 Partially replaces Sb2O3 Benefits in HFFR materials Improved char strength and consistency with P flame retardants Improved char strength and consistency with P flame retardants Improved char strength and consistency
Polyurethane Foam synergism with zinc hydroxy stannate Component (phr) PUR PUR/AAP PUR/ZHS PUR/AAP/ZHS PU Silpak 200 A + B 100 85 95 80 Alkyl aryl phosphate/phosphonate 15 15 Zinc hydroxy stannate 5 5 Cone Calorimeter @ 35 k/m 2 Peak rate of Heat Release (kw/m 2) 1079 834 1033 619 Time of Peak RHR (s) 75 76 85 81 Avg heat Release Rate (kw/m 2 ) 349 327 373 294 Total Heat Released (MJ/m 2 /g) 58.8 49.3 62.1 47.7 Avg Mass Loss Rate (g/m 2 s) 21.4 21.8 22.8 16.6 Mass Residue (w%) 7.7 5.9 4.5 9.7 Feng Yang, Gordon Nelson, Florida Institute of Technology, Melbourne, FL 32901
Polyurethane Foam char analysis after cone calorimeter burning Feng Yang, Gordon Nelson, Florida Institute of Technology, Melbourne, FL 32901
Polyamide Engineering Plastic synergism with zinc stannate Component (phr) 1 2 3 4 5 6 7 8 9 PA6T/66 (Vestamid HT) 55 55 55 55 55 55 55 55 55 Glass fiber ( 30 30 30 30 30 30 30 30 30 Alumina di-ethyl phosphinate 7.5 0 15 0 0 7.5 15 11.25 3.75 Zinc stannate 7.5 15 0 15 15 7.5 0 3.75 11.25 Polymer formulations were evaluated on flame retardant properties by UL94VB, 0.8 mm and in tested for rate of heat release, smoke formation in the Cone Calorimeter. Burned test specimen were analysed for char content and morphology. Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103
Polyamide Engineering Plastic synergism with zinc stannate Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103
Polyamide Engineering Plastic synergism with zinc stannate PA6T/66 Flamtard S (85/15) PA6T/66 AliP Flamtard S (85/7.5/7.5) PA6T/66 AliP Flamtard S (85/15/0) Test Specimen Residues after Cone Calorimeter Experiment 50kW/m 2 heat flux Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103
Polyamide Engineering Plastic synergism with zinc stannate Horrocks, Polymer Degradation and Stability, 104, (2014), 95-103
Examples Silicon Elastomer synergism with low melting glass Mechanical strength of chars after burning silicon polymer mica compounds Investigation of the ceramifying process of modified silicone silicate compositions, Mansouri, Burford, J. Mater. Sci., Aug 2007
Conclusions Flamtard synergists are used at low loadings to improve: a. Char formation in PVC and phosphate based FR polymer materials, leading to lower smoke and rate of heat release (Flamtard H, S) b. Barrier properties of char by filling micro cracks, voids, and and build viscosity in the decomposition zone, leading to improved flame retardant mechanisms (Flamtard V)