Polypropylene with and without Ammonium Phosphate Flame Retardant by TGA-GC/MS-FTIR

Introduction

Thermal analysis is frequently used to assess the effectiveness of different flame-retardants added to polymeric material. The interaction of flame retardants with the chemical environment during pyrolysis was readily investigated by TGA coupled to FTIR and GC/MS. FTIR easily identifies functional groups (e.g. those of alcohols or aromatic substances, etc.), permitting conclusions to be drawn about the decomposition products involved. On the other hand, FTIR is less suitable when the IR spectra of simultaneously emitted decomposition gases overlap. In such cases, a TGA coupled to a GC/MS by means of a heated storage interface (IST16) is preferred as it can unequivocally identify compounds evolved at a particular temperature.

As both techniques often provide complimentary data, it is recommended to use them in combination as shown in Figure 1. The following application illustrates the effectiveness of TGA-IST-GC/MS-FTIR for characterizing polypropylene (PP) samples with and without flame retardant (FR).

Sample: Two PP samples with and without FR:

• Reference polypropylene (PP-ref) without FR
• Polypropylene (PP-FR) containing 20% EXOLIT AP760 (ammonium polyphosphate) and 10% calcium carbonate (CaCO₃)

Measuring cells: TGA/DSC-IST-GCMS-FTIR

^{Polypropylene with and without Ammonium Phosphate Flame Retardant by TGA-GC/MS-FTIR | Thermal Analysis Application No. HB 624 | Application published in METTLER TOLEDO TA Application Handbook Evolved Gas Analysis}