Sulfamic acid-intercalated MgAl-layered double hydroxide (SA-LDH) was prepared and added with aluminum phosphinate (AlPi) into polyamide 11 (PA11). The results showed that AlPi/SA-LDH made a positive contribution to both flame retardancy and thermostability, and the effect was demonstrated with the limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimetry (CONE), and thermogravimetric analysis (TGA). The char morphologies were observed by SEM, and its chemical composition was investigated by Fourier transform infrared spectroscopy (FTIR). The decomposition mechanism was examined by TGA-FTIR. The results showed that the LOI of PA11 was only 23.0 and cannot pass any UL-94 rating. The addition of 20% AlPi increased the LOI to 31.5 and passed the UL-94 V-1 rating, and AlPi/SA-LDH 15%/5% increased the LOI to 32.4 and also passed the UL-94 V-1 rating. The CONE results revealed that 20% of either AlPi or AlPi/SA-LDH brought about a 30% decrease in the peak heat release rate (pHRR). The contribution of SA-LDH to flame behavior was especially reflected in the postponement of pHRR. SEM showed that the char morphologies became denser after SA-LDH incorporation. The improvement in thermal stability of the AlPi/SA-LDH combination was documented by TGA in both N₂ and air atmospheres. The mechanical performance deterioration caused by AlPi was partly improved by SA-LDH. The storage modulus (E′) below the T_g of AlPi/SA-LDH 15%/5% was about 300 MPa higher than with 20% AlPi. This was attributed to a compatibility improvement. The interaction forces among PA11, AlPi, and SA-LDH were probed by X-ray photoelectron spectrometry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43370.

Dihydrogen phosphate anion-intercalated layered double hydroxides (M-LDHs) was prepared by modification of Mg-Al-CO₃²⁻ layered double hydroxides (LDHs) with anion exchange procedure. The structure of the M-LDHs was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscope (TEM). Polypropylene (PP)/LDHs and PP/M-LDHs composites were prepared by melt compounding. The morphology of PP composites was investigated by TEM and XRD, which demonstrated that M-LDHs could be well dispersed in PP matrix to form a nano-scale exfoliated structure. Thermogravimetric analysis showed that thermal stability of PP composites was improved by the presence of LDHs and M-LDHs. The flammability of PP composites was characterized by limited oxygen index, vertical burning test (UL-94), FTIR, and cone calorimeter test, and the result showed the fire performance were significantly improved after the addition of LDHs and/or M-LDHs which can remarkably decrease the heat release rate, total heat release, and the fire performance index. It was proposed that the lamellar structure of LDHs can block the heat, dilute the flammable gases and decrease the temperature, while the replaced H₂PO₄⁻ into LDHs molecules can enhance the charred layer formation during burning procedure. Inductively coupled plasma mass spectrometer analysis showed that most phosphorus remained in the char layer, suggesting the replaced H₂PO₄⁻ in LDHs molecules mainly function in the condensed phase. POLYM. COMPOS., 36:2230–2237, 2015. © 2014 Society of Plastics Engineers

Exfoliatied kaolinite (E-Kaol) was prepared by intercalating DMSO and KAc into kaolinite successively followed by irradiation under ultrasonic. The modified kaolinite was then introduced to polypropylene (PP) by melt blending in order to improve the fire performance of the composite. The flammability and thermal behaviors of PP composite were analyzed by limit oxygen index, vertical burning test, cone calorimeter test, and thermal-gravimetric analysis, respectively. The microstructure of PP composites was characterized by Fourier-transformed infrared spectroscopy, X-ray diffraction, and scanning electron microscope (SEM). It was demonstrated the presence of only 1 phr E-Kaol could improve the LOI values of PP/MCAPP/ATH composite from 26.4 to 28.0, and decrease the peak value of heat release rate and smoke production rate of the PP/MCAPP/ATH by 60.7% and 39.1%, respectively, compared with that of PP sample. Morphology analysis by SEM showed that E-Kaol in PP composite was beneficial to forming rigid and compact char structure. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41761.

Kaolin clay was introduced into an intumescent flame retardant (IFR) system containing ammonium polyphosphate as an acid source and pentaerythritol as a carbonization agent in order to improve the thermal stability and flame retardancy of polypropylene (PP) composite. The flame retardancy and smoke suppression was evaluated by the limiting oxygen index, vertical burning UL-94, and cone calorimeter (CONE) tests. The limiting oxygen index value was increased from 30 to 33 at the presence of 2 phr kaolin. The peak heat release rate value decreased from 1002 kW/m² of neat PP to 318 kW/m² of PP/40 phr IFR and then to 222 kW/m² of PP/38 phr IFR/2 phr kaolin. The time of the peak heat release rate was significantly prolonged after the introduction of kaolin. The morphology of char after combustion was characterized by a scanning electron microscope, and it revealed more compact char structure that was obtained at the presence of kaolin. The mechanism of kaolin on improving the retardancy and smoke suppression of PP/IFR composite was proposed on the basis of X-ray photoelectron spectroscopy analysis. Copyright © 2014 John Wiley & Sons, Ltd.

Mg-Al-H₂PO₄^– layered double hydroxides (LDHs) was prepared by anion exchange method, and polypropylene (PP)-LDH composites were prepared by melt compounding. The dispersion of LDH in PP matrix was characterized by Transmission electron microscope and X-ray diffraction (XRD), and the results showed that both exfoliation structures and aggregation structures can be found in the composites. The effects of LDH on the crystal behaviors of PP was investigated by XRD and Differential scanning calorimetry (DSC), and it indicated that LDH can induce the formation of β crystal and serve as a heterogeneous nucleating agent in PP. The significant decrease of both the crystallization and the melting enthalpy (ΔH_c and ΔH_m) was observed in PP composite at the presence of LDH platelets. Both the peak heat release rate and total heat release (THR) were significantly decreased after the addition of treated LDH. The possible chemical structural change in the condensed phase of PP composite during heating was studied by Fourier transform infrared spectroscopy (FT-IR). The mechanism of modified LDH in improving the fire performance of PP and the possible relationship between flame retardancy and crystal behavior have been proposed and discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3645–3651, 2013