Abstract

In this work, polyamide 6 (PA6) composites with improved flame retardancy and thermal conductivity were prepared with different thermal conductive fillers (TC fillers) such as aluminum nitride (AlN) and boron nitride (BN) in a PA6 matrix with aluminum diethylphosphinate (AlPi) as a fire retardant. The resultant halogen-free flame retardant (HFFR) and thermal conductive (TC) PA6 (HFFR-TC-PA6) were investigated in detail with a mechanical property test, a limiting oxygen index (LOI), the vertical burning test (UL-94), a cone calorimeter, a thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of the impact fracture surface and char residue of the composites were analyzed by scanning electron microscopy (SEM). It was found that the thermal conductivity of the HFFR-TC-PA6 composite increased with the amount of TC fillers. The TC fillers exerted a positive effect for flame retardant PA6. For example, the HFFR-TC-PA6 composites with the thickness of 1.6 mm successfully passed the UL-94 V-0 rating with an LOI of more than 29% when the loading amount of AlN-550RFS, BN-SW08 and BN-NW04 was 30 wt%. The morphological structures of the char residues revealed that TC fillers formed a highly integrated char layer surface (without holes) during the combustion process, as compared to that of flame retardant PA6/AlPi composites. In addition, the thermal stability and crystallization behavior of the composites were studied.

Highlights

  • Modified engineering materials have been widely used for electronic devices, automobiles and aerospace applications in the past few decades [1,2,3,4]

  • Ma K. et al [19] reported that when the loading of aluminum diethylphosphinate (AlPi) was 13 wt%, thee limiting oxygen index (LOI) value of the polyamide 6 (PA6)/AlPi composites increased to 30% and passed the UL-94 V-0 rating

  • The halogen-free flame retardant (HFFR)-thermal conductive (TC)-PA6 composites with fire retardant AlPi and different types of TC fillers were compounded by using extrusion and injection molding, and the effect of TC fillers on the mechanical properties, thermal conductivity, flame retardance properties and thermal behavior of the HFFR-TC-PA6 composites were investigated

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Summary

Introduction

Modified engineering materials have been widely used for electronic devices, automobiles and aerospace applications in the past few decades [1,2,3,4]. The electrical components using PA6 are required to have high flame retardancy to avoid fires during electrical breakdown or other abnormal conditions With these considerations, exploring the PA6 composites with both flame retardancy and thermal conductivity is of academic significance and practical value. Ma K. et al [19] reported that when the loading of AlPi was 13 wt%, thee LOI value of the PA6/AlPi composites increased to 30% and passed the UL-94 V-0 rating These reports only focused on the flame retardancy properties of PA6; the thermal conductivity of flame retardant. The HFFR-TC-PA6 composites with fire retardant AlPi and different types of TC fillers were compounded by using extrusion and injection molding, and the effect of TC fillers on the mechanical properties, thermal conductivity, flame retardance properties and thermal behavior of the HFFR-TC-PA6 composites were investigated

Materials
Preparation of HFFR-TC-PA6 Composites
Characterization
Results
Effect
Thermal Analysis
Flammability
Cone with aa heat heat flux flux of of 50
The temperature
Conclusions
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