Si Chon Lao

Flame Retardant Polyamide 11 and 12 Nanocomposites: Thermal and Flammability Properties

Polyamide (nylon) 11 (PA11) and 12 (PA12) were melt-blended, dispersing low concentrations of nanoparticles, namely nanoclays (NCs), carbon nanofibers (CNFs), and nanosilicas (NSs) via twin-screw extrusion. To enhance their thermal and flame-retardant (FR) properties, an intumescent FR additive was added to the mechanically superior NC and CNF PA11 formulations. For neat and nanoparticle-reinforced PA11 and PA12, as well as for PA11 reinforced by both intumescent FR and select nanoparticles (NC or CNF), decomposition and heat deflection temperatures were measured, as were the peak heat release rates while burning the composites. All PA11 polymer systems infused with both nanoparticles and FR additive had higher decomposition temperatures than those infused with solely FR additive. For the PA11/FR/NC polymer blends, only the 20 wt% FR and 7.5 wt% clay formulation passed the UL 94 V-0 requirement, while all PA11/FR/ CNF formulations passed UL 94 V-0 requirement.

Flame-retardant polyamide 11 nanocomposites: further thermal and flammability studies

Polyamide (nylon) 11 (PA11) were melt-blended by dispersing low concentrations of nanoparticles (NPs), namely nanoclays (NCs) and carbon nanofibers (CNFs) via twin-screw extrusion. To enhance their thermal and flame retardant (FR) properties, an intumescent FR additive was added to the mechanically superior NC and CNF PA11 formulations. For neat and NP-reinforced PA11 as well as for PA11 reinforced by both intumescent FR and select NPs (NC or CNF), decomposition temperatures by TGA, flammability properties by UL 94, and cone calorimetry values were measured. All PA11 polymer systems infused with both NPs and FR additive had higher decomposition temperatures than those infused with solely FR additive. For the PA11/FR/NC polymer blends, Exolit® OP 1312 (FR2) is the preferred FR additive to pass the UL 94 V-0 requirement with 20 wt%. For the PA11/FR/CNF formulations, all Exolit® OP 1311 (FR1), OP 1312 (FR2), and OP 1230 (FR3) FR additives passed the UL 94 V-0 requirement with 20 wt%.

Flame-retardant Polyamide 11 and 12 Nanocomposites: Processing, Morphology, and Mechanical Properties

The objective of this study is to develop improved polyamide (nylon) 11 (PA11) and 12 (PA12) polymers with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering rapid manufacturing. PA11 and PA12 were melt-blended, dispersing low concentrations of nanoparticles, namely nanoclays (NCs), carbon nanofibers (CNFs), and nanosilicas (NSs) via twin-screw extrusion. To enhance their thermal and flammability properties, an intumescent flame retardant (FR) was added to the mechanically superior NC and CNF PA11 formulations. NC or CNF additions to either PA11 or PA12 generally increased its tensile strength and modulus, but sharply reduced its elongation at rupture. FR additives reduced PA11’s properties considerably. This substitution, however, only exacerbated the already steep drop in elongation at rupture due to FR additives alone; while elongation dropped 58% with the addition of 30 wt% FR, it dropped 98% with the addition of 25 wt% FR/5 wt% CNF.

Processing and characterization of cyanate ester- MWNT nanocomposites

In this study, a low viscosity, high performance cyanate ester (CE) resin system was used with non-functionalized and functionalized multiwall carbon nanotubes (MWNTs) to create cyanate ester-MWNT nanocomposites. Effects of three different standard functionalizations (i.e. ‐OH, -COOH, and -NH 2 ) of MWNTs on their dispersion into the CE resin will be studied. Different mixing instruments, such as a high shear mixer, ultrasonicater, planetary mixer, etc. were used to disperse the nanotubes in the cyanate ester resin matrix. Several processing parameters were examined to produce optimal uniform dispersions of nanoparticles into the resin matrix. The parameters studied were mixing speed and duration, and the combination of different mixing techniques. Polymer nanocomposites (PNCs) morphological microstructures were characterized by transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HR-SEM) to determine whether nanotubes are distributed uniformly within the polymer matrix. Thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC) were used to study the thermal stability and combustion characteristics of these nanocomposites. Dynamic mechanical thermal analysis (DMTA) was used to determine the glass transition temperature (T g ) of the PNCs.

Flame Retardant Intumescent Polyamide 11-Carbon Nanofiber Nanocomposites: Thermal and Flammability Properties

Current polyamide 11 and 12 are lacking in fire retardancy and high strength/high heat resistance characteristics for fabricated parts that are required for performance driven applications. The introduction of selected nanoparticles such as carbon nanofibers (CNFs), combined with a conventional intumescent flame retardant (FR) additive into the polyamide 11/polyamide 12 (PA11/PA12) by melt processing conditions has resulted in a family of intumescent polyamide nanocomposites. These intumescent PA11 and PA12 nanocomposites exhibit enhanced polymer performance characteristics, i.e., fire retardancy, high strength, and high heat resistance and are expected to expand the market opportunities for resin manufacturers. The overall objective of this research is to develop improved PA11 and PA12 polymers with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing. Arkema RILSAN® PA11 polymer was examined with CNFs and Clairant Exolit® OP 1230 intumescent FR additive. They were used to create a family of FR intumescent PA11-CNF nanocomposites. Transmission electron microscopy (TEM) was used to determine the degree of CNFs and intumescent FR additive dispersion in PA11. Injection molded specimens were fabricated for material properties measurements. Thermal stability of these polymer nanocomposites (PNs) was examined by TGA. Flammability and thermal properties of these PNs were obtained using the cone calorimeter, UL 94 test method, and heat deflection temperature.

Performance of Clays, Carbon Nanofibers, Multi-walled Carbon Nanotubes, and Nano-alumina in Polyamide 11 Nanocomposites

The objective of this research is to develop an improved polyamide 11 polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering rapid manufacturing. In the present study, a nanophase was introduced into the polyamide 11 and combine with a conventional intumescent flame retardant (FR) additive via twin screw extrusion. Polyamide 11 polymer pellets were blended separately with chemically modified montmorillonite nanoclays (NCs), or carbon nanofibers (CNFs), or multi-walled carbon nanotubes (MWNTs), or nano-alumina (NA) and an intumescent FR additive to create a family of intumescent FR polyamide 11 nanocomposites. Transmission electron microscopy (TEM) analyses indicated good dispersion of individual nanoparticles and intumescent FR additives were achieved in the polymer matrix. Injection molded specimens were fabricated for physical, thermal, flammability, and mechanical properties characterization. Thermal stability of these polyamide 11 nanocomposites was examined by TGA. All systems of polyamide 11 containing nanoparticles and FR additive have higher decomposition temperatures than those compositions with solely nanoparticles or FR additive alone. None of the nanoparticles alone was able to pass UL 94 V-0 rating. Selective FR-PA11-nanoclay and FR-PA11-CNF nanocomposites passed the UL 94 V-0 requirement and suggest synergism between FR and selected nanoparticles. Some trends and relationships were observed between the results of TGA, UL 94, heat deflection temperature, and cone calorimetry.