Intumescent Flame Retardant Polyamide 11 Nanocomposites

Current polyamide 11 and 12 are lacking in fire retardancy and high strength/high heat resistance characteristics for a plethora of fabricated parts that are desired and required for performance driven applications. The introduction of selected nanoparticles such as surface modified montmorillonite (MMT) clay or 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 the preparation of a family of intumescent polyamide nanocomposites. These intumescent polyamide 11 and 12 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 polyamide 11 and polyamide 12 polymer manufacturers. The objective of this research is to develop improved polyamide 11 and 12 polymers with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing (RM). In the present study, a nanophase was introduced into the polyamide 11 and combining it with a conventional intumescent FR additive via twin screw extrusion. Arkema RILSAN® polyamide 11 molding polymer pellets were examined with two types of nanoparticles: chemically modified montmorillonite (MMT) organoclays, and carbon nanofibers (CNFs); and Clairant’s Exolit® OP 1230 intumescent FR additive were used to create a family of FR intumescent polyamide 11 nanocomposites. Transmission electron microscopy (TEM) was used to determine the degree of nanoparticles dispersion. Injection molded specimens were fabricated for physical, thermal, and flammability measurements. Thermal stability of these intumescent polyamide 11 nanocomposites was examined by TGA. Flammability properties were obtained using the Cone Calorimeter at an external heat flux of 35 kW/m 2 and UL 94 Test Method. Heat deflection temperatures (HDT) were also measured. TEM micrographs, physical, thermal, and flammability properties are presented. FR intumescent polyamide 11 nanocomposites properties are compared with polyamide 11 baseline polymer. Based on flammability and mechanical material performance, selective polymers including polyamide 11 nanocomposites and control polyamide 11 will be cryogenically ground into fine powders for SLS RM processing. SLS specimens will be fabricated for thermal, flammability, and mechanical properties characterization.Mechanical Engineerin

Innovative Selective Laser Sintering Rapid Manufacturing using Nanotechnology

The objective of this research is to develop an improved nylon 11 (polyamide 11) polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing (RM). A nanophase was introduced into nylon 11 via twin screw extrusion to provide improved material properties of the polymer blends. Atofina (now known as Arkema) RILSAN® nylon 11 injection molding polymer pellets was used with three types of nanoparticles: chemically modified montmorillonite (MMT) organoclays, nanosilica, and carbon nanofibers (CNF) to create nylon 11 nanocomposites. Wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) were used to determine the degree of dispersion. Fifteen nylon 11 nanocomposites and control nylon 11 were fabricated by injection molding. Flammability properties (using a cone calorimeter with a radiant flux of 50 kW/m2 ) and mechanical properties such as tensile strength and modulus, flexural modulus, elongation at break were determined for the nylon 11 nanocomposites and compared with the baseline nylon 11. Based on flammability and mechanical material performance, five polymers including four nylon 11 nanocomposites and a control nylon 11 were cryogenically ground into fine powders for SLS RM. SLS specimens were fabricated for flammability, mechanical, and thermal properties characterization. Nylon 11-CNF nanocomposites exhibited the best overall properties for this study.Mechanical Engineerin

Pressure-stabilized tin selenide phase with an unexpected stoichiometry and a predicted superconducting state at low temperatures

published_or_final_versio

Comparison of chemical profiles and effectiveness between Erxian decoction and mixtures of decoctions of its individual herbs : a novel approach for identification of the standard chemicals

Acknowledgements This study was partially supported by grants from the Seed Funding Programme for Basic Research (Project Number 201211159146 and 201411159213), the University of Hong Kong. We thank Mr Keith Wong and Ms Cindy Lee for their technical assistances.Peer reviewedPublisher PD

Flame Retardant Intumescent Polyamide 11 Nanocomposites – Further Study

The objective of this research is to develop improved polyamide 11 and 12 polymers with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing (RM). 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. Arkema Rilsan® polyamide 11 molding polymer pellets were used with two types of nanoparticles such as: chemically modified montmorillonite (MMT) organoclays and carbon nanofibers (CNFs). Two types of Clariant’s Exolit® OP 1311 and 1312 intumescent FR additives were used to generate a family of FR intumescent polyamide 11 nanocomposites with anticipated synergism.Mechanical Engineerin

Polyamide 11-Carbon Nanotubes Nanocomposites: Preliminary Investigation

The objective of this research is to develop an improved polyamide 11 (PA11) polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing. In the present study, a nanophase was introduced into polyamide 11 via twin screw extrusion. Arkema Rilsan® polyamide 11 molding polymer pellets were used with 1, 3, 5, and 7 wt% loadings of Arkema’s GraphistrengthTM multi-wall carbon nanotubes (MWNTs) to create a family of PA11-MWNT nanocomposites. Transmission electron microscopy and scanning electron microscopy were used to determine the degree and uniformity of dispersion. Injection molded test specimens were fabricated for physical, thermal, mechanical properties, and flammability measurements. Thermal stability of these polyamide 11-MWNT nanocomposites was examined by TGA. Mechanical properties such as ultimate tensile strength, rupture tensile strength, and elongation at rupture were measured. Flammability properties were also obtained using the UL 94 test method. All these different methods and subsequent polymer characteristics are discussed in this paper.Mechanical Engineerin

Types of Control in Acupuncture Clinical Trials Might Affect the Conclusion of the Trials: A Review of Acupuncture on Pain Management

published_or_final_versio

Demonstration of high performance negative central magnetic shear discharges on the DIII-D tokamak

Reliable operation of discharges with negative central magnetic shear has led to significant increases in plasma performance and reactivity in both low confinement, L-mode, and high confinement, H-mode, regimes in the DIII-D tokamak. Using neutral beam injection early in the initial current ramp, a large range of negative shear discharges have been produced with durations lasting up to 3.2 s. The total non- inductive current (beam plus bootstrap) ranges from 50% to 80% in these discharges. In the region of shear reversal, significant peaking of the toroidal rotation [f{sub {phi}} {approx} 30-60 kHz] and ion temperature [T{sub i}(0) {approx} 15-22 keV] profiles are observed. In high power discharges with an L-mode edge, peaked density profiles are also observed. Confinement enhancement factors up to H {equivalent_to} {tau}{sub E}/{tau}{sub ITER-89P} {approx} 2.5 with an L-mode edge, and H {approx} 3.3 in an Edge Localized Mode (ELM)-free H-mode, are obtained. Transport analysis shows both ion thermal diffusivity and particle diffusivity to be near or below standard neoclassical values in the core. Large pressure peaking in L- mode leads to high disruptivity with {Beta}{sub N} {equivalent_to} {Beta}{sub T}/(I/aB) {<=} 2.3, while broader pressure profiles in H- mode gives low disruptivity with {Beta}{sub N} {<=} 4.2