Browsing by Subject "Flame retardant"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Flame retardant nylon 6 nanocomposite fibers : processing and characterization(2016-08) Wu, Hao, Doctorate in materials science and engineering; Krifa, Mourad; Koo, Joseph H.; Li, Wei; Ellison, Christopher J; Chen, Jonathan YOne type of engineering thermoplastic polymers that has significant commercial application is nylon. However, flammability and melt dripping is a major problem for polymers like nylon 6 because it can cause fire to spread to other flammable objects and escalate the fire in a short amount of time. Although high performance inherently flame-retardant (FR) fibers have been discovered and various durable FR finishes for nylon have been developed, cost-effective flame retardant nylon and nylon blend fabrics remain a challenge. The goal of this research is to develop non-drip inherently FR nylon 6 fibers as a cost-effective alternative for use in high volume FR fabrics. In this dissertation, a cost effective alternative of producing non-drip inherently flame retardant nylon 6 fibers with balanced performances was developed based on polymer nanocomposite systems incorporating intumescent FR and nanoclay additives. Nanoclay was added to the system to reduce FR particle loading and capitalize on the synergistic effect between nanoclay and intumescent additives. Adequate dispersion of the additives with exfoliation of the nanoclay platelets was observed using TEM and XRD. Injection molding was used as a tool for screening the performance of the nanocomposite formulations in bulk form before the fiber spinning process. Results of injection molded FR PA6 nanocomposites suggest that although a good FR performance could be achieved, mechanical properties, especially ductility, were significantly compromised. To solve this problem, rubber toughening was achieved using a thermoplastic elastomer with significant success in recovering material ductility without compromising FR performance. Ultra-sonication of the FR additives prior the fiber spinning could effectively reduce the FR particle size distribution. Single fiber tensile tests show that PA6/FR/elastomer/nanoclay formulation is able to improve both the tenacity and elongation at break from the original PA6/FR system. Moreover, flammability tests suggest that the nanocomposite FR fibers have significantly lower heat release properties and are able to retain a fibrous shape after combustion indicating the non-dripping property. Therefore, our experiments have yielded improved non-drip FR properties in PA6 through the infusion of nanoclay and non-halogenated intumescent particles (FR) via co-rotating twin-screw extrusion. One major implication of these results is that with the new non-drip FR nylon 6 fiber, it would be possible to achieve blends with higher nylon content than customary and not compromise the FR performance of the fabric, thus providing a cost effective solution for high-volume applications.Item Flame retardant polyamide 6 nanocomposites and nanofibers : processing and characterization(2012-05) Yin, Xiaoli; Koo, Joseph H.; Krifa, MouradPolyamide 6 (PA6) was melt-blended with an intumescent flame retardant (FR) and nanoparticles (multi-wall carbon nanotubes [MWNTs] and nanoclays) to produce multi-component FR-PA6 nanocomposites. Thermal, flammability properties, char residue morphology, and mechanical properties of FR-PA6 nanocomposites were characterized. The flame retardant properties were enhanced according to UL 94 and microscale combustion calorimeter (MCC) measurements, whereas the thermal stability was decreased. Mechanical properties of the bulk material, especially elongation at break, were severely reduced, with the exception of tensile modulus which increased significantly. FR-PA6 nanofibers were processed via electrospinning. Electrospinnability, morphology of the nanofibers, combustion, and thermal properties were also analyzed. As for the bulk-form nanocomposite, improved combustion properties of these nanofibers were successfully achieved though thermal stability was compromised. With proper FR additive, the synergism between MWNTs and nanoclays was observed in PA6 resin.Item Functional nanocomposite fibers through electrospinning : flame retardant and superhydrophobic(2012-05) Wu, Hao; Krifa, Mourad; Koo, Joseph H.Flame retardant (FR) intumescent additives and montmorillonite (MMT) organoclay incorporated nylon-6 nanocomposite (FR-NC-PA6) fibers with a diameter of about 200 nm were fabricated by electrospinning. Before electrospinning, dispersion and exfoliation of the FR additive and MMT in nylon-6 were achieved by twin-screw extrusion. Tensile, TGA and UL-94 flammability tests were first performed using injection-molded bulk samples. The tensile modulus of FR-NC-PA6 was 45% higher than that of neat PA6, but tensile strength and elongation at break decreased by 23% and 98.7%, respectively. It is worth noting that although the TGA results show that FR-NC-PA6 has a slightly earlier decomposition temperature than neat PA6, it did not drip under fire and had the best rating (V-0) in UL 94 test, while neat PA6 is only rated as V-2. SEM and EDX of char residues after the UL 94 test clearly show the oxygen-rich protective char layer on the surface. These results indicate the advantage of using clay and FR additive in bulk-form PA6. Flammability of electrospun nanocomposite fibers was characterized by Micro-combustion calorimeter (MCC), a small-scale test to screen flammability of polymer materials. The MCC results show that the nano-fillers in both bulk and fiber form could effectively improve flame retardant properties of the material. Electrospun fibers had similar combustion properties as bulk materials. In addition to FR applications, superhydrophobic surface was another area that was explored using the electrospun nanocomposite fibers. Static water contact angle (WCA) test showed that samples with 5wt% clay even without plasma treatment greatly improved the WCA to 140°, probably due to the barrier effect of nanoclay platelets. Plasma treatment was used to modify the surface energy, further improving WCA to as high as 160°. However, fiber structure was partially etched away when overexposed to the plasma. This etching effect increased the surface roughness. Clay incorporated samples had higher level of surface roughness and better resistance to plasma etching compared to neat nylon 6.