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This research studied the utilization of biodegradable polymer for nonwoven fabric production and applied to fabricate a sound absorbing panel by corporate with natural fiber nonwoven fabric. PLA was used as a biodegradable polymer and hemp nonwoven was used as a natural fiber nonwoven fabric. PLA nonwoven fabric was prepared using a melt jet spinning process. The spinning process was carried out at 250 and 260°C with screw speed of 10 rpm and air blown pressure of 0.3 and 0.5 MPa. The die-to-collector of fabric production was studied at 30 and 60 cm to compare the nonwoven fabric product property. It was found that the process temperature, air pressure and die-to-collector distance have significant effects on the nonwoven fabric thickness, GSM, and fabric density. Air permeability decreased with high fabric thickness as well as fine fibers which supported the property of sound absorbing panels. Therefore, the suitable conditions for sound absorbing panel fabrication were processed at temperature of 260°C, air pressure 0.5 MPa and die-to-collector distance of 60 cm. Sound absorbing coefficient measurement revealed that GSM fabric thickness had an effect on increasing sound absorption. The effect of nonwoven sheet order and arrangement of PLA nonwoven and hemp nonwoven of 3 layers sandwich indicated that the layers order of PLA/PLA/Hemp had high sound absorbing coefficient that was comparable with PLA/PLA/PLA due to fiber size and arrangement.

PET knitted fabric was melted and cooled by hot pressing at 250 °C to obtain a compacted sheet. Only white PET fabric (WF_PET) was used to study the recycling process by compression and grinding to powder and then melt spinning at different take-up speeds compared to PET bottle grade (BO_PET). PET knitted fabric had good fiber formability and was better suited for melt spinning of recycled PET (r-PET) fibers than the bottle grade. Thermal and mechanical properties of r-PET fibers improved in terms of crystallinity and tensile strength with increasing take-up speed (500 to 1500 m/min). Fading and color changes from the original fabric were relatively small compared with PET bottle grade. Results indicated that fiber structure and properties can be used as a guideline for improving and developing r-PET fibers from textile waste.

Tetraphenyl phosphonium-modified organoclay (TPP-Mt) was prepared by modifying montmorillonite-rich Thai bentonite via ion exchange. TGA results revealed that TPP-Mt possessed high thermal stability, where degradation occurred at a temperature range of 418-576°C. The obtained TPP-Mt/PP nanocomposites exhibited degradation at higher temperatures than PP (410-420°C vs. 403°C). Fibers of different cross-sectional shapes (circular, circular hollow, and cross) containing 1, 2 and 3%wt TPP-Mt were prepared and characterized. Nonwovens of 3%wt TPPMt/PP fibers were fabricated for flame retardant test. From results, nonwovens of TPP-Mt/PP fibers exhibited self-extinguishing characteristic and the areas of burning were less than that of PP nonwoven (14.5-31.6% vs. 95.6%). Nonwovens of cross-shaped fibers showed the best flame retardant property, followed by those of circular hollow and circular fibers. The flame retardant properties observed in nonwovens were explained due to the inter-fiber spaces between cross-shaped fibers and center hole in circular hollow fibers, which could trap initiating radicals inside, thus reducing flame propagation. In addition, large surface area in cross-shaped fibers could help in increasing the flame retardant effectiveness due to more exposure of TPP-Mt particles to the flame. Knowledge obtained in this study offered an approach to produce flame retardant nonwovens via a combination of modified organolcay and fiber shape.

Melt spinning of 50/50 hollow segmented-pie bicomponent fibers, each containing a pair of either poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) or PLA and polypropylene (PP), was conducted to investigate effects of constituent polymers on arrangement and properties of the obtained fibers. PLA/PBS fibers exhibited flat interfaces between PLA and PBS segments, while PLA/PP fibers exhibited curved interfaces having concave-shaped PLA segments and convex-shaped PP segments. The curvature at interfaces was due to the molten low-viscosity PLA encapsulating the high-viscosity PP. The results showed that fiber splitting was complex, and its mechanism depended not only on the properties of each polymer constituent but also interactions between them. PLA/PP fibers exhibited the tendency of fiber splitting due to the incompatibility between PLA and PP as well as an imbalance force at the interface. In PLA/PBS fibers, the fiber splitting was not observed. The balance force of flat interface between PLA and PBS could contribute to the reduction of interfacial tension. In addition, small domain size in a range of 3–5 µm could favor compatibility between the PLA and PBS segments. Observations from this study suggested a possibility of employing segmented-pie configuration as an alternative approach for developing PLA/PBS fibers of high PBS content without phase separation.

Polyacrylonitrile (PAN) nanofiber webs containing titanium dioxide (TiO2) were prepared via electrospinning. Either dimethyl formamide (DMF) or its mixture with small amount of water (3 and 5%w/w.) was employed to prepare 5%w/w.PAN/DMF or PAN/DMF/H2O solution, respectively. Introducing non-solvent water in PAN/DMF/H2O solution was attempted to induce phase separation, which may lead to formation of porous structure on nanofibers surface. Different amounts of TiO2 (1 to 3 wt.%) were added into PAN/DMF/(H2O) solutions and then electrospun into nanofiber webs. From SEM, nanofibers possessed rough surfaces and had averaged diameters in ranges of 170–430 nm., showing tendency to increase with amount of TiO2 and water. Porous structure on fiber surfaces was not clearly observed, which was suspected to be due to insufficient amount of water employed. Less homogeneity in polymer solution due to presence of TiO2 disfavored increasing water content higher than 5%w/w. EDS data confirmed presence of TiO2 in electrospun webs. From photocatalysis evaluation, webs containing 2 and 3 wt.% TiO2 showed good photocatalytic activity such that 80 percent of 10 ppm. methylene blue degraded in 24 hours. Slight increase in photocatalytic activity was observed in webs obtained from PAN/DMF/H2O solutions.

Novel organic luminescent substance (3,12-bis(dibutylamine)-7,8-dicyano-5,6,9,10-tetrahydro[5]helicene; M123) was successfully synthesized and employed to prepare luminescent polypropylene (PP/M123) fibers of different cross-sectional shapes via melt spinning. For all cross-sectional shapes (circular, hollow triangular, flat, star, and W), the PP/M123 fibers were continuously spun without fiber breakage, and possessed smooth surfaces. The designed structure of M123, containing 4 butyl groups, enabled its homogeneous mixing with hydrophobic polypropylene matrix. Addition of M123 did not alter the PP melt flow through complex spinneret orifices during fiber spinning, as evidenced by rheological measurements that melt viscosities of PP and PP/M123 at different shear rates (10–10,000 s−1) were almost identical. Results from differential scanning calorimetry also confirmed homogeneity of M123 and PP matrix as the melting temperatures and crystallinities of PP/M123 fibers were comparable to those of PP fibers. By employing organic luminescent M123, the processes of additive preparation and additive/polymer compounding were simplified, and small amount of luminescent substance as 0.05 % wt. could be used to yield effective luminescence. The PP/M123 fibers exhibited yellowish green color under normal light and emitted bright green light under ultraviolet (UV) light.

Melt spinning of side-by-side bicomponent fibers, containing ethylene octene copolymer (EOC) and polypropylene (PP) was conducted to investigate effects of composition ratios and fiber draw ratios on fiber crimp characteristics. The obtained EOC/PP bicomponent fibers exhibited self-crimping with different degree of crimpness when were fully stretched. Fiber crimpness tended to increase with increasing EOC content (up to 50%), but decreased with fiber draw ratio. Fibers of 50/50 EOC/PP ratio possessed highest fiber crimpness with regard to crimp length and extensibility. Self-crimping behavior was explained to yield from imbalance force, as a result of difference in elasticity and orientation, between EOC and PP phases.

Melt spinning of cross-shaped polypropylene (PP) and poly (lactic acid) (PLA) fibers was conducted to investigate influences of polymer properties and processing conditions on cross-sectional shape change in fibers. PP fibers possessed cross-shaped profile, resembling that of the original spinneret orifice, with dull edges due to die swell. Their shape factor (SF) values (1.4–1.6) were close to that of the spinneret orifice (1.7), indicating that the complex shape of the orifice could be maintained. High melt viscosity of PP, as well as its rapid crystallization, helped preventing shape change induced by surface tension. PLA fibers, on the other hand, exhibited shape change from cross to square and to round shape when spinning temperature was increased from 200 to 220 and 240 °C, respectively. Their SF values (1.1–1.2) were close to unity, indicating shape change towards circular shape. Shape deviation towards circular shape in PLA fibers was mainly driven by surface tension. Slow crystallization in PLA allowed great influence of surface tension in determining shape change of the extrudate. Increasing fiber take up speed tended to decrease SF value. Such effect was small compared to that of spinning temperature.