Fibers, PLA

PLA fiber combines the most desired properties of natural fibers, such as wool, and synthetics, such as polyester. This combination of properties opens up a wealth of textile applications including clothing, carpet tiles, diapers/acquisition distribution layers, upholstery, furnishings, and filtration. PLA has a high dyeability, and in comparison with polyester in activewear, it displays superior wicking properties. 

Fig. 4 Antibacterial activity against S. aureus after 12 h of incubation with (a) AgNO, (b) Ag/ PLA fibers (the AgNOa content in the spinning solution with respect to PLA was 32 wt%) (c) S. aureus was blank control...

Jun et al. electrospun PLA fibers and observed the cylindrical morphology of fibers with diameters ranging from 800-2400 nm (Jun et al. 2003). 

Kenawy et al. studied the potential of electrospun fiber mats as drug delivery system for the release of tetracycline hydrochloride (Kenawy et al. 2002). Electrospun PEVA + PLA blended fibers were 1—3 pm in diameter while the PLA fibers were around 3-6 pm. Srinivasan and Reneker 1995 examined the crystal structure and morphology of the electrospun Kevlar fibers (Srinivasan and Reneker 1995). Fibers from 40 nm to a few hundreds of nanometers were produced. 

Table Textile physical properties of drawn PHB und PLA fibers [31-33]...

PLA fibers show a considerably higher level of strength at a lower elongation at break than PHB fibers. Differences in the crystallization and orientation behavior during the structure formation are seen as the cause. 

Table 3 repeats the textile physical properties of PHB and PLA fibers conditioned at room temperature for 3 months in relation to the original state. 

The PLA fibers show neither embrittlement nor deterioration of properties due to the secondary crystallization, which means that the structures of PLA fibers are stable at these conditions and during this time. The reason for this could be the high crystallinity and the high orientation of the polymer chain of the highly drawn fibers to avoid the secondary crystallization. 

PLA Fambri et al. [27] compiled a list of present literature data on PLA fibers, which were spun under quite different technological conditions, dry spinning, solution spinning, melt spinning, and spin drawing. 

Figure 10.9. Comparison of the impacts on climate change and non-renewable resources of Ingeo PLA fibers from Nature works and recycled PET [NAT]...

Extremely low-dimensional conducting nanowires (as small as 3 nm in diameter) for use in nanoelectronics can be produced with the electrospinning technique [103]. Using template methods, insulating PLA fibers with an average diameter of 200-700 nm as core materials were electrospun and subsequently coated with thin 50-100 nm films of polyaniline or polypyrrole by in situ polymer deposition methods. The PLA core fibers decompose upon relatively mild thermal treatment under inert atmosphere, leaving... 

Schmack et al. [126] spun PLA fibers through the reactive extrusion polymerization of L-lactide (92 wt%) and meso-lactide (8 wt%). In many potential textile technological applications (e.g., for nonwoven materials) the fiber forming process is of general importance. An effective polymer synthesis requires also an effective spinning process to reduce the still high cost of the PLA fibers compared with those of established synthetic fibers. 

The unique features of PLA fibers offer distinct benefits in the fields of geotextiles and agricultural/horticultural applications... 

Both woven and nonwoven fabrics made from PLA fibers are being considered for automobile cabin parts applications. Toyota has already employed a new type of spare-tire box cover using Kenaf/PLA board, which is manufactured by heat compression molding of a Kenaf/PLA (weight-based blend ratio 7/3) fiber web... 

PLA fibers are environment-friendly material and the demand for PLA fibers as a substitute for the present synthetic fibers has been growing greatly in recent years. Furthermore, high water vapor transmission rate of PLA makes it a good candidate for fabricating fibers used in garments [e.g., shirts, dresses, underwear, shoes, etc.] to improve their "breathability. While PLA fibers are not as wettable as cotton, they exhibit much greater water vapor transmission than aromatic polyesters or nylon fibers. 

Similar to other polyesters, PLA displays crystal polymorphism and four different crystal modifications have been identified so far, named a-, P-, y-, and e-forms. The a-form of PLA grows upon melt- or cold-crystallization, as well as from solution [18-25]. Hot-drawn, melt-spun, or solution-spun PLA fibers of a high-draw ratio show the P-form [21-23]. The y-form is obtained via epitaxial crystallization on hexamethylbenzene substrate [24] and the s-modification is a crystalline complex formed below room temperature in the presence of specific organic solvents such as tetrahydrofuran and Af,Af-dimethylformamide [25]. Besides these four main crystal polymorphs, two disordered modifications of the a-form, named a and a , were recently proposed for PLA. The a -crystals grow via melt- or cold-crystallization below 110 °C [21, 26-29], whereas the a"-form develops upon crystallization under special processing conditions, below the glass transition temperature and in the presence of carbon dioxide [30]. 

On the basis of the DSC data summarized in Table 8.3, the crystallization temperature (T ) of PLA fibers becomes lower than that of as-received PLA pellets. It is convincing that the crystallization process can be accelerated by the well-structured PLA molecular chains when tailored into the fiber-like form. By decreasing HMW PCL concentration from 15 to 9wt%/v, the glass transition temperature (T ) of PCL within PLA/PCL blends is reduced whereas the of PLA is hardly identified in that its point has overlapped the melting peak of PCL. The different thermal properties in terms of and melting temperature (T ) may be influenced by the variation of fiber diameters as well as electrospinning process for the orientation of polymer chains [32]. In comparison to HMW PCL with PLA in blends, LMW PCL gives rise to an evident increase in the of PLA, but a considerable decline in the of PCL. The solvent effect on thermal... 

S. Chung, M.P. Gamcsik, M.W. King, Novel scaffold design with multi-grooved PLA fibers. Biomed. Mater. 6(4), 045001 (2011)... 

The application of sc-PLA products has just started to replace conventional oil-based polymers. It has been demonstrated that both the sc-PLA and the sb-PLA should have high potential as sustainable structural materials to make fibers, films, rods, and other processed plastics. Particularly, sc-PLA fibers show high thermal stability and can be... 

First studies about the fabrication of PLA fibers were made by Kulkami et al. [13, 14] and Kalb and Pennings [23]. PLA... 

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