Spinnable polymers, properties

Green fibers derived from melt-spinnable polymers have been cured in an ammonia atmosphere, then pyrolyzed in ammonia and nitrogen atmospheres to generate at 1800 °C boron nitride fibers with excellent mechanical properties. It was interesting to note that boron nitride fibers, with controlled mechanical properties and crystallinity, could be produced through simply changing the meltspinning conditions (Table 14.1) [35]. 

PMMA, a well spinnable polymer, and fabricated a bead-on-a-string nanofibrous film by electrospinning (Fig. 18.10b). With the increase of fluoroPOSS ratio, the nanofibrous film showed excellent superamphiphobic property in other words, the film was both superhydrophobic and superoleophobic (Fig. 18.10c-e) [14, 37], These works demonstrated the successful creation of new artificial materials beyond the performance of namral biomaterials. 

In our research,16171819 we first prepared a series of tris(/i-alkylamino)borazines that possess different pendent groups. This allowed us to investigate the effect of the nature of the /i-(alkylamino) substituents on both the viscoelastic behavior of the thermal properties and, therefore, the melt spinnability of the resulting poly[/i-(alkylamino)-borazines] polymers. 

The spinnability and spinning properties of a polymer are of the highest importance in the manufacturing of staple fibers and filaments. There are many analogies to the production of films, where breaks or splits are concerned. The frequency of yarn breaks determines the economic viability of the production process, as well as the competitiveness and the reputation of the manufacturer. Today, in the age of automation, it would be theoretically possible to manage the processing of the polymer with a minimum of staff if no yam breaks disturbed the processing. 

In order to improve the properties and the spinnability, fibroin sometimes has been electrospun together with other natural or synthetic polymers (Jin et al., 2002 Park et al., 2004, 2006 Wang et al., 2004, 2006). For instance, Jin et al. (2002) developed an aqueous process for silk electrospinning in combination with PEO. More recently, Cao (2008) used PVA/Silk Fibroin (SF), Gelatin/SF, and Hydroxyapatite (HAP)/SF to produce double-layered (core-shell) nanofibers (mats) by coelectrospinning. 

By contrast, other polymers such as polyolefins and PVA form immiscible blends with HKL. In fact, phase separation is observed in fibers produced from the thermal spinning of HKL and PP. The fiber spinning properties of several PP samples having various melt viscosities and tacticities were examined. Most of the HKL/PP blends show poor or bad fiber spinnability. However, excellent fiber spinning was achieved with PP samples having a thermal viscosity comparable to the HKL. 

The preparation of preceramic material involves processing a high purity, easily spinnable material, usually a preceramic polymer or sol. In either case, specialized equipment is required to produce the material because there is no other market for these exaet materials (although there are some close relatives). The high level of purity, the delicate balance of material properties, and the dedicated, customized equipment make preparation an expensive process. 

Variations on the diamine-diacid chloride theme have provided oth rigid linear aromatic polyamides which are ultra-high modulus fibre formers, structures Il-V being notable examples and numerous comonomers have been described. Polymer II is said only to give good fibre properties if its structure is deliberately disordered slightly by inclusion of small quantities of co-reactants, the effect being attributed to better solubility and consequent improved spinnability. However, this... 

In this work, the rheological behavior of several LCP/polymer blends has been studied. Their spinnability has also been investigated by measuring the MS and BSR, as well as the mechanical properties of as-spun fibers. The results are discussed with reference to the temperature dependence of the viscosities of the two phases, which clearly influences the blends behavior during the non-isothermal fiber drawing stage. 

---