As-spun fibres

During heat stabilisation of as-spun fibres coloured with quinacridone pigment the less thermodynamically stable p crystals transform into a crystals. 

Figure 2 The effect of spinning temperature on the orientation parameter (Pj) as-spun fibres produced from polymer 7069S. P values are obtained from the (a) 841 cm (b) 998 cm (c) 973 cm (d) 974 cm infrared peak.

Hot drawing of the extruded ( as-spun ) fibres was carried out on a small-scale drawing unit consisting of two pairs of advancing rollers and a hot plate. One- or two-stage drawing procedures were used. More detailed accounts of the extrusion and drawing conditions are published elsewhere (17,18). 

Tensile Testing- Tensile properties were measured on a Nene tensile tester at 20 C and 65% relative humidity. The as-spun fibres were tested with a gauge length of 20 mm and an extension rate of 2 mm min . The drawn fibres were tested with a gauge length of 20 mm and an extension rate of 20 mm min . Tests were carried out five to ten times for each sample, with a standard deviation generally less than 5%. 

As-spun fibres from the stage 1 could be drawn via the necking process both at as well as above room temperature the necking begins at a strain about 6-7%. The mechanical properties of the drawn fibres are shown in Table 7.4. 

During tensile testing the as-spun fibre is extended to its break point the draw ratio applied during the testing is... 

Alternatively, the as-spun fibre can be drawn (draw ratio A ) and then extended to the break point during the tensile test hence... 

For chemical characterisation of nanofibres, Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), circular dichroism (CD), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and X-ray scattering can be used. For molecular structural analysis, vibrational spectroscopic technique such as FTIR is employed. This technique allows to find the chemical reaction between constituent polymers in case of polymer blends [6, 259]. FTIR results demonstrated that in as-spun fibres, silk sericin was present in a random coil conformation, but after heat treatment, the molecular structure was transformed into a 3-sheet based structure [260]. 

In addition, emulsion electrospinning has been identified as an ideal best method to encapsulate drugs/therapeutics in an emulsified polymer mixture as an encapsulated core-sheath fibres. The as-spun fibres have markedly ease the release of drugs [69-74]. Water/oil based emulsions are preferred to carry bioactives in order to overcome the challenge of incorporation and sustained release of the hydrophilic bioactive molecules (such drugs, therapeutics, etc.) from a hydrophobic polymer nanofibres [72, 73]. 

---