Solution blowing is one of the most industrially viable processes for mass production of nanofibers without significant change of trade practices. In this work a novel industrially scalable approach to nanofiber production by solution blowing is demonstrated using Biax die. Blends of biopolymer soy protein isolate Clarisoy 100 and poly­(ethylene oxide) (M w = 600 kDa) were solution blown as aqueous solutions using a spinneret with 8 rows with 41 concentric annular nozzles. Nanofiber mats were collected on a drum, and samples with an area of the order of 0.1–1 m2 were formed in about 10 s. Nanofibers were relatively uniform with the diameters of about 500–600 nm. Theoretical aspects of capillary instability, dripping, and fly formation in solution blowing relevant from the experimental point of view are discussed, as well as ways of their prevention are revealed.

As‐received poly(ethylene terephthalate) (asr‐PET) may be reorganized by precipitation from trifluoroacetic acid upon gradual addition to a large excess of rapidly stirred acetone (p‐PET). Unlike asr‐PET, p‐PET repeatedly crystallizes rapidly from the melt, and can be used in small quantities (a few %) as an effective self‐nucleating agent to control and improve the bulk semi‐crystalline morphology and properties of asr‐PET. Nuc‐PET film has significantly increased hardness and Young's modulus and is much less permeable to CO2, while its un‐drawn fibers exhibit higher tenacities and moduli. Because nuc‐PET contains no incompatible additives, it may be readily recycled.

Cyclodextrins (CDs) are cyclic polysaccharides with nano-size, largely hydrophobic cavities, and exteriors covered with hydrophilic hydroxyl groups, making them water soluble. Threading and filling their cavities with polymer chains produces noncovalently bonded crystalline inclusion compounds (ICs). In this study, we formed fully covered, stoichiometric ICs between guest poly(L-lactic acid), poly(e-caprolactone), and nylon-6 chains and host a-CD. Coalesced samples of all three polymers were obtained after appropriately removing the stacked a-CD host channels from their ICs. Distinct differential scanning calorimetriy (DSC) thermograms were observed for as-received and coalesced samples, with the coalesced samples crystallizing faster at higher temperatures from their melts, and this distinction was maintained even after extensive, long-time melt-annealing (hours, days, and weeks). We believe this is due to the largely unentangled chains with extended conformations that are more densely packed in the initially coalesced samples. When small amounts ($2 wt %) of the coalesced polymers are used as self-nucleating agents for their as-received samples, the resulting self-nucleated samples show DSC thermograms similar to those of the neat coalesced polymers, including their long-time stability to melt-annealing. Coalesced polymers, whether neat or in samples they self-nucleate, may conserve their organization in the melt (largely extended and unentangled chains) for long periods, because the process of entangling the many chains influenced by a single initially extended unentangled coalesced chain, after it randomly coils, is extremely sluggish. By contrast, in melt-crystallized or solution-cast samples, polymer chains generally become fully randomly coiled, interpenetrate, and entangle after being heated and held in their melts for comparatively much shorter times. For example, we have recently observed (DSC) that ultra high molecular weight, gel-spun spectra polyethylene (PE) fibers V R did not conserve or retain any memory of their as-spun and highly drawn semicrystalline morphology even after spending as little as 2 min in the melt. As a consequence of the comparison to the behavior of coalesced polymer melts, we believe that polyethylene chains in Spectra fibers V R must be at least intimately dispersed within their crystalline regions, and likely partially coiled and entangled in their noncrystalline regions, thereby facilitating their rapid transformation into a full entanglement network of randomly coiling chains in the melt.

Nanostructured amorphous bulk polymer samples were produced by processing them with small molecule hosts. Urea (U) and gamma-cyclodextrin (c-CD) were utilized to form crystalline inclusion compounds (ICs) with low and high molecular weight as-received (asr-) poly(vinyl acetate) (PVAc), poly (methyl methacrylate) (PMMA), and their blends as included guests. Upon careful removal of the host crystalline U and c-CD lattices, nanostructured coalesced (c-) bulk PVAc, PMMA, and PVAc/PMMA blend samples were obtained, and their glass-transition temperatures, T g s, measured. In addition, nonstoichiometric (n-s)-IC samples of each were formed with c-CD as the host. The T g s of the un-threaded, un-included portions of their chains were observed as a function of their degree of inclusion. In all the cases, these nanostructured PVAc and PMMA samples exhibited T g s elevated above those of their asreceived and solution-cast samples. Based on their comparison, several conclusions were reached concerning how their molecular weights, the organization of chains in their coalesced samples, and the degree of constraint experienced by un-included portions of their chains in (n-s)-c-CD-IC samples with different stoichiometries affect their chain mobilities and resultant T g s.

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