Frank Hermanutz

Multifilament cellulose/chitin blend yarn spun from ionic liquids

Cellulose and chitin, both biopolymers, decompose before reaching their melting points. Therefore, processing these unmodified biopolymers into multifilament yarns is limited to solution chemistry. Especially the processing of chitin into fibers is rather limited to distinctive, often toxic or badly removable solvents often accompanied by chemical de-functionalization to chitosan (degree of acetylation, DA, <50%). This work proposes a novel method for the preparation of cellulose/chitin blend fibers using ionic liquids (ILs) as gentle, removable, recyclable and non-deacetylating solvents. Chitin and cellulose are dissolved in ethylmethylimidazolium propionate ([C2mim](+)[OPr](-)) and the obtained one-pot spinning dope is used to produce multifilament fibers by a continuous wet-spinning process. Both the rheology of the corresponding spinning dopes and the structural and physical properties of the obtained fibers have been determined for different biopolymer ratios. With respect to medical or hygienic application, the cellulose/chitin blend fiber show enhanced water retention capacity compared to pure cellulose fibers.

A new carbon precursor: synthesis and carbonization of triethylammonium-based poly(p-phenylenevinylene) (PPV) progenitors

Unsubstituted poly(p-phenylene vinylene) (PPV), when heated under an inert atmosphere, has very high char yields at temperatures up to 1800 °C and is a potential source of carbonaceous material. However, using unsubstituted PPVs in the synthesis of carbon materials is hindered by their limited processability into fibers or free-standing films before carbonization. To circumvent processability problems, the synthesis of soluble ammonium-based PPV precursors was accomplished, and the first ammonium-based PPV films were carbonized. 1-(Chloromethyl)-4-[(triethylammonium)methyl]benzene chloride was polymerized via an analogous approach to the Gilch reaction under basic conditions. Significant elimination of ammonium groups occurred during polymerization, but the 5–20% remaining ammonium functionalities allowed for solubility in polar aprotic solvents such as dimethylsulfoxide (DMSO). A post-polymerization exchange of the ammonium functionality to a larger counter anion, p-toluenesulfonate, provided more flexible, film-forming PPV-based polymers. Additionally, the low fraction of ammonium groups on the backbone facilitated a low weight loss during carbonization, up to 51 wt% remaining at carbonizations up to 1800 °C, and preservation of the final film structure. These films were carbonized at temperatures of 1000, 1400, and 1800 °C and were analyzed with scanning electron microscopy, Raman, Fourier-transformation infrared spectroscopy, X-ray diffraction, and conductivity measurements to examine the development of the carbon structure.

Synthesis and dry-spinning fibers of sulfinyl-based poly(p-phenylene vinylene) (ppv) for semi-conductive textile applications

Soluble, processable sulfinyl-based poly(p-phenylene vinylene) (PPV) precursors were synthesized, and the first sulfinyl-based PPV fibers were subsequently spun on a dry-spinning apparatus. 1-(Chloromethyl)-4-[(n-octylsulfinyl)methyl]benzene was synthesized in a 94% yield and polymerized via an analogous approach to the Gilch reaction. Post-polymerization, the sulfinyl group may be thermally eliminated from the backbone of the polymer to obtain conjugated PPV. 1H NMR, 13C NMR, and FTIR confirmed that the polymer structure contained both sulfinyl- and pure PPV-based units. Thermogravimetric analysis indicated that up to 60% elimination of sulfinyl groups occurred during the polymerization reactions and before additional thermal treatment. Spinning dopes were prepared with 45 wt% polymer from 45.0 to 50.0 g of polymer in chloroform and had zero shear viscosities around 60 Pa s at 20 °C. Fibers were dry-spun with and without tension and various jet draw ratios from 0 to 151% to investigate changes in crystallinity, and X-ray diffraction patterns indicated enhanced orientation in the fibers compared to the unprocessed polymers. The fluorescent, conjugated polymer fibers possessed diameters less than 60 μm by SEM and remained soluble until thermal treatment at 150 °C.

Single-component composites made from pure cellulose

Introduction Most fiber-reinforced plastics based on glass, carbon or natural fibers are produced using petroleum-based polymer matrices. With a production volume of 2.3 million tons p.a. in Europe, glass-f iber reinforced plastics (GFRP) used in construction and structural parts account for the largest share [1]. These materials, however, preclude the possibility of proper recycling. Since there is currently no technically viable method of fully recycling GFRP end-of-life waste (currently around 300,000 tons p.a. [2]), GFRP waste is disposed of through pyrolysis of the polymer matrix, with the residual ash having to go to landfill. In contrast, an alternative process