Rheology of natural fibers thermoplastic compounds: Flow length and fiber distribution

The presented study investigates the flow length and the corresponding fiber content distribution in the injection‐moulded natural fiber reinforced thermoplastics and its relation to fiber type and processing parameters such as injection pressure, temperature, injection rate and mould tempering by increasing die temperature. In this research, polypropylene compounds with nominally 30 wt % hemp and sisal fibers are investigated. The influence of the injection pressure (500 and 1000 bar), melt temperature (180°C, 200°C, and 220°C), and die temperature (23°C and 80°C) on the fiber content distribution all over the sample is investigated. An increasing linear trend of fiber content along the spiral length is observed as an evidence of a fiber/polymer multiflow system. A pattern for fiber content distribution with respect to the fiber length along the injected spiral can be distinguished, where the longer fibers are usually found at the end of the injected part and the shorter fibers remain near mould entrance point. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39861.     

Aerosol Process for the In Situ Coating of Nanoparticles with a Polymer Shell

This article presents a novel method to encapsulate gas-borne nanoparticles with a polymeric shell. This method implies heterogeneous condensation of monomer vapor around the surface of nanoparticles as nuclei and polymerization is then subsequently started by addition of NH₃ as aerosol initiator. Ag and SiO₂ nanoparticles were generated as inorganic core by spark discharge and nebulization, respectively, and glycidyl methacrylate (GMA) was used as organic monomer. The effect of several parameters, including vapor pressure of monomer and properties of inorganic core such as morphology, material, particle size, and production method on the thickness of polymeric shell and morphology of resulting nanocomposites has been investigated. The particle size distribution and morphology of the resulting core-shell nanoparticles have been studied via scanning mobility particle sizer (SMPS) and transmission electron microscope (TEM). Finally, the coating efficiency was determined by aerosol photoemission (APE) and the results show that monomer and polymer coating efficiency are 99% and 60%, respectively.

Copyright 2014 American Association for Aerosol Research     

Demonstration of the monolithic interconnection on CIS solar cells by picosecond laser structuring on 30 by 30 cm2 modules

In this paper, we present the selective structuring of all three patterns (P1, P2 and P3) of a monolithic interconnection of CIS (Cu(In,Ga)(S,Se)₂) thin film solar cells by picosecond laser pulses at a wavelength of 1064 nm. We show results for single pulse ablation threshold values and line scribing of molybdenum films on glass (P1), CIS on molybdenum (P2) and zinc oxide on CIS (P3). The purposes of these processes are the p‐type isolation (P1), cell interconnect (P2) and n‐type isolation (P3), which are required for complete cell architecture. The half micron thick molybdenum back electrode can be structured with a process speed of more than 15 m/s at about 15 W average power without detectable residues and damage by direct induced laser ablation from the back side (P1). The CIS layer can be structured selectively down to the molybdenum at process speeds up to 1 m/s at about 15 W average power, due to the precision of direct laser ablation in the ultrashort pulse regime (P2). The ZnO front electrode layer is separated by clean trenches with straight side walls at process speeds of up to 15 m/s at about 10 W average power, as a result of indirect induced laser ablation (P3). A validation of functionality of all processes is demonstrated on CIS solar cell modules (30 × 30 cm²). By replacing one state‐of‐the‐art process by a picosecond laser process at a time, solar efficiencies could be increased for P1 and P2 and stayed on a similar level for P3. After an optimization of the patterning processes in the R&D pilot line of AVANCIS, we achieved a new record efficiency for an all‐laser‐patterned CIS solar module: 14.7% as best value for the aperture area efficiency of a 30 × 30 cm² sized CIS module was reached. Copyright © 2014 John Wiley & Sons, Ltd.     

Pyryliumverbindungen. 31 [1]. Reaktion 3-alkylsubstituierter 2,4,6-Triaryl-pyryliumsalze mit 1,3-Diketonaten: Ein Weg zur Darstellung 3-acylsubstituierter Benzophenone

Pyrylium Compounds. 31. Reaction of 3-Alkyl-2,4,6-triarylpyrylium Salts with 1,3-Diketonates: A Method for the Preparation of 3-Acylsubstituted Benzophenones Reaction of 3-alkyl-2,4,6-triarylpyrylium salts with 1,3-diketones in the presence of one equivalent of triethylamine or potassium tert-butoxide does not lead — as originally suspected — to the primary adducts of 2H-pyran structure 6 , but to the open-chain valence isomers 7 . Treatment of the latter with one equivalent of tert-butoxide in tert-butyl alcohol gives the same 3-alkyl-2,4,6-triarylacetophenones 9 which are obtained directly from 5 , 1,3-diketones and two equivalents of potassium tert-butoxide. However, on treating 7 with aqueous ethanolic sodium hydroxide 3-acylsubstituted benzophenones 10 are formed in good yields. The reaction sequence 5→7→10 can also be performed through a one-pot-procedure. — The i.r., u.v., n.m.r. and mass spectroscopic data of the novel products 7, 9 , and 10 are reported.     

Pyryliumverbindungen. 37. Arylbenzene aus 2,4,6-Triaryl-pyryliumsalzen und Carbonsäureanhydriden

Pyrylium Compounds. 37. Arylbenzenes from 2,4,6-Triarylpyrylium Salts and Carboxylic Acid Anhydrides Refluxing 2,4,6-triarylpyrylium salts 1 with excess carboxylic acid anhydrides (RCH₂CO)₂O ( 2a : R = H, 2b : R = Me) in the presence of condensing agents like sodium or potassium acetate, sodium carbonate or methoxide, triethylamine or pyridine results in 1,3,5-triarylbenzenes 3 (R = H, Me). Under similar conditions, phenylacetic acid anhydride ( 2c ), generated in situ from sodium phenylacetate and excess 2a or 2b , yields 1,2,3,5-tetraarylbenzenes 3 (R = Ph). Thus, the reaction 1 + 2 → 3 represents a new and simple method for replacing the pyrylium heteroatom =O^⊕– by the =CR– moiety (R = H, Me, Ph). The structure of the arylbenzenes 3 was proved by spectroscopic methods, by comparison with literature data or by independent synthesis. As by-products 2-acyloxy-benzophenones 10 are formed. Reaction of 3,5-dimethyl-2,4,6-triphenyl-pyrylium perchlorate ( 11 ) with acetic acid anhydride/sodium acetate (or sodium phenylacetate) takes another course leading to 2-acetoxy-3,5-dimethyl-4,6-diphenyl-benzophenone ( 15 ), whereas treatment of 11 with propionic acid anhydride/sodium acetate follows the reaction scheme 1 + 2 → 3 giving 1,3,5-trimethyl-2,4,6-triphenylbenzene ( 16 ). The mechanisms of the different pyrylium ring transformations are discussed.     

Untersuchungen zur Tautomerie von o,o'-Dihydroxy-azofarbstoffen der Eriochrom-Reihe

Investigations on the Tautomerism of o,o'-Dihydroxy Azo Dyes of the Eriochrome Type Investigation of the u.v.-vis-, ¹H- and ¹³C-n.m.r. spectra of the title substances and the isomers 3 and 3p at different pH-values and in different solvent mixtures as well as of O,O'-dimethyl derivatives of 2 and 3 show that in aqueous solution as well the monoanions as the trianions exist in the azo forms only. The dianions exist in dependence on the solvents as mixtures of tautomers. The results of PPP calculations for different prototropic structures are in good accordance with the experimental results.     

针织物平幅丝光整理

针织物丝光工艺能使针织物的性能更好.光泽度、尺寸稳定性和顶破强度的提高是针织物丝光处理的主要目的.另一优点则是提高染色效率.特别是织物的光泽、清晰和平整的外观会迎合消费者.对于消费者,即使从初次水洗开始就可明显地看出尺寸稳定性的提高.此后,还会注意到顶破强度也大大改善.最重要的是,消费者将惊喜地发现用丝光棉制成的衣服可长期保持"崭新"的外观.     

Ringöffnungs- und SubstitutionsReaktionen von 4,4-Dihalogen-pyrazolin-5-onen durch Nucleophile

Ring Opening and Substitution Reactions of 4,4-Dihalo-pyrazolin-5-ones with Nucleophiles 1-Aryl-4,4-dihalo-3-methyl-pyrazolin-5-ones ( 1a – c ) undergo ring opening with alkoxides and form alkyl 3-arylazo-2-halo-2-butenoats ( 2a – d ). Analogous reactions take place with ammonia and amines. 4-Nitro-phenoxide reacts with substitution of both halogens to the 4,4-bis(4-nitro-phenyl)-compound ( 5 ). Phenols are selectively orthobrominated by the title compounds 1a and b .     

Pyryliumverbindungen. XVIII, 2-Alkoxy-2H-pyrane aus tetra- und pentasubstituierten Pyryliumsalzen

Pyrylium Compounds. XVIII. 2-Alkoxy-2H-pyrans from Tetra- and Pentasubstituted Pyrylium Salts Alkali alkoxides add regioselectively to 2,3,4,6-tetrasubstituted pyrylium salts 7 (R' H), affording high yields of colourless crystalline 2-alkoxy-2H-pyrans 9 . The latte are also formed simply on refluxing 7 in the corresponding alcohol with triethylamine as proton acceptor. 3,5-Dialkylsubstituted 2,4,6-triarylpyrylium salts react analogously. The 2H-pyran structure of the adducts obtained follows from their n.m.r., i.r., u.v. and mass spectra as well as from their reaction with tetracyanoethylene to cycloadducts of type 10 . Acids regenerate from 9 the original pyrylium cations, whereas reaction of 9 with nitromethane or ethyl cyanoacetate provides benzene derivatives. -- The novel starting pyrylium salts 7b--o are characterized by u.v./vis data and by transformation into the corresponding pyridine derivatives