Differentialthermoanalytische Untersuchungen zur effektivität einiger Stabilisatoren bei Polyäthylenterephthalat

The thermooxidative resistance of poly(ethylene terephthalate), synthesized in the presence of different stabilizers as well as combinations of stabilizers as well as combinations of stabilizers, is studied with the help of the dynamic and isothermal DTA-method. The stabilization coefficients (by the dynamic DTA) and the characteristic induction periods (by the isothermal DTA) are determined. A good correlation is established between the data obtained by both methods.     

Modelluntersuchungen zur Wirkungsweise von Oxidationsstabilisatoren für Polyäthylenterephthalat

The behaviour of some stabilizing additives to poly(ethylene terephthalate) (PETP) is studied in the model oxidation reaction of isopropylbenzene. On the basis of the course of accumulation curves for cumene hydroperoxide conclusions were drawn for the way of formation and consumption of hydroperoxides in the presence of different types of stabilizers and combinations of stabilizers under investigation.     

Beiträge zur Kenntnis der Lipoid-Zusammensetzung im menschlichen Blutserum bei gestörtem Fettstoffwechsel

Contribution to the Knowledge of Lipid Compositions of Human Blood Serum during Disorder in Fat Metabolism The lipids of human blood serum were investigated with the help of thin-layer chromatography. In the blood serum of patients with disturbed fat metabolism a further fraction was observed between the fractions of triglyceride and cholesterol ester. The authors concluded that this fraction, obtained after the extraction of the lipid with a methanol containing solvent mixture, consists of methyl esters of fatty acids.     

Einfluß des Verstreckens und Temperns auf das Dehnungs- und Bruchverhalten von Polyäthylenterephthalat

The stress-strain diagrams of undrawn and drawn polyethylene terephthalate were measured at room temperature and above the glass transition temperature. Before the stress-strain measurements the undrawn samples had been crystallized at various temperatures, whereas the drawn samples had been crystallized in the undrawn state, then were drawn at various temperatures and finally were crystallized again. The influence of the temperature of crystallization and the temperature of drawing on the Young's modulus, the tensile strength, and the fracture strain were of special interest. The fracture strain as a function of the crystallization temperature shows a minimum at room temperature. This minimum disappears above the glass transition temperature. Young's modulus and tensile strength generally are found the higher, the higher the degree of orientation in the sample. Crystallization of the undrawn samples therefore does not change these values significantly. But a drawing of the samples leads to a significant increase which is still more pronounced if the sample is crystallized after the drawing. Crystallization before drawing of a sample leads to a decrease of Young's modulus and tensile strength because in this case apparently the formation of a sufficient orientation during the drawing cannot take place. An increase of the drawing temperature above the glass transition temperature also leads to a decrease in the mentioned values.     

Beiträge zur Analytik von Estersulfonaten

Contributions to the Analysis of Sulfonated Esters Several methods for the characterization and determination of α-Sulfo fatty acid methyl esters are described. The sulfonated ester is detected by thin layer chromatography on silica gel plates with tetrahydrofuran + acetone (1+9 v/v) as solvent and with pinacryptol yellow/UV-light for the visualization. Pyrolysis-gas liquid chromatogrphy with heating a sample/P₂O₅-mixture at 400°C yields the chain length distribution of the fatty acids initially used. The amount of an α-sulfo fatty acid ester is determined by extraction with i-propanol and by two-phase titration (Epton). the saponification product of the sulfonated ester is in the i-propanol insoluble part. For a quantitative determination of the α-sulfo fatty acid methyl ester by thin layer chromatography the sample solution is directly applied to the thin layer plate. A range of defined volumes, with increasing amounts of the sample are applied to the plate by means of an applicator. The chromatograms are visually compared. Ion chromatogrphy with the mobile phase, NH₃/Acetonitrile separates the α-sulfo fatty acid esters by chain-length. Determination is achieved by standards with defined chain-length.     

Beiträge zur Synthese von Orthocarbonsäureamiden

The formamidinium salts 11a, c as well as the nitrile 12 react with sodiumhydride/dimethylamine in the presence of trimethylborate to give the ortho formic acid amide 3a . The orthoamides 6a and 16 can be prepared from the iminium salts 15 and 14 , resp. by the same procedure. Treatment of the azavinylogous formamidinium salt 15 with sodiumhydride and piperidine or morpholine in the presence of trime‐thylborate affords the orthoamides 6c and 6d , resp. By transamination of the azavinylogous aminalester 5a are accessible the orthoamides 6b—d . The vinylogous orthocarbonic acid derivative 17 can be obtained from the salt 14 and sodium alcoholates. The action of sodiumhydride, dimethylamine and trimethylborate on the iminium salt 18 produces a mixture of the orthocarbonic acid derivatives 7a, 8a, 9a . When the guanidinium salt 20 is treated with the same reagents the ortho‐amides 3a and 10a are obtained. The reduction of the salt 20 with sodiumhydride in the presence of several activating reagents (e.g. tetrabutyl orthotitanate, aluminiumisopropylate, trimethylborate) affords the orthoamide 3a . The reduction of the iminium salts 18 and 24 does not proceed clean, giving mixtures of various orthoformic acid derivatives. The form‐amidine 25 can be prepared by reduction of the salt 15 with sodiumhydride/trimethylborate with good yields. By the action of the corresponding carbanions on the guanidinium salt 20 can be obtained the carboxylic acid orthoamides 26—33 . By the same procedure the orthoamides of alkyne carboxylic acids 36a—h, j—n are accessible.     

Beiträge zur galvanisierung von polymeren, 5. Untersuchungen zur morphologie der galvanischen kupferschicht

The structure of a 15–20 μm thick copper layer, which is deposited electrochemically on copolymers of acrylonitrile, butadiene and styrene from bathes containing additives is extremely distorted. This is caused by microstresses and paracrystalline lattice distortions. On the other hand, the structure of the copper layer deposited from a pure bath is independent of the chemical pre-conditioning of the polymer surface, necessary for plating, and equal to that of a high crystalline pure copper.     

Zum Einfluß von Schutzgruppen bei der Metathese fettchemischer Verbindungen

The Influence of Protecting Groups in the Metathesis of Oleochemicals Unsaturated fatty acids and fatty alcohols can be only converted by metathesis in form of their derivatives requiring high concentrations of catalyst. Using the cross-metathesis of various esters (methyl, iso-propyl, tert.-butyl) of 10-undecenoic acid with 4-octene as well as the cross-metathesis of various derivatives (acetate, pivalate, tosylate, trimethylsilylether) of 10-undecenol or oleyl-alcohol with symmetric olefins (4-octene or ethylene) as model reactions, the influence of protecting groups for oleochemicals concerning their metathesis-reactivity was studied. The trimethylsilyl-group turned out to be an excellent protecting group for unsaturated fatty alcohols as educts for metathesis. With Re₂O₇/Al₂O₃-SnMe₄ as catalyst the cross-metathesis of 10-undecenyl-trimethylsilylether with 4-octene lead to a derivative of 10-tetradecenol and 1-pentene even using a molar ratio of Re₂O₇: trimethylsilylether of 1:500.     

Entwicklungsstand und Perspektiven der Modellierung von Transportvorgängen in durchströmten Festbetten

New model equations enable the consistent and accurate calculation of heat transport, mass transport and chemical reactions in packed beds with fluid flow. The main features of this approach are reviewed and summarized, and selected aspects are discussed. The modelling approach may be a good starting point for the development of, for instance, membrane reactors and separation processes such as chromatography or freeze drying for thermally sensitive products.     

Beiträge der Prozeßleittechnik zur Qualitätssicherung in der chemischen Produktion

Contributions of Process Control to Quality Assurance in the Chemical Industry. Through their functions of measurement, i.e. the acquisition of quantities relating to the process and the product, and adjustment, i.e. the modification of control values, process control engineering and process automation represent the basis of all operative control of quality. The functions of control, regulation, and operator support are likewise instruments ensuring the maintenance of quality-relevant process and product specifications. Utilisation of the considerable potential of these tried and tested control methods is logical in the case of chemical processes and should receive more attention in quality management.     

Beiträge zur galvanisierung von polymeren, 7. Metallisierung von epoxidharzen mit hilfe von haftvermittlern

Epoxy resins can be coated with a metal after being covered with a platable adhesive. Such an adhesive consists of a partly epoxidized styrene-butadiene-styrene block copolymer, an epoxy prepolymer and an amine curer. The contents of these substances in the mixture and the nature of the amine influence the peel strength of the metal layer. The maximum peel strength with a value of about 45 N/25 mm was obtained after using a low molecular weight amine, while values of only about 10 N/25 mm could be obtained with amines of higher molecular weight.     

Beiträge zur Untersuchung und Beurteilung von naturbelassenen Sonnenblumenölen

Investigation and Adjudgement of Sunflower Oils of Natural Purity Colour reactions, which were employed till now and found suitable for differentiating unrefined from refined sunflower oils are reported. The qualitative detection of the substances responsible for the colour reaction can be carried out with unsaponifiables, however, it is also possible to use the oil directly after a certain enrichment. Under the experimental conditions chosen, and using antimony trichloride spray the pressed oils give two blue spots with similar Rf-values on the thin-layer chromatogram located slightly above the start. These substances giving a blue colour, which were found to be keto-steroids, were absent in refined sunflower oils.     

Beiträge zur konfigurativen Zuordnung von Isophorondiamin und -diisocyanat sowie Derivaten

X-ray analyses of the pure, crystalline isomeric bis-(dimethylamino)ureas 3a and 3b have been made to provide configurative distinction of the isomeric mixture of isophorondiamine and -diisocyanate (IPDA and IPDI). The results show in agreement with Hatada et al. and contrary to earlier work 3a to be cis and 3b trans configurated. The main components of IPDA and IPDI are without any doubt the cis isomers. ¹³C-NMR data of 1 to 5 allow configurational assignments of virtually any derivative of IPDA and IPDI.     

Beiträge zur galvanisierung von polymeren, 11. Metallisierung von mischungen aus epoxidharzen und acrylnitril-butadien-copolymeren

The metallization of mixtures containing epoxy resins and acrylonitrile-butadiene copolymers depends on taking the suitable ratio of components and on the hardener, which was brought to reaction with the epoxy prepolymer in presence of the copolymer. Using triethylenetetramine as curing agent the highest values of peel strength have been reached and have been increased up to 150 N/25 mm by short-time-treatment with ozone. Longer ozonization times lead to lower values of peel strength and impairment of the material. Caverns occur only in mixtures which are rich on epoxy resin, and increase in size with increasing time of ozone treatment. These samples have relatively low values of peel strength.