Abstract:
The invention relates to a process for the analysis of plastic mixtures by infrared transmission spectroscopy in which the spectra are run while the samples are rotated. This measure improves the accuracy and reproducibility of the spectra and, hence, the determination of individual components of the plastic mixture.
Abstract:
A pressure-resistant process window (1) for visual or spectroscopic examinations of pressurized products in pipes and reactors. The process window (1) consists of at least a measurement-cell body (2), which is connected to the pipe or the reactor, and a transparent window pane (3), a seal (4) between the measurement-cell body (2) and the window pane (3) for sealing the reactor or pipe interior off from the environment, where the window pane (3) is held against the measurement-cell body (2) in a sealing manner by use of a screw barrel (5) having an external thread (6), which can be screwed into a hollow barrel (7) with internal thread (8) which is connected to the measurement-cell body (2).
Abstract:
This invention relates to a procedure for the controlled production or for the modification of polymeric products using IR-ATR spectroscopy, wherein the case of a polymerization reaction the extinction is determined of the characteristic IR absorption bands for the monomer used and the resulting polymeric product or in the case of a polymer modification the characteristic IR absorption bands of the starting material used and of the modified polymeric product are determined, the degree of conversion or the degree of modification is calculated from the absorption bands, and when the desired degree of conversion or the desired degree of modification is reached the reaction is stopped by suitable measures. By means of the procedure, which is described according to the invention, it is possible to carry out polymerization reactions or the modification of polymeric products to the desired degree of conversion or degree of modification by means of IR-ATR spectroscopy, without high technical expenditure and under accurately controlled conditions.
Abstract:
The present invention relates to a process for the preparation of partially hydrogenated acrylonitrile-butadiene rubber in a pressurised reactor by hydrogenation of acrylonitrile-butadiene rubber by means of homogeneous or heterogeneous catalysis, in which the reactor contents are rendered inert before commencement of the hydrogenation, the Raman spectra of the reactor contents are recorded at short time intervals and the actual degree of hydrogenation of the product is determined from the intensities of the Raman emission lines and, on attainment of the required degree of hydrogenation, the reaction is arrested by suitable means.
Abstract:
A process for monitoring and/or controlling a nitrating process, having the following steps: measuring inline infrared spectra of nitric acid content in a reaction mixture stream downstream of the nitration reaction, preferably near-infrared spectra, evaluating the measured spectra by means of a computer-assisted, matrix-specific calibration model for the purpose of determining the content of nitric acid, transmitting the results of spectrometric examination to a process control system, inputting the results of spectrometric examination for the purpose of specifying the content of nitric acid in the acid phase into a regulator (224) for control of the metering (207,217) of nitric acid into a nitrating reactor.
Abstract:
Optical fibres, and a process for their production, are described which comprise tubular plastic cladding and a core of a polymer whose refractive index is at least 1% greater than that of the cladding material. The core is obtained from a polymerisable mixture which comprises compounds containing epoxy groups, of which at least 10% by weight are siloxanes containing epoxy groups.
Abstract:
The invention relates to a method for determining the isomer composition in an isocyanate isomer mixture, wherein a spectrum of the isomer mixture is recorded and the spectrum is entered into a chemometric calibration model.
Abstract:
A method of using Raman Spectra for determining the progress of a graft polymerization reaction is disclosed. The method entails (a) measuring at the beginning of the reaction and at a plurality of time intervals in the course of the reaction, continuously and on-site, the Raman spectrum in the wave number range of 100 to 4000 cm−1 of one or more of the monomers and/or polymers entailed in the reaction and of at least one internal standard and (b) recording the spectra and (c) adding reaction partners necessary to the reaction continuously and/or discontinuously and (d) calculating the change in concentration of the monomers and polymers by comparing the spectra of the monomers or polymers with the internal standard.