Prediction of Residual Curing Capacity of Melamine-Formaldehyde Resins at an Early Stage of Synthesis by In-Line FTIR Spectroscopy

Melamine-formaldehyde (MF) resins are widely used as surface finishes for engineered wood-based panels in decorative laminates. Since no additional glue is applied in lamination, the overall residual curing capacity of MF resins is of great technological importance. Residual curing capacity is measured by differential scanning calorimetry (DSC) as the exothermic curing enthalpy is integral to the liquid resin. After resin synthesis is completed, the resulting pre-polymer has a defined chemical structure with a corresponding residual curing capacity. Predicting the residual curing capacity of a resin batch already at an early stage during synthesis would enable corrective measures to be taken by making adjustments in the reaction conditions. Thereby, discarding faulty batches could be avoided. Here, by using a batch modelling approach, it is demonstrated how quantitative predictions of MF residual curing capacity can be derived from inline Fourier Transform infrared (FTIR) spectra recorded during resin synthesis using partial least squares regression. Not only is there a strong correlation (R2 = 0.89) between the infrared spectra measured at the end of MF resin synthesis and the residual curing capacity, but also the inline reaction spectra obtained already at the point of complete dissolution of melamine upon methylolation during the initial stage of resin synthesis are also well suited for predicting final curing performance of the resin and a valid regression model (R2 = 0.85) can be established using information obtained at a very early stage of MF resin synthesis.

A Process Analytical Concept for In-Line FTIR Monitoring of Polysiloxane Formation

The chemical synthesis of polysiloxanes from monomeric starting materials involves a series of hydrolysis, condensation and modification reactions with complex monomeric and oligomeric reaction mixtures. Real-time monitoring and precise process control of the synthesis process is of great importance to ensure reproducible intermediates and products and can readily be performed by optical spectroscopy. In chemical reactions involving rapid and simultaneous functional group transformations and complex reaction mixtures, however, the spectroscopic signals are often ambiguous due to overlapping bands, shifting peaks and changing baselines. The univariate analysis of individual absorbance signals is hence often only of limited use. In contrast, batch modelling based on the multivariate analysis of the time course of principal components (PCs) derived from the reaction spectra provides a more efficient tool for real-time monitoring. In batch modelling, not only single absorbance bands are used but information over a broad range of wavelengths is extracted from the evolving spectral fingerprints and used for analysis. Thereby, process control can be based on numerous chemical and morphological changes taking place during synthesis. “Bad” (or abnormal) batches can quickly be distinguished from “normal” ones by comparing the respective reaction trajectories in real time. In this work, FTIR spectroscopy was combined with multivariate data analysis for the in-line process characterization and batch modelling of polysiloxane formation. The synthesis was conducted under different starting conditions using various reactant concentrations. The complex spectral information was evaluated using chemometrics (principal component analysis, PCA). Specific spectral features at different stages of the reaction were assigned to the corresponding reaction steps. Reaction trajectories were derived based on batch modelling using a wide range of wavelengths. Subsequently, complexity was reduced again to the most relevant absorbance signals in order to derive a concept for a low-cost process spectroscopic set-up which could be used for real-time process monitoring and reaction control.

RESEARCH AND IMPLEMENTATION OF 3D CITY BATCH RAPID MODELLING METHOD

For the current 3D city modelling, the use of computer programs for batch modelling of non-fine models can only ensure the building height information, and cannot effectively use the attribute information of 2D data; and the manual modelling method for the road ancillary facilities has the disadvantages of modelling and placement of streetlamps, low efficiency, and inaccurate positions, a 3D modelling method based on parametric modelling technology and 3DMax modelling technology to realize batch modelling of non-fine buildings and urban streetlamps was proposed. Firstly, the spatial and attribute information of two-dimensional surveying data is used as basic data; then, through the geometric functions provided by CityEngine, combined with the characteristics of the main building and roof structure of the village in the city, the functions of generating the building structure is constructed, and the batch-based automatic modelling is compiled. The program uses the bottom attribute information to control the structure and texture of the model. . The external model was introduced through geometric function, use the attribute information and the adjacent angle of the road centerline to control the style, size and direction of the streetlamp, realize the batch automatic construction at the streetlamp coordinate point. Finally, the Python language bulk export model plug-in and a MaxScript script bulk import model plugin are compiled to improve work efficiency and model compatibility. Through experiments and performance analysis, it is shown that the method can guarantee the rapid establishment of 3D models of buildings and streetlamps, and the structure and texture are vivid. It is well compatible with 3DMax and can be directly modified and format converted.

Model and Kinetic Parameters Identification for Therapeutical Product Obtained According to the GMP Guidelines

The technological solutions were elaborated to achieve the design of the production flow with respect of the Good Manufacturing Practice (GMP) guidelines. To be in line with the GMP rules a fed-batch operation mode is be designed based on the batch modelling results. As the production rate of the microbial immunomodulator is associated with the biomass growth rate, it was required to study the bacterium growth kinetics in batch process. After the selection of the kinetic model based on several batches experimental data by using the analysis criteria - modelling error and estimation rule convergence, the limiting substrate concentration to be maintained during fed-batch cells exponential growth was determined as 115 - 125 mg/L. The batch bioprocess was performed in a Bioengineering AG bioreactor with a software based control of the main variables.