Microwave Solvothermal Synthesis (MSS) is a chemical technology, where apart from possible effects of microwaves on the chemical reaction paths, microwave heating allows the precise planning of a time-temperature schedule, as well as to achieve high super-saturation of the reagents uniformly in the reactor vessel. Thus, MSS is suitable for production of nanoparticles with small grain size distribution and a high degree of crystallinity. A further advantage of the technology is a much lower synthesis temperature than for gas phase, plasma or sol-gel technologies. New reactors have been developed to exploit these advantages of the MSS technology of nanoparticles synthesis and to scale up the production rate. Reactor design and realization has been shown to be decisive and critical for the control of the MSS technology. Examples of oxidic and phosphatic nanoparticles synthesis have been reported.

The article presents a novel microwave reactor for hydrothermal synthesis of nanopowders. The reactor has a unique design of a process chamber, which, when used in conjunction with a batch control system, allows a highly efficient production of nanopowders. The design of the reactor together with the new principles of operation, structural materials and distribution of electromagnetic field are described. The article also presents a control system for the reactor, which allows for an automatic operation in the stop–flow mode, control of process pressure, continuous monitoring of process parameters and safe operation of the device. The device verification process is shown on the basis of the results of cobalt-doped zinc oxide nanopowder synthesis.

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The commonly used flax process of decortication allows the mechanical extraction of fibre from plant stems without prior retting. The one-type fibre obtained in this process is characterised by very low quality, as it is poorly divided, has high linear mass and high amounts of impurities. This paper presents a description of a newly developed method of obtaining high quality flax cottonized fibre from low quality decorticated fibre by application of a wet degumming process for fibre. The experiment involved studying the parameters of flax fibres after each step of the technological process i.e. after decortication, wet degumming and final mechanical cottonisation. The study covered tests of the following fiber parameters: linear mass, length, impurities, chemical composition as well as thermogravimetric analysis, Fourier transform infrared spectroscopy analysis and scanning electron microscopy images. The results confirm the efficiency of the method applied for obtaining high quality fibre from decorticated flax fibre.

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