Tvaika sprādzienā no kaņepju spaļiem iegūti beramie siltumizolācijas materiāli = Loose-fill heat insulation material obtained from hemp shives by steam explosion: promocijas darbs zinātnes doktora grāda zinātnes doktors (Ph.D.) inženierzinātnēs un tehnoloģijās iegūšanai

The doctoral thesis was developed in the Biorefining Laboratory of the Latvian State Institute of Wood Chemistry by support of the European Union 7th Framework Programme Wood Wisdom project “ProLignin” (2012–2014), National Research Program “ResProd” (2014–2017), European Regional Development Fund research results commercialization project No 1.2.1.2/16/I/001/ KC-PI-2020/13 "Commercialisation of the technology for the production of lignocellulosic bulk thermal insulation material" (2020–2022) and Fundamental and Applied Research lzp-2021/1-0599 “Investigation of eco-friendly thermal insulation materials from sustainable and renewable industrial crops residuals” project (2022–2024). Regulations’ of the European Union and global best practice trends for limiting climate change have forced Latvia to implement actions for the rational consumption and saving of heat energy. Latvia has the lowest housing quality in the European Union, including buildings with relatively low thermal stability. EU regulations and society demand sustainable, health and environmentally friendly thermal insulation materials. As a solution to the urgent need for a new thermal insulation material produced from non-woody lignocellulosic biomass of local origin, a new loose-fill thermal insulation material that meets current regulations and environmental requirements has been developed from the by-product of agricultural plants – hemp shives – in the research of the doctoral thesis. The thesis is a detailed and fundamental, but at the same time a technological study, which includes the development of the pre-treatment methodology for the hemp shaves by the steam explosion of hemp shives, the study of the properties of the obtained fibrous materials and the evaluation of loose-fill thermal insulation material samples. As a result of the research, a steam explosion method was applied for the production of environmentally friendly thermal insulation material. The influence of the variable parameters of the steam explosion technology on the structure, properties and application possibilities of the obtained material in heat and sound insulation was studied, thus creating new knowledge about the application of the steam explosion technology in the processing of agricultural residues. The optimal processing parameters of the steam explosion method for obtaining loose-fill thermal insulation material from hemp shives are at a temperature of 235 °C, a pressure of 32 Bar with release immediately after reaching it, i.e. holding time 0 minutes. One of the most important scientific findings in the development of loose-fill thermal insulation material with steam explosion technology is the discovery that the most important is the adiabatic process (second phase – explosion), which performs fibrillation of the sample, maximally shortening the thermochemical process (first phase). By choosing the optimal processing conditions, it is possible to reduce the bulkiness up to 2.3 times, obtaining the best indicators of thermal inertia and thermal conductivity. The thermal insulation properties of the developed fibre loose-fill material (λ=0.043 W·m⁻¹·K⁻¹) are equivalent to analogues on the market. The research of the thesis has a significant practical value, as a practically applicable technology has been developed for the processing of by-products of hemp fibre production – hemp shives – into products with high added value, thus creating a knowledge-intensive, innovative product with commercialization and export potential. The developed product contributes to the growing demand for sustainable thermal insulation materials, as well as contributes to the achievement of Latvia’s climate neutrality goals and the reduction of CO₂ emissions in the field of energy efficiency. The thesis text includes 10 tables, 60 images, 21 formulas and 225 references to the used literature sources.