Sigitas Vėjelis

Development and investigation of thermal insulation from hemp-polylactide fibres

AbstractIn the last two decades intensive grow of industry of building materials from renewable resources is observed. Such situation is related to some aspects: global warming, environmental pollution, impact on human health, environmental impact of materials at their end-of-life.In current study development of thermal insulation materials from hemp and polylactide fibres are analysed. While main parameter for thermal insulation materials is thermal conductivity, rational density of composite 40 kg/m3 was chosen. For experiments 11 compositions were prepared. One composition was prepared just with hemp and polylactide fibres, five compositions with different amount of hydrophobic agent and 5 compositions with different amount of fire retardant. Experimentally thermal conductivity, sound absorption coefficient, short-term water absorption, fire resistance, water vapour transfer properties and compressive strength were determined. Rational amount of hydrophobic agent and fire retardants was chosen.

The Use of Sapropel in Development of Effective Thermal Insulating Materials

This paper presents investigations of thermal conductivity, tensile strength and compressive stress at 10% deformation of effective thermal insulation composites made from hemp shives and sapropel. Images of hemp shives and hemp composite microstructure obtained by scaning electron microscope (SEM) are analised. The paper presents properties of composite from seven compositions. Composite forming mixture contains different amount of sapropel as well as paper production wastes (PPW) obtained in paper processing industry.

Development and Research of Thermal Insulation Materials from Natural Fibres

Natural fibres from flax and hemp are used as raw materials for efficient thermal insulation. In current work, tests were carried out using chopped and combed long flax fibres as well as chopped and combed long hemp fibres. Investigations have shown that thermal conductivity of natural fibres depends on their preparation method (combing, chopping) and materials density.

Šiaudų naudojimo galimybių termoizoliacinių medžiagų gamybai tyrimai@@@Analysis of Thermal Insulation from Renewable Resources

Santrauka Vienas esminių statinio reikalavimų – energijos taupymas ir silumos issaugojimas. Apytiksliai 40 % visos Europos Sąjungoje suvartojamos energijos tenka sildomų pastatų eksploatacijai. Didžiąją sių sąnaudų dalį sudaro energija, suvartojama pastatams sildyti saltuoju metų laikotarpiu ir jiems vėsinti siltuoju metų laikotarpiu. Kelis kartus mažiau energijos galima suvartoti gaminant termoizoliacines medžiagas is atsinaujinanciųjų isteklių ir jomis siltinant pastatus. Tokių medžiagų silumos laidumo koeficientas yra apytiksliai 0,040 W/(mK). Darbe nagrinėjamos siaudų naudojimo galimybės termoizoliacinių medžiagų gamybai. Pateikti atliktų įvairaus tankio siaudų silumos laidumo tyrimų laboratorinėmis sąlygomis ir vakuumuotoje aplinkoje rezultatai.

A Study of Rapeseed Oil-Based Polyol Substitution with Bio-based Products to Obtain Dimensionally and Structurally Stable Rigid Polyurethane Foam

Water-blown polyurethane foams from low functionality polyols are characterized by intensive shrinkage, high density, post blowing, and longer demold time. These drawbacks can be partially, or fully, eliminated by varying chemical parameters of the main components. Therefore, an aliphatic polyester rapeseed oil-based polyol was modified with bio-based glycerin (RGL) and propylene glycol (RPG). The impact of the molecular weight and hydroxyl value of the blends were evaluated by testing obtained bio-based polyurethane foams. Compared to RGL-based foams, RPG-modified foams had the strictest standard (EN 13165) requirements regarding dimensional stability. These foams demonstrated a reduced apparent density from 12.6 to 20.8%, a faster foam curing capability by 47%, and the shortest demold time due to the open cell structure. The RGL modified foams had better cross-linking capability, slower ageing of thermal conductivity, and an increased compressive strength of 82.7% compared to the non-modified foam.

Development and Research of Thermal-Acoustical Insulating Materials Based on Natural Fibres and Polylactide Binder

Recently natural fibres are becoming more and more popular and their significance to the industry is increasing as well. In the last two decades, natural fibres are more widely used in the production of thermal–acoustical insulating materials. It was brought to attention that these fibrous materials have good thermal and acoustical properties in comparison to glass fibres. Also, the product, made from natural fibres, can be recycled for several times, and eventually, easily utilized, when it becomes non- recyclable. Therefore, in order to implement such innovative solutions in environmental and building sectors e.g. to install energetically effective thermal–acoustical insulation materials in building industry, scientific research is required. The object of this research is to produce fibrous composites made from natural fibres (hemp fibres and sheep wool waste) and binder of polylactide fibres, which are made from plant products – corn – by biotechnological method. In current research thermal conductivity and sound absorption coefficient of fibrous composites were determined. The microstructure of fibrous composites were investigated as well. The paper describes the manufacturing possibilities with regard to thermal–acoustical insulating materials based on hemp fibres and sheep wool waste from easily renewable material resources provided by the agriculture.

Loose Fill Material from Hemp Shives and Binding Material for Thermal Insulation and Structural Use

Currently building sector requires the use of new technologies and innovative materials. Realization of mentioned requirements allow ensuring rate of performed works, reducing labour building constructions costs and improving building performance. In current work, loose fill material from hemp shives and binding material are analysed. The mixture of hemp shives and binder may be used in frame constructions as blown or poured loose fill material for thermal insulation or structural use. Hardened composite is characterized by high strength and excellent thermal conductivity when it is used in building partitions and enclosures. In our work hemp shives are mineralized with different amount of liquid sodium silicate and mixed with cementitious binder. Macro-and microstructures of hardened composite are analysed, influence of amount of mineralizer on the strength and thermal conductivity of composite is evaluated.

Investigation of Mechanical Properties of Composite Made from Hemp and Polylactide

This paper presents the research on the structure, short-term compression and tension of hemp fibers composite. The density of hemp fibers composite varied from ~40 to ~96 kg/m3. The mechanical characteristics of such hemp fibers composite mostly depend on the materials structure and density. By the mechanical tests it was determined that compressive stress of the hemp fibers composite depends on the direction of the load to the specimens face (perpendicular, across and parallel to the direction of formation).

Titanate-Based Surface Modification of Paper Waste Particles and its Impact on Rigid Polyurethane Foam Properties

Producing particulate filled polymer composites, even dispersion and sufficient adhesion between filler and polymer matrix is of great importance. In order to solve these issues, methodologies, such as ultrasonic dispersing and coupling agents, are proposed. The impact of particle surface modification with three different titanate coupling agents having the tradenames of TCA L44, TCA L38 and TCA K44 on paper waste sludge particles surface, polyurethane foam composite density, compressive and tensile strengths as well as water absorption and water vapour permeability is evaluated. Apparently, titanates form layer on the particle surface, thus increasing the interfacial adhesion between particles and polymer matrix. Basing on the obtained results, the optimal amount and type of titanate is 1 wt.% of TCA K44.