Wyniki wyszukiwania - BazTech

1

Ultralekki pianobeton z dodatkiem materiału zmiennofazowego do stosowania jako termoizolacja

Klemczak Barbara, Koenders Eduardus A. B., Jonkers Henk, Fachinotti Victor, Mankel Christoph, Röser Frank, Dolado Jorge S., Erkizia Edurne, Dauvergne Jean-Luc, Ortega Amaya, Zanoni Francesca, Červenka Jan, Düngfelder Michael, Stunz Christina, Zhilyaev Dmitry, Kolev Vesselin A.

Materiały Budowlane

|

2024

|

nr 2

45--49

PL

W artykule przedstawiono wybrane wyniki projektu NRG-STORAGE, którego celem jest opracowanie ultralekkiego pianobetonu z dodatkiem materiału zmiennofazowego (PCM), który ma zdolność do magazynowania i uwalniania ciepła. Uzyskane wyniki pokazały, że badany pianobeton o gęstości objętościowej 240 kg/m3 z dodatkiem 10% PCM charakteryzuje się wystarczającą wytrzymałością mechaniczną jako materiał termoizolacyjny, dobrymi właściwościami termofizycznymi oraz zdolnością do akumulacji i oddawania ciepła.

EN

The article presents selected results of the NRG-STORAGE project, aiming to develop ultralight foamed concrete with the addition of phase change material (PCM), which has the ability to store and release heat. The obtained results showed that the tested foamed concrete with a bulk density of 240 kg/m3 and with the addition of 10% PCM is characterised by sufficient mechanical strength for thermal insulation applications, good thermophysical properties, and the ability to accumulate and release heat.

2

Study on the Modification and Properties of Silk Sericin Protein/Nano-Titanium Dioxide Composite for Textile Applications

Yang Chen, Lin Yanping, Zhang Xiangai, Zhu Chunyan

Fibres & Textiles in Eastern Europe

|

2024

|

Vol. 32, no. 1

68--75

EN

Silk sericin protein is a natural high-molecular-weight compound that contains eighteen types of amino acids. It is non-toxic, biodegradable, and biocompatible, with simple preparation methods and low cost. It finds widespread application in functional clothing, medical and pharmaceutical fields, tissue engineering, and more. Nano-titanium dioxide, on the other hand, possesses non-toxic, self-cleaning, antibacterial, and deodorizing properties. To develop multifunctional textiles with deodorization, UV protection, and good thermal and mechanical properties, this study utilized a compounding method to modify citric acid-pretreated cotton fabrics through a two-dipping and two-padding process using a blend finishing solution of silk sericin protein and nano-titanium dioxide. Observations of the microstructure before and after fabric finishing, along with evaluations of deodorization, UV protection, and thermal properties, revealed that controlling the proportion of the silk sericin protein/nano-titanium dioxide blend finishing solution can result in a smooth surface of the modified cotton fabric. This modification not only enhances the fabric’s UV protection and tensile strength but also improves its thermal properties while imparting certain deodorization capabilities. Comprehensive analysis concludes that using silk sericin protein and nano-titanium dioxide for modifying cotton fabric to prepare multifunctional textiles with deodorization, UV protection, and good thermal and mechanical performance is feasibly viable.

3

Synthesis of a New Random Copolymer Based on Glycidyl Nitrate and Tetrahydrofuran : A Thermal, Kinetic, and Theoretical Study

Alizadeh Milad, Bayat Yadollah

Central European Journal of Energetic Materials

|

2024

|

Vol. 21, no. 1

5--21

EN

Today, polymeric binders are regarded as playing a crucial role in solid propellants. Therefore, research aimed at improving the performance of the binder is particularly important. In this study, a new energetic random copolymer of glycidyl nitrate (GN) and tetrahydrofuran (THF), poly (THF-ran-GN) (Mn = 1561 g mol⁻¹) was synthesized using the cationic ring-opening polymerization process. The chemical structure of the prepared copolymers was characterized utilizing FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The thermal properties of the copolymers and their molecular weights were investigated by thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the glass transition temperatures (Tg) of the synthesized copolymers (Tg= -59 °C) were lower than those of pure PGN (Tg= -32 °C). Therefore, copolymerization led to a decrease in the Tg temperature. The kinetic parameters of the DSC were determined in the non-isothermal framework described by Kissinger. The electronic structure of the copolymers was also simulated with the Gaussian 09 program package in order to investigate the optoelectronic properties of the copolymers based on time dependent density functional theory (TD-DFT) computations. In addition, the existence of three peaks featuring significant excitations associated with electron transition in frontier orbitals was demonstrated. The results showed that the new synthesized random copolymer has energetic properties.

4

Synergistic toughening and strengthening of an epoxy resin modified by simultaneous use of two different modifiers

Białkowska Anita, Suroń Patryk, Kucharczyk Wojciech, Hanulikova Barbora, Bakar Mohamed

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2024

|

Vol. 72, nr 3

art. no. e149176

EN

The present work investigates the effect of modifying an epoxy resin using two different modifiers. The mechanical and thermal properties were evaluated as a function of modifier type and content. The structure and morphology were also analyzed and related to the measured properties. Polyurethane (PUR) was used as a liquid modifier, while Cloisite Na+ and Nanomer I.28E are solid nanoparticles. Impact strength (IS) of hybrid nanocomposites based on 3.5 wt% PUR and 2 wt% Cloisite or 3.5 wt% PUR and 1 wt% Nanomer was maximally increased by 55% and 30%, respectively, as compared to the virgin epoxy matrix, exceeding that of the two epoxy/nanoparticle binaries but not that of the epoxy/PUR binary. Furthermore, a maximum increase in IS of approximately 20% as compared to the pristine matrix was obtained with the hybrid epoxy nanocomposite containing 0.5 wt% Cloisite and 1 wt% Nanomer, including a synergistic effect, due most likely to specific interactions between the nanoparticles and the epoxy matrix. The addition of polyurethane and nanoclays increased the thermal stability of epoxy composites significantly. However, DSC results showed that the addition of flexible polyurethane chains decreased the glass transition temperatures, while the softening point and the service temperature range of epoxy nanocomposites containing nanofillers were increased. FTIR analysis confirmed the occurrence of interaction between the epoxy matrix and added modifiers. All SEM micrographs showed significant roughness of the fracture surfaces with the formation of elongated platelets, explaining the increase in mechanical properties of the epoxy matrix.

5

Influence of the annealing temperature of the shape memory alloy actuator on its thermal characteristics

Kuś Krzysztof, Frączyk Adam

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

|

2024

|

Vol. 13

50--60

EN

Shape memory alloys (SMA) are used in different areas of engineering and science thanks to their unique properties. They also continue to be an innovative material for the sustainable construction industry. In this study, a commercial helical-type SMA spring actuator was investigated by subjecting it to annealing at various parameters. The thermal shape memory properties were evaluated by means of the DSC method. In most cases, the higher the annealing temperatures for the material were in the range up to 595°C, the lower the transformation temperatures. As the DSC runs showed, a different character of the changes especially in characteristic temperatures, was observed for annealing temperatures above 600°C. The results showed that the different annealing temperatures, and even the method of cooling, provide a wide range of possibilities to control the SMA spring reaction – transformation behaviour and temperatures. Such treatment can be a simple technical procedurę used for the preparation of the selected SMA functional properties if required. This means that the same SMA element can be reused without having to source a new one. This may be desirable from the point of view of sustainability.

6

Experimental research on the thermal properties of innovative insulation boards made of polyurethane-polyisocyanurate (PUR/PIR)

Prałat Karol, Ciemnicka Justyna, Jankowski Piotr, Wierzbicka Ewa, Plis Arkadiusz

Polish Journal of Chemical Technology

|

2023

|

Vol. 25, nr 1

40--46

EN

In this work, the results of investigations of polyurethane materials were presented. Innovative materials based on polyurethane-polyisocyanurate (PUR/PIR) foam were obtained. Different types of additives (flame retardants, aerogels – additives that decrease thermal conductivity) are used in the composition of PUR/PIR foam. Foams are a type of composite composed of two phases: continuous (polyurethane polymers) and dispersed (composed of gases). All samples have been tested for thermal parameters: thermal conductivity, specific heat, and thermal diffusivity. Then they have been compared with each other and with a reference sample (RS) without additives. Based on the research, it was shown that innovative insulation materials were characterized by thermal conductivity λ in the range of 0.0254–0.0294 W/(m · K). The thermal properties of foams depending on the type and chemical composition of the material. Depending on the used substrates, their molar ratio, type, synthesis conditions, modifying agents and catalysts, a different polyurethane material is obtained.

7

Synthesis and characterization of modified PVC waste with different diamines for Hg(II) removal

Mohammed Ameen Hadi, Hamed Ameera Hassan, Aldabbagh Areej Kamal Assim

Polimery

|

2023

|

Vol. 68, nr 11-12

640--645

EN

PVC waste, after removing contamination (P1), was cross-linked with 1,3-diaminopropane, hexamethylenediamine and 1,4-diaminonaphthalene (P2, P3 and P4). The cross-linked PVC was charac-terized by FTIR, SEM and CHN elemental analysis. The influence of the type of crosslinking agent on the thermal properties and swelling of PVC was also investigated. P3 was characterized by the highest water absorption, and P4 had the best thermal stability. All cross-linked polymers showed good effectiveness in removing Hg(II) ions, especially PVC modified with hexamethylenediamine.

PL

Odpady PVC po usunięciu zanieczyszczeń (P1) sieciowano 1,3-diaminopropanem, heksametylenodiaminą i 1,4-diaminonaftalenem (P2, P3 i P4). Usieciowany PVC scharakteryzowano za pomocą FTIR, SEM i analizy pierwiastkowej CHN. Zbadano także wpływ rodzaju środka sieciującego na właściwości termiczne i pęcznienie PVC. P3 charakteryzował się największą absorpcją wody, a P4 najlepszą stabilnością termiczną. Wszystkie usieciowane polimery wykazały dobrą skuteczność w usuwaniu jonów Hg(II), zwłaszcza PVC modyfikowany heksametylenodiaminą.

8

Effect of alternative carbon-based filler on rubber compounds properties

Božeková Slavomíra, Ondrušová Darina, Pajtášová Mariana, Ďurišová Silvia, Mičicová Zuzana, Labaj Ivan, Moricová Katarína, Klepka Tomasz Waldemar

Polimery

|

2023

|

Vol. 68, nr 11-12

585--592

EN

Instead of conventional carbon black, an alternative carbon filler (ACB) obtained in the pyrolysis process from tire waste was used for rubber compounds. The fillers were characterized using FTIR and TGA methods. The mechanical properties of the obtained rubber compounds and the influence of the fillers used on the vulcanization process, as well as the Payne effect, were examined. The results confirm the possibility of replacing conventional carbon black with an alternative carbon filler in rubber compounds.

PL

Do mieszanek gumowych zamiast konwencjonalnej sadzy zastosowano alternatywny napełniacz węglowy (ACB) otrzymany w procesie pirolizy z odpadów opon. Napełniacze scharakteryzowano za pomocą FTIR i TGA. Zbadano właściwości mechaniczne otrzymanych mieszanek gumowych oraz wpływ stosowanych napełniaczy na przebieg procesu wulkanizacji, a także na efekt Payne’a. Wyniki potwierdzają możliwość zastąpienia konwencjonalnej sadzy alternatywnym napełniaczem węglowym w mieszankach gumowych.

9

PLA filament is not equal to PLA filament: Experimental studies of the influence of the type of pigment on the mechanical and thermal properties of poly(lactic acid) products

Iwko Jacek, Jaruga Tomasz, Trzaska Oliwia, Stachowiak Tomasz

Materials Science Poland

|

2023

|

Vol. 41, No. 1

177-190

EN

The correct manufacture of products using FDM printers is not an easy task, taking into account the value and repeatability of material properties. The properties of elements manufactured in this way depend on many factors, both technological and material. Poly(lactic acid) PLA is one of the most willingly used materials in additive techniques. It is sold in a very wide range of colours. This work was intended to answer the question of how the type of pigment affects the mechanical and thermal properties of products obtained from PLA. The correlation between the material properties and the structure of the material as well as the macroscopic structure of the product has also been investigated. The paper analyses the mechanical and thermal properties of products made of PLA filaments in 12 basic colours obtained from one supplier. Bending, impact strength, HDT and Vicat softening point tests were carried out. The percentage content of residues after calcination the samples was determined. Additional analysis (DSC) was performed to interpret the obtained tests results. They indicate that the mechanical properties differ significantly between different types of PLA with differences of up to 45%. Vicat softening point tests indicate differences of 5°C between the extreme values of these parameters. The DSC interpretive study did not clearly show the reasons for these differences in the properties of the filaments.

10

A Numerical Study to Determine the Effect of an Insulator Location on the Transient Heat Transfer

Mageed Ridha Hameed, Kurji Hayder J., Abdulrasool Ali A.

Journal of Ecological Engineering

|

2023

|

Vol. 24, nr 10

105--114

EN

Given the importance of thermal insulation in the walls of buildings to provide both electrical energy and thermal comfort in different weathers. In this research, the ANSYS-14 simulation program was used, considered one of the programs used to evaluate the thermal behavior of buildings, considering the effect of weather changes and building components during the steady and unsteady heat transfer of a composite wall from several layers. The simulation program was used for four types of insulation inside the wall with different thermal properties (Glass-Fiber Slab, Polyurethane Board, Hardboard (Medium) and Softwoods). A model was built for a traditional wall without an insulator and a model for a traditional wall that contains an insulator in different locations (from the outside, in the middle, and from the inside). Also, the model was isolated from the top and bottom surfaces, and each insulation material was applied in three locations in the wall. The conventional composite wall was exposed to a constant thermal load of 60 °C from the outside, and the inside wall was exposed to a thermal load of 25 °C This study focused on three steps. The first step is to know the best type of the four thermal insulators used in this study. The second step was to evaluate the best location of the insulator in the wall. The third step included the results of the previous two steps through which the best insulator was chosen and the best location in the wall. Three values of insulator thickness 2, 5 and 8 cm were used. Through the results of the study, it was found that placing the insulator on the outside of the wall plays a large role in reducing the rate of unsteady heat transfer and that its effect decreases by approaching the steady state, as it does not affect it in the case of the total steady state. The results also showed that the rate of unsteady heat transfer decreases by decreasing the thermal diffusivity of materials. It is also noticeable that the effect of the density and specific heat capacity appears clearly at the beginning of the thermal loading on the material. That effect decreases by approaching the steady state as the effect of the heat transfer coefficient of conduction appears. It was also found that both hardboard and polyurethane are the best in thermal insulation. It was also observed that the relationship between heat transfer rate and thickness is inverse-linear.

11

Thermal and physicochemical properties of silicone-based composites reinforced with silanized magnetic powder

Powojska Anna, Niewęgłowska Joanna, Mystkowska Joanna

Engineering of Biomaterials

|

2023

|

vol. 26, no. 170

2--8

EN

Silicone-based materials are of great interest in medicine and cosmetic applications because of their biocompatibility and elasticity. Recently, there has been a significant focus on the development of functional materials that integrate multiple desirable characteristics. Elastic composites reinforced with magnetic filler are active in a magnetic field. These materials can be an interesting alternative to the currently used materials, after appropriate modification of the NdFeB powder. From the point of view of the use of materials in biomedical engineering, they require a lot of research and analysis to determine whether they are useful and will not cause potentially negative effects on a living organism. The aim of the work was to verify the influence of the powder silanization method on the thermal and physicochemical properties of silicone-based composites reinforced with NdFeB powder. The appropriate selection of the silanization parameters used in the process allows control of the properties of the composite. The powder surface silanization execution affects the physicochemical and thermal stability of the prepared composites. It has been established that, depending on the method of silanization, the composite properties were changed. The obtained experimental results may lead to further research on the functionalization of elastic composites reinforced with magnetic powder.

12

Comparative study on the impact transition behaviour of PPS reinforces with 40% VF Glass

Kadhim Rand Fadhil, Jassim Noor Alhuda Sabah, Abdulhasan Maryam Jawad

Diagnostyka

|

2023

|

Vol. 24, No. 3

art. no. 2023314

EN

Composite materials, in most cases polymers reinforced with fibers, are these days utilized in numerous applications such as aerospace applications in which lightweight, high strength, high specific modulus and low temperature resistance are critical issues. As these materials have possible applications in different designing areas, a lot of work has been put into enhancing their performance. This study's aim was to study the impact transition behavior of PPS and its composite under different ranges of temperatures by investigating their thermal, mechanical and structural characteristics. PPS and its composite reinforced with 40% vf (volume fraction) glass fibers are employed in this study. The impact transition behavior of PPS and 40%Vf glass fibers composite were investigated by analyzing the mechanical properties: impact, tensile, bending and, hardness at the following temperature ranges: 23°C, -26°C, and -78°C. A particular refrigerator and dry ice were used to achieve the extremely low temperatures (-26 C and -78 C, respectively). The results showed that the addition of 40% glass fibers improved the impact transition behavior of 40%GF PPS composite with temperature decreasing. Which with decreasing in temperature from 23˚C to -78˚C, the impact strength of PPS decreased by fifty five percent while it increased by twenty three percent for 40%GF PPS composite.

13

Analysis of the influence of the geometric features of the filler on the thermal properties and structure of the composites in the polypropylene matrix

Postawa Przemysław, Jeż Bartłomiej, Norwiński Sylwester, Kalwik Aleksandra

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2023

|

Vol. 71, nr 5

art. no. e147064

EN

The article presents the results of research on polymer composites based on polypropylene filled with various fillers. The physical and thermal properties of the composites are the result of the used polymer matrix as well as the properties and geometric features of the used filler. The geometric shape of the filler is particularly important in the processing of plastics in which the flow is forced, and high shearing tension occurs, which determines the high macromolecular orientation and specific arrangement of the filler particles. Thermal analysis (STA) was used in the research and photographs were taken using a scanning electron microscope (SEM) of fractures of polymer composites. The following fillers were used: talc, fibreglass, glass beads, and a halogen-free nitrogen-phosphorus flame retardant. The test material was obtained by extrusion. Shapes for strength tests, which were subjected to scanning microscopy tests after a static tensile test, were obtained by injection. The carried-out tests allowed us to determine the influence of the type and shape of individual fillers on structural changes in the structure of polypropylene composites and the degree of sample weight loss in a specific temperature range, depending on the used filler.

14

The influence of thermophysical properties of frozen soil on the temperature of the cast-in-place concrete pile in a negative temperature environment

Liu Ziying, Yu Tianlai, Yan Ning, Gu Lipeng

Archives of Thermodynamics

|

2023

|

Vol. 44, no 2

21--48

EN

Thermophysical properties of frozen soil have a great influence on the quality of cast-in-place concrete piles. In this paper, the embedded concrete temperature monitoring system is used to test the variation law of the concrete temperature during the construction of the bored pile. Thermophysical properties of permafrost around piles are tested. Based on the theory of three-phase unsteady heat conduction of soil, the influence of specific heat capacity, thermal conductivity, thermal diffusivity, and latent heat of phase transformation on the temperature change of a concrete pile is systematically studied. The thermal parameter is obtained which exerts the most significant influence on the temperature field. According to the influence degree of frozen soil on pile temperature, the order from high to low is thermal conductivity, thermal diffusivity, latent heat of phase change, and specific heat capacity. The changes in pile wall temperature caused by the change of these properties range between 2.60–10.97◦C, 1.49– 9.39◦C, 2.16–2.36◦C, and 0.24–3.45◦C, respectively. The change percentages of parameters vary between 35.77–47.12%, 12.22–40.20%, 12.46–32.25%, and 3.83–20.31%, respectively. Therefore, when designing and constructing concrete foundation piles, the influence of the thermal conductivity of frozen soil on concrete pile temperature should be considered first. The differences between the simulated and measured temperature along the concrete pile in the frozen soil varying with the respective thermal properties are: –2.99– 7.98◦C, –1.89–4.99◦C, –1.20–1.99◦C, and –1.76–1.27◦C. Polyurethane foam and other materials with small thermal conductivity can be added around the pile to achieve pile insulation.

15

Characterization of Ijero-Ekiti Quartz as Refractory Raw Material for Industrial Furnace

Omidiji B. V., Ogundipe O. B., Owolabi H. A.

Archives of Foundry Engineering

|

2023

|

Vol. 23, iss. 4

14--21

EN

This study investigated the suitability of Ijero-Ekiti quartz as a refractory raw material for industrial furnace applications. In order to ascertain its prospective applications, the thermal behaviour, mineralogical composition and chemical composition were determined. Ijero-Ekiti quartz was characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric and Differential Thermal analysis (TGA and DTA). Its thermal conductivity with specific heat coefficient was determined. The outcome revealed that the quartz sample has a high purity of 94.3% SiO2, making it suitable as a refractory material. The XRD analysis revealed the presence of alpha-quartz as the dominant crystal phase, which is desirable for refractory applications. The FTIR analysis indicated the absence of hydroxyl (-OH) groups. This indicates a low risk of failure and damage such as spalling, cracking and other forms of damage when produced into bricks. The TGA and DTA displayed significant mass losses and large endothermic bands, which were connected to the dehydroxylation of the quartz rock samples. Based on the demonstrated qualities, the quartz rock sample could be subjected to thermal processing. This study therefore established that Ijero-Ekiti quartz is a suitable raw material for refractory applications due to its high purity, alpha-quartz dominant crystal phase, absence of hydroxyl groups, and uniform morphology.

16

Study of Crystalline and Thermal Properties of Nanocomposites Based on Polyamide-6 and Modified Montmorillonite

Krasinskyi Volodymyr, Dulebova Ludmila, Gajdoš Ivan, Krasinska Oksana, Jachowicz Tomasz

Advances in Science and Technology. Research Journal

|

2023

|

Vol. 17, no 6

88--97

EN

The main operational characteristics of polyamide-6-montmorillonite (PA6/MMT) nanocomposites, which determine their fields of application, mainly depend on the crystal structure and crystallinity of the polymer. Therefore, the study of the crystalline behavior of PA6 in such nanocomposites is of considerable scientific and practical importance. In this work, the structure, crystalline, and thermal properties of nanocomposites based on PA6 and modified MMT prepared in a formic acid solution were investigated using the methods of differential scanning calorimetry (DSC) and X-ray Diffraction (XRD). It was established that during the manufacture of PA6/MMT nanocomposites in a solution, the dominant crystal structures are the thermodynamically stable α structures of PA6. The crystallinity degree of PA6 in nanocomposites is about 1.5 times higher than that of the original PA6. It is shown that after additional thermomechanical treatment of nanocomposites on a capillary viscometer at 230°С and a load of 5 kg, the uniformity of the distribution of exfoliated MMT in the polymer matrix increases, as a result of which the crystalline structure of PA6 changes and its glass transition and melting temperatures increase. These changes in the PA6 structure also have a significant impact on the melt flow index and the softening temperature of nanocomposites.

17

Correlation and interpretation of thermal properties of volcanic rocks from Austria

Gegenhuber Nina, Dertnig Florian

Acta Geophysica

|

2023

|

Vol. 71, no. 3

1251--1258

EN

Thermal properties of rocks are of great importance not only for geothermal projects. The focus of petrophysical data presented here is laid mainly on volcanic rocks. Thermal properties include not only thermal conductivity but also heat production and heat capacity. A full range of dataset and analysis out of it is presented here. The target of this study is to deliver new insights in the thermal properties of volcanic rocks of Austria. The focus is laid on thermal conductivity—understanding of influencing factors and correlations with other properties, like compressional wave velocity, electrical resistivity or radiogenic heat production. Therefore, a set of data from various volcanic rocks of Austria is presented, analysed in detail and new correlations are presented. The correlations can be further applied on logging data to derive thermal properties in the field. These improved correlations and further interpretations can help in planning geothermal projects and can improve the output of simulations because of the better input data.

18

Identyfikacja właściwości termicznych materiałów fazowo zmiennych z dodatkiem wybranych nanomateriałów

Wołoszyn Jerzy

Przemysł Chemiczny

|

2022

|

T. 101, nr 11

1023--1026

PL

Główną wadą organicznych materiałów fazowo zmiennych, które są coraz częściej stosowane w magazynach energii termicznej, jest ich niska przewodność cieplna. Zmniejszenie oporu cieplnego po stronie medium magazynującego realizowane poprzez dodanie nanomateriałów to jeden ze sposobów na poprawę efektywności procesu wymiany ciepła. Przeprowadzono badania entalpii i temperatury przemiany fazowej, ciepła właściwego oraz czasu przemiany fazowej w trakcie topnienia i krzepnięcia komercyjnie dostępnego materiału fazowo zmiennego z dodatkiem dwóch rodzajów nanoproszków (a-Fe₂O₃ i a-Al₂O₃) o udziale masowym 0,8%, 6,5% oraz 13%. Nie stwierdzono znacznego obniżenia entalpii i temperatury przemiany fazowej dla każdej z przygotowanych próbek. Istotnym negatywnym efektem towarzyszącym przy wzroście udziału nanomateriału był znaczny wzrost czasu przemiany fazowej w trakcie topnienia.

EN

The enthalpy and phase transition temp., sp. heat and phase transition time were detd. during melting and solidification of com. available phase transition material and with the addn. of 2 types of nanopowders (a-Fe₂O₃, a-Al₂O₃) in the amt. of 0.8%, 6.5 % or 13%. No significant decrease in enthalpy and phase transition temp. was observed for each of the prepared samples. A significant neg. effect accompanying the increase in nanomaterial content was a significant extension of the phase transition time during melting.

19

Vegetable Waste in Freezing Process as a High Quality Material for Freeze-Drying ®

Ciurzyńska Agnieszka, Rybak Katarzyna, Karwacka Magdalena, Galus Sabina, Janowicz Monika

Postępy Techniki Przetwórstwa Spożywczego

|

2022

|

nr 1

91--104

EN

The article of the study was to investigate selected physical and chemical properties of freeze-dried vegetables which were rejected as a waste of freezing process due to non-compliance with the size criterion. Cauliflower, carrot, yellow bean, potato and onion were freeze-dried with registration of drying kinetics and next sugars, anthocyanin and polyphenols content were determined, rehydration and sorption properties as well as colour, water activity and content and thermal properties. It was shown that obtained samples were characterized typical properties for freeze-dried vegetables and may be used as an e.g. component of freeze-dried vegetable mix or innovative food product.

PL

Celem artykułu było przedstawienie zbadanych wybranych właściwości fizykochemicznych warzyw liofilizowanych, które zostały odrzucone jako odpad z procesu mrożenia z powodu niespełnienia kryterium wielkości. Liofilizowano kalafior, marchew, żółtą fasolę, ziemniak i cebulę z rejestracją kinetyki suszenia, a następnie oznaczono zawartość cukrów, antocyjanów i polifenoli, właściwości rehydratacyjne i sorpcyjne, a także barwę, aktywność wody oraz zawartość i właściwości termiczne. Wykazano, że otrzymane próbki charakteryzowały się właściwościami typowymi dla warzyw liofilizowanych i mogą być wykorzystywane m.in. jako składnik liofilizowanej mieszanki warzywnej lub innowacyjnego produktu spożywczego.

20

Thermal properties and processability of modified poly(L-lactide): the role of phenylacetic acid hydrazide derivative

Huang Hao, Cai Yanhua, Zhao Lisha

Polimery

|

2022

|

Vol. 67, nr 9

423--432

EN

The influence of phenylacetic acid hydrazide (NAPAH) derivative content, melt temperature (170−200°C) and cooling rate (1−20°C/min) on poly(L-lactide) (PLLA) nucleation were investigated. Increasing the content of NAPAH (0.5−3.0 wt.%) had a positive effect on PLLA crystallization, while an increase in the cooling rate and heating temperature had a negative effect. In the case of isothermal crystallization carried out for a long time (180 min), the melting process depended only on the crystal lization temperature. NAPAH also influenced the cold crystallization temperature, reduced thermal stability and improved PLLA processability (MFR).

PL

Zbadano wpływ zawartości pochodnej hydrazydu kwasu fenylooctowego (NAPAH), temperatury stopu (170−200°C) i szybkości chłodzenia (1–20°C/min) na nukleację poli(L-laktydu) (PLLA). Zwiększenie zawartości NAPAH (0,5–3,0% mas.) miało pozytywny wpływ na krystalizację PLLA, natomiast wzrost szybkości chłodzenia i temperatury ogrzewania negatywny. W przypadku krystalizacji izotermicznej prowadzonej przez długi czas (180 min), proces topnienia zależał tylko od temperatury krystalizacji. NAPAH wpływał również na temperaturę zimnej krystalizacji, zmniejszał stabilność ter miczną i poprawiał właściwości przetwórcze PLLA (MFR).