scholarly journals Application of Walnut Shells-Derived Biopolyol in the Synthesis of Rigid Polyurethane Foams

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2687 ◽  
Author(s):  
Sylwia Członka ◽  
Anna Strąkowska ◽  
Agnė Kairytė
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Characteristics ◽  
Cell Structure ◽  
Weight Ratio ◽  
Polyurethane Foams ◽  
Maximum Temperature ◽  
Walnut Shells ◽  
Foam Properties ◽  
The Fourier Transform ◽  
The Impact

This study aimed to examine rigid polyurethane (PUR) foam properties that were synthesized from walnut shells (WS)-based polyol. The Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the liquefaction of walnut shells was successfully performed. The three types of polyurethane (PUR) foams were synthesized by replacement of 10, 20, and 30 wt% of a petrochemical polyol with WS-based polyol. The impact of WS-based polyol on the cellular morphology, mechanical, thermal, and insulating characteristics of PUR foams was examined. The produced PUR foams had apparent densities from 37 to 39 kg m−3, depending on the weight ratio of WS-based polyol. PUR foams that were obtained from WS-based polyol exhibited improved mechanical characteristics when compared with PUR foams that were derived from the petrochemical polyol. PUR foams produced from WS-based polyol showed compressive strength from 255 to 310 kPa, flexural strength from 420 to 458 kPa, and impact strength from 340 to 368 kPa. The foams that were produced from WS-based polyol exhibited less uniform cell structure than foams derived from the petrochemical polyol. The thermal conductivity of the PUR foams ranged between 0.026 and 0.032 W m−1K−1, depending on the concentration of WS-based polyol. The addition of WS-based polyol had no significant influence on the thermal degradation characteristics of PUR foams. The maximum temperature of thermal decomposition was observed for PUR foams with the highest loading of WS-based polyol.

scholarly journals Rigid Polyurethane Foams Based on Bio-Polyol and Additionally Reinforced with Silanized and Acetylated Walnut Shells for the Synthesis of Environmentally Friendly Insulating Materials

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3245 ◽  
Author(s):  
Sylwia Członka ◽  
Anna Strąkowska
Keyword(s):  
Morphological Analysis ◽  
Mechanical Characteristics ◽  
Thermal Characteristics ◽  
Mechanical Analysis ◽  
Polyurethane Foams ◽  
Walnut Shells ◽  
Chemically Treated ◽  
The Impact ◽  
And Storage ◽  
Insulating Properties

Rigid polyurethane (PUR) foams produced from walnut shells-derived polyol (20 wt.%) were successfully reinforced with 2 wt.% of non-treated, acetylated, and silanized walnut shells (WS). The impact of non-treated and chemically-treated WS on the morphology, mechanical, and thermal characteristics of PUR composites was determined. The morphological analysis confirmed that the addition of WS fillers promoted a reduction in cell size, compared to pure PUR foams. Among all the modified PUR foams, the greatest improvement of mechanical characteristics was observed for PUR foams with the addition of silanized WS—the compressive, flexural, and impact strength were enhanced by 21, 16, and 13%, respectively. The addition of non-treated and chemically-treated WS improved the thermomechanical stability of PUR foams. The results of the dynamic mechanical analysis confirmed an increase in glass transition temperature and storage modulus of PUR foams after the incorporation of chemically-treated WS. The addition of non-treated and chemically-treated WS did not affect the insulating properties of PUR foams, and the thermal conductivity value did not show any significant improvement and deterioration due to the addition of WS fillers.

Bio-based Polyurethane-clay Nanocomposite Foams: Systheses and Properties

2009 ◽  
Vol 1188 ◽  
Author(s):  
Min Liu ◽  
Zoran S. Petrovic ◽  
Yijin Xu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Cell Structure ◽  
Polyurethane Foams ◽  
Mechanical And Thermal Properties ◽  
Cell Content ◽  
Modified Clay ◽  
Rigid Polyurethane Foams ◽  
Nanocomposite Foams ◽  
Organically Modified

AbstractStarting from a bio-based polyol through modification of soybean oil, BIOH™ X-210, two series of bio-based polyurethanes-clay nanocomposite foams have been prepared. The effects of organically-modified clay types and loadings on foam morphology, cell structure, and the mechanical and thermal properties of these bio-based polyurethanes-clay nanocomposite foams have been studied with optical microscopy, compression test, thermal conductivity, DMA and TGA characterization. Density of nanocomposite foams decreases with the increase of clay loadings, while reduced 10% compressive stress and yield stress keep constant up to 2.5% clay loading in polyol. The friability of rigid polyurethane-clay nanocomposite foams is high than that of foam without clay, and the friability for nanofoams from Cloisite® 10A is higher than that from 30B at the same clay loadings. The incorporation of clay nanoplatelets decreases the cell size in nanocomposite foams, meanwhile increases the cell density; which would be helpful in terms of improving thermal insulation properties. All the nanocomposite foams were characterized by increased closed cell content compared with the control foam from X-210 without clay, suggesting the potential to improve thermal insulation of rigid polyurethane foams by utilizing organically modified clay. Incorporation of clay into rigid polyurethane foams results in the increase in glass transition temperature: the Tg increased from 186 to 197 to 204 °C when 30B concentration in X-210 increased from 0 to 0.5 to 2.5%, respectively. Even though the thermal conductivity of nanocomposite foams from 30B is lower than or equal to that of rigid polyurethane control foam from X-210, thermal conductivity of nanocomposite foams from 10A is higher than that of control at all 10A concentrations. The reason for this abnormal phenomenon is not clear at this moment; investigation on this is on progress.

Design and Optimization of a Composite Heat Spreader to Improve the Thermal Management of a 3D Integrated Circuit

2021 ◽  
Author(s):  
Andisheh Tavakoli ◽  
Kambiz Vafai
Keyword(s):  
Thermal Conductivity ◽  
Heat Sink ◽  
Variable Temperature ◽  
Heat Removal ◽  
High Conductivity ◽  
High Thermal Conductivity ◽  
Maximum Temperature ◽  
Optimal Distribution ◽  
Heat Spreader ◽  
The Impact

Abstract The present study analyzes the optimal distribution of a limited amount of high thermal conductivity material to enhance the heat removal of circular 3D integrated circuits, IC. The structure of the heat spreader is designed as a composite of high thermal conductivity (Boron Arsenide) and moderate thermal conductivity (copper) materials. The volume ratio of high-conductivity inserts to the total volume of the spreader is set at a fixed pertinent ratio. Two different boundary conditions of constant and variable temperature are considered for the heat sink. To examine the impact of adding high-conductivity inserts on the cooling performance of the heat spreader, various patterns of the single and double ring inserts are studied. A parametric study is performed to find the optimal location of the rings. Moreover, the optimal distribution of the high-conductivity material between the inner and outer rings is found. The results show that for the optimal conditions, the maximum temperature of the 3D IC is reduced up to 10%; while the size of the heat sink, and heat spreader can be diminished by as much as 200%.

scholarly journals Viscoelastic Polyurethane Foams with Reduced Flammability and Cytotoxicity

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 151
Author(s):  
Małgorzata Okrasa ◽  
Milena Leszczyńska ◽  
Kamila Sałasińska ◽  
Leonard Szczepkowski ◽  
Paweł Kozikowski ◽  
...  
Keyword(s):  
Polyurethane Foams ◽  
Test Results ◽  
Scanning Calorimetry ◽  
Simultaneous Reduction ◽  
Protective Devices ◽  
Respiratory Protective Devices ◽  
The Face ◽  
Foam Properties ◽  
Risk Of Exposure ◽  
The Impact

Consistent and proper use of respiratory protective devices (RPD) is one of the essential actions that can be taken to reduce the risk of exposure to airborne hazards, i.e., biological and nonbiological aerosols, vapours, and gases. Proper fit of the facepiece and comfort properties of RPDs play a crucial role in effective protection and acceptance of RPDs by workers. The objective of the present paper was to develop viscoelastic polyurethane foams for use in RPD seals characterised by proper elasticity, allowing for the enhancement of the device fit to the face and the capability of removing moisture from the skin in order to improve the comfort of RPD use. Moreover, it was pivotal to ensure the non-flammability of the foams, as well as a simultaneous reduction in their cytotoxicity. The obtained foams were characterised using scanning electron microscopy, infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. Measurements also involved gel fraction, apparent density, compression set, rebound resilience, wettability, flammability, and cytotoxicity. The results are discussed in the context of the impact of modifications to the foam formulation (i.e., flame-retardant type and content) on the desired foam properties. The test results set directions for future works aimed to develop viscoelastic polyurethane foams that could be applied in the design of respiratory protective devices.

scholarly journals Use of a Mixture of Polyols Based on Metasilicic Acid and Recycled PLA for Synthesis of Rigid Polyurethane Foams Susceptible to Biodegradation

2020 ◽  
Vol 22 (1) ◽  
pp. 69
Author(s):  
Joanna Paciorek-Sadowska ◽  
Marcin Borowicz ◽  
Ewelina Chmiel ◽  
Jacek Lubczak
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Raw Materials ◽  
Weight Ratio ◽  
Acid Number ◽  
Polyurethane Foams ◽  
Poly Lactic Acid ◽  
Rigid Polyurethane Foams ◽  
Sustainable Resource Management ◽  
Metasilicic Acid

Two polyol raw materials were obtained in the conducted research, one based on metasilicic acid (MSA), the other based on poly(lactic acid) (PLA) waste. The obtained polyols were characterized in terms of their applicability for the production of rigid polyurethane foams (RPUFs). Their basic analytical properties (hydroxyl number, acid number, elemental analysis) and physicochemical properties (density, viscosity) were determined. The assumed chemical structure of the obtained new compounds was confirmed by performing FTIR and 1H NMR spectroscopic tests. Formulations for the synthesis of RPUFs were developed on the basis of the obtained research results. A mixture of polyols based on MSA and PLA in a weight ratio of 1:1 was used as the polyol component in the polyurethane formulation. The reference foam in these tests was a foam that was synthesized only on the basis of MSA-polyol. The obtained RPUFs were tested for basic functional properties (apparent density, compressive strength, water absorption, thermal conductivity coefficient etc.). Susceptibility to biodegradation in soil environment was also tested. It was found that the use of mixture of polyols based on MSA and PLA positively affected the properties of the obtained foam. The polyurethane foam based on this polyol mixture showed good thermal resistance and significantly reduced flammability in comparison with the foam based MSA-polyol. Moreover, it showed higher compressive strength, lower thermal conductivity and biodegradability in soil. The results of the conducted tests confirmed that the new foam was characterized by very good performance properties. In addition, this research provides information on new waste management opportunities and fits into the doctrine of sustainable resource management offered by the circular economy.

Influence study of mixture composition «polyisocyanate—polyether—foamer» on polyurethane foam properties

2020 ◽  
pp. 32-35
Author(s):  
Maxim Arzhakov ◽  
◽  
Pavel Yakovlev ◽  
Alexander Lopatkin ◽  
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Polyurethane Foams ◽  
Mixture Composition ◽  
Thermal Shrinkage ◽  
Mechanical Parameters ◽  
Foam Properties

The influence of the base mixture composition (polyisocyanate — polyether — foamer) on density, thermal conductivity, mechanical parameters and thermal shrinkage of polyurethane foams has been studied. The unshrinkable foams with thermal conductivity comparable with thermal conductivity of the air were obtained. A variation of the ratio between polyisocyanate and polyether allows one to control thermal shrinkage of the foamed material in the range from 0 to 78%.

scholarly journals Bio-Polyurethane Foams Modified with a Mixture of Bio-Polyols of Different Chemical Structures

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2469
Author(s):  
Aleksander Prociak ◽  
Maria Kurańska ◽  
Katarzyna Uram ◽  
Monika Wójtowicz
Keyword(s):  
Ring Opening ◽  
Polyurethane Foams ◽  
Maximum Temperature ◽  
Foaming Agent ◽  
Chemical Structures ◽  
Density Reduction ◽  
Foaming Process ◽  
Ring Opening Reaction ◽  
Foam Properties ◽  
Mechanical Strengths

We report on rigid polyurethane (PUR) foams prepared using different contents of a mixture of two bio-polyols (20–40 php). The bio-polyols were obtained through epoxidation and a ring opening reaction. Different chemical structures of the bio-polyols resulted from the use of 1-hexanol and 1,6-hexanediol as opening agents. The bio-polyols were characterized by hydroxyl values of 104 and 250 mgKOH/g and viscosities of 643 and 5128 mPa·s, respectively. Next, the influence of the bio-polyols on the foaming process of PUR systems as well as the foam properties was evaluated. The bio-foams modified with different contents of the bio-polyols were next compared with a reference foam obtained using a polyether petrochemical polyol. The effect of the apparent density reduction as a result of replacing the petrochemical polyol was minimized by decreasing the water content in the formulation. It was found that the modification of the recipe by changing the content of water, acting as a chemical foaming agent, did not affect the foaming process. However, the introduction of the bio-polyols mixture limited the reactivity of the systems by reducing the maximum temperature of the foaming process. The bio-materials with comparable apparent densities to that of the reference material were characterized by similar values of the thermal conductivity coefficient and a decrease in their mechanical strengths. A deterioration of mechanical properties was caused by the plasticization of the polyurethane matrices with the bio-polyols containing dangling chains. However, all materials were dimensionally stable at room temperature.

scholarly journals Thermal and Natural Particles Addition Effects on the Mechanical and Physical Properties of Epoxy–Polyurethane Resin Blend Polymer

2018 ◽  
Vol 3 (8) ◽  
pp. 1
Author(s):  
Aseel Kais Rasheed ◽  
Noor Kais Rasheed ◽  
Ismail Ibrahim Marhoon
Keyword(s):  
Thermal Conductivity ◽  
Impact Strength ◽  
Physical Properties ◽  
Volume Fraction ◽  
Resin Composite ◽  
Weight Ratio ◽  
Polymer Resin ◽  
Mechanical And Physical Properties ◽  
The Impact ◽  
Blend Polymer

In this study, natural particles were added to blend polymer resin. Composite material prepared from pistachio shells was added to epoxy–polyurethane blend polymer. The weight ratio of additive for liquid polyurethane to epoxy was 12 wt.%. In addition, their mechanical and physical properties were studied depending on a range of variables, such as temperature (25 °C, 35 °C, 45 °C and 55 °C) and volume fraction (3%, 6%, 9% and 12%). Hardness, impact strength and thermal conductivity were studied. Results showed that the impact strength was increased and that the hardness and thermal conductivity values were reduced at high temperatures. Meanwhile, the impact strength and hardness increased and the thermal conductivity values decreased with increased volume fracture of pistachio shells particles.

scholarly journals Effect of sulfuric acid solution on thermal conductivity and impact strength of epoxy resin reinforced by silicon dioxide powder

2019 ◽  
Vol 17 (41) ◽  
pp. 82-90
Author(s):  
Baraa Khalil Ibrahim
Keyword(s):  
Thermal Conductivity ◽  
Sulfuric Acid ◽  
Impact Strength ◽  
Epoxy Resin ◽  
Weight Ratio ◽  
Chemical Solution ◽  
Dioxide Powder ◽  
Before And After ◽  
Percentage Weight ◽  
The Impact

In this search, Ep/SiO2 at (3, 6, 9, 12 %) composites is prepared by hand Lay-up method, to measure the change in the thermal conductivity and Impact Strength of epoxy resin before and after immersion in H2SO4 Solution with a 0.3N for 10 days. The results before immersion decreases with the increase of the weight ratios of the reinforcement material (SiO2), It changed from (82.6×10-2 to 38.7×10-2 W/m.°C) with change weight ratios from (3 to 12) % respectively, but after immersion time in the chemical solution where it was (65.6×10-2 W/m.°C) at the weight ratios (6 %) and became (46.6 × 10-2 W/m.°C) after immersion in sulfuric acid. The results of the Impact strength decreased by increasing the percentage weight ratio, it changed from (1.48 to 0.87 kJ/m2) with change weight ratios from (3 to 12) % respectively, but found an increase in the value of Impact Strength after immersion in the chemical solution Where it was (1.28 kJ/m2) at the weight ratio of 6 % and became (1.82 kJ/m2) at the same weight ratio after immersion in sulfuric acid at normality of 0.3 for 10 days.

scholarly journals Vegetable Fillers and Rapeseed Oil-Based Polyol as Natural Raw Materials for the Production of Rigid Polyurethane Foams

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1772
Author(s):  
Milena Leszczyńska ◽  
Elżbieta Malewska ◽  
Joanna Ryszkowska ◽  
Maria Kurańska ◽  
Michał Gloc ◽  
...  
Keyword(s):  
Rapeseed Oil ◽  
Raw Materials ◽  
Cell Structure ◽  
Polyurethane Foams ◽  
Maximum Temperature ◽  
Renewable Raw Materials ◽  
The Sustainable Development ◽  
Rigid Polyurethane Foams ◽  
Foaming Process ◽  
Reported Study

The reported study concerns the introduction of renewable raw materials into the formulation of rigid polyurethane foams in the quest for the sustainable development of polymer composites. In this study, rigid polyurethane foam composites were prepared using 75 wt.% of rapeseed oil-based polyol and 15 parts per hundred parts of polyol (php) of natural fillers such as chokeberry pomace, raspberry seeds, as well as hazelnut and walnut shells. The influence of the used raw materials on the foaming process, structure, and properties of foams was investigated using a FOAMAT analyzer and a wide selection of characterization techniques. The introduction of renewable raw materials limited reactivity of the system, which reduced maximum temperature of the foaming process. Moreover, foams prepared using renewable raw materials were characterized by a more regular cell structure, a higher share of closed cells, lower apparent density, lower compressive strength and glass transition temperature, low friability (<2%), low water absorption (<1%), high dimensional stability (<±0.5%) and increased thermal stability. The proper selection and preparation of the renewable raw materials and the rational development of the polyurethane recipe composition allow for the preparation of environmentally-friendly foam products with beneficial application properties considering the demands of the circular economy in the synthesis of rigid foams.

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