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 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 Determination of the Influence of Hydraulic Additives on the Foaming Process and Stability of the Produced Geopolymer Foams

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5090
Author(s):  
Michał Łach ◽  
Kinga Pławecka ◽  
Agnieszka Bąk ◽  
Katarzyna Lichocka ◽  
Kinga Korniejenko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Polyurethane Foams ◽  
Expanded Polystyrene ◽  
Foaming Agent ◽  
Foaming Agents ◽  
Foaming Process ◽  
Al Powder ◽  
The Stability

The research described in this article was aimed at determining the influence of hydraulic additives on the foaming process and the stability of the produced geopolymer foams. These foams can be used as insulation materials to replace the currently commonly used insulations such as expanded polystyrene or polyurethane foams. Geopolymers have low thermal conductivity, excellent fire- and heat-resistant properties, and have fairly good mechanical properties. Research on foamed materials shows that they have the highest class of fire resistance; therefore, they are most often used as insulation products in construction. Geopolymer foams were made of aluminosilicate materials (fly ash) and foaming agents (H2O2 and Al powder), and the stabilizers were gypsum and portland cement. Additionally, surfactants were also used. It was found that better foaming effects were obtained for H2O2—it is a better foaming agent for geopolymers than Al powder. When using a hydraulic additive—a stabilizer in the form of cement—lower densities and better insulation parameters were obtained than when using gypsum. Portland cement is a better stabilizer than gypsum (calcium sulfates), although the effect may change due to the addition of surfactants, for example.

scholarly journals Production of Biopolymer Foams Based on Polylactic Acid Plasticized With Lactic Acid Oligomer

2021 ◽  
Vol 4 (1) ◽  
pp. 32-37
Author(s):  
Katalin Litauszki ◽  
Ákos Kmetty
Keyword(s):  
Electron Microscopy ◽  
Lactic Acid ◽  
Polylactic Acid ◽  
Cell Structure ◽  
Processing Temperature ◽  
Foaming Agent ◽  
Fracture Surfaces ◽  
Density Reduction ◽  
Foaming Process ◽  
The Future

Abstract In our work, we modified polylactic acid biopolymer using oligomeric lactic acid. We have successfully plasticised polylactic acid compounds with 5, 10, 20 wt% oligomeric lactic acid using a liquid dosing system connected to a compounder extruder. The produced compounds were foamed with an exothermic chemical foaming agent. The density of the foams was measured and the fracture surfaces were examined by electron microscopy to assess the homogeneity of the cell structure. Based on this, we believe that the plasticising effect of oligomeric lactic acid is undeniable, but a processing temperature of 190 °C is not optimal for the foaming process. In the future, the production of biopolymer foam structures with a higher density reduction can be achieved by reducing and optimizing the foam processing temperature.

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.

On the Conrotatory Ring Opening of 3-Carbomethoxycyclobutene Vis-À-Vis 3-Carbomethoxy-1,2-Benzocyclobutene and the Predominant Inward Opening of 3-Dimethylaminocarbonyl-1,2-Benzocyclobutene

2018 ◽  
Author(s):  
Veejendra Yadav ◽  
Dasari L V K Prasad ◽  
Arpita Yadav ◽  
Maddali L N Rao
Keyword(s):  
Transition State ◽  
Ring Opening ◽  
Electron Process ◽  
Ring Opening Reaction ◽  
Stable Species ◽  
Electron Event

<p>The torquoselectivity of conrotatory ring opening of 3-carbomethoxycyclobutene is controlled by p<sub>C1C2</sub>→s*<sub>C3C4</sub> and s<sub>C3C4</sub>→p*<sub>CO</sub> interactions in the transition state in a 4-electron process as opposed to only s<sub>C3C4</sub>→p*<sub>CO</sub> interaction in an apparently 8-electron event in 3-carbomethoxy-1,2-benzocyclobutene. The ring opening of 3-carbomethoxy-1,2-benzocyclobutene is sufficiently endothermic. We therefore argue that the reverse ring closing reaction is faster than the forward ring opening reaction and, thus, it establishes an equilibrium between the two and subsequently allows formation of the more stable species <i>via</i> outward ring opening reaction. Application of this argument to 3-dimethylaminocarbonyl-1,2-benzocyclobutene explains the predominantly observed inward opening.</p>

scholarly journals Expanding Monomers as Anti-Shrinkage Additives

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 806
Author(s):  
Philipp Marx ◽  
Frank Wiesbrock
Keyword(s):  
Ring Opening ◽  
Covalent Bond ◽  
Volumetric Shrinkage ◽  
Structure Property ◽  
Atomic Packing ◽  
Materials Properties ◽  
Volumetric Expansion ◽  
Structure Property Relationships ◽  
Ring Opening Reaction ◽  
Measuring Techniques

Commonly, volumetric shrinkage occurs during polymerizations due to the shortening of the equilibrium Van der Waals distance of two molecules to the length of a (significantly shorter) covalent bond. This volumetric shrinkage can have severe influence on the materials’ properties. One strategy to overcome this volumetric shrinkage is the use of expanding monomers that show volumetric expansion during polymerization reactions. Such monomers exhibit cyclic or even oligocyclic structural motifs with a correspondingly dense atomic packing. During the ring-opening reaction of such monomers, linear structures with atomic packing of lower density are formed, which results in volumetric expansion or at least reduced volumetric shrinkage. This review provides a concise overview of expanding monomers with a focus on the elucidation of structure-property relationships. Preceded by a brief introduction of measuring techniques for the quantification of volumetric changes, the most prominent classes of expanding monomers will be presented and discussed, namely cycloalkanes and cycloalkenes, oxacycles, benzoxazines, as well as thiocyclic compounds. Spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and benzoxazines are particularly highlighted.

Design and synthesis of 1,8-Naphthalimide Functionalized Benzothiadiazoles

2021 ◽  
Author(s):  
Rajneesh Misra ◽  
Yogjivan Rout
Keyword(s):  
Ring Opening ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Design And Synthesis ◽  
Cross Coupling Reaction ◽  
Ring Opening Reaction

A series of multi acceptor based push-pull derivatives BTD2–BTD5 were designed and synthesized via Pd-catalyzed Sonogashira cross-coupling reaction followed by [2+2] cycloaddition–electrocyclic ring-opening reaction in which benzothiadiazole (BTD, A1), naphthalimide...

scholarly journals (1R,4S,5S)-5-((3-Hydroxypropyl)amino)-4-((1-Methyl-1H-tetrazol-5-yl)thio)Cyclopent-2-en-1-ol

Molbank ◽  
10.3390/m1199 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1199
Author(s):  
Milene A. G. Fortunato ◽  
Filipa Siopa ◽  
Carlos A. M. Afonso
Keyword(s):  
Spectral Data ◽  
13C Nmr ◽  
Ring Opening ◽  
Environmentally Friendly ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Excellent Yield ◽  
Ring Opening Reaction ◽  
Nucleophilic Ring Opening

Using environmentally friendly conditions, the nucleophilic ring-opening reaction of 6-azabicyclo[3.1.0]hex-3-en-2-ol with 1-methyl-1H-tetrazole-5-thiol provided a novel thiol-incorporated aminocyclopentitol, (1R,4S,5S)-5-((3-hydroxypropyl)amino)-4-((1-methyl-1H-tetrazol-5-yl)thio)cyclopent-2-en-1-ol, in excellent yield (95%). The newly synthesized compound was analyzed and characterized via 1H, 13C-NMR, HSQC, and mass spectral data.

Sign in / Sign up

Export Citation Format

Share Document