scholarly journals Chemically Functionalized Cellulose Nanocrystals as Reactive Filler in Bio-Based Polyurethane Foams

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2556
Author(s):  
Francesca Coccia ◽  
Liudmyla Gryshchuk ◽  
Pierluigi Moimare ◽  
Ferdinando de Luca Bossa ◽  
Chiara Santillo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cellulose Nanocrystals ◽  
Aqueous Media ◽  
Polyurethane Foams ◽  
Coupling Agents ◽  
Ftir Analysis ◽  
Thermal And Mechanical Properties ◽  
Efficient Coupling ◽  
Flexible Polyurethane ◽  
Pu Foams

Cellulose Nanocrystals, CNC, opportunely functionalized are proposed as reactive fillers in bio-based flexible polyurethane foams to improve, mainly, their mechanical properties. To overcome the cellulose hydrophilicity, CNC was functionalized on its surface by linking covalently a suitable bio-based polyol to obtain a grafted-CNC. The polyols grafted with CNC will react with the isocyanate in the preparation of the polyurethane foams. An attractive way to introduce functionalities on cellulose surfaces in aqueous media is silane chemistry by using functional trialkoxy silanes, X-Si (OR)3. Here, we report the synthesis of CNC-grafted-biopolyol to be used as a successful reactive filler in bio-based polyurethane foams, PUFs. The alkyl silanes were used as efficient coupling agents for the grafting of CNC and bio-polyols. Four strategies to obtain CNC-grafted-polyol were fine-tuned to use CNC as an active filler in PUFs. The effective grafting of the bio polyol on CNC was evaluated by FTIR analysis, and the amount of grafted polyol by thermogravimetric analysis. Finally, the morphological, thermal and mechanical properties and hydrophobicity of filled PUFs were thoughtfully assessed as well as the structure of the foams and, in particular, of the edges and walls of the cell foams by means of the Gibson–Ashby model. Improved thermal stability and mechanical properties of PU foams containing CNC-functionalized-polyol are observed. The morphology of the PU foams is also influenced by the functionalization of the CNC.

scholarly journals Effects of Various Types of Expandable Graphite and Blackcurrant Pomace on the Properties of Viscoelastic Polyurethane Foams

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1801
Author(s):  
Rafał Oliwa ◽  
Joanna Ryszkowska ◽  
Mariusz Oleksy ◽  
Monika Auguścik-Królikowska ◽  
Małgorzata Gzik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Structure ◽  
Oxygen Index ◽  
Polyurethane Foams ◽  
Expandable Graphite ◽  
Ftir Analysis ◽  
Limiting Oxygen Index ◽  
Peak Heat Release Rate ◽  
Physical And Chemical ◽  
Scanning Electron

We investigated the effect of the type and amount of expandable graphite (EG) and blackcurrant pomace (BCP) on the flammability, thermal stability, mechanical properties, physical, and chemical structure of viscoelastic polyurethane foams (VEF). For this purpose, the polyurethane foams containing EG, BCP, and EG with BCP were obtained. The content of EG varied in the range of 3–15 per hundred polyols (php), while the BCP content was 30 php. Based on the obtained results, it was found that the additional introduction of BCPs into EG-containing composites allows for an additive effect in improving the functional properties of viscoelastic polyurethane foams. As a result, the composite containing 30 php of BCP and 15 php of EG with the largest particle size and expanded volume shows the largest change in the studied parameters (hardness (H) = 2.65 kPa (+16.2%), limiting oxygen index (LOI) = 26% (+44.4%), and peak heat release rate (pHRR) = 15.5 kW/m2 (−87.4%)). In addition, this composite was characterized by the highest char yield (m600 = 17.9% (+44.1%)). In turn, the change in mechanical properties is related to a change in the physical and chemical structure of the foams as indicated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis.

Cryogenic thermal insulating and mechanical properties of rigid polyurethane foams blown with hydrofluoroolefin: Effect of perfluoroalkane

2021 ◽  
pp. 0021955X2110626
Author(s):  
Tae Seok Kim ◽  
Yeongbeom Lee ◽  
Chul Hyun Hwang ◽  
Kwang Ho Song ◽  
Woo Nyon Kim
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Stability ◽  
Cell Size ◽  
Thermal Insulation ◽  
Coefficient Of Thermal Expansion ◽  
Lower Surface ◽  
Polyurethane Foams ◽  
Insulation Material ◽  
Pu Foams

The effect of perfluoroalkane (PFA) on the morphology, thermal conductivity, mechanical properties and thermal stability of rigid polyurethane (PU) foams was investigated under ambient and cryogenic conditions. The PU foams were blown with hydrofluorolefin. Morphological results showed that the minimum cell size (153 μm) was observed when the PFA content was 1.0 part per hundred polyols by weight (php). This was due to the lower surface tension of the mixed polyol solution when the PFA content was 1.0 php. The thermal conductivity of PU foams measured under ambient (0.0215 W/mK) and cryogenic (0.0179 W/mK at −100°C) conditions reached a minimum when the PFA content was 1.0 php. The low value of thermal conductivity was a result of the small cell size of the foams. The above results suggest that PFA acted as a nucleating agent to enhanced the thermal insulation properties of PU foams. The compressive and shear strengths of the PU foams did not appreciably change with PFA content at either −170°C or 20°C. However, it shows that the mechanical strengths at −170°C and 20°C for the PU foams meet the specification. Coefficient of thermal expansion, and thermal shock tests of the PU foams showed enough thermal stability for the LNG carrier’s operation temperature. Therefore, it is suggested that the PU foams blown by HFO with the PFA addition can be used as a thermal insulation material for a conventional LNG carrier.

scholarly journals Reinforcement Efficiency of Cellulose Microfibers for the Tensile Stiffness and Strength of Rigid Low-Density Polyurethane Foams

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2725 ◽  
Author(s):  
Jānis Andersons ◽  
Mikelis Kirpluks ◽  
Ugis Cabulis
Keyword(s):  
Mechanical Properties ◽  
Polyurethane Foams ◽  
Low Density ◽  
Mechanical Reinforcement ◽  
Tensile Stiffness ◽  
Structural Applications ◽  
Cellulose Microfibers ◽  
Renewable Material ◽  
Reinforcement Efficiency ◽  
Pu Foams

Rigid low-density closed-cell polyurethane (PU) foams are widely used in both thermal insulation and structural applications. The sustainability of PU foam production can be increased by using bio-based components and fillers that ensure both enhanced mechanical properties and higher renewable material content. Such bio-based foams were produced using polyols derived from rapeseed oil and microcrystalline cellulose (MCC) fibers as filler. The effect of MCC fiber loading of up to 10 wt % on the morphology, tensile stiffness, and strength of foams has been evaluated. For estimation of the mechanical reinforcement efficiency of foams, a model allowing for the partial alignment of filler fibers in foam struts was developed and validated against test results. It is shown that although applying MCC fibers leads to modest gains in the mechanical properties of PU foams compared with cellulose nanocrystal reinforcement, it may provide a higher content of renewable material in the foams.

scholarly journals Some Key Factors Influencing the Flame Retardancy of EDA-DOPO Containing Flexible Polyurethane Foams

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1115 ◽  
Author(s):  
Agnieszka Przystas ◽  
Milijana Jovic ◽  
Khalifah Salmeia ◽  
Daniel Rentsch ◽  
Laurent Ferry ◽  
...  
Keyword(s):  
Flame Retardancy ◽  
High Speed ◽  
Combustion Efficiency ◽  
Polyurethane Foams ◽  
Key Factors ◽  
Ul 94 ◽  
Microscale Combustion Calorimeter ◽  
Flexible Polyurethane ◽  
Combustion Calorimeter ◽  
Pu Foams

The role of various additives (emulsifier, anti-dripping agent) and formulation procedures (pre-dispersion of solid additives in polyol via milling) which influence the flame retardancy of 6,6′-[ethan-1,2-diylbis(azandiyl)]bis(6H-dibenzo[c,e][1,2]oxaphosphin-6-oxid) (EDA-DOPO) containing flexible polyurethane foams has been investigated in this work. For comparison, the flame retardancy of two additional structurally-analogous bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based compounds, i.e., ethanolamine-DOPO (ETA-DOPO) and ethylene glycol-DOPO (EG-DOPO) were also evaluated together with EDA-DOPO in flexible PU foams of various formulations. The flame retardancy of these three bridged-DOPO compounds depends on the type of PU formulation. For certain PU formulations containing EDA-DOPO, lower fire performance was observed. Addition of emulsifier and polytetrafluoroethylene (PTFE) to these PU formulations influenced positively the flame retardancy of EDA-DOPO/PU foams. In addition, dispersion of EDA-DOPO and PTFE via milling in polyol improved the flame retardancy of the PU foams. Mechanistic studies performed using a microscale combustion calorimeter (MCC) and its coupling to FTIR showed no difference in the combustion efficiency of the bridged-DOPO compounds in PU foams. From MCC experiments it can be concluded that these bridged-DOPO compounds and their decomposition products may work primarily in the gas phase as flame inhibitors. The physiochemical behavior of additives in PU formulation responsible for the improvement in the flame retardancy of PU foams was further investigated by studying the dripping behavior of the PU foams in the UL 94 HB test. A high-speed camera was used to study the dripping behavior in the UL 94 HB test and results indicate a considerable reduction of the total number of melt drips and flaming drips for the flame retardant formulations. This reduction in melt drips and flaming drips during the UL 94 HB tests help PU foams achieve higher fire classification.

scholarly journals Development of Flexible Polyurethane Nanostructured Biocomposite Foams Derived from Palm Olein-Based Polyol

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Srihanum Adnan ◽  
Tuan Noor Maznee Tuan Ismail ◽  
Norhayati Mohd Noor ◽  
Nik Siti Mariam Nek Mat Din ◽  
Nurul ‘Ain Hanzah ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Palm Olein ◽  
Nanocomposite Foams ◽  
Transmission Electron ◽  
Flexible Polyurethane ◽  
Pu Foams ◽  
Scanning Electron

This study examined the effect of organoclay montmorillonite (OMMT) on the mechanical properties and morphology of flexible polyurethane/OMMT nanocomposite (PU/OMMT) foams prepared from petroleum- and palm olein-based polyols. Palm-based PU foams exhibited inferior mechanical strength as compared to neat petroleum PU foams. However, addition of OMMT significantly improved the foams strength of flexible polyurethane/OMMT nanocomposite foams prepared from palm olein-based polyol (PU bionanocomposite foam). The morphology analysed by scanning electron microscopy (SEM) showed that the cell size of the foam decreased with increasing OMMT content. PU bionanocomposite foam with 5 wt% of OMMT had the most improved tensile (63%) and tear (48%) strengths compared to its neat counterpart. Transmission electron microscopy (TEM) revealed the exfoliated structure of the respective foam. It was concluded that OMMT improved mechanical properties and morphology of PU foams.

scholarly journals The Effects of Various Additive Components on the Sound Absorption Performances of Polyurethane Foams

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Shuming Chen ◽  
Yang Jiang ◽  
Jing Chen ◽  
Dengfeng Wang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Polyurethane Foams ◽  
Acoustic Properties ◽  
Acoustic Absorption ◽  
Absorption Properties ◽  
Maximum Enhancement ◽  
Flexible Polyurethane ◽  
Pu Foams

Flexible polyurethane (PU) foams comprising various additive components were synthesized to improve their acoustic performances. The purpose of this study was to investigate the effects of various additive components of the PU foams on the resultant sound absorption, which was characterized by the impedance tube technique to obtain the incident sound absorption coefficient and transmission loss. The maximum enhancement in the acoustic properties of the foams was obtained by adding fluorine-dichloroethane (141b) and triethanolamine. The results showed that the acoustic absorption properties of the PU foams were improved by adding 141b and triethanolamine and depended on the amount of the water, 141b, and triethanolamine.

Effects of chain extender in biodegradable polyurethane foams

2014 ◽  
Vol 34 (6) ◽  
pp. 555-559 ◽  
Author(s):  
Sung Moon Kang ◽  
Moo Seok Kang ◽  
Sun Hong Kwon ◽  
Hyun Park ◽  
Byung Kyu Kim
Keyword(s):  
Hard Segment ◽  
Crosslinking Density ◽  
Polyurethane Foams ◽  
Chain Extender ◽  
Toluene Diisocyanate ◽  
Foam Formation ◽  
Buffer Solution ◽  
Biodegradable Polyurethane ◽  
Flexible Polyurethane ◽  
Pu Foams

Abstract Molded flexible polyurethane (PU) foams were synthesized from a starch/petroleum based polyol, 2,4/2,6-toluene diisocyanate (TDI-80), using a one shot method with water as the blowing agent. The effects of chain extender type [starch (S series), diethanolamine (DEA, D series), glycerol (G series)] and content (0, 2, 5, 10 pphr) were extensively studied. The rate of foam formation, density, compression strength, glass transition temperature (Tg) and rubbery modulus of the foam increased with the addition and increasing content of extender. At the same extender content, DEA showed the highest of these properties, while starch showed the lowest. The rate of biodegradation in a buffer solution decreased with the addition of DEA and glycerol, due to the increased crosslinking density and hard segment content, but increased with starch, owing to its biodegradability.

Isocyanate Modification of Wood Fiber in Enhancing the Performance of its Composites with High Density Polyethylene

2012 ◽  
Vol 3 (2) ◽  
pp. 43-60 ◽  
Author(s):  
Fereshteh Arjmand ◽  
Mohammad Barmar ◽  
Mehdi Barikani
Keyword(s):  
Mechanical Properties ◽  
Interfacial Adhesion ◽  
Moisture Absorption ◽  
Wood Fiber ◽  
Cetyl Alcohol ◽  
Toluene Diisocyanate ◽  
Coupling Agents ◽  
Ftir Analysis ◽  
Moisture Uptake ◽  
Chemical Treatments

This study is focused on the modification of wood fiber by using a reactive diisocyanate (toluene diisocyanate, TDI) linker to couple wood fiber with cetyl alcohol and the investigation of its effects on mechanical properties of wood fiber–HDPE composites. The reaction of TDI with wood fiber and then cetyl alcohol resulted in the formation of new urethane bonds assessed by FTIR analysis. Therefore, TDI ended cetyl alcohol was used as a coupling agent in the preparation of wood fiber/ HDPE composite. The outcomes showed that the addition of such coupling agents resulted in greater reinforcement of composites, as indicated by the improvement in mechanical properties. Tensile strength of prepared composites increased by almost 64%, whereas 47% increase in flexural strength and 113% increase in impact properties was observed. However, the moisture absorption of the composites decreased by about 43%. All chemically treated composites showed lower moisture uptake than the untreated composites. This may be due to chemical treatment of wood fiber which reduces its hydrophilicity. These chemical treatments promote interfacial adhesion of fiber and HDPE matrix. Furthermore, scanning electron microscopy (SEM) revealed the improved morphology of the fractured surfaces of composites.

Impact of blowing agent-blends on polyurethane foams thermal and mechanical properties

2020 ◽  
Author(s):  
Harith H. Al-Moameri ◽  
Baydaa Jaber Nabhan ◽  
Tawfeeq Wasmi M. ◽  
Mohammed Ali Abdulrehman
Keyword(s):  
Mechanical Properties ◽  
Polyurethane Foams ◽  
Thermal And Mechanical Properties ◽  
Blowing Agent
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