scholarly journals Properties of polyurethane foam with fourth-generation blowing agent

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 763-769
Author(s):  
Vladimir Yakushin ◽  
Ugis Cabulis ◽  
Velta Fridrihsone ◽  
Sergey Kravchenko ◽  
Romass Pauliks
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Cellular Structure ◽  
Fourth Generation ◽  
Low Density ◽  
Technological Parameters ◽  
Blowing Agent ◽  
Foam Properties ◽  
Rise Direction ◽  
Foam Production

Abstract Climate change makes it imperative to use materials with minimum global warming potential. The fourth-generation blowing agent HCFO-1233zd-E is one of them. The use of HCFO allows the production of polyurethane foam with low thermal conductivity. Thermal conductivity, like other foam properties, depends not only on the density but also on the cellular structure of the foam. The cellular structure, in turn, depends on the technological parameters of foam production. A comparison of pouring and spray foams of the same low density has shown that the cellular structure of spray foam consists of cells with much less sizes than pouring foam. Due to the small size of cells, spray foam has a lower radiative constituent in the foam conductivity and, as a result, a lower overall thermal conductivity than pouring foam. The water absorption of spray foam, due to the fine cellular structure, also is lower than that of pouring foam. Pouring foam with bigger cells has higher compressive strength and modulus of elasticity in the foam rise direction. On the contrary, spray foam with a fine cellular structure has higher strength and modulus in the perpendicular direction. The effect of foam aging on thermal conductivity was also studied.

Temperature dependency of the long-term thermal conductivity of spray polyurethane foam

2021 ◽  
pp. 174425912110454
Author(s):  
Neal Holcroft
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Cellular Structure ◽  
Gas Diffusion ◽  
Temperature Dependent ◽  
Blowing Agent ◽  
Closed Cell ◽  
Wall Assembly ◽  
Cell Foam

The thermal properties of closed-cell foam insulation display a more complex behaviour than other construction materials due to the properties of the blowing agent captured in their cellular structure. Over time, blowing agent diffuses out from and air into the cellular structure resulting in an increase in thermal conductivity, a process that is temperature dependent. Some blowing agents also condense at temperatures within the in-service range of the insulation, resulting in non-linear temperature dependent relationships. Moreover, diffusion of moisture into the cellular structure increases thermal conductivity. Standards exist to quantify the effect of gas diffusion on thermal conductivity, however only at standard laboratory conditions. In this paper a new test procedure is described that includes calculation methods to determine Temperature Dependent Long-Term Thermal Conductivity (LTTC(T)) functions for closed-cell foam insulation using as a test material, a Medium-Density Spray Polyurethane Foam (MDSPF). Tests results are provided to show the validity of the method and to investigate the effects of both conditioning and mean test temperature on change in thermal conductivity. In addition, testing was conducted to produce a moisture dependent thermal conductivity function. The resulting functions were used in hygrothermal simulations to assess the effect of foam aging, in-service temperature and moisture content on the performance of a typical wall assembly incorporating MDSPF located in four Canadian climate zones. Results show that after 1 year, mean thermal conductivity increased 15%–16% and after 5 years 23%–24%, depending on climate zone. Furthermore, the use of the LTTC(T) function to calculate the wall assembly U-value improved accuracy between 3% and 5%.

Rigid Polyurethane Foam: A Versatile Energy Efficient Material

2016 ◽  
Vol 678 ◽  
pp. 88-98 ◽  
Author(s):  
Harpal Singh
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Weight Ratio ◽  
Building Envelope ◽  
Polymerization Reaction ◽  
Low Density ◽  
High Porosity ◽  
Rigid Polyurethane Foam ◽  
Low Thermal Conductivity ◽  
Moisture Permeability

Rigid polyurethane foam (RPUF) is typically prepared by the reaction of an isocyanate, such as methyl diphenyl diisocyanate (MDI) with a polyol blend. During the polymerization reaction, a blowing agent expands the reacting mixture. The finished product is a solid, cellular polymer with a high thermal resistance. RPUF is an outstanding material for different applications. It has many desirable properties such as low thermal conductivity, low density, low water absorption, low moisture permeability, excellent dimensional stability, high strength to weight ratio. So, it is the best insulating material for industrial buildings, cold storages, telecom and defense shelters due to low thermal conductivity, low density, low moisture permeability and high porosity. It works to reduce heating and cooling loss, improving the efficiency of the building envelope. Thus, RPUF insulation in building envelopes brings additional benefits in energy savings, resulting in lower energy bills and protecting the environment by cutting CO2 emissions.

Study on the Foaming Behavior of PS-CO2 by Using Water or Ethanol as Co-Blowing Agent

2013 ◽  
Vol 748 ◽  
pp. 112-116 ◽  
Author(s):  
Yi Wei Luo ◽  
Chun Ling Xin ◽  
Jiao Sun ◽  
Bao Rui Yan ◽  
Ya Dong He
Keyword(s):  
Cell Size ◽  
Cell Density ◽  
Apparent Density ◽  
Expansion Ratio ◽  
Low Density ◽  
Blowing Agents ◽  
Blowing Agent ◽  
Foaming Behavior ◽  
Low Solubility ◽  
Foam Production

Carbon dioxide (CO2) has been reported as an interesting substitute of banned ozone-depleting blowing agents, such as HCFC and HFC etc., for low-density polystyrene (PS) foam production, but it is difficult to industrialize due to its low solubility in PS matrix; therefore, high pressure is always needed in order to obtain the required gas concentrations for low density foam. Mixtures of blowing agents might be a practical way to make foam processing easy to control. In this paper, the foaming behaviors of PS-CO2 by using water or ethanol as co-blowing agent were investigated. The performances of foams obtained by PS-CO2, PS-CO2-water and PS-CO2-ethanol systems were tested respectively. It was found that cell size increased owing to the existence of co-blowing agent; in particular, the expansion ratio of PS foam obtained by CO2-ethanol was 1.3 times greater than that by CO2. At the same time, cell density as well as apparent density decreased with temperature increasing, while cell size showed the opposite. Cell size and apparent density, rather than cell density, decreased with pressure. These results were explained by the solution behavior of each of blowing agent.

Preparation of microporous thermoplastic polyurethane by low-temperature supercritical CO2 foaming

2016 ◽  
Vol 53 (2) ◽  
pp. 135-150 ◽  
Author(s):  
Chien-Chia Chu ◽  
Shu-Kai Yeh ◽  
Sheng-Ping Peng ◽  
Ting-Wei Kang ◽  
Wen-Jeng Guo ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Supercritical Co2 ◽  
Thermoplastic Polyurethane ◽  
Saturation Temperature ◽  
Phenyl Isocyanate ◽  
Blowing Agent ◽  
Soft Segments ◽  
Hard Segments ◽  
Poly Propylene ◽  
Foam Production

Thermoplastic polyurethane possesses many special characteristics. Its flexibility, rigidity, and elasticity can be adjusted by controlling the ratio of soft segments to hard segments. Due to its versatile physical properties, thermoplastic polyurethane is commonly used in transportation, construction, and biomaterials. However, methods for thermoplastic polyurethane foam production using CO2 are still under investigation. We have previously prepared nanoporous thermoplastic polyurethane foam using commercially available thermoplastic polyurethane; however, in this study, thermoplastic polyurethane was synthesized using 4,4′-methylenebis(phenyl isocyanate), poly(propylene glycol) and 1,4-butanediol, without solvents, using a pre-polymer method. The properties of the synthesized thermoplastic polyurethane were characterized by Fourier transform infrared spectroscopy, thermal analysis, and their mechanical properties were measured. The synthesized thermoplastic polyurethane was foamed by batch foaming using supercritical CO2 as the blowing agent. The effect of saturation temperature and saturation time on the cell morphology of the thermoplastic polyurethane foam was examined.

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 Advances in Low-Density Flexible Polyurethane Foams by Optimized Incorporation of High Amount of Recycled Polyol

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1736
Author(s):  
Gabriel Kiss ◽  
Gerlinde Rusu ◽  
Geza Bandur ◽  
Iosif Hulka ◽  
Daniel Romecki ◽  
...  
Keyword(s):  
Polyurethane Foam ◽  
Raw Materials ◽  
Polyurethane Foams ◽  
Low Density ◽  
Emission Data ◽  
Polyurethane Waste ◽  
Volatile Organic ◽  
Foam Properties ◽  
Flexible Polyurethane ◽  
First Time

An industrially manufactured recycled polyol, obtained by acidolysis process, was for the first time proved to be a possible replacement of the reference fossil-based polyol in a low-density formulation suitable for industrial production of flexible polyurethane foams. The influence of increasing recycled polyol amounts on the properties of the polyurethane foam has been studied, also performing foam emission tests to evaluate the environmental impact. Using 10 pbw recycled polyol in the standard formulation, significant differences of the physical properties were not observed, but increase of the recycled polyol amount to 30 pbw led to a dramatic decrease of the foam air flow and a very tight foam. To overcome this drawback, N,N′-bis[3-(dimethylamino)propyl]urea was selected as tertiary amine catalyst, enabling the preservation of foam properties even at high recycled polyol level (30 pbw). Foam emission data demonstrated that this optimized foam formulation also led to an important reduction of volatile organic compounds. The results open the way for further optimization studies in low-density flexible polyurethane foam formulations, to increase the reutilization of the polyurethane waste and reduce the amount of petroleum-based raw materials.

Gas transport properties of cellular hollow fiber membranes based on LLDPE/LDPE blends

2020 ◽  
pp. 026248932092930
Author(s):  
Zahir Razzaz ◽  
Abolfazl Mohebbi ◽  
Denis Rodrigue
Keyword(s):  
Hollow Fiber ◽  
Cellular Structure ◽  
Gas Transport ◽  
Gas Permeability ◽  
Continuous Production ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Hollow Fiber Membranes ◽  
Blowing Agent ◽  
Fiber Membranes

The production of foamed hollow fiber membranes (HFMs) is presented based on polymer blends using various concentrations of linear low-density polyethylene (LLDPE) and low-density polyethylene (LPDE) combined with azodicarbonamide (chemical blowing agent) to prepare samples via twin-screw extrusion. In particular, the blowing agent concentration as well as the stretching speed were found to be the most important parameters to achieve a good cellular structure for membrane application. From the samples obtained, a complete set of morphological, thermal, and gas transport characterization was performed. The results show that LLDPE/LDPE blends compared to neat LLDPE lead to higher cell density at high stretching speed, which is appropriate for membranes having higher gas permeability and selectivity due to lower cell wall thickness. The results also show that the developed cellular structure has high potential for the continuous production of HFMs for different gas separation, especially for hydrogen recovery.

scholarly journals Thermophysical Properties of Multifunctional Syntactic Foams Containing Phase Change Microcapsules for Thermal Energy Storage

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1790
Author(s):  
Francesco Galvagnini ◽  
Andrea Dorigato ◽  
Luca Fambri ◽  
Giulia Fredi ◽  
Alessandro Pegoretti
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Epoxy Resin ◽  
Storage Modulus ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Neat Epoxy ◽  
Low Density ◽  
Syntactic Foams

Syntactic foams (SFs) combining an epoxy resin and hollow glass microspheres (HGM) feature a unique combination of low density, high mechanical properties, and low thermal conductivity which can be tuned according to specific applications. In this work, the versatility of epoxy/HGM SFs was further expanded by adding a microencapsulated phase change material (PCM) providing thermal energy storage (TES) ability at a phase change temperature of 43 °C. At this aim, fifteen epoxy (HGM/PCM) compositions with a total filler content (HGM + PCM) of up to 40 vol% were prepared and characterized. The experimental results were fitted with statistical models, which resulted in ternary diagrams that visually represented the properties of the ternary systems and simplified trend identification. Dynamic rheological tests showed that the PCM increased the viscosity of the epoxy resin more than HGM due to the smaller average size (20 µm vs. 60 µm) and that the systems containing both HGM and PCM showed lower viscosity than those containing only one filler type, due to the higher packing efficiency of bimodal filler distributions. HGM strongly reduced the gravimetric density and the thermal insulation properties. In fact, the sample with 40 vol% of HGM showed a density of 0.735 g/cm3 (−35% than neat epoxy) and a thermal conductivity of 0.12 W/(m∙K) (−40% than neat epoxy). Moreover, the increase in the PCM content increased the specific phase change enthalpy, which was up to 68 J/g for the sample with 40 vol% of PCM, with a consequent improvement in the thermal management ability that was also evidenced by temperature profiling tests in transient heating and cooling regimes. Finally, dynamical mechanical thermal analysis (DMTA) showed that both fillers decreased the storage modulus but generally increased the storage modulus normalized by density (E′/ρ) up to 2440 MPa/(g/cm3) at 25 °C with 40 vol% of HGM (+48% than neat epoxy). These results confirmed that the main asset of these ternary multifunctional syntactic foams is their versatility, as the composition can be tuned to reach the property set that best matches the application requirements in terms of TES ability, thermal insulation, and low density.

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