Production Of Rigid Polyurethane Foams Research Articles

Study of Sound Absorption Properties on Rigid Polyurethane Foams using FEA

Objective: The range of raw material used for the manufacture of Polyurethane using Polyol has grown enormously during the past fifty years. A wide range of products is now available, which allows the researchers to produce, collectively known as Polyurethane Foams as Porous Material. This paper examines the sound absorption properties of porous material from the view point of the manufacturer by the experimental and analysis way. Method/Analysis: In this experimental study, finite element method is well established in estimating acoustic transmission loss or sound absorption coefficient of a porous material. Impedance tube is used to measure the acoustic impedance of a sound absorbing porous material, with acoustic source at one end and an acoustic porous material. That is polyurethane foam at other end. There are two common methods used to measure the impedance value of the porous material. The first method involves a moveable microphone that transverses along the impedance tube and the second method is named as “transfer function” or “two-microphone”, the two microphone method is followed in this section. In this study, a 3D impedance tube is modelled using finite element software and the results will be compared with experimental data. Finding: The effort for this study determines a straight forward route to the production of Rigid Polyurethane foams through a direct reaction process. This system has potentially wide relevance as polyurethane foams. Here, an initial study has shown that using different way to calculate the sound absorption coefficient of a material, either by experimental way or by analysis using FEA software ansys. Application/ Improvement: Besides much other application, rigid polyurethane foam is used as acoustic layer in automobile industries, thermal insulation and as energy absorber medium in front bumper of auto motives. Hence by comparing the sound absorption coefficient value of the foam by the both experimental and analysis method we can improve the understanding level and efficiency of the rigid polyurethane foam.

Fractionation of flash pyrolysis condensates by staged condensation

The utilization of condensates from flash pyrolysis is challenging due to several unwanted properties. The condensates consist of a mixture of many high value compounds, but each of them is only contained in a low concentration. As additional challenge instantaneous phase separation into an aqueous and a sludgy heavy organic phase takes place, if agricultural residues like barley straw are used as raw material for pyrolysis. A separation by means of distillation is not possible as the compounds undergo polymerization reactions when exposed to higher temperature. A different approach for separation based on boiling temperature is staged condensation of original vapors. Ablative flash pyrolysis is performed in a laboratory. The pyrolysis vapors are condensed in either two or three stages, each composed of a double-effect cooler followed by an electrostatic precipitator. The higher boiling fractions are low in water and acid and show a high heating value. This makes it applicable as sulfur-free bunker fuel and replacement of heavy fuel oil. It can also serve as fuel for gasification plants for the production of either combined heat and power or 2nd generation biofuels. Depending on condensation configuration the first fractions can also be utilized for the production of rigid polyurethane foams or phenolic resins. The last fraction obtained at the lowest cooling temperature mainly consists of water and acids. The production of pure acetic acid seems economically feasible and utilization in agricultural biogas plants is also possible. This is proved by batch fermentation experiments in the biological laboratories.

Value-added conversion of waste cooking oil and post-consumer PET bottles into biodiesel and polyurethane foams

A sustainable process of value-added utilization of wastes including waste cooking oil (WCO) and post-consumer PET bottles for the production of biodiesel and polyurethane (PU) foams was developed. WCO collected from campus cafeteria was firstly converted into biodiesel, which can be used as vehicle fuel. Then crude glycerol (CG), a byproduct of the above biodiesel process, was incorporated into the glycolysis process of post-consumer PET bottles collected from campus to produce polyols. Thirdly, PU foams were synthesized through the reaction of the above produced polyols with isocyanate in the presence of catalysts and other additives. The characterization of the produced biodiesel demonstrated that its properties meet the specification of biodiesel standard. The effect of crude glycerol loading on the properties of polyols and PU foams were investigated. All the polyols showed satisfactory properties for the production of rigid PU foams which had performance comparable to those of some petroleum-based analogs. A mass balance and a cost analysis for the conversion of WCO and waste PET into biodiesel and PU foams were also discussed. This study demonstrated the potential of WCO and PET waste for the production of value-added products.

Functionality and physico-chemical characteristics of wheat straw lignin, Biolignin™, derivatives formed in the oxypropylation process

Abstract The new organosolv process of wheat straw fractionation elaborated by Compagnie Industrielle de la matiere Vegetale (France) corresponds to the biorefinery approach, which allows separating cellulose, hemicelluloses, and lignin. The straw lignin (Biolignin™) is an attractive product, for which new applications are sought. In the present work, straw lignin (L) was converted into liquid lignopolyols via a batch reaction with propylene oxide (PO). The effects of the lignin content (L%) in the initial reaction mixture (L/(L+PO) on the oxypropylation process and the properties of whole lignopolyols and L/PO copolymers were studied. Almost complete disappearance of L-OHphen and L-COOH groups in copolymers was accompanied by an increase in the L-OHaliph groups’ content therein. The polydispersity (M w /M n ) of all copolymers obtained decreased essentially compared to the reference. The extent of PO grafting onto OH groups increased with decreasing lignin content in the initial reaction mixture. At a lignin content of 15–30% in the initial reaction mixture, the lignopolyols fulfil the requirements of polyol polyethers for rigid polyurethane foam production. The further increase in the lignin content leads to the appearance of the non-liquefied fraction and the undesirable increase in the viscosity of the liquefied part.

Producing Lignin-Based Polyols through Microwave-Assisted Liquefaction for Rigid Polyurethane Foam Production.

Lignin-based polyols were synthesized through microwave-assisted liquefaction under different microwave heating times (5–30 min). The liquefaction reactions were carried out using polyethylene glycol (PEG-400)/glycerol as liquefying solvents and 97 wt% sulfur acid as a catalyst at 140 °C. The polyols obtained were analyzed for their yield, composition and structural characteristics using gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectra. FT-IR and NMR spectra showed that the liquefying solvents reacted with the phenol hydroxyl groups of the lignin in the liquefied product. With increasing microwave heating time, the viscosity of polyols was slightly increased and their corresponding molecular weight (MW) was gradually reduced. The optimal condition at the microwave heating time (5 min) ensured a high liquefaction yield (97.47%) and polyol with a suitable hydroxyl number (8.628 mmol/g). Polyurethane (PU) foams were prepared by polyols and methylene diphenylene diisocyanate (MDI) using the one-shot method. With the isocyanate/hydroxyl group ([NCO]/[OH]) ratio increasing from 0.6 to 1.0, their mechanical properties were gradually increased. This study provided some insight into the microwave-assisted liquefied lignin polyols for the production of rigid PU foam.

Rigid polyurethane foams obtained from tall oil and filled with natural fibers: Application as a support for immobilization of lignin-degrading microorganisms

The forest biomass represents an abundant, renewable, non-food competition, and low-cost resource that can play an alternative role to petro-resources. The first topic of the research activity is focused on the use of wood and a pulp mill by-product—tall oil —as raw materials for the production of rigid polyurethane foams. The maximum content of the renewable resource in ready foams is 26%. By using biopolymers as a matrix, a natural way is to reinforce them with natural fibers. Further advantages are significant weight and cost savings and, at the same time, replacement of petrochemical raw materials. Three different natural fibers (cellulose, wood, and modified cellulose) were tested as a filler of foams. Rigid polyurethane foams was used as biomass support particles for immobilization of microorganisms. Suspension cultures of the organism with biomass support particles can promote the adhesion of cells to the porous matrix surface, and subsequently the cells become immobilized during the cultivation. This method for cell immobilization has a great potential for enhancing the production of proteins or chemicals in culture supernatants. The presence of natural fibers in the matrix promotes the enzyme production because the material not only functions as an attachment place but also supplies some nutrients to the microorganism and induces the production of ligninolytic enzymes. This paper discusses the studies into the use of tall oil as a renewable source in rigid polyurethane foam production

Significantly Reduced Catalyst Consumption in Rigid Foams

The use of Mannich base initiated polyether polyols for the production of rigid polyurethane foams has been employed for many years. The use of this class of polyols has primarily been directed toward sprayed polyurethane foam applications. The inherent properties of these polyols include aromatic character, increased compatibility and inherent catalytic capabilities. The use of this family of polyols has not widely spread to other rigid foam applications. During the transition to HCFC-141b as the primary blowing agent for rigid polyurethane foams, increased catalyst levels were required. This introduced additional cost and handling concerns. This paper presents 20 rigid foam formulations which show how the use of a variety of Mannich polyols can reduce catalyst consumption by more than 40% while maintaining compressive strength, flowability and maintaining or improving the insulation properties of the foam (K-factor) and dimensional stability.

Formic acid as a co-blowing agent in rigid polyurethane foams

A valid substitute for CFC-11 (trichlorofluoromethane) for the production of rigid polyurethane foams for thermal insulating materials, with blowing agents having low environmental impact, is not available yet. HCFC-141b and n-pentane, at present the most utilized physical blowing agents (PBAs), cannot definitely replace CFCs because of their environmental impact and flammability, respectively. The aim of the present work is to investigate the opportunity of employing HCOOH as a chemical blowing agent (CBA), other than water, which can in some applications replace physical blowing agents. Advantages and disadvantages have been highlighted after studying the isocyanate–formic acid reaction. Evidently, the introduction of new reactions into the polyurethane chemistry introduces a wide range of opportunities and challenges.

Factors Affecting the Solubility of Gaseous HCFC and HFC Blowing Agents

The majority of the current production of rigid polyurethane foams utilizes HCFC-141b (1,1-dichloro-1-fluoroethane) as either the blowing or co-blowing agent to expand the foam. With the phase-out of hydrochlorofluorocarbons (HCFCs) scheduled for the year 2003, the usage of HCFC-141b will need to be reduced or terminated at that time. The existing options for rigid polyurethane foam blowing agents after the phase-out will be hydrofluorocarbon (HFC), carbon dioxide, or hydrocarbon based compounds. One possible candidate for HFC blowing agents is HFC-134a (1,1,1,2-tetrafluoroethane). Reasons for its use include its commercial availability, zero ozone depletion potential, low toxicity, low foam k factors at low temperatures, better dimensional stability, and the lack of flammability limits in air [1,2]. The major challenge in the use of HFC-134a is the difficulty in foam processing due to its low boiling point and moderate solubility in rigid foam polyols. During foam production, the reacting mixture rapidly expands and froths. This expansion can lead to isolated large cells in a matrix of smaller cells (worm hole formation) and can adversely affect the k factor and quality of the foam. A slower expansion is desirable to achieve better processibility and the lowest k factor possible. One way to influence the expansion is to increase the intermolecular interactions between the blowing agent and the foaming mixture. It may be possible to increase these intermolecular forces through the judicious selection of polyols and additives. Moreover, if a good understanding of the intermolecular interactions is gained, an opportunity exists to design rigid foam polyols to meet processing difficulties.

Synthesis of C4-C10 aliphatic dicarboxylic acids by oxidation of aliphatic n-paraffins

1. A continuous process has been developed for the production of mixtures of dicarboxylic acids by oxidizing liquid n-paraffins with air under pressure without using chemical reagents. 2. It has been shown possible to convert n-paraffins extensively in the oxidation process into mixtures of C4-C10 dicarboxylic acids and their derivatives. 3. The possibility has been shown experimentally of using mixtures of synthetic and dicarboxylic acids instead of sebacic and adipic acids in the production of rigid polyurethane foams, electrically insulating lacquers, and glass-reinforced plastics, as well as in the production of film-forming substances.

Use of gas‐liquid chromatography in the analysis of rigid polyurethane foam polyols

AbstractDetailed characterization of the low molecular weight polyols used as intermediates in rigid polyurethane foam production has not been feasible to date. Gas‐liquid chromatography of the trimethylsilyl ether derivatives of the polyols now offers a more complete picture of polyol composition, particularly with regard to the molecular weight distribution. The data may be interpreted on a semiquantitative basis. The study of processing variables in polyol manufacture, detection of impurities and analysis of unknown polyols or those based on mixed initiators may all be facilitated by use of this GLC technique.