Polyurethanes History

Although these new lightweight porous materials were envisioned as supportive materials as well as insulative materials in the base patents [3,4] their market development remained slow. This can be seen by the fact that even in 1952 polyisocyanates, mainly toluene diisocyanate (TDI), were available worldwide in quantities of less than 100 tonnes. After this rather hesitant start of polyurethane history and the first major switch from solid materials to porous foamed plastics, the industry has been characterised by significant changes in concept and the resulting industrial application of these switches. 

The hard segments may be formed by the reaction of a diisocyanate and a chain extender . Early in the history of polyurethanes, high molecular weight urethanes were formed in two steps. The prepolymer step was the reaction between an excess... 

History. The first attempts to desensitize RDX were reported by Frankel and Carle ton (Refs 1 thru 5) who made use of polymeric materials such as polyurethanes to coat expl crysts by means of emulsion or soln techniques. The first true PB-RDX was developed in 1952 at the Univ of Califs Los Alamos Lab and consisted of RDX coated with polystyrene plasticized with DOP (Refs 6 21). Since then the Lawrence Livermore Lab has evolved a series of PBX formulations, many of which are listed in Tables 3,4 5. These compns are described in Ref 77... 

The history of polyurethanes begins with Otto Bayer3 at Germany s I. G. Farben-industrie (tire predecessor company of Bayer AG4) in 1937, tire year of tire first disclosure of diisocyanate addition polymerization to form polyurethanes and polyureas. The main impetus for this work was tire success of Wallace Caro titers... 

For more on the development history of polyurethanes at I. G. Farben and elsewhere, see (a) O. Bayer, Angew. Chem, A59, 275 (1947) (b) O. Bayer, E. Mueller, S. Peterson, H. Piepenbrink and E. Windemuth, Angew. Chem, 62, 57 (1950) (c) O. Bayer, E. Mueller, S. Peterson, H. Piepenbrink, andE. Windemuth, Rubber Chem. Technol., 23, 812 (1950) (d) Urethanes Technology, Vol. 4, March and June issues (1987), Crain Communications, London (e) K. C. Frisch, Historical Developments of Polyurethanes, in 60 Years of Polyurethanes, International Symposium and Exhibition, January 15-16, 1998, Technomic Publishing, Lancaster, PA, 1998. 

EFFECT OF THERMAL HISTORY ON THE RHEOLOGICAL BEHAVIOR OF THERMOPLASTIC POLYURETHANES... 

Readers, however, should not be prejudiced by these comments. The important consideration is the condensation of any polyalcohol with an isocyanate. Inasmuch as the polyalcohol is the compound that gives us the opportunity to produce a chemically active polymer, a researcher should not be limited by the history of polyurethanes that was guided by the need for a physically strong polymer system. In any case, discussing polyether polyols is a suitable starting point. 

One more factor must be considered before we summarize this foundation and discuss case histories the factor concept that could explain why hydrophilic polyurethane has shown an improved efficiency in development of biofllms. In a reconsideration of the biofilm model (Figure 5.4), let us consider a model in which the substratum has reservoir capacity (Figure 5.5). 

A panel of researchers at the FDA studied both effects and developed procedures to calculate the chronic risk. The confirmation of the risk, albeit very small, led to special attention rightfully paid to implantable devices based on TDI. Due in part to the long history of implanted polyurethanes based on MDI, such polyurethanes... 

In this case of three-monomer polyurethane synthesis, there is no thermodynamic driving force for phase separation. The formation of clusters is fully controlled by the initial composition of the system, the reactivity of functional groups, and the network formation history (one or two stages, macrodiol or triol reacted with diisocyanate first, etc.). 

Characterization. Film samples about 0.25-mm thick were prepared by compression molding the polyurethanes under dry nitrogen at 180°C and 3 MPa pressure. After molding for 20 min, the samples were allowed to cool slowly in the press under dry nitrogen flow. Figure 2 shows the thermal history of the 180°C-molded films. No discoloration was observed when the samples were removed from the mold. The two soft-segment polyurethanes were compression molded at 120°C. The films were allowed to stand at least one week at room temperature in a dessicator before being evaluated with the Rheovibron DDV-IIB Dynamic Visco-... 

Several 2,4-T-2P samples were reevaluated and gave results identical within experimental error to the first determination, indicating that thermal history has a negligible effect on these polyurethanes. 

Photoresponsive membranes of cellulose-2,4-diacetate incorporating 6-nitro-l, 3, 3 -trimethylspiro-(2H-l-benzopyran-2,2 -indoline) have been prepared and chiroptical and fluorescence properties of optically active co-polymers of acenaphthalene with methyl acrylate/methacrylate have been investigated. Marked optical activity is induced in the aromatic units only for the co-polymer with methyl methacrylate. This difference in behaviour is associated with an overall higher main-chain flexibility and conformational freedom in acrylates compared with methacrylates. Photoisomerization in polyurethanes containing azo-links has been found to be dependent upon the thermal history of the polymer, and photoisomerization of linoleic acid and... 

As with any chemical products, persons known to have a history of dermatitis, skin sensitisation or asthma should not work in direct contact with polyurethanes. Ingestion, inhalation, skin contact and eye contact should be avoided. Prolonged contact in any form with the skin may cause localised irritation leading to dermatitis and must be avoided. In case of skin contact, remove excess with clean cloth. Clean with proprietary cleansing cream and wash with soap and water. Do not use any solvent. Contaminated clothing should be removed immediately and not reused until it is laundered. 

Exposures to sick buildings may stimulate respiratory responses in healthy individuals with no previous history of asthma, allergic rhinitis, chronic respiratory disease, recent acute respiratory illness, or extensive exposure to pollutants. Chemicals typically found in sick buildings arise from carpeting, paint, wood products, cleaners, and other sources. These chemicals are mixtures of lipophilic and hydrophilic chemicals and, with the exception of isocyanates from polyurethane wood finishes, are usually... 

Bayer consolidated its American holdings at about the same time as BASF. But, given its history, it focused on a somewhat different set of product lines, especially pharmaceuticals. In 1977, partly from antitrust pressure, Bayer acquired Monsanto s 50 percent in Mobay, the joint venture that had expanded its line to polyurethane and agricultural chemicals. Bayer s primary drive, however, continued to be in pharmaceuticals. In the same year, it also purchased Cutter Laboratories, makers of nutrients and ethical drugs. Soon thereafter. Cutter recorded its first profit. Bayer s success in turning around... 

In the polyurethane (PU) industry the development of polyols based on renewable resources always played an important role. One can say that all the history of PU was strongly linked to the renewable resources [1-5]. 

Polyurethanes (PU) are polymers which, in a fire, burn totally. During the not very long history of PU, intensive research efforts were made to produce fire resistant PU. 

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