Adnan A. R. Sayigh

Isocyanu rate Foams: Chemistry, Properties and Processing

The literature has become replete with references to the physical and mechanical properties of laboratory prepared isocyanurate foams and methods of modifying these products. Little attention has been given to the chemistry and mechanism of isocyanurate formation, or to methods of adopting this reaction to produce foams on a commercial scale. Accordingly, the purpose of this paper is to review the chemistry of isocyanurates and the mechanism for their formation. Also presented are general chemical formulations, physical properties and processing conditions for continuous lamination, bun, pour and spray applications. Typical physical properties of these low density isocyanurate foams, including laboratory flammability characteristics,

Pellethane®: A New Generation of Polyurethane Thermoplastic Elastomers

This paper reviews a series of new thermoplastic polyurethanes with emphasis on their general and specific physical properties. The useful envi ronmental data are presented also, along with handling, storage, curing, compounding, regrind, and processing procedures Special attention is fo cused on alloys with other polymers, such as PVC and ABS. In addition, the paper contains useful information concerning polyurethane elasto plastics in general.

Thermal Degradative Behavior of Selected Urethane Foams Related to Variations of Constituents Part II. Chemical Reactions in Urethane Decomposition

arylisocyanates), carbon dioxide and olefin, the olefin having arisen from the polyol part, and (3) a different cleavage involving loss of CO2 and coupling of the polyol residue with the aromatic amine to form secondary amines. These most important reactions are indicated in Figures 12 and 13. Later reactions may occur involving all these fragments, especially those not distilling off and perhaps certain oxidations in the presence of air. In summary, there can be (1) fragmentation, (2) interaction of fragments. (3) air oxida-

Thermal Degradative Behavior of Selected Urethane Foams Related to Variations of Constituents: Part I. Thermal Stability and Test Methods

Relating the thermal stability of a rigid urethane foam to its chemical composition and structure is made difficult by two basic characteristics. These are the overall composition of the urethane foam and the perhaps vague term, thermal stability. A typical urethane foam formulation includes at least six components: isocyanate and polyol comprising the bulk, with lesser amounts of fire retardants, fillers, catalysts, and blowing agent. Thermal stability is a rather vague term. Each problem encountered in studying heat stability might itself be considered as a working definition of such stability and could establish criteria. Among these are: weight and strength loss versus time and

A New Generation of Structural Foam Polymers

pioblem of designing a functional or decorative part he has many choices of materials before him. Should the part be fabricated from metal by conventional pressing and assembly techniques or should the part under consideration be made from plastic? If a plastic part is feasible or indicated, the engineci is now faced with the difficult choice of which polymer and which process should be used to arrive at the most satisfactory part, with regard to function, at the lowest possible cost. The engineer will consider the dimensions and complexity of the part, together with the stress and temperature environment to which it will be exposed in finishing and in service. This knowledge will suggest possible polymers and processes, however, before any final decisions can be made consideration must inevitably be given to such factors as the volume of production required, the tooling cost, capital investment related to possible

Polymers from Unconventional Reactions of Isocyanates

HE RAPID GROWTH of the polyurethane industry over the past twenty years has T been adequately documented in trade journals and market reports [ l ] . The remarkable versatility of polyurethane as a class may be illustrated by the varied forms available: rigid, semi-flexible and flexible foams, microcellular elastomers, thermoplastic elastomers, coatings, spandex fibers, and integral skin cellular products, to name a few [2]. All of these products are derived from reacting a very few types of isocyanates with an almost endless variety of polyols or polyamines or water. It has been the task of the applications chemist to select from these materials, the functionality, molecular weight and structural types of reactants which, when combined, will yield the desired properties. Much has been written concerning the chemistry and structure-property relationships of the polyurethanes [2,3]. The most common fault of these otherwise versatile materials i s their relatively low upper use temperature. This report describes other polymers derived from isocyanates, which utilize the many other reaction routes open to these very reactive monomers to produce a large number of potentially useful polymers of greatly improved thermal stability. The general reactions of isocyanates are outlined in Scheme I. From these reactions may be derived the polymers to be described subsequently. Most of the reactions outlined are strongly susceptible to catalysis, as described in Table 1.

Computer Simulation of Isocyanate Based Structural Foam Molding

Table 1. Formulation of Dermathane ID-386-12. over designed and sometimes parts were underdesigned. Material suppliers have recognized this problem but to date very little of this needed information has been published. To appreciate why, let us define the problem. What are the physical properties of non-cellular structural materials such as, ABS, epoxy, steel? They are numbers, absolute values. Flexural strength, flexural modulus, tensile strength etc.,

Solventless Urethane Coatings

This paper reviews recent progress in the development of solventless solid urethanes for spray and spread coating applications. Formulations based on liquid MDI (Isonate 143L), equipment, compounding, handling, and processing procedures are described in detail. Solventless urethane coatings offer an attractive alternative to conventional materials and practices. Their development is aimed at eliminating atmospheric pollution from manufacturing and application processes.

Polyurethane Chair Shells

but is reprinted here as a service to our subscribers. shapes. However, it is more expensive to fabricate and difficult to attach padding and fabrics. Rigid low density polyurethane foam is the first serious competition for the hardwood skeletons. It competes with extreme design versatility and it competes economically. To substantiate this, consider the process. Two reactive liquids are mechanically mixed and poured into a chair shell mold

Unisystem—A New Concept in Urethane Foam Moldings

The literature has become replete with references to various polyurethane foam formulations and their applications. Each reference generally describes a limited number of formulations directed to specific applications. Anyone involved in a molding operation, and in particular molding parts for the automotive industry, fully realizes that specific requirements and formulations are needed for each part being molded. If a large number of parts are being manufactured, with diverse property requirements, than an inventory of a variety of chemicals are required to produce these parts. This can become an expensive proposition in terms of inventory and quality control requirements, and needless to say, that purchasing of fewer chemicals in large volume could be made more economically. This article describes the UNISYSTEM approach to urethane foam technology wherein semiflexible, integral skin flexible, microcellular and integral skin rigid foams, suitable for a variety of applications, can be prepared from a basic set of