Rigid foam test methods

RIGID FOAM TEST METHODS 14.2.1. Density (ASTM D 1622, ISO 845)... 

Foam Properties and Testing Methods. In general, most physical properties of foams, both flexible and rigid, are proportional to the foam density. Therefore, at all times, the first physical property to be determined is foam density. Foam density can be calculated fi om the following equation ... 

Flame-retardant rigid foams can be classified by the testing methods employed, but the results do not reflect actual fire situation. Fire-retardant rigid urethane foams can be prepared by using flame retardants of the additive type, reactive type, or a combination thereof. A review of flame retardants for polyurethane foams has been prepared by Hilado (154). 

This standard consists of 22 test methods, some of which are used in evaluating high-density rigid polyurethane foams for furniture applications. These methods are concerned with fastener-holding properties Lateral Nail Resistance Test, Nail Withdrawal Test, Nail-Head Pull-through Test, and Direct Screw Withdrawal Test. 

ASTM D 5113-90 Standard Test Method for Determining Adhesive Attack on Rigid Cellular Polystyrene Foam, 2 pp (Comm D-14)... 

This test method is useful in determining the effect of using adhesives on rigid cellular polystyrene (RCPS) foam in building construction. The method covers a practical means of measuring the degree of foam cavitation damage when an adhesive is used to bond these foam substrates. 

Some polymers can be used to produce foam possessing a wide range of properties. For example, polyurethane can be made hard or soft, flexible or rigid, at high or low densities. Polyurethane has an exceptional range of physical property variation and provides an unprecedented example to which many of the other cellular polymer test methods can be compared. Indeed, many of the methods used for the polyurethane family of polymers are eommon to the other polymeric foams. This subject is extensive, and a chapter such as this cannot hope to be exhaustive. However, it is hoped that most major physical property measurements are covered or at least guidance given to the reader as to where details can be obtained. 

The test methods mostly follow British Standards, but some are more closely related to the ISO tests. Care must be taken to ensure that the correct sample size is u.sed. The determination of water absorption by diffusion is based on the Swiss Standard SIA 279 Part 5.07 [13] (see Section 2.6 below). Similarly the properties of extruded board are specified in BS 3837, Part 2, 1990 [14]. BS 3927, 1986 [15], specifies rigid phenolic foam for thermal insulation in the form of slabs and profiled sections. The material is classified as types A. B. and C. which differ principally in thermal conductivity, water vapor permeability and apparent water absorption. Thermal conductivity is measured by methods described in BS 4370, Part 2, Method 7 [16] or Appendix B of BS 874 [17]. ... 

The water absorption of flexible foams is much more difficult to measure than that of rigid foams, and when this property is requested it is usually in relation to a specific application need. There is no standard test method. 

The friability of a rigid foam is not an easy property to determine, and it is seldom used as a quality control measurement. However, for certain materials such as phenol-formaldehyde foam it can be a useful tool in formulation work to ensure that the product is suitable for the application area. In certain instances the test method is best adapted to the foam being tested, for example the time duration of the test may be shortened if the material is being abraded too harshly. 

There is a wide range of polymers from soft foams to rigid composites for which. separate industries have developed. Each has its own individual test methods and. for the major types of polymers, texts exist that detail these procedures. There are, however, many similarities between different polymer types and frequently it is necessary for laboratories to consider a spectrum of materials. Consequently, there are advantages in a book that comprehensively covers the whole polymer family, describing the individual methods as well as discussing the approaches taken in different branches of the industry. 

The compressibility test is one of the most important mechanical property indicators of rigid polyurethane foam, which is in according to Test method for compression of rigid cellular plastics (GB 8813-88). 

The dimension stability test is an indicator of rigid polyurethane foam, which tests according to the test method for Dimensional Stabihty of Rigid Cellular Plastics (GB 8811 8). 

Conventional rigid polyisocyanurate foams blown with HCFC-141b often suffer from poorer compressive strengths, dimensional stability and inferior inflammability properties when compared to foams blown with CFC-11. An improved isocyanurate conversion test by photoacoustic Fourier Transform Infra Red technique is introduced. The method is not limited to polyisocyanurate foam, as isocyanate conversion is an important parameter to follow in PU foams as well, especially in all carbon dioxide blown foams. The method is found to be quite reproducible and further statistical analysis to ensure the validity of this technique is under way. 8 refs. 

Standardized methods cover tests of rigid self-supporting specimens, flexible films, and expanded materials with a bulk density not lower than 100 kg/m. Types of specimens laid down by the standard ISO/DIS 4589-1983 are listed in Table 3.5. Specimens for other standards are essentially identical to these except for ASTM D 2863-1977 in which specimens I, II and III are not involved instead, the oxygen index of rigid solids is determined on specimen IV, while specimens with cross section of 12.5 mm square are used for testing plastic foams. Testing flexible films is the same for all standards. 

Zhang and co-workers [79] investigated flame retardency and thermal behaviour of rigid PU foams prepared with different blowing agents and FR. Char yields produced upon combustion of the polymers were evaluated by the Butler Chimney Standard test method and pyrolysis - mass spectrometry (pyrolysis at 700 °C). 

Cellular plastics are used extensively in flotation applications because of their ability to maintain a low buoyancy factor. The buoyancy factor is directly affected by the amount of water a particular foam plastic will absorb. The test method developed to determine water absorption of rigid cellular plastics is fully described in the ASTM Standards Manual. Basically, the test consists of determining the volume of initial dry weight of the object and calculating the initial buoyancy force. The object is then immersed in water and, at the end of the immersion period, the final buoyancy force is measured with an underwater weighing assembly. The difference between the initial and final buoyancy force is the weight of water absorbed. This difference is expressed in terms of water absorbed per unit of specimen volume. The test results are seriously affected if proper steps are not followed closely and variables are not controlled carefully. 

The test methods developed for testing flexible cellular plastics are quite different from those developed for rigid foams. For rigid cellular plastics, separate test methods were developed for specific properties. No such separate test methods relating to specific properties are developed for flexible cellular plastics. Instead, a series of test procedures that describe a variety of physical properties of a particular type of material are commonly used to test flexible cellular plastics. 

Flammability. Rigid polyurethane foams, along with other organic plastics, have been the subject of much work in the field of flame retardance. A variety of phosphorus and/or halogen containing additives (reactive and non-reactive) are now available which improve the flame resistance of polyurethane foams. The choice of additives and of test methods is however best decided upon in the light of the application envisaged. Table 7 shows some typical properties. 

Usually, different methods are recommended for each particular type of material (film, fabric, carpet, rigid plastic foam, elastoplastics, etc.) to characterize its flammability adequately. Test procedures are divided into small-, medium-, large- and real-scale experiments, depending on the sample size. 

Semirigid foam is usually tested using methods normally applied to rigid or flexible foams. In some instances they are tested for ultimate elongation (as a percentage to BS903. Part A2 [74]). The surface hardne.ss is also important in. some molded part applications, and that property can be measured using standard Shore A hardness procedures. 

The testing and evaluation methods refer to the building materials groups PVC (rigid, soft), polyolefins (PE, PP), PMMA, GF-UP, elastomers (CR, EPDM, butyl rubber), and PUR (foamed) as the plastics generally regarded as typical in building construction [154]. 

The test to determine compressive strength and compressive modulus of rigid cellular plastics is somewhat similar to the one developed for noncellular plastics and discussed in Chapter 2. The test is very useful in comparing the compressive strengths of various foam plastic formulations. It provides a standard method of obtaining data for research and development, quality control, and verifying specification. However, the test is not a direct indication of how the cellular plastic will... 

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