Flexible foam test method

ASTM International (1981) D3574-81, Test H. Standard test methods for flexible cellular materials - slab, bonded, and molded urethane foams. ASTM International, West Conshohocken... 

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 ... 

Representative test methods of flexible foam properties, as defined by the ASTM D-3574 are density, IFD (indentation force deflection), CFD (compression force deflection), sag factor, compression set, tensile and tear strengths, elongation, resilience, dry-heat aging and steam autoclave aging. 

ASTM C 384 is another method used for acoustical materials. This method is an impedance-tube method. In the test a flexible-foam specimen is placed in a cavity over a vacuum chamber. A specified constant-air-pressure differential is then created. The air-flow value is the rate of flow of air required to maintain this pressure differential. The test is carried out 1) with air flow parallel to foam rise, and 2) with air flow perpendicular to foam rise. Air-flow values are proportional to porosity in flexible foams. 

ASTM D 3574 - Test G is another method used for air flow of flexible foams. The test measures the ease with which air passes through a cellular structure. The test consists in placing a flexible-foam core specimen in a cavity over a chamber and creating a specified constant air-pressure differential. The rate of flow of air require to maintain this pressure differential (125 Pa) is the air-flow value. The results are reported in cubic decimeters per second (dm /sec). Tests are usually carried out in two directions parallel to foam rise and perpendicular to foam rise. 

ASTM D 1565, a specification, outlines a test method for dynamic flexing of flexible vinyl cellular materials. This test uses a flexing machine which oscillates at 1 Hz. A minimum of 250,000 flexes are applied. After alternate compression and relaxation the effect on the structure and thickness of the foam is observed. The percentage loss of thickness is reported. Flexural modulus of microcellular urethane is described in ASTM D 3489. This method uses the general procedure in ASTM D 790, Method I. ASTM D 3768 outlines a procedure for determining flexural recovery of microcellular urethanes. The method is used to indicate the ability of a material to recover after a 180° bend around a 12.7-mm (0.5 in.) diameter mandrel at room temperature. 

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 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. 

Most of the test methods outlined in this. section for flexible foams are described in ISO tests or the related BS4443 [44]. These methods usually can be applied to flexible foams in general (The BS standard encompasses flexible cellular materials of polymeric origin ), although in some instances the standards include only certain polymer types, for example ISO 2439, 1980 [45] includes only latex, urethane, and open-cell PVC. Care must be exercised when using the test methods for foams not covered in the scope of the test method. ASTM D 3574-95 [46] relates specifically to urethane foams. 

The American test method for indentation force deflection (IFD). ASTM D 3574-95, de.scribes a procedure similar to the British Standard, but it differs in several ways that must be recognized if direct comparisons are to be made. D 3574- 95 is specifically for "Flexible Cellular Materials Slab. Bonded, and Molded Urethane Foams. Specimen... 

Considering the importance of the open or closed cell nature of a foam (and hence its porosity) it is perhaps rather surprising that the measurement of this property is generally neglected in terms of quality control procedures. It is only when a secondary application or process dictates the use of a certain foam porosity that the property is measured. In the flexible foam market it is also found that specific company test methods are in widespread use as opposed to international or national standards. 

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. 

Standard Test Methods for Flexible Cellular Materials - Slab, Bonded, and Molded Urethanes Foams. 

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. 

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. 

ASTM D 3675 Surface Flammability of Flexible Cellular Materials Using a Radiant Heat Energy Source This method may be used on cellular elastomeric materials such as flexible polyurethane foam and neoprene foam. It employs a radiant panel heat source consisting of a 300 by 460-nun (12 by 18 in.) panel in front of which an inclined 150 by 460-m (6 by 18 in.) specimen of the material is placed. The orientation of the specimen is such that ignition is forced near its upper edge, and the flame front progresses downward. Factors derived from the rate of progress of the flame front and heat liberated by the material under test are combined to provide a flame spread index. The method was developed to test cellular elastomeric materials which could not be tested by ASTM E 162. 

ASTM D 3574 Methods of Testing Flexible Cellular Materials. Although not included in the body of this standard, an Appendix lists U.S. Government and ASTM tests covering combustibility of flexible urethane foam used in cushioning. These include DOT and FAA tests not listed in this book. 

ASTM D 3574-86 Standard Methods of Testing Flexible Cellular Materials — Slab, Bonded and Molded Urethane Foams, 22 pp (DOD Adopted) (FSC 9320) (MR) (Comm D-11)... 

American Society for Testing and Materials, ASTM D 3574-86, Standard Methods for Testing Flexible Cellular Materials - Slab, Bonded and Molded Urethane Foams, (1986) pp. 22... 

No differences in flammability characteristics between the 0.1% Cu20-treated and untreated flexible polyurethane foam were observed. These characteristics were examined to assure that the positive effect on toxicity was not contradicted by negative effects on the flammability properties. The flammability characteristics examined were (1) ignitability in three systems (the NIST Cup Furnace Smoke Toxicity method, the Cone Calorimeter, and Lateral Ignition and Flame Spread Test (LIFT)), (2) heat release rates under small-scale (Cone Calorimeter) and medium-scale (furniture calorimeter) conditions, (3) heats of combustion under small-scale (Cone Calorimeter) and medium-scale (furniture calorimeter) conditions, (4) CO/CO2 ratios under small-scale (Cone Calorimeter) and medium-scale (furniture calorimeter) conditions, (5) smoke obscuration (Cone Calorimeter), and (6) rate of flame spread (LIFT). 

BS3667 (withdrawn). Methods of testing flexible polyurethane foam. 

Flame spread flammability evaluates how far away from the ignition source a flame travels across a liquid or solid surface. The test is carried out in accordance with ASTM E162 [12]. Only flexible cellular foams are tested using a variant of the method ASTM D3675 [13]. 

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