Testing foaming behaviour

An example of a non-foaming system is one where a reflux condenser can be used to cool the reactor if the mixture were a natural foamer, the condenser would not work properly because it would be full of foam. However, it should be established that the circumstances leading to runaway do not cause foaming. Small-scale equipment for testing foaming behaviour has been proposed. ... 

The mechanical response of polypropylene foam was studied over a wide range of strain rates and the linear and non-linear viscoelastic behaviour was analysed. The material was tested in creep and dynamic mechanical experiments and a correlation between strain rate effects and viscoelastic properties of the foam was obtained using viscoelasticity theory and separating strain and time effects. A scheme for the prediction of the stress-strain curve at any strain rate was developed in which a strain rate-dependent scaling factor was introduced. An energy absorption diagram was constructed. 14 refs. 

A crash test rig was developed to simulate the high loads on components in and on street vehicles in the case of a colhsion. It provides profiles of deformation, energy dissipation and retardation as a function of time. The effect of test velocity and temp, on the behaviour of PP foam (Neopolen P) samples of various density was examined. 2 refs. 

BS 5946 1980 Method of Test for Detetmination of die Funking Behaviour of Phenol-Formaldehyde Foam, 9 pp... 

There was no clearance between the core and skin in the tested sandwich pieces, which is an important factor in upgrading the flammability behaviour. Any material used in the manufacture of sandwich panels must be at least as fire resistant as the skin and core materials. For example, when phenol/formaldehyde foam cored sandwich elements were mounted on firwood frames, the flames were conducted by the frame, thus enhancing the fire risk. 

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). 

It can be anticipated that all gas-flood projects, as they are presently being carried out, will leave a large fraction of the reservoir oil uncontacted by the injected fluids. This bypassed oil will remain inplace, undisplaced by the injected fluid. Thus, in each current field project, the amount of incremental oil produced by gas flooding could be substantially increased if the uncontacted oil could be reached. The improvement of the vertical and areal distribution of injected fluids through-out the reservoir requires much better methods of sweep and mobility control. The utility of the foams, in general, as mobility control agents has not been extensively tested. In principle they offer a spectrum of fluid mobility behaviour depending on the in-situ foam phase stability. 

In instrumented creep tests taken to failure, one learns not only how long specimens last but also how deformation increases throughout the creep process. For lap joints, delay times have been seen in creep tests, probably due to the increasing uniformity of the shear stress state, as predicted by the shear lag model as the creep compliance of the adhesive increases with time. In other situations, no such delay time is seen. A schematic illustration of a creep curve for an adhesive bond consisting of a butt joint bonded with a pressure sensitive foam tape is shown in Fig. 2, exhibiting classical primary, secondary and tertiary regions of creep behaviour. 

Full-scale fire tests can give more useful information than small-scale tests with tiny specimens. They can simulate the behaviour of plastics articles such as foam-filled furniture and television sets in fires. Examples include the Steiner tunnel test, the ISO 9705 room comer test and the CAL 133 test. Many fire test procedures are specific to a given industry, such as construction or the railways. In the latter case, the standard of flammability required may depend on whether a train is to be operated through long tunnels. 

It has proved difficult to determine any correlation between the test result of the various national procedures [53]. Because of this, the experts of TC92 of the International Standards Organisation (ISO) have undertaken the development of a test procedure to characterise independently ignitability, flame spread, rates of heat release, and other fire-related parameters [54-56]. Worldwide efforts continue to correlate laboratory tests to real-life fires [57]. Examples of such programmes are the corner test programme carried out by Factory Mutual and the corrugated metal tool deck [58] trials [59, 60] carried out by TNO. The corner test has been used to determine the fire behaviour of rigid foam materials when exposed to severe wood crib fire. 

An experimental investigation was undertaken to assess the failure behaviour of a series of PU foams of variable specific density. All the foam materials examined were transversely isotropic materials, whose axis of symmetry was, however, the weak axis of the medium. Simple uniaxial tension and compression tests were executed and the experimental data were introduced into the elliptic... 

Figure 7.8 The storage modulus ( ), loss modulus (f") and mechanical loss tangent (tan 8) of the foamed SIS/THFMA blends (a) 30/70, (b) 50/50, (c) 70/30 versus temperature. Cylindrical samples were tested in compression on five repeat specimens which were sinusoidally loaded at a frequency of 1 Hz. A temperature scan from 25 to 120°C at 4°C/min was applied while nitrogen gas was used as purge in the furnace. A clear trend can be seen in the behaviour of the blends as the percentage of SIS decreases. (From [12] reproduced by permission of The Royal Society of Chemistry.)...

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