Impact deformation

Zytel Polyamine Stable to temperatures up to about 325°F (163°C) resistant to impact, deformation, and fatigue Fuel rails filter housings... 

Figure 25.11 Force time record of rubber modified (MSP1) S/DPE (30%) during three-point bending impact (deformation speed 2.9 m/s)...

Actually, the strain-rate sensitivity is often used as a usefiil basis for examining different aspects of deformation. From the impact deformation standpoint, the value of strain-rate... 

If substantial growth is required, what is the deformability of the formulation Does it readily grow, or is the formulation stiffer, requiring an induction time to work moisture to the surface How much moisture is required, and how does it impact deformability ... 

Resilience and recovery from both slow and impact deformation, primarily in open-cell foams, again because of the fluidity of air as it rushes back into the foam after the deforming force is released. 

Increasing relative molecular mass of the binder in the polymer film improves properties such as elasticity, hardness, and impact deformation, but also leads to higher solution viscosity of the binder. While the usefulness of a coating is enhanced by good mechanical film properties, low viscosity combined with low solvent content are also desirable for ease of application and for environmental reasons. Therefore, a compromise is necessary. 

Figure 53.3 summarizes injury mechanisms associated with torso impact deformation. For low speeds of deformation, the limiting factor is crush injury from compression of the body (C). This occurs at C = 35-40% depending on the contact area and orientation of loading. For deformation speeds above 3 m/sec, injury is related to a peak viscous response of VC = 1.0 m/sec. In a particular situation, injury can occur by a compression or viscous responses, or both, as these responses occur at different times in an impact. At extreme rates of loading, such as in a blast-wave exposure, injury occurs with less than 10 15% compression by high-energy transfer to viscous elements of the body. 

Impact deformation Pfefferkorn Average Average Production of test samples required... 

Measuring of the plasticity according to Pfefferkorn is based on the principle of impact deformation. 

The initial height ho is related to the impact deformation height hi, the result of which is the ratio of deformation. As a rule this measurement is taken with bodies of varying moisture content. 

The ratios of deformation ho/hi or the impact deformation heights hi are plotted on a graph over the moisture content figixres. The steeper the curve, the shorter (more lean) is the body, i.e. the more intensely the body will react to variations in the moisture content. 

Experience shows that the impact deformation heights according to Pfefferkorn for bodies to be extruded lie within a span of approx. 25 mm for soft extrusion and approx. 37 mm for stiff extrusion. 

The Pfefferkorn method is widely accepted in practice and was originally developed for soft silicate ceramic materials. The Pfefferkorn method is less suitable for stiffer bodies, as usually processed in the advanced ceramics industry, as the low resolution at a small impact deformation height impedes the reproducibility. 

Gilchrist, G., Mills, N. J. Impact Deformation of Rigid Polymeric Foams Experiments and FEA Modelling. IntemationalJoumal of Impact Engineering, 2001 25 767-86. 

Mechanical damage in the form of impact deformation or scratches not only affects the appearance of the film loss of adhesion can also result. Tests have been developed to determine the resistance of a paint film from these occurrences. 

Thus, the strength decreases with increasing Tg. In fact, / is larger than that of vulcanized rubber. However, glassy plastics are vulnerable to impact deformation. 

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