Rubber energy absorption

Elastomers are used for their flexibility in seals, gaskets and hoses and to resist abrasion (through absorption of the kinetic energy of the impinging particles). The range of materials includes natural and synthetic rubbers and modem elastomers with chemical resistance. 

An instrument for measuring the mechanical properties of rubbers in relation to their use as materials for the absorption and isolation of vibration. These properties are resilience, modulus (static and dynamic), kinetic energy, creep and set. The introduction of an improved version has recently been announced. 

European machines in particular are operated with very low water levels in order to save energy and water. It is therefore important to ensure that the laundry load is soaked in water or suds as quickly as possible so that dry textiles do not rub unnecessarily against the drum or the rubber seal. This is achieved in European machines by constructional features that improve water absorption, shown in Fig. 3.3, such as lifter bars, circulation (jet) systems or direct injection. 

Jao, S.H. and McGarry, F.J. (1992b). Interphase bond strength and energy absorption of injection-molded rubber coated glass/nylon composites. J. Reinforced Plast. Composite II, 811-835. 

Several such failure mechanisms may take place simultaneously in a toughened resin, depending on the type of particles, whether liquid rubber or rigid particles, and the matrix material. Each of these mechanisms contributes to the energy absorption of the whole structure. 

By combining elastomeric and brittle glassy phases it is often possible to obtain improved properties over a range of temperature and frequency. However, relatively little attention has been given to fatigue in IPNs, and to energy absorption in polyurethane rubber/poly(methyl methacrylate) (PU/PMMA) systems. 

Further, electron micrographs such as those of Matsuo (25) indicate that matrix craze bands are as wide as rubber particle diameter. Thus, energy absorption in the rubber during the important craze phase is... 

Rubber Content. In the theories of toughening where the role of rubber particles is (a) to absorb energy directly or (b) to induce matrix yielding through stress concentration or hydrostatic tension effects, energy absorption should increase linearly with the number of rubber particles (proportional to rubber content if particle size is invariant). On the other hand, if dynamic craze/crack branching is the operative mechanism, evidence of an exponential law may be expected. The exponential form of the law may be derived as follows. 

A good dispersion of rubber particles appears to favor the nucleation and growth of a large number of thick crazes uniformly distributed in the polystyrene matrix. This is believed to be an efficient source of energy absorption for the material under mechanical loading. The concepts of stress field overlap and critical volume of stress concentration zone for craze initiation were introduced to explain the observed mechanical behavior of HIPS. 

Thus at a given rate the lowest rubber content which can induce ductility and suppress spallation will result in maximum energy absorption under impact. If this yield-spall transition coincides with the ductile-brittle transition which occurs in these tensile tests, the effective strain rate of the onset of spallation could be predicted by tests of this type. This ductile-brittle transition occurs at low effective strain rates for the unmodified material since it is brittle through the range of conditions used in these tests. For the 4% material at the highest effective strain rates achieved in these tests, the load maximum is just beginning to disappear. Thus, if rate-temperature equivalence holds, extension of these test to... 

Aromatic azides are stable photosensitive compounds and some of them mixed in cycllzed rubber are practically used as photosensitive resines.(j ) Such photosensitive polymers as poly(vinyl p-azidobenzo-ate)(2 ) and poly(vlnyl p-azldoclnnamate)(3) are also Investigated. These photosensitive resines are known to be spectrally sensitized by triplet sensitlzers(l,2,3) But the energies E(Ti) of the lowest triplet states Ti of aromatic azides have not been known, because these compounds emit no phosphorescence( ) and the trials on the measurement of their Sq- Ti absorptions are failed(4,3) ... 

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