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Speed, test parameter, effect

Measuring loads in high speed tests is difficult because of the short times involved and the presence of transient effects from stress waves. The more simple method which has been developed in both the Izod and Qiarpy tests is to break the spedmoi with a pendulum and measure the energy absorbed. Some form of scaling parameter from the specimen dimmsions is then applied and an impact number derived. The practical utility of these numbers is beyond question but they have many, weU known, drawbacks. In particular, the nund)ers are geometry dependent and do not agree, for example, between the Izod and Charpy tests. [Pg.113]

The toughening of PA depends on materials and on structural and test parameters. The toughening behavior at high speeds as a function of temperature gives an S-curve with a discontinuous transition. The materials and structural limit have a shift effect on this S-curve. Deformation occurs first by cavitation of the rubber, and then by plastic deformation of the cavitated ma-... [Pg.323]

Our first step was to develop a simple effective wind tunnel which allowed us to age formulations in the laboratory under very nearly natural conditions. Rather than attempt to control all climatic parameters - temperature, pressure, humidity, light intensity, wind speed, turbulence, etc. - which would have been a formidable engineering task, a very simple design was chosen in which only air speed, temperature and illumination were controlled The only real deficiency in this system is the lack of control of humidity. However, that aspect was addressed separately by measuring the pheromone release rate of each formulation under conditions of very high and very low humidity. To date, none of the candidates tested has shown a major humidity dependence. [Pg.210]

Tape test >2.5 Melt temperature, injection speed, hold pressure, hold time Increasing any one of these parameters increases tape test quality. Speed is by far the most effective, other three have approximately equal effect. [Pg.206]

Indeed, as obvious from both exemples given in Fig. 2, the transition could thus be determined accurately within 0.1-0.2 decades of test speeds with few samples in a relative short time frame. Moreover, as the apparent values (Kimax) are always lower than the effective parameters (Keff), none of the material descriptor would be overestimated. In addition, since Kjmax-values have been shown to provide a semi-quantitative evaluation (in terms of test speed or temperature) of fracture resistance parameters, a coherent material comparison would be possible over the whole investigated range. This remark remains true as long as the grades have similar rp. For iPP grades, it should be checked (and considered with more caution) when materials exhibit different particle and matrix melt flow rates, or different crystalline structures. It should also be investigated in detail when different polymer families (ABS versus HIPS or rubber modified iPP) are compared. [Pg.140]


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Effective speed

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