Stiffness modulus

All three softeners migrate from one compound to another and this must be considered when compounding for a set range of stiffness (modulus) gradiations in the tire components designed to alleviate stress. 

The benefits of SiC whisker-reinforced aluminum can be seen in Figure 5.109. The room-temperature stiffness (modulus) of the composite is about 50% higher than that... 

Measuring Vulcanization. The formation of a three-dimensional structure during vulcanization increases the stiffness (modulus) of the compound. Therefore, following the modulus increase versus cure time provides a continuous picture of the vulcanization process. Oscillating disk rheometers provide a useful method to do this (17). In this test, a preweighed sample of uncured mbber is placed into a preheated cavity containing a conical rotor. The cavity is closed and the rotor is set to oscillate within the mbber sample. As vulcanization proceeds, the compound s resistance to rotor movement increases and this resistance is followed as a function of time, thereby generating a continuous profile of cure behavior. These cure curves,... 

One of the principal limitations of thermoplastic polymers is their low stiffness (modulus), especially at elevated temperatures (heat distortion). Certain filler types are very good at improving these properties and this is another of the main reasons why fillers are used in these polymers. 

Table 3. Mechanisms contributing to increased stiffness, modulus, and rupture energy11(...

The stiffness modulus is, in most cases, measured in dynamical - mechanical experiments, for instance with a torsion pendulum, on a time scale of a few seconds. This experiment results in the shear modulus, G (which is related to Young s modulus, E), while the damping shows a strong maximum at Tg. 

Hydrophobic polymers and films, such as paraffin wax and poly (vinyl chloride), show no change in stiffness modulus when flooded with water. On the other hand, butyl alcohol on a paraffin wax film causes a slow, slight increase of stiffness modulus over a period of several minutes. The effect of benzene on paraffin films is similar to that of methanol on PVA. A poly (vinyl chloride) film is unaffected by plasticizers such as dimethyl and diethyl phthalate over short time periods. However, PVC gives rise to the ultrasonic modulus anomaly when contacted with tetrahydrofuran, a strong solvent for PVC. The plasticizing effect of dibutyl phthalate on polystyrene has been demonstrated by ultrasonic impedometry (16). No anomalies were found. 

The type of plot shown in Figure 11 combines low-temperature stiffness modulus at slow loading (thermal) with high temperature stiffness at fast loading times (traffic, using a decade shift in the values of the left and right ordinates. A transition zone of about —6° to +4°C... 

The Indirect Tensile Stiffness Modulus (ITSM) Test... 

Samples tested imder this experimental work are nominally with 100 mm diameter and 70 mm height for ITSM test. Before determination of stiffness modulus, the resilient modulus of samples were ealeulated (According to the ASTM D 4123)[7],... 

Figure 3 indicate the stififness modulus versus bitumen percent. As it can be seen clearly, the waste rubber reinforcement can improve the stiffness modulus, in contrast to non-reinforced samples. According to the experiments with certain bitumen percent, the value of stiffness modulus in reinforced specimen is more than the value of stiffness modulus in non-reinforced specimen, specially, when bitumen percent increased the cohesion between waste rubber, talus material and bitumen will increase, therefore, difference between stiffness... 

In figure 4 we can observe the variations of stiffness modulus versus temperature at 6% bitumen. As it can be seen, the waste rubber reinforcement can cause better characters in asphaltic samples. 

The waste rubber reinforcement can increase the stiffness modulus. It is clear that the reinforced sample can show a high stiffness than non-reinforced one. 

As the temperature decreased, the cohesion between waste rubber, aggregates, material and bitumen increased. Therefore, by decreasing temperature, the stiffness modulus is decreased as well. Meanwhile, stiffness modulus in temperature of 25 °c is more than 40°c. This different between stiffness modulus at 25 °c and 40°c is about 53%. 

The stiffness modulus is a fimction of load, stress, horizontal deformation, percentage of bitumen and poisson ratio. The Poisson ratio s normally assumed to be 0.35 which is a representative value for most asphalt. 

In both reinforced and normal asphaltic samples. It can be seen that with increasing the bitumen percent, the stiffness modulus is increased but this increasing in reinforced samples is more than normal samples. This topic due to twin effects of bitumen and tire thread mesh. 

The detection of chemical analytes can be based on changes in one or more of the physical characteristics of a thin film or layer in contact with the device surface. Some of the intrinsic film properties that can be utilized for detection include mass/area, elastic stiffness (modulus), viscoelasticity, viscosity, electrical conductivity, and permittivity. In addition, changes in extrinsic variables such as... 

Because the specific volume of polymers increases at Tg in order to accommodate the increased segmental chain motion, Tg values may be estimated from plots of the change in specific volume with temperature. Other properties such as stiffness (modulus), refractive index, dielectric properties, gas permeability. X-ray adsorption, and heat capacity all change at Tg. Thus, Tg may be estimated by noting the change in any of these values such as the increase in gas permeability. 

The stiffness modulus of the sulfurized asphalt paving material can be five times greater than that of asphaltic concrete at intermediate rates of loading. 

Assumption 1 was made by interpolation from data reported by Shell Canada (1, 2). According to Shell Canada findings, the stiffness modulus of a S-A-S mix at 50°F and 50 Hz is about two-thirds of the Shell design charts modulus used for asphaltic concrete. At lower loading... 

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