Mechanical loss factor tan

Fig. 4. Effect of nanocomposites on mechanical loss factor tan 8 vs temperature...

Fig. 33a. Storage modulus, E (at 5 Hz), as a function of temperature for drawn and isotropic POM Delrin 500) samples. Numbers on curves refer to deformation ratio b. The mechanical loss factor, tan 6. corresponding to the data of (a)...

Fig. 32. Storage modulus, E, and mechanical loss factor, tan 6, for GM61 polypropylene (M, = 400,000). Frequency 5 Hz X = 15. As-drawn, A after 60 min annealing at 135 °C...

Figure 10-26. Mechanical loss factor tan 6 of poly(cyclohexyl methacrylate) as a function of temperature for various frequencies (after J. Heijboer).

There are no abrupt transitions. The dynamic loss modulus or storage modulus (E") which relates to the polymer s ability to absorb mechanical shock and the mechanical loss factor tan delta (E /E ) show that glass transition of the polymer is at -30 C and that there is an alpha transition around 60 C. In general, the KYHAR homopolymer possesses useful mechanical properties from -80 c to 150 C. 

Dynamic storage modulus ( ) is the most important property to assess the load-bearing capability of a composite material. The ratio of the loss modulus (E") to be storage modulus (F) is known as a mechanical loss factor (tan S), which quantifies the measure of balance between the elastic phase and the viscous phase in a polymeric structure. This can relate to impact properties of a material. Generally, the tan S peak (at low frequency) is at a temperature 10-20 °C above the Tg as measured by dilatometer or differential thermal analysis (DTA). The temperature of maximum loss modulus E" is very close to Tg. 

Figure 6. Storage modulus, E and mechanical loss factor, tan, as a function of temperature, T, for a melt-compounded poly (ether-6-urethane) (PEBU, Shore A 80) with and without 5 phr organoclay the organoclays contained primary amine (Nanomer I.30P) or hydroxyl functionalized quaternary ammonium intercaJants (Cloisite 30B)...

Ideally, short-term behavior under thermal loading is described in terms of mechanical properties as a function of temperature. Useful pointers when determined as a function of temperature are the modulus and damping values, modulus of shear G, and mechanical loss factor tan(5. 

The loss factor, tan 8, can be measured with the aid of dynamic-mechanical experiments (such as the torsion pendulum). The deformation in such a test varies as indicated in Figure 7.13 the damping follows from the logarithmic decrement , A, it can be easily shown that... 

The effect of the fillers on the dynamic mechanical property of NR material was analysed by DMA in this work. The elastic modulus ( ") and the loss factor (tan 5) of the neat NR and NR composites were characterized as functions of temperature. Under an oscillating force, the resultant strain in specimen depends upon both elastic and viscous behaviour of materials. The storage modulus reflects the elastic modulus of the rubber materials which measures t recoverable strain energy in a deformed specimen, and the loss factor is related to the energy damped due to energy dissipation as heat. 

Figure 23.8 (a) Variation of Storage modulus ( ) as a function of temperature (b) Variation of Loss modulus (E") as a function of temperature (c) Variation of tan 8 (mechanical loss factor) as a fimcUon of temperature. 

The Tg is better evidenced in dynamical mechanical thermal analysis (DMTA) as shown in Figures 9.5 and 9.6, where the storage modulus E, loss modulus E", and the damping or loss factor tan 6 = E"IE are presented [51,52]. In... 

Figure 10.7 Shear modulus and loss factor tan S for PVC plasticised with diethyl phthalate (DEP), dibutyl phthalate (DBF) and n-dioctylphthalate (DOP). (Reproduced from Neilsen, LE. Buchdahl, R. and Levreault, R., (1950) Mechanical and electrical properties of plasticised vinyl chloride compositions, j. Appl. Phys., 21, 607. Copyright (1950) American Institute of Physics.)...

As all electrical insulating materials, EP-resins exhibit low electrical conductivity which results in current loss in operation. Thermal losses from current load in an encapsulated conductor or device and the dielectric dissipation loss generated in the EP-resin-molding material result in temperature increases that lower electrical con-ductibility and dielectric strength [885], because in principle, all mechanisms participating in DC current transport and displacement processes also cause dielectric losses in the alternating field. The dielectric behavior of insulating materials is described by the temperature-, frequency-, and stress-dependent (i.e. field intensity dependent) loss factor tan 6 and the dielectric constant s. 

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