Other Mechanical Properties

Folding endurance is a measure of the material s resistance to flexure or creasing. Folding endurance is greatly influenced by the polymer s glass transition temperature and the presence of plasticizers. ASTM D2176 describes a standard procedure for determination of the number of folds necessary to break a film. 

Pinhole flex resistance is the ability of a plastic film to resist the formation of pinholes (tiny holes) during repeated folding. Films having a low value of pinhole flex resistance will tend to generate pinholes at the fold line during repeated flexing. The test is described in ASTM Standard F456. Pinhole flex resistance is related to 

Abrasion resistance is a difficult property to define as well as to measure. It is normally accepted that abrasion resistance depends on the polymer s hardness and resilience, frictional forces, load, and actual area of contact. ASTM D1044 evaluates the resistance of transparent plastics to one kind of surface abrasion by measuring its effects on the transmission of light. Another test method to evaluate abrasion, ASTM D1242, measures the volume lost using two different types of abrasion machines loose abrasion and bonded abrasion. 

Tensile yield strength decreases with an increase in the plasticizer concerrtratiorr At higher values of stress intensity, fatigue occrrrs by shear yielding and this is more likely to occur as a function of increased concerrtration of the plasticizer The creep resistance of PVC was increased by use of reactive plasticizer Flexural modtrlus of PC and PPE was increased by the increase in concentration of plasticizers such as aromatic phosphates and phthalates.  

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Ytterbium metal has possible use in improving the grain refinement, strength, and other mechanical properties of stainless steel. One isotope is reported to have been used as a radiation source substitute for a portable X-ray machine where electricity is unavailable. Few other uses have been found. 

Equation (2.61) predicts a 3.5-power dependence of viscosity on molecular weight, amazingly close to the observed 3.4-power dependence. In this respect the model is a success. Unfortunately, there are other mechanical properties of highly entangled molecules in which the agreement between the Bueche theory and experiment are less satisfactory. Since we have not established the basis for these other criteria, we shall not go into specific details. It is informative to recognize that Eq. (2.61) contains many of the same factors as Eq. (2.56), the Debye expression for viscosity, which we symbolize t . If we factor the Bueche expression so as to separate the Debye terms, we obtain... 

The first four types are most conveniently distinguished by reference to formulations A to D in Table 12.5. Formulation A is a conventional plastisol. The viscosity of the paste is largely controlled by the choice of type and amount of polymer and plasticiser. In order to achieve a sufficiently low viscosity for processing, large quantities of plasticiser must be added, thereby giving a product of lower hardness, modulus, tensile strength and other mechanical properties than would be the case if less plasticiser could be used. In many applications this is not a serious problem and plastisols are of some considerable importance commercially. 

Despite the large differences in respect of other mechanical properties, it has been established that the wear resistance of copper deposits, which is markedly inferior to, for example, that of electrodeposited nickel, is not significantly affected by either type of bath or addition agents. 

In other instances, heat treatments involving quenching, tempering, or holding at some temperature to precipitate an age-hardening compound are employed to secure some desired level of hardness or other mechanical properties. It is obviously necessary to explore what effects such heat treatments may have on the corrosion resistance of the material in the condition, or conditions, of heat treatment in which it is to be used. 

The present review shows how the microhardness technique can be used to elucidate the dependence of a variety of local deformational processes upon polymer texture and morphology. Microhardness is a rather elusive quantity, that is really a combination of other mechanical properties. It is most suitably defined in terms of the pyramid indentation test. Hardness is primarily taken as a measure of the irreversible deformation mechanisms which characterize a polymeric material, though it also involves elastic and time dependent effects which depend on microstructural details. In isotropic lamellar polymers a hardness depression from ideal values, due to the finite crystal thickness, occurs. The interlamellar non-crystalline layer introduces an additional weak component which contributes further to a lowering of the hardness value. Annealing effects and chemical etching are shown to produce, on the contrary, a significant hardening of the material. The prevalent mechanisms for plastic deformation are proposed. Anisotropy behaviour for several oriented materials is critically discussed. 

In the matrix of PLA/ polycaprilactone (PCL)/OMMT nano-composites, the silicate layers of the organoclay were intercalated and randomly distributed (Zhenyang et at, 2007). The PLA/PCL blend significantly improved the tensile and other mechanical properties by addition of OMMT. Thermal stability of PLA/PCL blends was also explicitly improved when the OMMT content is less than 5%wt. Preparation of PLA/thermoplastic starch/MMT nano-composites have been investigated and the products have been characterized using X-Ray diffraction, transmission electron microscopy and tensile measurements. The results show improvement in the tensile and modulus, and reduction in fracture toughness (Arroyo et ah, 2010). 

VIII. Other Mechanical Properties A. Impact strength 8. Heat distortion temperature... 

Butene is used in the plastics industry to make both homopolymers and copolymers. Polybutylene (1-polybutene), polymerized from 1-butene, is a plastic with high tensile strength and other mechanical properties that makes it a tough, strong plastic. High-density polyethylenes and linear low-density polyethylenes are produced through co-polymerization by incorporating butene as a comonomer with ethene. Similarly, butene is used with propene to produce different types of polypropylenes. 

The recent report by the National Research Council of the National Academy of Sciences entitled "Limitations of Rock Mechanics in Energy Resource Recovery and Development", highlighted some of the problems which must be addressed. The rock strength and other mechanical properties of the media must be understood both under the impact of the thermal pulse represented by the release of heat from decaying radioactive waste materials and the perturbation represented by construction of the mine. The resulting thermal stresses must be understood in developing the layout and the allowable rate of heat generation from the individual canisters. 

T = 140 °C. Here, during solidification, the H increase from 140 °C down to about 100 °C is the result of a double contribution of (a) the crystallization of the fraction of molten crystals and (b) the thermal contraction of the nonpolar phase crystals. The hysteresis behavior is also found in other mechanical properties (dynamic modulus) derived from micromechanical spectroscopy [66, 67], where it is shown that the hysteresis cycle shifts to lower temperatures if the samples are irradiated with electrons. It has also been pointed out that the samples remain in the paraelectric phase, when cooling, if the irradiation dose is larger than 100 Mrad. 

Crude reaction products having a total rubber content of 9% yield substances characterized by high impact strength without any remarkable variation in the other mechanical properties. 

Typical materials for the electrolyte are YSZ, samaria doped ceria (SDC), and LaGaC>3. The intrinsic property of the thermal expansion behavior of an electrolyte depends only on the material species. However, the other mechanical properties (Young s modulus, Poisson s ratio, and strength) depend on the morphology through the manufacturing processes. Accordingly, the reported mechanical properties are not unique. The reported thermal expansion coefficient (TEC) and other mechanical properties for the electrolyte materials are listed in Table 10.1. 

The composition dependence of the flexural strength of the aMS/AN-copolymer blend with polyarylether K appears in Figure 13. As the composition of the copolymer increases, the strength first increases, reaches a maximum, and then decreases. It actually exhibits a minimum at about 80% < MS/AN. This behavior can only substantiate earlier suggestions regarding the possible immiscibility of these systems. All of the other mechanical properties indicate that mixtures with polyarylether K may not be miscible but are mechanically compatible. Finally, it is interesting to note that at least one of the pendant chemical groups present on K exists on either of the a-methyl styrene interpolymers. It... 

The other mechanical properties of polymers have the typical character of product properties they are not only dependent on the intrinsic nature of the material but also on the environmental conditions, in other words, they are systemic quantities. They will be treated separately in Chap. 24. 

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