State Mechanical Properties

The most pertinent feature in Table 3.7 is the vast range of mechanical properties that have been reported for PPy. It is apparent that the composition of the polymer (e.g., counterion type) and the polymerization conditions have a significant effect on the polymer properties. However, the relationships are not straightforward. For example, Wynne and Street113 have shown that acetonitrile solvent yields PPy films with very good mechanical properties, whereas Sun and coworkers11 and others have reported the opposite. It is clear that systematic analyses are required to elucidate the determinants of the mechanical properties of PPy s. 

Most of the previous studies have been empirical in nature. However, they have been important in demonstrating those factors that influence the mechanical properties. For example, mechanical properties of PPy films have been observed to improve as the polymerization temperature decreases. Sun and coworkers11 have observed that the tensile strength of PPy/pTS increases as the synthesis temperature 

Eapp and CD during polymerization Action of water during polymerization Different counterions 

Plasticizing effect of residual solvent Effect of polymerization solvent 

1 mm plates prepared CD during polymerization varied Plasticizing effect of water 

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Figure 6.1 Schematic evolution of steady-state mechanical properties of a thermoset as a function of reaction time or conversion. Representative properties are the steady shear viscosity for the liquid state and the equilibrium modulus for the solid state.

Studies of epoxy-amine polymers, considered in the present article, offer a rather clear picture of structure-properties relationships for many properties of network polymers depending on their chemical composition in the glassy state near Tg and in the rubbery state. Mechanical properties in the rubbery state at a given chemical composition depend on network topology. 

This paper attempts to further explore the modification of ionic associations by a crystalline ionic plasticizer, such as zinc stearate, at the solid state. Mechanical properties, swelling behavior, and morphological aspects were studied in order to better understand the role of such crystalline polar additives. 

Cyclic loads were applied to the specimens using a hydraulic feedback load system which could be either load-, stroke-, or strain-controlled. Sinusoidal and linear-ramp waveforms were generally used. Fatigue frequencies were varied from 0.1 to 15 Hz. Unless otherwise stated, mechanical property data were obtained at a fatigue frequency of 10 Hz. 

Thermodynamically stable, bicontinuous microemulsions have recently been shown to be obtainable in symmetric ternary blends of two homopolymers and a diblock copolymer by formulating alloys with compositions near mean-field isotropic Lifshitz points. In the present paper, it is argued that practical apphcation of this design criterion could require use of homopolymers of unequal molec.wts. and block copolymers of different structure. The existence of, and explicit location of, mean-field isotropic Lifshitz points in ternary blends with homopolymer molec.wt. asymmetry and either AB diblock or ABA triblock copolymer structures were demonstrated. These calculations significantly expanded the parameter space for observing bicontinuous miCToemulsions and allowed for more flexibility in tailoring melt rheological properties and solid-state mechanical properties. 29 refs. 

ProLastin films are mechanically stable and flexible in their dry states. Mechanical properties of some dry SELP and CLP films are shown in Table 3. Those films w hich are stable in water soften and become quite flexible upon wetting. The tensile strength of w et SELP8 films decreases to about 1-2 MPa as compared to almost 20 MPa for the dry film and the elastic modulus decreases by about 5 fold. These properties should be considered minimums since the mechanical testing of film specimens is extremely sensitive to specimen defects. 

As previously stated, mechanical properties indicate a material s reaction to the application of forces and their values are determined through a series of standard tests. These tests are carried out on small specimens of the material under test until deformed or destroyed. Such tests are referred to as destructive tests. These tests include tensile, compressive, torsion, bend and impact testing and are used to determine the mechanical properties already outlined. 

Fig. 2. Steady-state mechanical properties (schematic) of cross-linking polymers with different stoichiometric ratios r, defined as ratio of cross-linking sites of two reacting polymers. The reaction is presumably brought to completion. Steady critical gel behavior is found at the lower and the upper critical values, n and r .

Dry state mechanical properties Environmental effects on mechanical properties Conclusions References... 

The objective of the present work is to develop an understanding of the effects of molecular parameters such as length, architecture and length distribution on the solid-state mechanical properties of polymers. In this paper we report measurements of the craze initiation stress in isochronal 3-point bending creep experiments on a wide variety of well-characterized grades of atactic polystyrene (PS) and put forward a simple model that relates molecular parameters to craze initiation. A novel miniature crazing test was employed, to enable study of materials where only small quantities are available. 

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