Pseudo mechanical properties

Hyperbranched polyurethanes are constmcted using phenol-blocked trifunctional monomers in combination with 4-methylbenzyl alcohol for end capping (11). Polyurethane interpenetrating polymer networks (IPNs) are mixtures of two cross-linked polymer networks, prepared by latex blending, sequential polymerization, or simultaneous polymerization. IPNs have improved mechanical properties, as weU as thermal stabiHties, compared to the single cross-linked polymers. In pseudo-IPNs, only one of the involved polymers is cross-linked. Numerous polymers are involved in the formation of polyurethane-derived IPNs (12). 

A. Effect of Different Compositions of PU/VMCC on the Mechanical Properties of Pseudo-IPN Coatings with and without Opposite Charge Groups... 

The resulting star-like macromers with CTA were solid materials with distinct crystallinity, even at 20 and 40% HPL (Fig. 6). This suggests that even short CTA chains (i.e., DP 12) have the ability to organize into a crystalline lattice, thereby serving as pseudo-crosslinks. Depending on the chemical nature, and the molecular weight, multiphase materials result with variable mechanical properties. Above Tm of the chain segment,... 

Finally, Putz et al. in another study on PMMA and SWNT observed an increase in stiffness as measured by DMA from 0.3 to 0.38 GPa. However, this increase occurred at the extremely low volume fraetion of 8 x 10 . This corresponds to a reinforcement value of d YId V[ 960 GPa. This is close to the theoretical rule of mixtures maximum for long, well-aligned, well-graphitised nanotubes. However, it should be pointed out that this study was carried out at 100 rad s , which is a reasonably high frequency. Time-temperature equivalence of mechanical properties for visco-elastic materials suggests that this may be an over-estimate as compared with values obtained by pseudo-static measurements. ... 

However, in sharp contradistinction, the mechanical properties of the MAX phases cannot be more different than those of their binary cousins. The mechanical properties of the MAX phases are dominated by the fact that basal-plane dislocations multiply and are mobile at temperatures as low as 77 K and higher. The presence of basal slip is thus crucial to understanding their response to stress. This is true despite the fact that the number of independent slip systems is less than the five needed for ductility. In typical ceramics at room temperature, the number of independent slip systems is essentially zero. The MAX phases, thus occupy an interesting middle ground, in which in constraineddeformationmodes,highly oriented microstructures, and/or at higher temperatures they are pseudo-ductile. In unconstrained deformation, and especially in tension at lower temperatures, they behave in a brittle fashion. 

M.A. Maleque, F.Y Belal, and S.M. Sapuan, Mechanical properties study of pseudo-stem banana fiber reinforced epoxy composite. Arab. J. Sci. Eng. 32 (2B) 359-364 (2007). 

The effect on bulk mechanical properties of these physical forces and states, especially paracrystallinity and hydrogen bonding, is to pseudo-... 

D. Klempner, H. K. Yoon, K. C. Frisch, and H. L. Frisch, Polyurethane-Polyacrylate Pseudo-Interpenetrating Networks Chemical Properties of Crosslinked Polymers, in Chemistry and Properties of Crosslinked Polymers, S. S. Labana, ed.. Academic, New York (1977). SINs of urethane rubbers. Morphological and mechanical properties. Glass temperature, transitions and polymer morphology of urethane rubber/acrylic copolymer SINs. 

Elevated temperature applications require materials that can maintain good mechanical properties such as strength and hardness. Ceramics have good mechanical properties at high temperature and, thus, appear to be good candidates for elevated temperature applications. However, due to their brittle nature, monolithic ceramics are unsuitable for many applications where reliability is a critical issue. In the last few years, a new class of ceramic materials has been developed and studied. It is understood that two brittle materials can show non-brittle behavior if they are properly mixed. Fiber-reinforced ceramic matrix composites (CMCs) exhibit pseudo-plastic behavior at room temperature, as well as in an elevated temperature environment. Since the fiber and the matrix are made of ceramic material, creep behavior and hazardous emissions are reduced considerably. 

In contrast, carbon nanotubes were discovered much more recently, first observed by lijima, and since then they have been the focus of considerable research activity. This pseudo-one-dimensional form of carbon has remarkable physical and mechanical properties, such as structure-tunable electronic properties, ultrahigh thermal conductivity, and umnatched mechanical properties (e.g., stiffness, strength, and resilience). These characteristics, combined with recent advances enabling high-volume production of multi- and single-walled... 

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