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Behavioral tactic

With regard to male behavior, several recent reports have delineated the time course of maturation of male sexual response, its diel periodicity and circadian regulation, and behavioral tactics employed by males in orienting to females. As in other insects, cockroaches integrate visual and olfactory cues, but the orientation mechanisms have been little studied, especially under natural conditions. In... [Pg.230]

Poly(methacrylic acid) in the nonionized form in solution has a compact conformation and low intrinsic viscosity. Upon ionization to the polyelectrolyte form, chain expansion occurs and viscosity increases. Unlike PAA, PMAA shows inverse solubility-temperature behavior. The presence of chain-stiffening methyl groups and their added hydrophobicity are responsible for the phase and viscosity behavior. Tacticity also plays an important role. [Pg.9193]

The shortest distance between A and B is not always a straight line. Keep in mind as you consider intangible factors that you must influence behavior in order to improve companywide safety performance. Achieving this may require a combination of skills and tactics, some of which may not be directly related to explicit PSM requirements. [Pg.160]

While the study of diarylpentanes is helpful in understanding the conformational behavior of aryl vinyl polymers, a simple weighting of the properties of the model compounds by the tacticity of the polymer does not yield the properties of the polymer. For example, the presence of dl dyads surrounding a meso dyad will suppress the tt conformer in the meso dyad 14fl). Thus, in order to obtain the fraction of tt meso conformers within an atactic P2VN sample, it is necessary to resort to a Monte Carlo calculation utilizing an extended product of statistical weight matrices, 26). [Pg.58]

Earlier studies of macromolecules with flexible, non-mesogenic side-chains had revealed that the transition properties change with increasing side-chain length from typical polymeric behavior to that of the small molecule which corresponds to the side chain 72,73). With short side-chains and proper backbone geometry (tacticity),... [Pg.25]

Today, the majority of all polymeric materials is produced using the free-radical polymerization technique [11-17]. Unfortunately, however, in conventional free-radical copolymerization, control of the incorporation of monomer species into a copolymer chain is practically impossible. Furthermore, in this process, the propagating macroradicals usually attach monomeric units in a random way, governed by the relative reactivities of polymerizing comonomers. This lack of control confines the versatility of the free-radical process, because the microscopic polymer properties, such as chemical composition distribution and tacticity are key parameters that determine the macroscopic behavior of the resultant product. [Pg.8]

Differences in tacticity were also reflected by thermal data. While the iso-tropization temperature of (-)-poly-(IV-ll) and ( )-poly-(IV-ll),synthesized using initiator 1, stayed approximately unchanged, the isotropization temperatures for the chiral liquid crystalline polymers shifted to higher values when initiators 2 or 3 were used. The difference was up to 7 °C. If the decreased glass transition temperatures (Tg) for the chiral analogues were taken into account, the temperature range of the liquid crystalline phase was broadened by up to 12 °C. This means that a certain diad must be responsible for this behavior. The authors assumed that the diad cmHT was most suitable one for the formation of stable liquid crystalline phases in poly(norbornene) main chains. [Pg.56]

Whereas atactic PS is an amorphous polymer with a Tg of 100 CC, syndio-tactic PS is semicrystalline with a Tg similar to aPS and a Tm in the range 255-275 °C. The crystallization rate of sPS is comparable to that of polyethylene terephthalate). sPS exhibits a polymorphic crystalline behavior which is relevant for blend properties. In fact, it can crystallize in four main forms, a, (3, -y and 8. Several studies [8] based on FTIR, Raman and solid-state NMR spectroscopy and WAXD, led the a and (3 forms to be assigned to a trans-planar zig-zag molecular chain having a (TTTT) conformation, whereas the y and 8 forms contain a helical chain with (TTG G )2 or (G+G+TT)2 conformations. In turn, on the basis of WAXD results, the a form is said to comply with a unitary hexagonal cell [9] or with a rhombohedral cell [10]. Furthermore, two distinct modifications called a and a" were devised, and assigned to two limiting disordered and ordered forms, respectively [10]. [Pg.432]

LiOEEM (30) has an effect on the E/Z molar ratio of the enolate propagating in THF (ElZ = 11.5/88.5 instead of 0/100) but not on the chain tacticity (Table 5) ". Nevertheless, in toluene, a substantial increase in the syndiotactic fraction is observed at the expense of the isotactic one, although the chain tacticity is the same as in THF when the Ugand-to-initiator molar ratio exceeds 3 (Table 5) ". This stereochemical behavior is the signature of a single living species,whatever the solvent. [Pg.849]


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