Synthesis,polymerization, and effects on the flame retardancy of boron‐containing styrenic monomers

A boron‐containing styrenic monomer, 5‐benzyl‐2‐phenyl‐5‐(4‐vinylbenzyl)‐[1,3,2]‐dioxaborinane, was synthesized to study the influence of boron on the properties of the homopolymer and copolymer with styrene. A similar monomer without boron was also prepared and polymerized so that the properties of its polymer could be compared with the aforementioned boron‐containing polymers. These monomers were characterized by elemental analysis, mass spectrometry, Fourier transform infrared, and ¹H and ¹³C NMR. The thermal degradation of boron‐containing styrenic polymers was studied by means of Fourier transform infrared, which showed the presence of boric acid as char. The flame‐retardant effect was assessed by the measurement of the limiting oxygen indices and char yields during heating in nitrogen and air. The boron‐containing polymers had higher limiting oxygen indices and gave greater yields of char than those without boron. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem43: 6419–6430, 2005     

Non-Debye relaxation and the glass transition

A review of some long-standing problems, as well as some new theoretical results regarding non-Debye relaxation and the glass transition is given. The question of whether a phase transition below (or above) the glass transition temperature, T_g, exists is considered. The result that the glass transition temperature and jumps in the dynamic heat capacity and volume expansion coefficient can be calculated if the relevant frequency-dependent linear response functions are known makes the question of the origin of non-Debye relaxation even more important. In effective medium theories, certainly valid at high temperatures, non-Debye relaxation is apparently due to dynamic effects of interactions. At lower temperatures, energy disorder is larger compared with kT, and percolation-based theories may be more appropriate. The question as to the actual magnitude of disorder in energies cannot be conclusively resolved at this time. Certainly, it has been shown that systems exist in which non-Debye relaxation is due exclusively to disorder but, in many systems, an important component of the energy disorder is a manifestation of the influence of topological disorder on interactions. Thus, in these systems, an increase in the magnitude of dynamic interactions relative to kT accompanies the increase in the disorder. The question as to whether universal properties imply universality in the mechanism of non-Debye relaxation is explored in some depth. The present article reaches the tentative conclusion that the relative importance of ‘disorder’ and ‘interactions’ may be dependent on the type of glass considered, and possibly even on specific systems. Certainly, the relative importance of dynamic interaction effects increases as the frequency of an applied ‘force’ is reduced. If their respective influences ‘crossover’ in importance at some finite frequency, ω^*, the relevant question is whether ω^* is above, at, or below the relaxation peak frequency, ω^*. If universality exists, it relates to the role of disorder, but such a conclusion would require that ω^* ≤ _c always, the generality of which has not been established.     

Formation of spectral lines in planetary atmospheres—III. The use of analytic scattering diagrams in computations of synthetic spectra for cloudy atmospheres

In order to interpret planetary spectra formed in a cloudy atmosphere in a meaningful way, it is necessary to compute synthetic spectra from realistic models where the physical processes are accurately taken into account. Anisotropic scattering diagrams for the cloud particles must be used.     

Physiological differences between the trained and untrained speaking and singing voice

This study concerns the premier singing voice and its relationship to physiological aptitude. Research literature is reviewed that indicates that during singing the trained singer uses different physiological strategies in comparison with the untrained singer, and that the noted physiological differences (respiratory, laryngeal, articulatory) occur during singing only and not during speech. Further, a study was conducted that compared the ability of trained singers versus untrained individuals to (a) discriminate differences in self-generated air pressures and (b) produce and maintain a constant level of air pressure. No significant differences were found between the trained and untrained groups in their ability to discriminate and/or control breath pressure. Combined results of previous studies and present findings lead to the tentative conclusion that the excelled singer is not physiologically endowed and/or “gifted,” but rather has benefited from technical voice training     

Closed-form and asymptotic solutions for an interactive buckling model

Exact, closed-form, solutions to a recent interactive buckling model proposed by Budiansky and Hutchinson (1979) are presented in full for the first time. These exhibit a form of Bifurcation involving looping equilibrium paths, identified recently from topological considerations, and are put forward as evidence of its typicality. A second, related, typical form is also identified in the response of the model. The predictions of two different asymptotic approaches, the first from traditional structural mechanics and the second making use of the mathematical concept of determinacy, are compared with the exact solutions.     

Uniqueness of analytic continuation: Necessary and sufficient conditions

Necessary and sufficient conditions for uniqueness of analytic continuation are investigated for a system of m ? 1 first-order linear homogeneous partial differential equations in one unknown, with complex-valued $\text{b}$^∞ coefficients, in some connected open subset of $\text{R}$^k, k ? 2. The type of system considered is one for which there exists a real k-dimensional, $\text{b}$^∞, connected C-R submanifold M^k of $\text{C}$ⁿ, for k, n ? 2, such that the system may be identified with the induced Cauchy-Riemann operators on M^k. The question of uniqueness of analytic continuation for a system of partial differential equations is thus transformed to the question of uniqueness of analytic continuation for C-R functions on the manifold M^k ? Cⁿ. Under the assumption that the Levi algebra of M^k has constant dimension, it is shown that if the excess dimension of this algebra is maximal at every point, then M^k has the property of uniqueness of analytic continuation for its C-R functions. Conversely, under certain mild conditions, it is shown that if M^k has the property of uniqueness of analytic continuation for all $\text{b}$^∞ C-R functions, and if the Levi algebra has constant dimension on all of M^k, then the excess dimension must be maximal at every point of M^k.     

Infrared radiative transfer in planetary atmospheres—I. Effects of computational and spectroscopic economies on thermal heating/cooling rates

The availability of accurate spectroscopic data and improved knowledge of continuum absorption characteristics has required a further detailed study of i.r. radiative transfer. A sophisticated radiative transfer scheme based upon the Mayer-Goody random band model is developed and the derived transmissivities for H₂O, CO₂ and O₃ are calibrated against laboratory measurements. This calibrated scheme is used to assess the effects on calculated heating/cooling rate profiles of introducing computational and spectroscopic economies.