A Linear Theory of Porous Elastic Solids

The theory of porous elastic solids with large vacuous interstices, considered by Giovine like materials with ellipsoidal structure, includes, as a particular case, the nonlinear theory of Nunziato and Cowin of elastic materials with small spherical voids finely dispersed in the matrix.In this paper we propose appropriate constitutive relations and then specialize the basic balance equations of Giovine to the linear theory. Also, generalizing the developments of Cowin and Nunziato, we formulate boundary-initial-value problems and examine classical applications as responses to homogeneous deformations and small-amplitude acoustic waves.     

Chemoselectivity in 4-methyl-1,3-pentadiene polymerization in the presence of homogeneous Ti-based catalysts

The homogeneous catalyst CpTiCl₃-MAO is able to produce a random copolymer of 4-methyl-1,3-pentadiene with ethylene. ¹³C NMR analysis of the copolymers shows that after insertion of ethylene units, the next 4-ymethyl-1,3-pentadiene unit can be inserted in either 1,2 or 1,4 arrangement. The high chemoselectivity observed in the 1,2-syndiotactic homopolymerization of 4-methyl-1,3-pentadiene with respect to the lower one observed in the copolymerization with ethylene is attributed to a back-biting coordination to the Ti of the active species of the penultimate monomer unit of the growing chain.     

Redox Materials by the Covalent Entrapment of Redox‐Active Dirhodium(II,II) Species in a Siloxane Network

Summary: Hydrolysis and polycondensation of the coupling agent (aminopropyl)triethoxysilane (APS), axially coordinated to the redox‐active complex [Rh₂(form)₂(CH₃COO)₂(APS)₂], lead to the insertion of redox‐active inorganic microdomains into a siloxane network; the new polymers undergo cyclic redox reactions indicating that dirhodium(II ,II ) centres retain their redox activity even when incorporated into siloxane networks.

The redox‐active complex [Rh₂(form)₂(CH₃COO)₂(APS)₂] (form = N,N′‐di‐p‐tolylformamidinate) incorporated into a siloxane network here.     

Synthesis and characterization of novel poly(arylene ether)s containing 1,3,4-oxadiazole units

Starting from some new 2,5-disubstituted-1,3,4-oxadiazole difluorides, synthesized by cyclocondensation of dihydrazides with 4-fluorobenzoic acid, novel poly(arylene ether)s were prepared by halo displacement polymerizations with bisphenol A in the presence of potassium carbonate. Model reactions demonstrated the unsuitableness for halo displacement reactions of the difluoride containing the SO₂ group. The synthesis and characterization of polymers are discussed and the thermal properties are compared with those of other polymers reported in literature.     

Experimental and mechanistic study of the bromomalonic acid/bromate oscillating system catalyzed by [Fe(phen)3]2+

The oscillatory behavior of a [Fe(phen)₃]²⁺ -catalyzed/bromomalonic acid/acidic bromate Belousov–Zhabotinsky system in aerated batch conditions has been reinvestigated. An 18-step skeleton mechanism is proposed. Reactions involving oxygen in the aqueous phase as well as reactions involving organic radicals are included in the skeleton mechanism. The numerical treatment of the corresponding differential equations leads to simulated behaviors in satisfactory agreement with the experimental ones. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 291–300, 1998.     

Alkyl-substituted poly(2,5-benzophenone)s synthesized via Ni(0)-catalyzed coupling of aromatic dichlorides and their miscible blends

High molecular weight poly(2,5-benzophenone) derivatives were prepared by Ni(0)-catalyzed coupling of 4′-substituted 2,5-dichlorobenzophenones. Monomers were synthesized by the Friedel–Crafts reaction of 2,5-dichlorobenzoyl chloride and alkyl-substituted benzenes in the presence of aluminum chloride. The resulting polymers are soluble and show no evidence of crystallinity by DSC. Number average molecular weights are in the range of 9.2 × 10³–11.7 × 10³ g/mol by multiple angle laser light scattering (MALLS). Molecular weights obtained by MALLS are only slightly lower (∼90%) than those obtained by GPC (polystyrene standards). These polymers exhibit high thermal stability with glass transition temperatures ranging from 173 to 225°C and weight loss occurring above 450°C in nitrogen and 430°C in air. Additionally, the polymers were blended and the resulting polymer films appear to be miscible by DSC results. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2611–2618, 1998     

Quantile composite-based path modeling: algorithms,properties and applications

Advances in Data Analysis and Classification - Composite-based path modeling aims to study the relationships among a set of constructs, that is a representation of theoretical concepts. Such...