Application of Silsesquioxanes in the Preparation of Polyolefin-Based Materials.

This paper is a review of studies on the use of the polyhedral oligomeric silsesquioxanes (POSS) of various structures in the synthesis of polyolefins and the modification of their properties, namely: (1) components of organometallic catalytic systems for the polymerization of olefins, (2) comonomers in the copolymerization with ethylene, and (3) fillers in composites based on polyolefins. In addition, studies on the use of new silicon compounds, i.e.

Ionic Liquids as Homogeneous Catalysts for Glycerol Oligomerization.

Ionic liquids (ILs) were used for the first time as catalysts for the glycerin condensation reaction. A series of imidazolium and ammonium ionic liquids differing in the length of the alkyl substituent (C, C, and C) and the type of anion (Br, CHCOO, and NaHPO) were synthesized using a typical two-step method. The structure of the obtained ILs was confirmed by nuclear magnetic resonance C NMR, and their base power was determined on the basis of the Hammett function.

Thermal Stability and Flame Retardancy of Polypropylene Composites Containing Siloxane-Silsesquioxane Resins.

A novel group of silsesquioxane derivatives, which are siloxane-silsesquioxane resins (S4SQ), was for the first time examined as possible flame retardants in polypropylene (PP) materials. Thermal stability of the PP/S4SQ composites compared to the S4SQ resins and neat PP was estimated using thermogravimetric (TG) analysis under nitrogen and in air atmosphere. The effects of the non-functionalized and -alkyl-functionalized siloxane-silsesquioxane resins on thermostability and flame retardancy of PP materials were also evaluated by thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) and by cone calorimeter tests.

The Formation of Glycerol Oligomers with Two New Types of End Groups in the Presence of a Homogeneous Alkaline Catalyst.

The purpose of this work was to synthesize and characterize oligoglycerols with the chains of more than four repeating units. Those oligoglycerols may have some interesting applications, among others, as polyoxyalkylation starters. The glycerol oligomerization process was carried out during 12 h, at 230 °C, under the pressure of 0.

Multi-Alkenylsilsesquioxanes as Comonomers and Active Species Modifiers of Metallocene Catalyst in Copolymerization with Ethylene.

The copolymers of ethylene (E) with open-caged -butyl-substituted tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3) and phenyl-substituted tetra-alkenyl-silsesquioxane (POSS-10-4) were synthesized by copolymerization over the ansa-metallocene catalyst. The influence of the kind of silsesquioxane and of the copolymerization conditions on the reaction performance and on the properties of the copolymers was studied. In the case of copolymerization of E/POSS-6-3, the positive comonomer effect was observed, which was associated with the influence of POSS-6-3 on transformation of the bimetallic ion pair to the active catalytic species.

[Evaluation of Chirulen biopolymer properties based on molecular and super-molecular structure changes caused by plastic strain and radiation sterilization].

The paper presents an analysis of the effect of plastic strain and sterilization treatment by an electron beam as well as the joint effect of both of the two external factors on the change of molecular and supermolecular characteristics of the Chirulen biopolymer which is used for the production of Weller endoprosthesis cups. It has been shown how, due to these influences, the weighted mean molar mass, differentiation of macromolecule sizes, crystalline phase fraction and the degree of order of polymer internal structure are changing. In terms of such changes the effects on the cup material are presented connected with hardness, the modulus of elasticity and polymer susceptibility to undurable deformations.