Monika Dobrzyńska-Mizera

Thermal Stability and Flammability of Polypropylene-Silsesquioxane Nanocomposites

This article presents a study of the thermal stability of polypropylene-based nanocomposites filled with tetrasilanolphenyl silsesquioxane (phPOSS). Nanofillers were introduced into a polypropylene matrix in three different amounts: 2, 5, and 10 wt.%. Investigations were carried out by means of thermogravimetric analyses conducted in inert and oxidizing atmospheres, Fourier transform-infrared spectroscopy, scanning electron microscopy, and flammability UL-94 test. The addition of phPOSS into the polymeric matrix increased thermal stability in comparison to neat iPP and introduced significant changes in the flammability of iPP/phPOSS nanocomposites.

Synthesis and Influence of Sodium Benzoate Silsesquioxane Based Nucleating Agent on Thermal and Mechanical Properties of Isotactic Polypropylene

Novel sodium benzoate modified silsesquioxane (nbPOSS) for isotactic polypropylene modification was synthesized and characterized. The influence of the novel silsesqioxane based nucleating agent on mechanical and thermal properties of commercial isotactic polypropylene was observed and compared with sodium benzoate. The mechanical investigations revealed changes in polymeric structure indicating that nucleating process had occurred. Synthetic route of 1-(3-benzoyloxypropyl)-3,5,7,9,11,13,15-hepta(isobutyl)pentacyclo-[9.5.1.13,9.15,15.17,13]octasiloxane and its characterization were presented.

Interfacial enhancement of polypropylene composites modified with sorbitol derivatives and siloxane-silsesquioxane resin

Composites based on polypropylene (iPP) modified with a sorbitol derivative (NX8000) and siloxane-silsesquioxane resin (SiOPh) containing maleated polypropylene (MAPP) as compatibilizer were prepared by melt extrusion. Calorimetric investigations were carried out using differential scanning calorimetry (DSC), whereas the morphological and mechanical properties were investigated by scanning electron microscopy (SEM) and static tensile tests. DSC measurements revealed no influence of SiOPh and a slight effect of MAPP addition on the crystallization kinetics of polypropylene. Additionally, the introduction of MAPP into the iPP+NX8000+SiOPh composites increased plastic properties of the samples. All the above was attributed to the compatibilizing effect of MAPP which improved interfacial adhesion between iPP, NX8000 and SiOPh. This phenomenon was also confirmed by the SEM images illustrating more homogenous distribution of the filler in the compatibilized samples.

Influence of heterogeneous nucleation on thermodynamic properties of isotactic polypropylene

Abstract In this paper we have investigated the effect of 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol sorbitol used in varying amounts (0.01 - 1 wt %) on isotactic polypropylene (iPP) matrix. We have used dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) to study glass transition temperatures and crystallinity as a function of the nucleating agent concentration. Isotactic polypropylene samples showed a strong dependency on amount of α nucleating agent used. An increasing content of sorbitol based nucleating agent led to an increase of crystallization temperature upon cooling from the melt at constant rate and a decrease of the glass transition temperatures.

Physico-chemical evaluation of hydrophobically modified pectin derivatives: Step toward application

Abstract Present study reports synthesis and physico-chemical evaluation of hydrophobically modified pectin derivatives, obtained by reacting of pectin with di-acyl chlorides (glutaryl and sebacoyl chloride). Depending on length of the inserted carbon chains, the acylation resulted in possible formation of mono-grafted (isolated chains) and bi-grafted (chemical gels) structures. The structural features of obtained derivatives were investigated using FTIR spectroscopy, confirming the successful synthesis. The concentrated aqueous solutions of modified pectin showed interesting rheological properties, having lower values of apparent viscosity compared to neat pectin. Since the GPC analysis indicated that no degradation occurred, the viscosity decrease was explained by more heterogeneous organization within modified pectin solutions (microparticles together with sticky polymer entanglement). A shift in particle size distribution proved that proposed modifications also affected pectin solution properties in diluted regime. The modified samples turned to be more sensible to thermal degradation than neat pectin, whereby the increasing size of flexible acyl chains attached to a polymer backbone reduced the glass transition temperature. The hydrophobicity of obtained derivatives was evaluated by sessile drop and du Nouy ring methods. It was found that acylation enhanced hydrophobicity of the pectin molecule, while hydrophobically associative character turned to be inconsistent in aqueous and non-aqueous environment.