Krzysztof Strzelec

The use of rye, oat and triticale straw as fillers of natural rubber composites

Up to date, there are no evident research works carried out to improve and verify the physical, mechanical, barrier and damping properties of bioelastomer composites with addition of straw. Moreover, the problem of improving the reuse of straw is now demanding attention in the major cereal-growing areas of the world. The aim of this study was to receive knowledge of characteristic and producing multifunctional elastomer biocomposite filled with straw. Rye, oat and triticale were found to be active fillers improving wide range of rubber composites functional properties like: static mechanical, damping, barrier properties and hardness. The use of straw as a filler also increased cross-linking density. Dynamic-mechanical analysis indicates the presence of strongly developed secondary structure of examined fillers in vulcanizates. Moreover, all of the vulcanizates proved to be resistant to thermo-oxidative degradation. The application of straw as a filler allowed obtaining composites with lower value of oxygen index, that reflecting higher tendency of smoke generation. Introducing the straw into polymer matrix reduced the manufacturing costs of composites through the use of a significant amount of inexpensive and renewable filler. Furthermore straw fillers modify natural rubber, obtaining high-performance materials with meaningly enhanced applications.

Influence of lignocellulose fillers on properties natural rubber composites

The present article presents unreported yet in the subject literature examinations of the effect of a lignocellulose filler obtained from an alkalized wheat straw treated with di-potassium phosphate on the properties of natural rubber composites. The thermal and mechanical properties as well as the fire hazard of the composites obtained were tested also in the presence of an additive flame-retardant compound (poly(ammonium phosphate)), exploiting the synergism of its action with pentaerythritol, antimony trioxide, aluminum hydroxide and zinc borate. Based on the results obtained by the methods of thermal and mechanical analyses, micro-calorimetry and cone calorimetry, it has been found that the bio-filler increases, especially in the presence of additive flame-retardant, the resistance of the bio-composites tested to the action of fire, without a significant deterioration in their mechanical properties.

Novel biocompatible transversal pneumatic artificial muscles made of PDMS/PET satin composite

Abstract In this study novel transversal pneumatic artificial muscles (TPAM), made from composite – poly(dimethylsiloxane) (PDMS) matrix membrane and poly(ethylene terephthalate) (PET) satin reinforcement, are presented. Miniature TPAM consists of a flexible internal braid (IB) reinforcing the membrane and the external braid (EB). EB, with fibers arranged transversely to the IB, is placed laterally. Differently prepared TPAMs were tested for their effectiveness as actuators for robot drive and the PDMS/PET composite suitability was evaluated for applications in human gastrointestinal tract (chemical resistance, thermal characteristic). FT-IR spectra of the composite were compared for study PDMS impregnation process of PET satin and effect of immersion in selected solution. The composite shows outstanding biocompatibility and the muscles have competitive static load characteristics in comparison with other pneumatic artificial muscles (PAM). These results lead to believe, that in the near future painless examination of the gastrointestinal tract using a secure robot will be possible.

Hydrogenation of cinnamaldehyde over supported palladium catalysts

Abstract The selective hydrogenation of cinnamaldehyde has been studied using palladium catalysts based on epoxy resin cured with ionic liquids. Characterization of palladium catalysts has involved the following methods: IR spectroscopy, X-ray photoelectron spectroscopy (XPS), AAS spectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The investigated catalysts showed high stability and good recycling efficiency what makes them useful for a prolonged use. The factors influencing the selectivity of the supported catalysts were discussed.

Recycable complex catalysts immobilized on mercaptan-functionalized glass-polymer supports

The use of the mercaptan-functionalized bisphenol A diglycidyl ether epoxy (base material) encapsulated on glass core as matrices for metal catalysts was investigated. Here, the acquiring knowledge of recyclable palladium catalysts for organic reaction which can be mechanically separated from the reaction media and next use as a heterogeneous catalyst in large-scale industries was the most important goal. Homogeneous Pd precursor [PdCl2(PhCN)2] has been heterogenized by attaching to prepared glass-polymeric supports via ligand exchange process. Collected research results indicate that mercaptans used to cure epoxy resin can greatly affect the catalytic properties of the epoxy resin with supported palladium catalyst. The epoxy system modified with mercaptans has a few possible catalytic coordination centers especially oxygen and sulfur to which the palladium ion can be bound. It should be noted that although various concentrations of palladium complex were used, the amount of metal attached to epoxide supports remained the same, that is below the sorption capacity of the polymers. Presented new type of glass-polymer supports comparing to other used corresponding organic carriers offers several practical advantages such as morphological and chemical structure of the matrix, which affect the properties of the heterogenized catalyst in the selected organic reactions: Heck reaction and hydrogenation reaction were investigated. The catalytic activity of all formulated systems was similar to homogeneous palladium precursor PdCl2(PhCN)2. The resulting glass-polymeric matrices and heterogenized palladium catalysts were characterized by varied research techniques such as surface analysis technique (ToF–SIMS) and scanning electron microscopy with energy-dispersive X-ray analyzer (SEM-EDX). We used likewise the atomic absorption spectroscopy (AAS) method to quantify the amount of palladium loaded in the recyclable support and also the BET method to determine specific pore size distribution parameters. Furthermore, XPS spectroscopy showed information about surface structure and chemical states in the palladium-supported catalysts.

POSS as promoters of self-healing process in silicone composites

AbstractThis article focuses on the methods used to create self-healing silicone composites. It has been shown how incorporation of polyhedral oligomeric silsesquioxanes (POSS) molecules with acid and basic groups into silicone rubber affects the barrier properties, mechanical properties in room temperature or the influences on relaxation rates of the methylvinylsilicone rubber vulcanizates. Moreover, the presence of silsesquioxanes, their content and the way of composites preparation affect the amount of ionic bonds, as indicated by measurements of equilibrium swelling in toluene. The self-healing effect of preparing samples is best visualized by SEM images of samples after destruction and conditioning. Composites presented in this work based on the methylvinylsilicone rubber with fumed silica as the fillers were manufactured and studied. To obtain self-healing effect, various silsesquioxanes were used, such as amic acid-isobutyl POSS (AAIb-POSS), aminopropylisobutyl-POSS (APIb-POSS) and aminoethylaminopropylisobutyl-POSS (AEAPIb-POSS). Every tested sample demonstrated the ability to the self-treatment. The most significant effect was observed for system containing amic acid-isobutyl POSS/aminopropylisobutyl-POSS.

Natural Rubber Composites Filled with Cereals Straw Modified with Acetic and Maleic Anhydride: Preparation and Properties

This research paper aims to provide an examinations on biocomposites based on natural rubber (NR), natural straw fibers as well as their production techniques and properties. After pre-alkalization of the fillers, two main modification methods were carried out, with the usage of acetic or maleic anhydride to improve the adhesion of the fibers to the elastomeric matrix. Firstly, physicochemical characterization of straw particles, both pure and modified, using scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transmission infrared spectroscopy (FTIR) was performed. Moreover full characterization of the produced composites was also executed, which included: rheogical properties, static and dynamic mechanical properties, crosslinking density, damping properties, tear strength and resistance to simulated aging processes. Increased adhesion between modified straw fibers and the elastomeric matrix was observed for 10 phr filled composites, which was confirmed by dynamic mechanical thermal analysis (DMTA). In addition, the impact of the applied modifications was confirmed by higher values of the Payne effect, which resulted from the presence of developed secondary structure of the filler in vulcanizates. Furthermore, the crosslinking density of composites increased, which was reflected in the improvement of tensile properties, determined by tensile and tear strength and relative damping.

Silanized cereal straw as a novel, functional filler of natural rubber biocomposites

The aim of the presented research paper was to modify the biofiller in the form of milled cereal straw with 3-aminopropyl(diethoxy)methyl silane, and apply it to the natural rubber. To determine the material properties, an in-depth characterization of both the treated lignocellulosic material and the composites was studied. On the basis of thermogravimetric analysis, scanning electron microscopy, infrared spectroscopy and analysis of contact angle measurements, it was found that the silanization process significantly influenced thermal stability and hygroscopicity of the straw, its hydrophobicity as well as dispersion in polymeric matrix. Analyses of the new composites included static and dynamic mechanical properties, hardness, and barrier and damping properties, all of which showed improvement. This was because of improved interactions at the filler–elastomer, which resulted from better adhesion of the treated bio-additive to natural rubber. Biocomposites have also demonstrated greater resistance to flammability as well as thermo-oxidative aging processes. The research clearly indicates the application potential of these new multifunctional and biocompatible materials.Graphical abstract