This study examined how hydrophobic and hydrophilic nanofiller surface functionalization affects the mechanical and thermal properties of crosslinked liquid silicone rubbers. For this purpose, siloxane networks were prepared from poly(methyl-hydrogen siloxane) and divinyl poly(dimethylsiloxane) with a ratio of 60/40; 50/50, and 40/60 with the addition of different contents of hydrophobic and hydrophilic silicon(IV)oxide nanoparticles (1, 5, and 20 wt.

In this research, hybrid materials based on aliphatic polyurethanes and hydrophilic aluminum(III) oxide nanoparticles were synthesized. From an environmental point of view, synthesized hybrid materials represent significant engineering materials because the products of their thermal degradation are significantly less toxic compared to the products of thermal decomposition of polyurethane, for which production aromatic isocyanates are used. The presence of uniformly distributed Al2O3 nanoparticles in the sample containing 0.5 wt. % of inorganic filler influenced the additional formation of hydrogen bonds, as well as the improvement of the mechanical properties of the obtained polyurethane hybrid materials. Good mechanical properties, together with appropriate properties of thermal stability, allow the obtained hybrid materials based on aliphatic polyurethanes and Al2O3 inorganic filler to be used in the automotive industry (hydraulic seals, protective films), furniture and in the production of sports equipment.

A series of polyurethanes (PU) were synthesised via one-step polymerisation without a chain extender, using toluene diisocyanate as well as a variety of soft segments composed of different macrodiols. Poly(D,L-lactide) (PDLLA) and polycaprolactone diol (PCL) were synthesised as a polyester type polyols to obtain soft segments. The process of varying the molar ratio of newly synthesised PDLLA in soft segments has been confirmed as a powerful tool for fine-tuning the final properties of PU. Fourier-transformed infrared spectroscopy was used for evaluation of molecular structures of synthesised PDLLA polyol and final PU. Nuclear magnetic resonance spectrometry was used to confirm the presumed structure of PU. The influence of soft segment composition on polyurethane thermal characteristics was examined using thermogravimetric analysis and differential scanning calorimetry. The composition of soft segments had little impact on the thermal stability of PU materials, which is explained by the comparable structures of both polyester polyols. Wide-angle X-ray scattering was utilised to evaluate the effect of amorphous PDLLA on the degree of crystallinity of PCL in soft PU segments. It was discovered that not only did the PDLLA ratio in the soft segment have a substantial influence on the degree of microphase separation in the soft and hard segments, but it also influenced the crystallisation behaviour of the materials. Furthermore, the restriction of crystallisation of the PCL soft segment has been verified to be dependent on the hard segment concentration and the ratio of PDLLA/PCL polyols. The sample with pure PCL as the polyol component achieved the highest degree of crystallinity (34.8%). The results demonstrated that the composition of soft segments directly affected the properties of obtained polyurethane films. These results can be utilised to easily achieve a desirable set of properties required for application in biomaterials.

In modern hydrogel science, it is necessary to understand the properties of hydrogels related to their structure. Hydrogels generally differ in functions according to the specific needs of particular applications. Improvements in understanding the hydrogel structure are of great importance for their potential use. Hydrogels as a hydrophilic three-dimensional polymer network can be chemically or physically crosslinked and formed into almost any size and architecture. This chapter deals with different aspects of hydrogel architecture, which are crucial for their application. Hydrogels are classified according to the origin, composition, and structure of the polymer network, pore size, and type of crosslinking. From the structural point of view, the architecture of the polymer network has two levels of organization: molecular and supramolecular. The architecture of hydrogels is determined by measurable properties such as pore size, mesh size, and crosslinking density.

In addition to potentially resolving environmental issues that come from plastic and food waste, active biodegradable packaging is being developed to increase the shelf life, quality, and safety of packaged food. In order to overcome the drawbacks of monolayer hydrocolloid-based coating, such as poor mechanical and barrier properties, the design of bilayer hydrocolloid-based coating has been structured using pullulan and gelatin. Sugar alcohols are widely used for the plasticizing of biopolymer-based films. The aim of this work is to investigate the influence of different sugar alcohols – xylitol, mannitol, and glycerol on the mechanical properties of pullulan/gelatin bilayer films. Among investigated plasticizers, glycerol has demonstrated the best plasticizing effect, giving a bilayer film with the value of elongation at break which is 66.5 and 88.4% greater than the same values for the bilayer films prepared using xylitol and mannitol. The formulation with glycerol has been applied for the preparation of active edible coating using the mixture of two hydrolats – lemongrass and curry plant. Obtained coatings have shown great potential for the improvement of packaged cheese shelf-life.

An active packaging based on the composite film was developed by incorporation of oregano oil as an antimicrobial agent into a cellulose acetate/polycaprolactone diol blend (CA/PCL-diol). A novel plasticizer based on polyethylene terephthalate (PET) glycolysis product (bis(hydroxyethyl terephthalate)) and tartaric acid was synthesized and its influence on the structural, surface, mechanical, barrier, and thermal properties were investigated. The obtained results have shown that plasticizer also has a compatibilizing effect, improving the miscibility of polymers in a blend. A sample with the optimal amount of plasticizer (30 wt%), as well as the best mechanical and barrier properties, was used for the preparation of series with different amounts of oregano oil (3, 6, and 9 wt%). The synthesized azo dye—5-(4-bromo-phenyl azo)-3-amido-6-hydroxy-4-methyl-2-pyridone, soluble in acetone, as well as a blend and plasticizer, has been shown as an adequate one for this composition, due to its ability to achieve a good pigmentation in a low amount (0.3 wt% per polymer blend weight), to absorb UV light, and decrease the aging of the material. Contemporary lifestyle has imposed a need for ready-to-eat (RTE) meals which saves consumers time. RTE food packaging should meet certain requirements such as the ability to prolong shelf-life and preserve the freshness of the food product, and at the same time to make a minimal amount of waste after usage, considering the fact that it is mostly single-use plastic food packaging. Optimal mechanical properties, biodegradability, and additional functions make these films suitable for the packaging of ready-to-eat (RTE) food such as fresh salad.

Nanocomposites based on siloxane and silicon(IV)oxide nanoparticles (with a hydrophilic and hydrophobic surface) were synthesized to design the desired final properties of the composite material. Masterbatch, a mixture of siloxane containing vinyl functional groups and reinforcing fillers, was added to improve the mechanical properties and topology of siloxane networks. Silicon(IV)oxide was added in amounts of 1, 5, 10, and 20 wt% and masterbatch in amounts of 5 and 10 wt% to examine the effect of the amounts of fillers and masterbatch in the synthesized samples. Fourier transform infrared spectroscopy was used to analyze the chemical structure of the obtained materials. Transmission electron microscopy (TEM) was used to examine the dispersion of filler particles in siloxane nanocomposites. To examine the thermal stability and phase transition temperature of siloxane materials, thermogravimetric analyzes (TGA) and differential scanning calorimetry (DSC) were performed. The addition of masterbatch did not lead to a significant difference in melting temperature, but stoichiometry was disturbed, which decreased the thermal stability compared to samples without masterbatch. The addition of masterbatch to nanocomposites with hydrophilic fillers increases both elongations at break and tensile strength. According to the results, the combination of masterbatch and nanofillers affects the properties of siloxane materials, which could enable obtaining materials with the desired properties.

Addition of poly(diallyldimethylammonium chloride) (PDDA) on the performances of urea-formaldehyde (UF) adhesives was evaluated in this work. Three types of UF adhesives were prepared, one without PDDA addition, and two types with PDDA addition of 1 and 3 wt.% per dry UF adhesive mass. These UF adhesive systems were used for producing experimental particleboard panels. The addition of PDDA decreased the thickness swelling of the panel samples, while the internal bond of the particleboards increased significantly only at the highest PDDA content (3 wt.%). Differential scanning calorimetry (DSC) was applied to address the influence of PDDA on UF adhesive curing kinetics. DSC scans were performed in non-isothermal regimes using different heating rates (5, 10, and 20 ?C?min?1). The activation energy (Ea) of the curing reaction showed slightly lower values for the UF adhesive systems containing PDDA. However, the peak temperatures and enthalpy of reaction did not change significantly. The Kissinger-Akahira-Sunose and Friedman iso-conversional methods were applied to investigate the effects of PDDA addition on the UF adhesive curing process.

The packaging industry is highly dependent on fossil resources and have serious environmental drawbacks. The largest part of the total volume of plastic waste is generated from food packaging, so new packaging strategies with green materials are required. Using the edible packaging films which are renewable, biodegradable and versatile, can reduce the amount of plastic waste. Also, there is an increasing demand of higher quality foods and a growing interest from consumers for minimally processed fresh-like foods with an extended shelf life. Edible films can be effective barriers which prevent unwanted mass transfers in foods. They can be green alternative to synthetic petroleum-based polymer packaging materials and nowadays this topic is a fast-growing area. Sodium alginate as a natural polysaccharide can be used for edible films with excellent properties such as transparency. But, sodium alginate practical applications in food packaging are limited as single-component because of poor mechanical and barrier properties. At the same time, pullulan is an extracellular and water-soluble microbial polysaccharide with good film-formation properties. The packaging materials made from pullulan and alginate may be better candidates for edible packaging films. The objective of this study was to formulate pullulan and sodium alginate based edible films for food packaging. For that purpose a series of pullulan/alginate films with different ratios were prepared. To improve film flexibility and processability, glycerol was added as plasticizers in the film formulation. Designed films were solvent cast from aqueous polymer solution. Understanding the film-forming mechanism during the drying process is crucial to predict properties of the obtained films, so rheological properties of prepared solutions were investigated. Formulated films have the potential to be used as inner primary packaging and can be manufactured by preparing a film-forming composition and enclosing a food product with the film. Using this kind of packaging material, no waste is generated contributing to the circular economy.

Biodegradable active packaging films based on a cellulose acetate and poly(caprolactone diol) blend with incorporated lemongrass oil were developed. Films were prepared using a novel bio-based plasticizer, glycerol tritartarate, synthesized using the principles of green chemistry. The influence of the plasticizer, as well as the essential oil amount, on the structural, surface, mechanical, and thermal properties of the blend was investigated. The plasticizer was shown to work as a compatibilizer for two polymers, according to the results of scanning electron microscopy and surface energy analysis. Blends with a greater amount of plasticizer possessed better mechanical properties but showed worse resistance to water. The antimicrobial property of the blend with lemongrass oil was found to be superior to that of the blend without essential oil. The incorporation of lemongrass oil into the polymer blend resulted in one more step longer thermal degradation process. The optimal film properties, biodegradability, cost-effective preparation method, and additional functions made these films suitable for the production of packaging for grapefruit.

The scientific studies on drug delivery systems that transport drugs to the targeted tissues, at a certain rate and desired time intervals, have gained popularity. The main goal of the drug delivery and release systems is to maintain the drug level in the blood plasma by balancing the amount of active ingredient. In this study, pH and temperature sensitive drug carriers were prepared using chitosan as a biopolymer and clay as a natural material. The characterization of the prepared materials was performed for structural analysis by FT-IR and for morphological analysis by SEM instruments. The swelling properties of the prepared materials were investigated. In this work, Ranitidine-HCl was used as a model drug. The prepared drug carriers were first loaded with Ranitidine-HCl and release properties of the materials were investigated at two different temperatures (25oC, 37oC) and various pH medium. The data obtained from the experiments indicated that the maximum release of Ranitidine–HCl from the prepared sample was observed at pH=7,6 buffer solution at both temperatures by comparing buffer solutions. It has been shown that the materials prepared in this study are suitable carriers for the Ranitidine-HCl drug active ingredient.

Chitosan based hydrogel was synthesized via free-radical polymerization in a two-step procedure, after modification of chitosan by acrylic acid. Dynamic swelling test was carried out in distilled water at room temperature. Swelling kinetics was modeling using the principle of assuming the equation for a swelling ratio-time empirical dependence. Using regression analysis in this way gives the possibility for simpler determination of swelling ratio-time empirical dependence, knowing the graph functions. Obtained hydrogel was used for preparation of new bilayer hydrogel system which has potential application in wound dressing systems and other fields where pH sensitivity and improved mechanical properties of biopolymers are required in framework of green, cost-effective process.

The main aim of this work was to obtain conductive polymer-based materials by incorporation of different amounts of multiwalled carbon nanotubes (MWCNTs) into poly(lactide)(PLA) using the electrospinning technique. Fiber-based nonwovens with 0.2, 0.5, 1, and 3 wt% of MWCNTs were characterized regarding conductivity, morphology, thermal, and mechanical properties. It was confirmed that an increase of the MWCNTs content does not influence the increase of the material conductivity, since the conductivity was 170 ohm sq−1 for all composites. Scanning electron microscopy and transmission electron microscopy analyses revealed that smooth and beadless fibers were obtained, but also average diameters of composite nanofibers decreased with the increase of the MWCNTs content. Differential scanning calorimetry analysis showed that the presence of MWCNTs in the PLA matrix had a significant influence on the crystallization behavior of PLA nanofibers, because the decrease in crystallization temperature ( Tc) was detected. Also, the incorporation of MWCNTs into PLA fibers affected the melting process, enabling the generation of α′ form, while had no influence on ordered α crystal. The enthalpy of composite degradation decreased, because MWCNTs are well-known for good heat conductivity, and with that the second step of degradation slowed down, as it was confirmed by thermogravimetric analysis. The addition of MWCNTs improved mechanical properties of composite fibers and caused the increase of both elasticity and tensile strengths of nanofibers.

In this study, the influence of nanosilicon(IV)-oxide (with hydrophobic and hydrophilic functionalized surfaces) on the properties of siloxane elastomers was studied. The elastomers were prepared from vinyl and hydrogen oligosiloxanes, while the nanocomposites were obtained by addition of nanofillers at different concentrations (1, 5, 10 and 20 wt%). The chemical structure of the obtained materials was analyzed by Fourier transform infrared spectroscopy. Transmission electron microscopy confirmed good dispersion of the hydrophobic filler within the polymer matrix, while the hydrophilic filler formed a net on the siloxane sample. Type of the filler modification did not affect hardness of the siloxane hybrid materials, while the samples with the highest content of hydrophobic nanosilica have shown the highest value of tensile strength. Influence of the nanosilica type on thermal degradation of elastomeric materials was investigated by using thermogravimetric analysis, while the influence of the fillers on the phase transition temperature was analyzed by differential scanning calorimetry. Lower compatibility of the hydrophobic matrix and hydrophilic filler caused a decrease in the crystalline melting temperature with the lowest value determined for the sample with the highest filler loading. Increase in the nanofiller content resulted in the improved thermal stability of the obtained hybrid materials.

Mikroporozni elastomeri predstavljaju prostorno umrežene makromolekule sa izraženom ćelijskom strukturom. Količine izabranih komponenti umrežavajuće smese određuju eksploataciona svojstva ovih materijala. Za specifične primene elastomera neophodno je ostvariti željeni nivo umreženja kao i gustinu materijala. U ovom radu ispitan je uticaj sadržaja sredstva za ekspandiranje na svojstva mikroporoznih materijala na osnovu terpolimera poli-(etilen-ko-propilen-ko-2-etiliden-5-norbornen) kaučuka (EPDM)umreženih sumporom i ojačanih česticama čađi. Variran je sadržaj sredstva za ekspandiranje (1,3; 1,8 i 2,0 phr). Ustanovljeno je da su dobijeni elastomerni materijali pogodni za primenu u oblasti proizvodnje zaptivnih profila za potrebe automobilske industrije.

For the preparation of elastomer materials, besides the rubber and cross-linking system, a lot of additives are used, in order to improve the physical-mechanical properties, reduce the costs and achieve particular properties of the final material. The amounts of cross-linking compound components, determine the exploitation properties of elastomer materials. Micro-porous elastomer materials are cross-linked macro-molecules with a cellular structure formed using blowing agents which form cells by releasing gases at higher temperatures. The most important properties of micro-porous elastomers are low density, excellent damping properties, owing to the cellular structure, as well as high strength versus mass. In this work, the influence of the blowing agent content on the physical-mechanical properties of micro-porous elastomers based on terpolymer poly(ethylene-co-propylene-co-2-ethylidene-5-norbornene) rubber (EPDM) cross-linked with sulfur and reinforced with carbon black particles, was investigated. The content of a chemical blowing agent (oxybis(benzenesulphonyl hydrazide)) was varied (1.3; 1.8 and 2.0 phr). Based on rheological measurements, the rubber compound curing behavior was determined. The density of the final materials shows significant differences depending on the blowing agent content in the prepared samples. It was assessed that prepared cellular elastomer materials are suitable for use in the fabrication of sealing profiles the automotive industry. The obtained elastomers with lower density can be used for the profile seals, as for, static parts that are not exposed to tangential impacts, while for the micro-porous seals of movable parts, higher density elastomers can be used.

Damping materials have been widely used in the vibration and noise control to reduce their harmful consequences in different areas such as their application in the drilling equipment, aerospace and naval vessels, transportation vehicles, bridges and high buildings. Because of severe environmental standards, the oil fabrication is developing synthetic environmentally friendly drilling fluids. For a vehicle, applications are produced: the outer and inner beltline seals and the glass run channel. The compression set is the important characteristic of elastomeric sealing materials as spontaneous stress release during application due to the internal pressure or external forces variations. The temperature and frequency-insensitive damping are of significance for industrial uses. Elastomeric hybrid materials based on terpolymers as network precursor are very common for sealants fabrication. The focus of this work was to prepare oil-extended elastomeric hybrid materials based on ethylenepropylene-diene monomer rubber (EPDM), ground calcium carbonate and furnace nano carbon black. Cure characteristics were carried out on oscillating disc rheometer. The crosslinking of rubber compounds was performed in a molding press. The compression set was assessed using the standard procedure. The morphology of the cryogenically fractured surface of samples with different content of paraffin oil was characterized by scanning electron microscopy (SEM). Mechanical properties and hardness were analyzed before and after the aging of obtained samples. Damping properties of prepared materials were determined using bending mode. The loss tangent, tan δ, was used as a measure of vibration energy dissipation.

This paper presents influence of the type of carbon nanotube functionalization on properties of poly(L-lactide) (PLLA) based nanocomposite materials. For this purpose surface modifications of multi-walled carbon nanotubes (MWCNTs) were performed by chemical and irradiation techniques, while thermo gravimetric analysis, UV-Visible and Fourier-transform infrared (FT-IR) spectroscopies confirmed successful covalent functionalization. Series of PLLA bionanocomposites with different contents of functionalized MWCNTs (0.7; 1.6; 2.1 wt%), were synthesized via ring-opening solution polymerisation of L-lactide. FT-IR analysis confirmed that grafting of L-lactide, under controlled condition, is possible to perform starting from the surface of functionalized MWCNTs. From differential scanning calorimetry results it was concluded that even low contents of chemically and irradiation functionalized MWCNTs had a significant effect on thermal properties of the prepared nanocomposites, raising the values of melting and glass transition temperatures. Thermogravimetric analysis (TGA) has shown that the degradation onset temperature for composites with chemically functionalized MWCNTs, was much higher than that for the neat poly(L-lactide) sample and composites with irradiation functionalized MWCNTs. Morphology studies by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that poly(L-lactide) covered surfaces and separated functionalized MWCNTs. Good dispersion of carbon nanotubes in polymer matrix enabled conductivity of synthesized materials, as determined by conductivity tests.

Hirurški konci su niti materijala namenjeni za ušivanje oštećenog tkiva (rana) ilipodvezivanje (ligiranje) krvnih sudova. U ovom radu proučavana su mehaničkasvojstva hirurških konaca dobijenih od različitih tipova polimernih materijala.Prikazani su i tehnološki postupci dobijanja osnovnih vlakana za proizvodnjuhirurških konca. Analizirani su uzorci: monofilamentnih neresorptivnih konaca (naosnovu poliamida, polipropilena, politetrafluoretilena i polivinilfluorida),multifilamentnih konaca (na osnovu poliamida, svile i poliestera), resorptivnihmultifilamentnih hirurških konaca (na osnovu poliglikolne kiseline i poliglikonata) iresorptivnih monofilamentnih hirurških konaca na osnovu polidioksanona. Određenesu prekidne čvrstoće i prekidna izduženja neresorptivnih konaca i čvrstoće u čvoruresorptivnih konaca.

The use of reclaiming scrap waste rubber is of great ecological interest due to itssignificant influence to the environment. Powdered waste rubber (WRP) can be used asa filler in mixtures with rubbers, thermoplastics, and as modifiers for asphalt. In this workthe composites based on natural rubber (NR) and chlorosufonated polyethylene (CSM)filled with different content of WRP were prepared on a laboratory-size two-roll mixingmill. The curing by sulfur was done at 160º C. The mechanical properties, namely tensilestrength, tensile modulus at 100% elongation, elongation at break and hardness have beenfollowed up as a function of irradiation dose (100; 200; 300; 400 kGy), as well as wasterubber powder content (0; 20; 40; 60; 80; 100 phr). It was assessed that the addition of20 phr waste rubber has improved the properties of obtained elastomeric materials. Theimprovement of composites mechanical properties is in correlation with homogeneousWRP distribution which has been assigned by scanning electron microscopy (SEM).