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Gloves are one of the most important elements of personal protective equipment (PPE). To improve gloves properties, a lot of different methods of surface modifications are used. In this work, the application of geometric, chemical, and plasma surface modifications to improve the hydrophobicity of butyl (IIR) and silicone (MVQ) rubber are described. To characterise surface properties contact angle measurements, FT-IR spectroscopy and scanning electron microscopy were used. This study showed that when the chemical modification applied, the contact angle value increases compared to non-modified samples. In addition, plasma modification raised the contact angle value and smoothed the surface morphology. An increase in the polymer surfaces hydrophobicity was the observed effect of the three modifications of rubber.

The goal of this study was to compare the mechanical properties of experimental resin dental composites containing a conventional photoinitiating system (camphorquinone CQ and 2-(dimethylami-no)ethyl methacrylate (DMAEMA)) to a photoinitiator system containing 1-phenyl-1,2 propanedione (PPD) with 2-(dimethylami-no)ethyl methacrylate) or acting alone phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxide (BAPO). The manually produced composites consisted of an organic matrix: bis-GMA (60 wt. %), TEGDMA (40 wt. %), and silanized silica filler (45 wt. %). The composites contained 0.4/0.8 wt. %, 0.8/1.6 wt. %, and 1/2 wt. % of PPD/DMAEMA and another group included 0.25, 0.5, or 1 wt. % of BAPO. Vickers hardness, microhardness (in the nanoindentation test), diametral tensile strength, and flexural strength were assessed, and CIE L* a* b* colorimetric analysis was conducted for each composite produced. The highest average Vickers hardness values were obtained for the composite containing 1 wt. % BAPO (43.73 ± 3.52 HV). There was no statistical difference in the results of diametral tensile strength for the experimental composites tested. The results of 3-point bending tests were the highest for composites containing CQ (77.3 ± 8.84 MPa). Despite the higher hardness of experimental composites including PPD or BAPO, compared with composites with CQ, the overall results indicate that the composite with CQ still represents a better solution when used as a photoinitiator system. Moreover, the composites containing PPD and DMAEMA are not promising in terms of color or mechanical properties, especially as they require significantly longer irradiation times.

The aim of this article was to compare the biomechanical properties of commercial composites containing different photoinitiators: Filtek Ultimate (3M ESPE) containing camphorquinone (CQ), Estelite Σ Quick (Tokuyama Dental) with CQ in RAP Technology®, Tetric EvoCeram Bleach BLXL (Ivoclar Vivadent AG) with CQ and Lucirin TPO, and Tetric Evoceram Powerfill IVB (Ivoclar Vivadent AG) with CQ and Ivocerin TPO. All samples were cured with a polywave Valo Lamp (Ultradent Products Inc.) with 1450 mW/cm2. The microhardness, hardness by Vicker’s method, diametral tensile strength, flexural strength and contraction stress with photoelastic analysis were tested. The highest hardness and microhardness were observed for Filtek Ultimate (93.82 ± 17.44 HV), but other composites also displayed sufficient values (from 52 ± 3.92 to 58,82 ± 7.33 HV). Filtek Ultimate not only demonstrated the highest DTS (48.03 ± 5.97 MPa) and FS (87.32 ± 19.03 MPa) but also the highest contraction stress (13.7 ± 0.4 MPa) during polymerization. The TetricEvoCeram Powerfill has optimal microhardness (54.27 ± 4.1 HV), DTS (32.5 ± 5.29 MPa) and FS (79.3 ± 14.37 MPa) and the lowest contraction stress (7.4 ± 1 MPa) during photopolymerization. To summarize, Filtek Ultimate demonstrated the highest microhardness, FS and DTS values, however, composites with additional photoinitiators such as Lucirin TPO and Ivocerin have the lowest polymerization shrinkage. These composites also have higher FS and DTS and microhardness than material containing CQ in Rap Technology.

Dual-curing composites have a wide spectrum of use in practice (rebuilding, reconstruction, and luting). The characterization of this type of material and comparative study of selected mechanical properties with light-cured materials were carried out for this paper. In this study, we used six materials with a dual-cure system—Bulk EZ, Fill-Up!, StarFill 2B, Rebilda DC, MultiCore Flow, Activa Bioactive-Restorative—and three light-cured materials—Filtek Bulk Fill Posterior, Charisma Classic, and G-aenial Universal Flo. The materials were conditioned for 24 h in water at 37 °C before testing. Selected material properties were determined: three-point bending flexural strength, diametral tensile strength, hardness, microhardness, and shrinkage stress. The highest three-point bending flexural strength (TPB) was 137.0 MPa (G-aenial Universal Flo), while the lowest amounted to 86.5 MPa (Activa Bioactive). The diametral tensile strength (DTS) values were in a range from 39.2 MPa (Rebilda DC) to 54.1 MPa (Charisma Classic). The lowest hardness (HV) value of 26 was obtained by the Activa Bioactive material, while the highest values were recorded for Filtek Bulk Fill Posterior and Charisma Classic-53. The shrinkage stress of the tested materials ranged from 6.3 MPa (Charisma Classic) to 13.2 MPa (G-aenial Universal Flo). Dual-curing composites were found to have similar properties to light-cured composites.

The aim of the study was the evaluation of properties of variously composed composite materials based onpolyurethane filled with tea tree oil (TTO) and addition of other ingredients. The tea tree oil/cyclodextrin inclusioncomplex was prepared by using the ‘Paste method’ described in Shrestha, M and others. (2017) (Shrestha et al. 2017). Toanalyse the properties of composite materials following testing methods were conducted: density, tensile strength,compression test, impact resistance. In the study, pursued in the Lodz University of Technology in Poland, thirteenmaterials with different percentile content of additives: TTO/β-CD, propolis, TTO/β-CD/Propolis, TTO were preparedand tested to establish the most favourable characteristics. Properties of sample containing Tea tree oil/ β-cyclodextrin/Propolis were the most satisfying and were assumed to be accurate in fulfilling the role of the hoof crackfiller the best in the first study. With the higher amount of the additive the mechanical properties weakened preventingthe use of the product in the hoof cracks.

Novel sulfur-silsesquioxane random copolymer (poly(S-r-POSS)) was synthesized via the radical reaction between liquid sulfur and octavinyl silsesquioxane. Particulate solid POSS was dispersed in molten sulfur and heated in order to initiate the free radical reaction (inverse vulcanization). The appearance of new C–S bonds along with the disappearance of C=C bonds from vinyl groups was confirmed by Raman and FTIR spectroscopy. Moreover, the formation of saturated single C–C bonds from the reacting vinyl groups was revealed by FTIR. Microhomogenity of the copolymer was analyzed by means of SEM-EDS mapping and its thermal properties were studied using the TG-DSC method. After the extraction of free unreacted sulfur and POSS the copolymer exhibits porous micromorphology promising for application in lithium–sulfur batteries or heavy metals ion capturing. HighlightsSynthesis of silsesquioxane-sulfur hybrid copolymer via inversed vulcanizationHighly porous cross-linked morphologyPotential utilization for lithium–sulfur batteries or heavy metals ion capturing Synthesis of silsesquioxane-sulfur hybrid copolymer via inversed vulcanization Highly porous cross-linked morphology Potential utilization for lithium–sulfur batteries or heavy metals ion capturing

In modern polymer industry, there still is a room for new generations of fillers capable of enhancing the performance of composite materials. Currently, much effort is being put into a process of improving mechanical properties of elastomer materials. In this work, multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GnPs) were modified with silane, titanate, or zirconate using plasma treatment, in order to apply them as fillers for styrene/butadiene rubber. Following its modification, filler surface was analyzed: Surface free energy (SFE) was measured with tensiometry, and micromorphology and chemical composition were studied with scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS), while elemental composition and bonding were assessed with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Low-temperature oxygen plasma activation of MWCNT fillers leads to a significant increase in the SFE polar component, with the same effect being much weaker for GnP fillers. Grafting silanes, zirconates, and titanates on activated filler surface results in a decrease in SFE polar component—surface oxygen-containing active groups react with silane/zirconate/titanate molecules. Fillers modified in this way exhibit different micromorphology and surface chemical composition what is revealed with the SEM–EDS, ToF-SIMS, and XPS techniques. As the ultimate step, either MWCNT or GnP rubber nanocomposites were manufactured using the modified fillers with their mechanical properties and cross-link density being studied. Filler modification resulted in substantial changes both in composite performance, and in its cross-linking density. In the case of modified filler containing composites, improved tensile strength and elongation at break were observed.

Fly ash (FA) fractions with a particle size of 63 µm < FA < 250 µm obtained by sieve fractionation were used as a partial carbon black (CB) replacement in a rubber mixture based on styrene-butadiene rubber (SBR). In order to improve the interactions at the interface between rubber and fractionated ash, at the stage of preparing the rubber mixtures, two different vinyl silanes were added to the system: Vinyltrimethoxysilane (U-611) or Vinyl-tris (2-methoxy-ethoxy) silane (LUVOMAXX VTMOEO DL50), silane with epoxy groups: 3-(glycidoxypropyl)trimethoxysilane (U-50) or sulfur functionalized silanes: containing sulfide bridges: Bis(triethoxysilylpropyl)polysulfide silane (Si-266) or mercapto groups: Mercaptopropyltrimethoxysilane (Dynaslan MTMO). The conducted research confirmed the effectiveness of silanization with selected functional silanes, from the point of view of improving the processing and operational properties of vulcanizates, in which CB is partially replaced with the finest fractions of fly ash. The silanization generally increased the interaction at the rubber–ash interface, while improving the degree of filler dispersion in the rubber mixture. The results of TGA and FTIR analyses confirmed the presence of silanes chemically bonded to the surface of fly ash particles. SEM tests and determination of the bound rubber (BdR) content show that the introduction of the silanes to the mixture increases the degree of ash dispersion (DI) and the Payne effect, which is the greatest when mercaptosilane was used for modification. The highest increase in torque, which was recorded in the case of rubber mixtures containing sulfur silanes and silane with epoxy groups, may be due to their participation in the vulcanization process, which is confirmed by the results of vulcametric studies. The lowest values of mechanical strength, elongation at break, and the highest hardness of vulcanizates obtained in this case may be the result of the over-crosslinking of the rubber. The addition of sulfur-containing silanes significantly slowed down the vulcanization process, which is particularly visible (up to three times extension of the t90 parameter, compared to mixtures without silane) in the case of Si-266. The addition of silanes, except for Si-266 (with a polysulfide fragment), generally improved the abrasion resistance of vulcanizates. The Dynaslan MTMO silane (with mercapto groups) performs best in this respect. Proper selection of silane for the finest fraction of fly ash in the rubber mixtures tested allows for an increase in the mechanical strength of their vulcanizates from 9.1 to 17 MPa, elongation at break from 290 to 500%, hardness from 68 to 74 °ShA, and reduction in abrasion from 171 to 147 mm3.

Ground tire rubber (GTR) is used to decrease the cost of vulcanizates. However, insufficient interactions between GTR particles and rubber matrices make mechanical properties of vulcanizates containing GTR deteriorate. This paper compares original methods of GTR modification. The effects of surface activation of GTR by sulfuric acid (A), its modification by (3-mercaptopropyl)trimethoxy silane (M), or the hybrid treatment—combining both approaches (H), were analyzed in terms of surface energy, specific surface area and morphology of GTR particles. Vulcanizates containing virgin GTR were compared to the rubber filled with the modified GTR particles keeping the same amount of CB in the rubber mix, according to their crosslink density, mechanical and tribological properties. Contrary to the virgin GTR, the addition of modified GTR increases the stiffness of the vulcanizates. The highest changes have been observed for the samples filled with ca. 12 phr of the GTR modified with silane and ca. 25 phr of the GTR subjected to the hybrid treatment, representing the highest crosslink density of rubber vulcanizates filled with GTR. Furthermore, the addition of modified GTR, especially in the case of the samples where 10 phr of rubber was replaced, results in the significant lowering of friction but higher abrasive wear.

This paper examines the influence of the morphology of zinc oxide nanoparticles (n-ZnO) on the activation energy, vulcanization parameters, crosslink density, crosslink structure, and mechanical properties in the extension of the sulfur vulcanizates of styrene-butadiene rubber (SBR). Scanning electron microscopy was used to determine the particle size distribution and morphology, whereas the specific surface area (SSA) and squalene wettability of the n-ZnO nanoparticles were adequately evaluated using the Brunauer–Emmet–Teller (BET) equation and tensiometry. The n-ZnO were then added to the SBR in conventional (CV) or efficient (EV) vulcanization systems. The vulcametric curves were plotted, from which the cure rate index (CRI) rate of the vulcanization and the activation energy were calculated. The influence on the mechanical properties of the SBR vulcanizates was stronger in the case of the EV curing system than when the CV curing system was used. Of the vulcanizates produced in the EV curing system, the best performance was detected for n-ZnO particles with a hybrid morphology (flat-ended rod-like particles on a “cauliflower” base) and high SSA. Vulcanizates produced using the CV curing system showed slightly better mechanical properties after the addition of nanoparticles with a “cauliflower” morphology than when the rod-like type were used, irrespective of their SSA. In general, nanoparticles with a rod-like structure reduced the activation energy and increased the speed of vulcanization, whereas the cauliflower type slowed the rate of the process and the vulcanizates required a higher activation energy, especially when using the EV system. The crosslink structures were also more clearly modified, as manifested by a reduction in the polysulfidic crosslink content, especially when n-ZnO activators with a rod-like morphology were applied.

With the continuing growth of waste sulfur production from the petroleum industry processes, its utilization for the production of useful, low-cost, and environmentally beneficial materials is of primary interest. Elemental sulfur has a significant and established history in the modification of bitumen binders, while the sulfur-containing high-molecular compounds are limited in this field. Herein, we report a novel possibility to utilize the sulfur/organic copolymers obtained via the inverse vulcanization process as modifiers for bitumen binders. Synthesis and thermal characterization (TGA-DSC) of polysulfides derived from elemental sulfur (S8) and unsaturated organic species (dicyclopentadiene, styrene, and limonene) have been carried out. The performance of modified bitumen binders has been studied by several mechanical measurements (softening point, ductility, penetration at 25 °C, frass breaking point, adhesion to glass and gravel) and compared to the unmodified bitumen from the perspective of normalized requirements concerning polymer-modified bitumen. The interaction of bitumen binder with sulfur/organic modifier has been studied by means of FTIR spectroscopy and DSC measurements. The impact of the modification on the performance properties of bitumen has been demonstrated. The bitumen binders modified with sulfur/organic copolymers are in general less sensitive to higher temperatures (higher softening point up to 7 °C), more resistant to permanent deformations (lower penetration depth), and more resistant to aging processes without intrusive deterioration of parameters at lower temperatures. What is more, the modification resulted in significantly higher adhesion of bitumen binders to both glass (from 25% up to 87%) and gravel surfaces in combination with a lower tendency to form permanent deformations (more elastic behavior of the modified materials).

This paper describes a method of laser ablation for improving the hydrophobic properties of vulcanized rubber. The treatment was tested on acrylonitrile rubber (NBR) and styrene butadiene rubber (SBR) containing carbon nanotubes and soot as fillers. The surface layer of the vulcanizates was modified using a nanosecond-pulsed laser at 1060 nm wavelength. The parameters of the ablation process were congruent, so no chemical changes in the polymeric material were observed. Evaluation of the surface condition of the laser-textured samples was performed using a Leica MZ6 stereoscopic microscope, operating with MultiScan 8.0 image analysis software. The contact angles were determined for all the samples before and after the surface modification process. Following modification of the surface morphology, with the best parameters of laser ablation, the contact angle increased, reaching 147&deg, which is very close to the threshold of superhydrophobicity (150&deg, ). On the basis of the results from several tests, laser ablation with a fiber-pulsed laser can be considered a very useful method for producing rubbers with superhydrophobic surfaces.

Ceramifiable styrene-butadiene (SBR)-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite) and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their thermal properties were analyzed by means of thermogravimetry and specific heat capacity determination. Activation energy of thermal decomposition was calculated using the Flynn-Wall-Ozawa method. Finally, compression strength of the composites after ceramification was measured and their micromorphology was studied by scanning electron microscopy. The addition of a ceramification-facilitating system resulted in the lowering of combustibility and significant improvement of the thermal stability of the composites. Moreover, the compression strength of the mineral structure formed after ceramification is considerably high. The most promising refractory fillers for SBR-based ceramifiable composites are mica and halloysite.

In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers' SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

The paper presents the test results of the effect of modified graphene and multi-wall carbon nanotubes on the thermal and mechanical properties and flammability of acrylic rubber and styrene-butadiene rubber. The rubbers were cross-linked with the use of organic peroxide. Based on the test results obtained by optic and AFM methods, a relationship between the surface morphology of the nanocomposites obtained was presented. By means of thermal analysis methods (TG, DTG, DTA) and a micro-calorimeter, it has been found that the nanofillers used considerably increase the thermal stability and decrease flammability of the nanocomposites. The mechanical properties of the elastomeric materials obtained depend on the type and content of nanofiller.

The aim of this work is to describe the changes in the properties of ceramifiable silicone rubber-based composites caused by the incorporation of novel alternative minerals in comparison to other popular, widely utilized fillers. TiO2, calcined kaolin and calcium-based minerals mix (CbMix) consisting of CaO (6.26 wt%), CaCO3 (26.18 wt%) and Ca(OH)2 (67.56 wt%) have not been considered as a dispersed phase of ceramifiable silicone composites destined for wire covers yet. Mineral fillers: TiO2 (anatase), mica (phlogopite), CbMix, CaCO3, Al(OH)3, kaolin and calcined kaolin affect the processing and the various properties of silicone rubber-based composites destined for wire covers differently. The properties— flammability, smoke intensity, micromorphology and mechanical durability after ceramification—are assessed by measuring: the kinetics of vulcanization, stress at different levels of elongation, tensile strength and the elongation at break of the materials. Although the curing process of the composites is disturbed by the addition of CbMix, it benefits from an increase in oxygen index value, which reaches 31.4%. What is more, also its flammability parameters measured by cone calorimetry improve, such as the total heat released (THR) reaching 9.3 MJ/m2. Samples containing kaolin and calcined kaolin exhibit the best mechanical properties before ceramification, whereas composites filled with calcium-based powders (CbMix, CaCO3) mechanically display the strongest mineral char after heat treatment, possibly due to a more homogenous micromorphology and the creation of calcium silicates at elevated temperature. Significant amounts of wollastonite, parawollas-tonite and pseudowollastonite are visible in their structure after ceramification.

Tribological properties of commercially available silicone-based ceramizable composites were studied. Friction forces of three different types of ceramizable composites were measured against three different-shape steel samples. Each friction pair contact was loaded with 15, 30, 45 or 60 N. Conducted studies reveal that tribological behavior of the composites vary considerably depending on the composite type and friction contact. However, friction force was increasing with an increase of the load, which mean that the composites behave accordingly to the classic friction theory.