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Polymers
Special Issues
Advanced Testing of Soft Polymer Materials
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Advanced Testing of Soft Polymer Materials

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Analysis and Characterization".

Deadline for manuscript submissions: closed (25 June 2022) | Viewed by 29041

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Radek Stoček

E-Mail Website
Guest Editor
1. Assoc. Prof. Dr.-Ing., PRL Polymer Research Lab., s.r.o., Nad Ovcirnou 3685, 76001 Zlín, Czech Republic
2. Assoc. Prof. Dr.-Ing., Centre of Polymer Systems, Tomas Bata University in Zlín, tř. Tomáše Bati, 5678 Zlín, Czech Republic
Interests: rubber material; testing; fatigue, fracture, friction and wear characterization of elastomers; characterisation of crack initiation and propagation in elastomers; development of advanced testing methodologies, hardware and equipment; engineering applications; rubber compound development
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Gert Heinrich

E-Mail Website
Guest Editor
1. Leibniz-Institut für Polymerforschung Dresden e.V., 01069 Dresden, Germany
2. Faculty of Mechanical Science and Engineering, Technische Universität Dresden, 01069 Dresden, Germany
Interests: polymer nanocomposites; friction and adhesion of polymer systems, wear; fracture mechanical characterization and modelling of crack formation and propagation in elastomers; statistical-mechanics of polymer networks, material laws, engineering applications; rubber elasticity and viscoelasticity of filled polymer networks; filler-polymer and filler-filler interactions in elastomers: modelling, testing, engineering applications; tire physics, mechanics and engineering (e.g. traction and braking, road-tire interactions), advanced tire materials compounding and testing
Special Issues, Collections and Topics in MDPI journals
Dipl.-Ing. Reinhold Kipscholl

E-Mail Website
Guest Editor
1. Coesfeld GmbH & Co.KG, Dortmund, Tronjestraße 8, 44319 Dortmund, Germany
2. PRL Polymer Research Lab, s.r.o., Nad Ovcirnou 3685, 76001 Zlín, Czech Republic
Interests: development of advanced testing methodologies, hardware and equipment; engineering applications; fatigue, fracture, friction and wear characterization of elastomers

Special Issue Information

Dear Colleagues,

Manufactures of rubber products and suppliers of polymers and raw materials are forced to apply predictive and advanced laboratory test methods and experiments when seeking for high-performance elastomers for future rubber products, as well as for better understanding of the overall materials properties. Ideally, predictive laboratory tests should balance accuracy, relevance, and instrument productivity. They should establish a connection to fundamental scientific principles that even show how test results from a simple piece of uncured rubber and/or a sheet of cured rubber are related to the realistic geometry and loading conditions of the final rubber product under service conditions. The rapid advancement of simulation tools is one way to do this, and several new advanced testing methods created new opportunities to link materials laboratory testing data to a real-world rubber product performance. 


We encourage authors to publish high value manuscripts related to the characterisation of soft rubbery materials. These manuscripts should be related (i) to the development and use of newly developed and/or unique resp. advanced rubber testing methods, and (ii) to predictive testing and real loading simulation concepts where complex information about the materials and final product performance in an early stage will be compiled. More specifically, the desired topics about advanced rubber testing methods and equipment in this special issue should illustrate progress in  fields like mechanical testing, dynamic-mechanical and thermal analysis, dielectric testing, NMR, spectroscopy, advanced optical methods, numerical and physical modeling of rubber testing, fracture and fatigue analysis and wear prediction, rubber friction testing, numerical and physical modeling of rubber testing methods, etc. 

Assoc. Prof. Radek Stoček
Prof. Dr. Gert Heinrich
Dipl.-Ing. Reinhold Kipscholl
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Advanced testing methods
  • Polymers
  • Elastomers
  • Fatigue
  • Fracture
  • Friction
  • Wear
  • Testing equipment
  • Testing methodologies
  • Development of methods
  • Quasistatic mechanical testing
  • Dynamic-Mechanical Testing
  • Thermodynamical / Caloric Testing
  • Dielectric Testing
  • NMR
  • X-ray and neutron-scattering
  • Spectroscopy
  • Advanced optical methods
  • Numerical and Physical Modelling of rubber testing methods

Published Papers (12 papers)

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Research

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17 pages, 4382 KiB  
Article
Testing of Rubber Composites Reinforced with Carbon Nanotubes
by Dana Bakošová and Alžbeta Bakošová
Polymers 2022, 14(15), 3039; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14153039 - 27 Jul 2022
Cited by 7 | Viewed by 2086
Abstract
Carbon nanotubes (CNTs) have attracted growing interest as a filler in rubber nanocomposites due to their mechanical and electrical properties. In this study, the mechanical properties of a NR/BR/IR/SBR compound reinforced with single-wall carbon nanotubes (SWCNTs) were investigated using atomic force microscopy (AFM), [...] Read more.
Carbon nanotubes (CNTs) have attracted growing interest as a filler in rubber nanocomposites due to their mechanical and electrical properties. In this study, the mechanical properties of a NR/BR/IR/SBR compound reinforced with single-wall carbon nanotubes (SWCNTs) were investigated using atomic force microscopy (AFM), tensile tests, hardness tests, and a dynamical mechanical analysis (DMA). The tested materials differed in SWCNT content (1.00–2.00 phr) and were compared with a reference compound without the nanofiller. AFM was used to obtain the topography and spectroscopic curves based on which local elasticity was characterized. The results of the tensile and hardness tests showed a reinforcing effect of the SWCNTs. It was observed that an addition of 2.00 phr of the SWCNTs resulted in increases in tensile strength by 9.5%, Young’s modulus by 15.44%, and hardness by 11.18%, while the elongation at break decreased by 8.39% compared with the reference compound. The results of the temperature and frequency sweep DMA showed higher values of storage and loss moduli, as well as lower values of tangent of phase angle, with increasing SWCNT content. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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19 pages, 15509 KiB  
Article
Kinetics of the Glass Transition of Silica-Filled Styrene–Butadiene Rubber: The Effect of Resins
by Niclas Lindemann, Jürgen E. K. Schawe and Jorge Lacayo-Pineda
Polymers 2022, 14(13), 2626; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14132626 - 28 Jun 2022
Cited by 2 | Viewed by 1824
Abstract
Resins are important for enhancing both the processability and performance of rubber. Their efficient utilization requires knowledge about their influence on the dynamic glass transition and their miscibility behavior in the specific rubber compound. The resins investigated, poly-(α-methylstyrene) (AMS) and indene-coumarone (IC), differ [...] Read more.
Resins are important for enhancing both the processability and performance of rubber. Their efficient utilization requires knowledge about their influence on the dynamic glass transition and their miscibility behavior in the specific rubber compound. The resins investigated, poly-(α-methylstyrene) (AMS) and indene-coumarone (IC), differ in molecular rigidity but have a similar aromaticity degree and glass transition temperature. Transmission electron microscopy (TEM) investigations show an accumulation of IC around the silanized silica in styrene–butadiene rubber (SBR) at high contents, while AMS does not show this effect. This higher affinity between IC and the silica surface leads to an increased compactness of the filler network, as determined by dynamic mechanical analysis (DMA). The influence of the resin content on the glass transition of the rubber compounds is evaluated in the sense of the Gordon–Taylor equation and suggests a rigid amorphous fraction for the accumulated IC. Broadband dielectric spectroscopy (BDS) and fast differential scanning calorimetry (FDSC) are applied for the characterization of the dielectric and thermal relaxations as well as for the corresponding vitrification kinetics. The cooling rate dependence of the vitrification process is combined with the thermal and dielectric relaxation time by one single Vogel–Fulcher–Tammann–Hesse equation, showing an increased fragility of the rubber containing AMS. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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13 pages, 4152 KiB  
Article
Characterization of Viscoelastic Poisson’s Ratio of Engineering Elastomers via DIC-Based Creep Testing
by Jonathan A. Sotomayor-del-Moral, Juan B. Pascual-Francisco, Orlando Susarrey-Huerta, Cesar D. Resendiz-Calderon, Ezequiel A. Gallardo-Hernández and Leonardo I. Farfan-Cabrera
Polymers 2022, 14(9), 1837; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14091837 - 29 Apr 2022
Cited by 8 | Viewed by 2361
Abstract
New data of creep and viscoelastic Poisson’s ratio, ν(t), of five engineering elastomers (Ethylene Propylene-Diene Monomer, Flouroelastomer (Viton®), nitrile butadiene rubber, silicone rubber and neoprene/chloroprene rubber) at different stress (200, 400 and 600 kPa) and temperature (25, [...] Read more.
New data of creep and viscoelastic Poisson’s ratio, ν(t), of five engineering elastomers (Ethylene Propylene-Diene Monomer, Flouroelastomer (Viton®), nitrile butadiene rubber, silicone rubber and neoprene/chloroprene rubber) at different stress (200, 400 and 600 kPa) and temperature (25, 50 and 80 °C) are presented. The ν(t) was characterized through an experimental methodological approach based on creep testing (30 min) and strain (axial and transverse) measurements by digital image correlation. Initially, creep behavior in axial and transverse directions was characterized for each elastomer and condition, and then each creep curve was fitted to a four-element creep model to obtain the corresponding functions. The obtained functions were used to estimate ν(t) for prolonged times (300 h) through a convolution equation. Overall, the characterization was achieved for the five elastomers results exhibiting ν(t) increasing with temperature and time from about 0.3 (for short-term loading) to reach and stabilize at about 0.48 (for long-term loading). Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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19 pages, 7300 KiB  
Article
The Influence of Colloidal Properties of Carbon Black on Static and Dynamic Mechanical Properties of Natural Rubber
by William Amoako Kyei-Manu, Charles R. Herd, Mahatab Chowdhury, James J. C. Busfield and Lewis B. Tunnicliffe
Polymers 2022, 14(6), 1194; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14061194 - 16 Mar 2022
Cited by 13 | Viewed by 3157
Abstract
The influence of carbon black (CB) structure and surface area on key rubber properties such as monotonic stress-strain, cyclic stress–strain, and dynamic mechanical behaviors are investigated in this paper. Natural rubber compounds containing eight different CBs were examined at equivalent particulate volume fractions. [...] Read more.
The influence of carbon black (CB) structure and surface area on key rubber properties such as monotonic stress-strain, cyclic stress–strain, and dynamic mechanical behaviors are investigated in this paper. Natural rubber compounds containing eight different CBs were examined at equivalent particulate volume fractions. The CBs varied in their surface area and structure properties according to a wide experimental design space, allowing robust correlations to the experimental data sets to be extracted. Carbon black structure plays a dominant role in defining the monotonic stress–strain properties (e.g., secant moduli) of the compounds. In line with the previous literature, this is primarily due to strain amplification and occluded rubber mechanisms. For cyclic stress–strain properties, which include the Mullins effect and cyclic softening, the observed mechanical hysteresis is strongly correlated with carbon black structure, which implies that hysteretic energy dissipation at medium to large strain values is isolated in the rubber matrix and arises due to matrix overstrain effects. Under small to medium dynamic strain conditions, classical strain dependence of viscoelastic moduli is observed (the Payne effect), the magnitude of which varies dramatically and systematically depending on the colloidal properties of the CB. At low strain amplitudes, both CB structure and surface area are positively correlated to the complex moduli. Beyond ~2% strain amplitude the effect of surface area vanishes, while structure plays an increasing and eventually dominant role in defining the complex modulus. This transition in colloidal correlations reflects the transition in stiffening mechanisms from flexing of rigid percolated particle networks at low strains to strain amplification at medium to high strains. By rescaling the dynamic mechanical data sets to peak dynamic stress and peak strain energy density, the influence of CB colloidal properties on compound hysteresis under strain, stress, and strain energy density control can be estimated. This has considerable significance for materials selection in rubber product development. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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17 pages, 5351 KiB  
Article
Advanced Characterisation of Soft Polymers under Cyclic Loading in Context of Engine Mounts
by Tomáš Gejguš, Jonas Schröder, Klara Loos, Alexander Lion and Michael Johlitz
Polymers 2022, 14(3), 429; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14030429 - 21 Jan 2022
Cited by 4 | Viewed by 1640
Abstract
The experimental investigation of viscoelastic behavior of cyclically loaded elastomeric components with respect to the time and the frequency domain is critical for industrial applications. Moreover, the validation of this behavior through numerical simulations as part of the concept of virtual prototypes is [...] Read more.
The experimental investigation of viscoelastic behavior of cyclically loaded elastomeric components with respect to the time and the frequency domain is critical for industrial applications. Moreover, the validation of this behavior through numerical simulations as part of the concept of virtual prototypes is equally important. Experiments, combined measurements and test setups for samples as well as for rubber-metal components are presented and evaluated with regard to their industrial application. For application in electric vehicles with relevant excitation frequencies substantially higher than by conventional drive trains, high-frequency dynamic stiffness measurements are performed up to 3000 Hz on a newly developed test bench for elastomeric samples and components. The new test bench is compared with the standard dynamic measurement method for characterization of soft polymers. A significant difference between the measured dynamic stiffness values, caused by internal resonance of the bushing, is presented. This effect has a direct impact on the acoustic behavior of the vehicle and goes undetected by conventional measurement methods due to their lower frequency range. Furthermore, for application in vehicles with internal combustion engine, where the mechanical excitation amplitudes are significantly larger than by vehicles with electric engines, a new concept for the identification of viscoelastic material parameters that is suitable for the representation of large periodic deformations under consideration of energy dissipation is described. This dissipated energy causes self-heating of the polymer and leads to the precocious aging and failure of the elastomeric component. The validation of this concept is carried out thermally and mechanically on specimen and component level. Using the approaches developed in this work, the behavior of cyclically loaded elastomeric engine mounts in different applications can be simulated to reduce the time spent and save on the costs necessary for the production of prototypes. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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13 pages, 2262 KiB  
Article
Fast Evaluation and Comparison of the Energy Performances of Elastomers from Relative Energy Stored Identification under Mechanical Loadings
by Jean-Benoît Le Cam
Polymers 2022, 14(3), 412; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14030412 - 20 Jan 2022
Viewed by 1545
Abstract
The way in which elastomers use mechanical energy to deform provides information about their mechanical performance in situations that require substantial characterization in terms of test time and cost. This is especially true since it is usually necessary to explore many chemical compositions [...] Read more.
The way in which elastomers use mechanical energy to deform provides information about their mechanical performance in situations that require substantial characterization in terms of test time and cost. This is especially true since it is usually necessary to explore many chemical compositions to obtain the most relevant one. This paper presents a simple and fast approach to characterizing the mechanical and energy behavior of elastomers, that is, how they use the mechanical energy brought to them. The methodology consists of performing one uniaxial cyclic tensile test with a simultaneous temperature measurement. The temperature measurement at the specimen surface is processed with the heat diffusion equation to reconstruct the heat source fields, which in fact amounts to surface calorimetry. Then, the part of the energy involved in the mechanical hysteresis loop that is not converted into heat can be identified and a quantity γse is introduced for evaluating the energy performance of the materials. This quantity is defined as an energy ratio and assesses the ability of the material to store and release a certain amount of mechanical energy through reversible microstructure changes. Therefore, it quantifies the relative energy that is not used to damage the material, for example to propagate cracks, and that is not dissipated as heat. In this paper, different crystallizable materials have been considered, filled and unfilled. This approach opens many perspectives to discriminate, in an accelerated way, the factors affecting these energetic performances of elastomers, at the first order are obviously the formulation, the aging and the mechanical loading. In addition, such an approach is well adapted to better characterize the elastocaloric effects in elastomeric materials. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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19 pages, 3868 KiB  
Article
Future-Oriented Experimental Characterization of 3D Printed and Conventional Elastomers Based on Their Swelling Behavior
by Klara Loos, Vivianne Marie Bruère, Benedikt Demmel, Yvonne Ilmberger, Alexander Lion and Michael Johlitz
Polymers 2021, 13(24), 4402; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13244402 - 15 Dec 2021
Cited by 8 | Viewed by 2176
Abstract
The present study investigates different elastomers with regard to their behavior towards liquids such as moisture, fuels, or fuel components. First, four additively manufactured materials are examined in detail with respect to their swelling in the fuel component toluene as well as in [...] Read more.
The present study investigates different elastomers with regard to their behavior towards liquids such as moisture, fuels, or fuel components. First, four additively manufactured materials are examined in detail with respect to their swelling in the fuel component toluene as well as in water. The chemical nature of the materials is elucidated by means of infrared spectroscopy. The experimentally derived absorption curves of the materials in the liquids are described mathematically using Fick’s diffusion law. The mechanical behavior is determined by uniaxial tensile tests, which are evaluated on the basis of stress and strain at break. The results of the study allow for deriving valuable recommendations regarding the printing process and postprocessing. Second, this article investigates the swelling behavior of new as well as thermo-oxidatively aged elastomers in synthetic fuels. For this purpose, an analysis routine is presented using sorption experiments combined with gas chromatography and mass spectrometry and is thus capable of analyzing the swelling behavior multifacetted. The transition of elastomer constituents into the surrounding fuel at different aging and sorption times is determined precisely. The change in mechanical properties is quantified using density measurements, micro Shore A hardness measurements, and the parameters stress and strain at break from uniaxial tensile tests. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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14 pages, 2572 KiB  
Article
Identifying the Co-Curing Effect of an Accelerated-Sulfur/Bismaleimide Combination on Natural Rubber/Halogenated Rubber Blends Using a Rubber Process Analyzer
by Marek Pöschl, Shibulal Gopi Sathi and Radek Stoček
Polymers 2021, 13(24), 4329; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13244329 - 10 Dec 2021
Cited by 5 | Viewed by 2836
Abstract
The rheometer curing curves of 50/50 blends of natural rubber (NR) and two different halogenated rubbers with a combination of conventional accelerated sulfur (CV) and 3 phr of a bismaleimide (MF3) at 170 °C indicates that a co-curing reaction has been [...] Read more.
The rheometer curing curves of 50/50 blends of natural rubber (NR) and two different halogenated rubbers with a combination of conventional accelerated sulfur (CV) and 3 phr of a bismaleimide (MF3) at 170 °C indicates that a co-curing reaction has been taken place between NR and the halogenated rubbers via Diels–Alder reaction. To further confirm whether the co-curing reaction has taken place in the early stage of curing, a complex test methodology was applied with the help of a rubber process analyzer. In this test, the blends with CV and with CVMF3 were subjected to cure at 170 °C for a predetermined time so that both the CV and CVMF3 cured blends will have the same magnitude of curing torque. It is then cooled down to 40 °C and the storage modulus (G′) was evaluated as a function of strain from 0.5% to 100% at a constant frequency of 1 Hz. The results reveal that the blends cured with CVMF3 exhibit a higher G′ due to the enhanced network strength because of the formation of bismaleimide crosslinks than the same cured with only the CV system. The swelling resistance and the mechanical properties of the blends cured with CVMF3 were significantly higher than those cured with only the CV system. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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17 pages, 6843 KiB  
Article
The Influence of Local Strain Distribution on the Effective Electrical Resistance of Carbon Black Filled Natural Rubber
by E. Harea, S. Datta, M. Stěnička, J. Maloch and R. Stoček
Polymers 2021, 13(15), 2411; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13152411 - 22 Jul 2021
Cited by 3 | Viewed by 1836
Abstract
A monotonous relation between strain and measured electric resistance is highly appreciated in stretchable elastomer sensors. In real-life application the voids or technological holes of strained samples often induce non-homogeneous local strain. The present article focused on studying the effect of non-homogeneous local [...] Read more.
A monotonous relation between strain and measured electric resistance is highly appreciated in stretchable elastomer sensors. In real-life application the voids or technological holes of strained samples often induce non-homogeneous local strain. The present article focused on studying the effect of non-homogeneous local strain on measured direct current (DC) effective electric resistance (EER) on samples of natural rubber (NR), reinforced with 50, 60 and 70 phr of carbon black (CB). Samples were imparted geometrical inhomogeneities to obtain varied local strains. The resulting strain distribution was analyzed using Digital Image Correlation (DIC). EER exhibited a well-detectable influence of locations of inhomogeneities. Expectedly, the EER globally decreased with an increase in CB loading, but showed a steady increase as a function of strain for 50 and 60 phr over the complete testing protocol. Interestingly, for 70 phr of CB, under the same testing conditions, an alternating trend in EER was encountered. This newly observed behavior was explained through a novel hypothesis—“current propagation mode switching phenomenon”. Finally, experimentally measured EERs were compared with the calculated ones, obtained by summing the global current flow through a diversity of strain dependent resistive domains. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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11 pages, 2555 KiB  
Article
Rheometer Evidences for the Co-Curing Effect of a Bismaleimide in Conjunction with the Accelerated Sulfur on Natural Rubber/Chloroprene Rubber Blends
by Marek Pöschl, Shibulal Gopi Sathi, Radek Stoček and Ondřej Kratina
Polymers 2021, 13(9), 1510; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13091510 - 07 May 2021
Cited by 9 | Viewed by 3864
Abstract
The rheometer curing curves of neat natural rubber (NR) and neat chloroprene rubber (CR) with maleide F (MF) exhibit considerable crosslinking torque at 180 °C. This indicates that MF can crosslink both these rubbers via Alder-ene reactions. Based on this knowledge, MF has [...] Read more.
The rheometer curing curves of neat natural rubber (NR) and neat chloroprene rubber (CR) with maleide F (MF) exhibit considerable crosslinking torque at 180 °C. This indicates that MF can crosslink both these rubbers via Alder-ene reactions. Based on this knowledge, MF has been introduced as a co-crosslinking agent for a 50/50 blend of NR and CR in conjunction with accelerated sulfur. The delta (Δ) torque obtained from the curing curves of a blend with the addition of 1 phr MF was around 62% higher than those without MF. As the content of MF increased to 3 phr, the Δ torque was further raised to 236%. Moreover, the mechanical properties, particularly the tensile strength of the blend with the addition of 1 phr MF in conjunction with the accelerated sulfur, was around 201% higher than the blend without MF. The overall tensile properties of the blends cured with MF were almost retained even after ageing the samples at 70 °C for 72 h. This significant improvement in the curing torque and the tensile properties of the blends indicates that MF can co-crosslink between NR and CR via the Diels–Alder reaction. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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17 pages, 5490 KiB  
Article
Influence of Ultraviolet Radiation on Mechanical Properties of a Photoinitiator Compounded High Vinyl Styrene–Butadiene–Styrene Block Copolymer
by Sanjoy Datta, Radek Stocek and Kinsuk Naskar
Polymers 2021, 13(8), 1287; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13081287 - 15 Apr 2021
Cited by 4 | Viewed by 2663
Abstract
Ultraviolet curing of elastomers is a special curing technique that has gained importance over the conventional chemical crosslinking method, because the former process is faster, and thus, time-saving. Usually, a suitable photoinitiator is required to initiate the process. Ultraviolet radiation of required frequency [...] Read more.
Ultraviolet curing of elastomers is a special curing technique that has gained importance over the conventional chemical crosslinking method, because the former process is faster, and thus, time-saving. Usually, a suitable photoinitiator is required to initiate the process. Ultraviolet radiation of required frequency and intensity excites the photoinitiator which abstracts labile hydrogen atoms from the polymer with the generation of free radicals. These radicals result in crosslinking of elastomers via radical–radical coupling. In the process, some photodegradation may also take place. In the present work, a high vinyl (~50%) styrene–butadiene–styrene (SBS) block copolymer which is a thermoplastic elastomer was used as the base polymer. An attempt was made to see the effect of ultraviolet radiation on the mechanical properties of the block copolymer. The process variables were time of exposure and photoinitiator concentration. Mechanical properties like tensile strength, elongation at break, modulus at different elongations and hardness of the irradiated samples were studied and compared with those of unirradiated ones. In this S-B-S block copolymer, a relatively low exposure time and low photoinitiator concentration were effective in obtaining optimized mechanical properties. Infrared spectroscopy, contact angle and scanning electron microscopy were used to characterize the results obtained from mechanical measurements. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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Review

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14 pages, 3274 KiB  
Review
Influence of the Polarity of the Plasticizer on the Mechanical Stability of the Filler Network by Simultaneous Mechanical and Dielectric Analysis
by Sahbi Aloui, Horst Deckmann, Jürgen Trimbach and Jorge Lacayo-Pineda
Polymers 2022, 14(10), 2126; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14102126 - 23 May 2022
Cited by 1 | Viewed by 1506
Abstract
Four styrene butadiene rubber (SBR) compounds were prepared to investigate the influence of the plasticizer polarity on the mechanical stability of the filler network using simultaneous mechanical and dielectric analysis. One compound was prepared without plasticizer and serves as a reference. The other [...] Read more.
Four styrene butadiene rubber (SBR) compounds were prepared to investigate the influence of the plasticizer polarity on the mechanical stability of the filler network using simultaneous mechanical and dielectric analysis. One compound was prepared without plasticizer and serves as a reference. The other three compounds were expanded with different plasticizers that have different polarities. Compared with an SBR sample without plasticizer, the conductivity of mechanically unloaded oil-extended SBR samples decreases by an order of magnitude. The polarity of the plasticizer shows hardly any influence because the plasticizers only affect the distribution of the filler clusters. Under static load, the dielectric properties seem to be oil-dependent. However, this behavior also results from the new distribution of the filler clusters caused by the mechanical damage and supported by the polarity grade of the plasticizer used. The Cole–Cole equation affirms these observations. The Cole–Cole relaxation time τ and thus, the position of maximal dielectric loss increases as the polarity of the plasticizer used is also increased. This, in turn, decreases the broadness parameter α implying a broader response function. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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