Mechanical Behavior of Polymeric Materials: Recent Study

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

Deadline for manuscript submissions: 31 March 2024 | Viewed by 14393

Special Issue Editors

Polymer Engineering Group (GIP), Polymer Science and Technology Institute (ICTP), Spanish Council for Scientific Research (CSIC), 28006 Madrid, Spain
Interests: polymers and environment; heterogeneous materials based on polymers; polyolefins; interfacial agents; interphase; interface; functionalization; plastic wastes; blends; composites
Special Issues, Collections and Topics in MDPI journals
Polymer Engineering Group (GIP), Polymer Science and Technology Institute (ICTP), Spanish Council for Scientific Research (CSIC), 28006 Madrid, Spain
Interests: polymers and environment; heterogeneous materials based on polymers; polyolefins; interfacial agents; interphase; interface; functionalization; plastic wastes; blends; composites
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Polymeric Materials, which means polymer-based materials partially or as a whole, are routinely used just from one hundred years ago, in a growing number of applications, all of them encompassed nowadays and in the context of a circular economy in the three main sectors of transport, communications and health. All those applications and anyone of the newest imaginative ones in the future had and will have in common the need to provide the polymeric matter with the structural integrity enough to be used in any given, or desired application. How to measure such structural integrity; How to study it; How a crack appears; How and When a failure becomes catastrophic; How the processing determines the mechanical responses of any polymeric material; How the aging, the outdoor, and the environment at the end, or the recycled material fraction, may affect that mechanical behavior, are questions that remain open today. Research works devoted to these and related topics will be welcome to this special issue entitled " Mechanical Behavior of Polymeric Materials: Recent Study "

Dr. Emilia P. Collar
Dr. Jesús-María García-Martínez
Guest Editors

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Keywords

  • mechanical properties
  • fracture
  • failure
  • standardizations
  • modeling and forecasting
  • mechanical behavior-processing relationship

Published Papers (9 papers)

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Research

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20 pages, 3758 KiB  
Article
Thermomechanical Properties of Virgin and Recycled Polypropylene—High-Density Polyethylene Blends
by Hannah Jones, Jake McClements, Dipa Ray, Colin S. Hindle, Michail Kalloudis and Vasileios Koutsos
Polymers 2023, 15(21), 4200; https://doi.org/10.3390/polym15214200 - 24 Oct 2023
Cited by 1 | Viewed by 1571
Abstract
This paper provides evidence and discusses the variability in the thermomechanical behaviour of virgin and recycled polypropylene/high-density polyethylene blends without the addition of other components, which is sparse in the literature. Understanding the performance variability in recycled polymer blends is of critical importance [...] Read more.
This paper provides evidence and discusses the variability in the thermomechanical behaviour of virgin and recycled polypropylene/high-density polyethylene blends without the addition of other components, which is sparse in the literature. Understanding the performance variability in recycled polymer blends is of critical importance in order to facilitate the re-entering of recycled materials to the consumer market and, thus, contribute towards a circular economy. This is an area that requires further research due to the inhomogeneity of recycled materials. Therefore, the thermal and mechanical properties of virgin and recycled polypropylene/high-density polyethylene blends were investigated systematically. Differential scanning calorimetry concludes that both the recycled and virgin blends are immiscible. Generally, recycled blends have lower overall crystallinity and melting temperatures compared with virgin blends while, remarkably, their crystallisation temperatures are compared favourably. Dynamical mechanical analysis showed little variation in the storage modulus of recycled and virgin blends. However, the alpha and beta relaxation temperatures are lower in recycled blends due to structural deterioration. Deterioration in the thermal and mechanical properties of recycled blends is thought to be caused by the presence of contaminants and structural degradation during reprocessing, resulting in shorter polymeric chains and the formation of imperfect crystallites. The tensile properties of recycled blends are also affected by the recycling process. The Young’s modulus and yield strength of the recycled blends are inferior to those of virgin blends due to the deterioration during the recycling process. However, the elongation at break of the recycled blends is higher compared with the virgin blends, possibly due to the plasticity effect of the low-molecular-weight chain fragments. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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18 pages, 6031 KiB  
Article
Study on the Tensile Behavior of Woven Non-Woven PLA/OLA/MgO Electrospun Fibers
by Adrián Leonés, Laura Peponi, Jesús-María García-Martínez and Emilia P. Collar
Polymers 2023, 15(19), 3973; https://doi.org/10.3390/polym15193973 - 03 Oct 2023
Viewed by 576
Abstract
The present work deeply studied the mechanical behavior of woven non-woven PLA/OLA/MgO electrospun fibers, efibers, by using Box–Wilson surface response methodology. This work follows up a previous one where both the diameters and the thermal response of such efibers were discussed in terms [...] Read more.
The present work deeply studied the mechanical behavior of woven non-woven PLA/OLA/MgO electrospun fibers, efibers, by using Box–Wilson surface response methodology. This work follows up a previous one where both the diameters and the thermal response of such efibers were discussed in terms of both the different amounts of magnesium oxide nanoparticles, MgO, as well as of the oligomer (lactic acid), OLA, used as plasticizer. The results of both works, in term of diameters, degree of crystallinity, and mechanical response, can be strongly correlated to each other, as reported here. In particular, the strain mechanism of PLA/OLA/MgO efibers was studied, showing an orientation of efibers parallel to the applied stress and identifying the mechanically weakest points that yielded the start of the breakage of efibers. Moreover, we identified 1.5 wt% as the critical amount of MgO, above which the plasticizing effect of OLA was weaker as the amount of both components increased. Moreover, the minimum elastic modulus value took place at 15 wt% of OLA, in agreement with the previously reported convergence point in the evolution of the degree of crystallinity. Regarding the yield point, a concentration of OLA between 20 and 30 wt% led to a slight improvement in the yielding capability in terms of tensile strength in comparison with neat PLA efibers. Therefore, the approach presented here permits the design of tailor-made electrospun nanocomposites with specific mechanical requirements. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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22 pages, 5107 KiB  
Article
Effect of Number of Tests on the Mechanical Characteristics of Agave sisalana Yarns for Composites Structures: Statistical Approach
by Mounir Gahgah, Ahmed Belaadi, Messaouda Boumaaza, Hassan Alshahrani and Mohammad K. A. Khan
Polymers 2023, 15(13), 2885; https://doi.org/10.3390/polym15132885 - 29 Jun 2023
Cited by 3 | Viewed by 750
Abstract
A designer of sustainable biocomposite structures and natural ropes needs to have a high confidence interval (95% CI) for mechanical characteristics data of performance materials, yet qualities for plant-based fibers are very diverse. A comprehensive study of the elements that enhance the performance [...] Read more.
A designer of sustainable biocomposite structures and natural ropes needs to have a high confidence interval (95% CI) for mechanical characteristics data of performance materials, yet qualities for plant-based fibers are very diverse. A comprehensive study of the elements that enhance the performance of biocomposites or sustainable ropes created from vegetable fibers is necessary. The current study included five groups with varying numbers (N) of tests of 20, 40, 60, 80, and 100 on the mechanical characteristics at room temperatures. The purpose of this study was to determine how changing N affects the mechanical properties of sisal yarn. These properties include its strength, Young’s modulus, and deformation at rupture. A significance testing program including more than 100 tests was performed. Owing to the heterogeneity of the plant yarn, each group received more than 20 samples at a gauge length (GL) of 100 mm. The tensile strength characteristics of sisal yarns produced a wide range of findings, as is common for natural fibers, necessitating a statistical analysis. Its dispersion was explored and measured using the statistical methods. The Weibull distribution with two parameters and a prediction model with a 95% confidence level for maximum likelihood (ML) and least squares (LS) were used to investigate and quantify its dispersion. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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15 pages, 7395 KiB  
Article
Enhanced Open-Hole Strength and Toughness of Sandwich Carbon-Kevlar Woven Composite Laminates
by Mohammad K. A. Khan, Harri Junaedi, Hassan Alshahrani, Ahmed Wagih, Gilles Lubineau and Tamer A. Sebaey
Polymers 2023, 15(10), 2276; https://doi.org/10.3390/polym15102276 - 11 May 2023
Cited by 1 | Viewed by 1607
Abstract
Fiber-reinforced plastic composites are sensitive to holes, as they cut the main load-carrying member in the composite (fibers) and they induce out-of-plane stresses. In this study, we demonstrated notch sensitivity enhancement in a hybrid carbon/epoxy (CFRP) composite with a Kevlar core sandwich compared [...] Read more.
Fiber-reinforced plastic composites are sensitive to holes, as they cut the main load-carrying member in the composite (fibers) and they induce out-of-plane stresses. In this study, we demonstrated notch sensitivity enhancement in a hybrid carbon/epoxy (CFRP) composite with a Kevlar core sandwich compared to monotonic CFRP and Kevlar composites. Open-hole tensile samples were cut using waterjet cutting at different width to diameter ratios and tested under tensile loading. We performed an open-hole tension (OHT) test to characterize the notch sensitivity of the composites via the comparison of the open-hole tensile strength and strain as well as the damage propagation (as monitored via CT scan). The results showed that hybrid laminate has lower notch sensitivity than CFRP and KFRP laminates because the strength reduction rate with hole size was lower. Moreover, this laminate showed no reduction in the failure strain by increasing the hole size up to 12 mm. At w/d = 6, the lowest drop in strength showed by the hybrid laminate was 65.4%, followed by the CFRP and KFRP laminates with 63.5% and 56.1%, respectively. For the specific strength, the hybrid laminate showed a 7% and 9% higher value as compared with CFRP and KFRP laminates, respectively. The enhancement in notch sensitivity was due to its progressive damage mode, which was initiated via delamination at the Kevlar–carbon interface, followed by matrix cracking and fiber breakage in the core layers. Finally, matrix cracking and fiber breakage occurred in the CFRP face sheet layers. The specific strength (normalized strength and strain to density) and strain were larger for the hybrid than the CFRP and KFRP laminates due to the lower density of Kevlar fibers and the progressive damage modes which delayed the final failure of the hybrid composite. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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22 pages, 29660 KiB  
Article
Mechanical Properties Degradation of Fiberglass Tubes during Biaxial Proportional Cyclic Loading
by Valeriy Wildemann, Oleg Staroverov, Elena Strungar, Artur Mugatarov and Artur Kuchukov
Polymers 2023, 15(9), 2017; https://doi.org/10.3390/polym15092017 - 24 Apr 2023
Cited by 2 | Viewed by 1322
Abstract
Composite structures during an operation are subjected to various types of external loading (impact, vibration, cyclic, etc.), which may lead to a decrease in mechanical properties. Previously, many experimental investigations of the mechanical behavior of composites under uniaxial cyclic loading were carried out. [...] Read more.
Composite structures during an operation are subjected to various types of external loading (impact, vibration, cyclic, etc.), which may lead to a decrease in mechanical properties. Previously, many experimental investigations of the mechanical behavior of composites under uniaxial cyclic loading were carried out. Acquisition of new data on the reduction of composite materials’ mechanical characteristics under conditions of multiaxial cyclic loading, as well as verification of existing models for calculation of the residual properties, are relevant. Therefore, this work is devoted to the experimental investigation of the mechanical behavior of fiberglass tubes under proportional cyclic loading. Static and fatigue tests were carried out under tension with torsion conditions. Inhomogeneous strain fields were obtained using a non-contact optical video system VIC-3D. The structural damage accumulation processes were analyzed by an AMSY-6 acoustic emission signals recording system. Surface defects were determined using a DinoLite microscope. Residual dynamic elastic modules were calculated during fatigue tests, and fatigue sensitivity curves were built. Data was approximated using various models, and their high descriptive capability was revealed. Damage accumulation stages were determined. The dependence of the models’ parameters on a stress state were observed. It was concluded that multiaxial cyclic loading leads to a significant decrease in mechanical properties, which should be taken into account in composite structure design. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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25 pages, 5814 KiB  
Article
Prediction of The Mechanical Behavior of Polylactic Acid Parts with Shape Memory Effect Fabricated by FDM
by Zhamila Issabayeva and Igor Shishkovsky
Polymers 2023, 15(5), 1162; https://doi.org/10.3390/polym15051162 - 25 Feb 2023
Cited by 6 | Viewed by 1702
Abstract
In this study, the mechanical as well as thermomechanical behaviors of shape memory PLA parts are presented. A total of 120 sets with five variable printing parameters were printed by the FDM method. The impact of the printing parameters on the tensile strength, [...] Read more.
In this study, the mechanical as well as thermomechanical behaviors of shape memory PLA parts are presented. A total of 120 sets with five variable printing parameters were printed by the FDM method. The impact of the printing parameters on the tensile strength, viscoelastic performance, shape fixity, and recovery coefficients were studied. The results show that two printing parameters, the temperature of the extruder and the nozzle diameter, were more significant for the mechanical properties. The values of tensile strength varied from 32 MPa to 50 MPa. The use of a suitable Mooney–Rivlin model to describe the hyperelastic behavior of the material allowed us to gain a good fit for the experimental and simulation curves. For the first time, using this material and method of 3D printing, the thermomechanical analysis (TMA) allowed us to evaluate the thermal deformation of the sample and obtain values of the coefficient of thermal expansion (CTE) at different temperatures, directions, and running curves from 71.37 ppm/K to 276.53 ppm/K. Dynamic mechanical analysis (DMA) showed a similar characteristic of curves and similar values with a deviation of 1–2% despite different printing parameters. The glass transition temperature for all samples with different measurement curves ranged from 63–69 °C. A material crystallinity of 2.2%, considered by differential scanning calorimetry (DSC), confirmed its amorphous nature. From the SMP cycle test, we observed that the stronger the sample, the lower the fatigue from cycle to cycle observed when restoring the initial shape after deformation, while the fixation of the shape did not almost decrease with each SMP cycle and was close to 100%. Comprehensive study demonstrated a complex operational relationship between determined mechanical and thermomechanical properties, combining the characteristics of a thermoplastic material with the shape memory effect and FDM printing parameters. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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15 pages, 1977 KiB  
Article
Sorption Properties of PET Copolyesters and New Approach for Foaming with Filament Extrusion Additive Manufacturing
by Nadiya Sova, Bohdan Savchenko, Victor Beloshenko, Aleksander Slieptsov and Iurii Vozniak
Polymers 2023, 15(5), 1138; https://doi.org/10.3390/polym15051138 - 24 Feb 2023
Cited by 1 | Viewed by 1406
Abstract
The mass transfer process of binary esters of acetic acid in polyethylene terephthalate (PET), polyethylene terephthalate with a high degree of glycol modification (PETG), and glycol-modified polycyclohexanedimethylene terephthalate (PCTG) was studied. It was found that the desorption rate of the complex ether at [...] Read more.
The mass transfer process of binary esters of acetic acid in polyethylene terephthalate (PET), polyethylene terephthalate with a high degree of glycol modification (PETG), and glycol-modified polycyclohexanedimethylene terephthalate (PCTG) was studied. It was found that the desorption rate of the complex ether at the equilibrium point is significantly lower than the sorption rate. The difference between these rates depends on the type of polyester and temperature and allows the accumulation of ester in the volume of the polyester. For example, the stable content of acetic ester in PETG at 20 °C is 5 wt.%. The remaining ester, which has the properties of a physical blowing agent, was used in the filament extrusion additive manufacturing (AM) process. By varying the technological parameters of the AM process, foams of PETG with densities ranging from 150 to 1000 g/cm3 were produced. Unlike conventional polyester foams, the resulting foams are not brittle. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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19 pages, 7149 KiB  
Article
Mechanical Properties of Polyurethane Mixture and Load Response Behaviour of Polyurethane Composite Pavement
by Wei Zhuang, Yufeng Bi, Baoju Liu, Derui Hou, Shuo Jing, Xiaojin Lu and Min Sun
Polymers 2023, 15(2), 417; https://doi.org/10.3390/polym15020417 - 12 Jan 2023
Cited by 2 | Viewed by 1471
Abstract
Finite element numerical simulation calculation of pavement structure load response is widely applied; however, there is still a lack of research on the polyurethane (PU) mixture composite pavement load response. The mechanical characteristics of PU mixture composite pavement are not well understood, and [...] Read more.
Finite element numerical simulation calculation of pavement structure load response is widely applied; however, there is still a lack of research on the polyurethane (PU) mixture composite pavement load response. The mechanical characteristics of PU mixture composite pavement are not well understood, and there is a lack of research on typical pavement structures of PU mixtures, which limits their application in pavement structures. Therefore, herein, the mechanical properties of PU mixtures are analysed using the dynamic modulus test, uniaxial penetration test, and fatigue test. Further, the finite element theory calculation method is used to realize the load response calculation of orthogonal design composite pavement structure. The results show that PU mixtures exhibit more obvious elastic characteristics and have good shear resistance, fatigue stability, and temperature stability, and can be used as shear and anti-fatigue layers. The structure of ‘4 cm SMA-13 + 5 cm PUM-20 + 6 cm PUM-25 + semi-rigid base’ is recommended for the PU mixture composite structure. In comparison to typical asphalt pavement, the analysis shows that except for shear stress, temperature has little effect on the load response of PU composite pavement structures, while high temperatures lead to a significant increase in the load response of typical asphalt pavement structures. The PU composite pavement can bear greater loads and has a reduced thickness of its surface layer by about 3 cm in comparison to conventional pavement. The results of this study provide theoretical support for the design of PU mixture pavement structures and promote the popularization and application of PU mixture pavement. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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Review

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22 pages, 7627 KiB  
Review
Stab-Resistant Polymers—Recent Developments in Materials and Structures
by Niklas Panneke and Andrea Ehrmann
Polymers 2023, 15(4), 983; https://doi.org/10.3390/polym15040983 - 16 Feb 2023
Cited by 4 | Viewed by 3247
Abstract
Stab-resistant garments have been used for centuries, utilizing metals, paper, or polymeric structures, often inspired by natural structures such as scales. Nowadays, stab-resistant vests or vest inserts are used by police and security personnel, but also by bus drivers, ambulance officers, and other [...] Read more.
Stab-resistant garments have been used for centuries, utilizing metals, paper, or polymeric structures, often inspired by natural structures such as scales. Nowadays, stab-resistant vests or vest inserts are used by police and security personnel, but also by bus drivers, ambulance officers, and other people who are empirically often attacked on duty. Since stab protection garments are often heavy and thus uncomfortable and not well accepted, whether in the form of chain-mail or metal inserts in protective vests, researchers are striving to find lightweight, drapable alternatives, often based on polymeric materials. These research attempts have recently focused on textile fabrics, mostly with impregnation by shear-thickening fluids (STFs) or ceramic coatings, as well as on lightweight composites. The first studies on 3D printed polymeric objects with tailored shapes, as well as theoretical investigations of the stab-protective effect of different materials, have been published throughout the last years. Here, we discuss different measurement methods, including dynamic and quasistatic methods, and correlations of stab-resistance with other physical properties, before we give an overview of recent developments of stab-resistant polymers, using different materials/material combinations and structures. Full article
(This article belongs to the Special Issue Mechanical Behavior of Polymeric Materials: Recent Study)
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