Structure and Mechanical Properties of Polymer Composites

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 July 2023) | Viewed by 9496

Special Issue Editors

Materials Science & Engineering, Vice President for Research and Dean of Graduate School, Tuskegee University, Tuskegee, AL, USA
Interests: polymer composites; structural composites; nanotechnology; bio based materials
Department of Materials Science and Engineering, Tuskegee University, Tuskegee, AL, USA
Interests: composites; sustainable materials; additive manufacturing; self-healing materials

Special Issue Information

Dear Colleagues,

Composites with diverse filler materials and polymeric matrix are being explored extensively for a variety of applications such as in the fields of aerospace, automotive, construction, electronics, and medicine. By leveraging useful properties of their constituent materials, polymeric composites can improve the structural reliability and mechanical performance of the bulk material. During the composite materials development process, the most important aspects to be considered are the characteristics of reinforcement fillers, the host matrix, and the interface between them. Various polymers can be used for the development of composite materials such as petroleum-based polymers and biopolymers. Similarly, there is a huge array of available reinforcement filler materials, depending on their source (synthetic or natural), size (nano, micro, short, or continuous), and inherent characteristics. With recent developments in the field of material synthesis, processing, and manufacturing, the need for the development of improved advanced and sustainable materials is increasing. Extensive research is being carried out in the field of materials science to address these challenges.

This Special Issue aims to report innovative work in the field of material synthesis and the processing of polymeric composite materials, particularly to improve the structural reliability and mechanical performance. 

Prof. Dr. Shaik Jeelani
Dr. Zaheeruddin Mohammed
Guest Editors

Manuscript Submission Information

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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

  • composite materials
  • structural composites
  • nanocomposites
  • fiber-reinforced composites
  • fracture and fatigue of composites
  • damage mechanics
  • additive manufacturing
  • sustainable materials

Published Papers (5 papers)

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Research

14 pages, 8008 KiB  
Article
Analysis of the Stress Field in Photoelasticity Used to Evaluate the Residual Stresses of a Plastic Injection-Molded Part
by Carlos Vargas-Isaza, Juan Posada-Correa and Juan Briñez-de León
Polymers 2023, 15(16), 3377; https://doi.org/10.3390/polym15163377 - 11 Aug 2023
Cited by 4 | Viewed by 1358
Abstract
The degree of quality of thermoplastic injection-molded parts can be established based on their weight, appearance, and defects. However, the conditions of the injection process may induce effects on the mechanical performance of the injected parts, and the residual stresses can cause cracks [...] Read more.
The degree of quality of thermoplastic injection-molded parts can be established based on their weight, appearance, and defects. However, the conditions of the injection process may induce effects on the mechanical performance of the injected parts, and the residual stresses can cause cracks or early failures when an external load or force is applied. To evaluate these mechanical behaviors, different experimental techniques have been reported in the literature, where digital photoelasticity has stood out both for being a non-contact technique and for achieving quantitative results through sophisticated computational algorithms. Against this background, our proposal consists of analyzing the overall residual stress distribution of parts injected under different molding conditions by using digital photoelasticity. In this case, the specimens are subjected to bending strength tests to identify possible effects of the injection process conditions. The findings show that, at mold temperatures of 80 °C, flow-induced residual stresses increase with packing pressure. However, these internal stress levels do not affect the external load applied by the mechanical bending test, while the mass injected at higher levels of packing pressure helps to increase the bending strength of the injected part. At lower mold temperatures (50 °C), the mechanical strength of the injected part is slightly reduced, possibly due to a lower effect of the packing pressure. Full article
(This article belongs to the Special Issue Structure and Mechanical Properties of Polymer Composites)
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17 pages, 7532 KiB  
Article
A Numerical Study on Carbon-Fiber-Reinforced Composite Cylindrical Skirts for Solid Propeller Rockets
by Ferdinando Baldieri, Emanuele Martelli and Aniello Riccio
Polymers 2023, 15(4), 908; https://doi.org/10.3390/polym15040908 - 11 Feb 2023
Viewed by 1245
Abstract
A solid rocket motor (SRM) is a rocket engine that uses a fuel/oxidizer mixture in a solid state; the most commonly employed propellants are Hydroxyl-Terminated Polybutadiene (HTPB) as the fuel and ammonium/potassium perchlorate as the oxidizer. To increase the flight range of this [...] Read more.
A solid rocket motor (SRM) is a rocket engine that uses a fuel/oxidizer mixture in a solid state; the most commonly employed propellants are Hydroxyl-Terminated Polybutadiene (HTPB) as the fuel and ammonium/potassium perchlorate as the oxidizer. To increase the flight range of this kind of vehicle, the weight has to be reduced as much as possible. A possible element that can be worked on is the coating of the combustion chamber: the skirt. The aim of this paper is to investigate the behavior of a cylindrical skirt subjected to internal pressure load and axial thrust and to compare the performance of a skirt made of a standard steel for aeronautics purposes with a carbon-fiber-reinforced composite skirt. The motor test case is taken from the ONERA C1xb and the flowfield is simulated with an axisymmetric k-ω turbulence model. The carbon-fiber-reinforced composite skirt is a cylindrical shell with a symmetric and balanced layup [90/0/45/−45]s. To check composite layer integrity, Hashin’s failure criteria were adopted while linearized buckling methods were used to assess the buckling behavior of the skirt. The composite layup was modeled by adopting the classical laminate theory. Full article
(This article belongs to the Special Issue Structure and Mechanical Properties of Polymer Composites)
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27 pages, 9880 KiB  
Article
Experimental Study on Mechanical Properties of Basalt Fiber Concrete after Cryogenic Freeze−Thaw Cycles
by Yang Li, Zhicong Gu, Ben Zhao, Jiangkun Zhang and Xu Zou
Polymers 2023, 15(1), 196; https://doi.org/10.3390/polym15010196 - 30 Dec 2022
Cited by 5 | Viewed by 1691
Abstract
Basalt fiber (BF) has received much attention in recent years for engineering practice and scientific research related to basalt fiber reinforced concrete (BFRC) due to its advantageous mechanical properties and cost-effectiveness. By researching its performance characteristics after cryogenic freeze–thaw cycles, the advantages of [...] Read more.
Basalt fiber (BF) has received much attention in recent years for engineering practice and scientific research related to basalt fiber reinforced concrete (BFRC) due to its advantageous mechanical properties and cost-effectiveness. By researching its performance characteristics after cryogenic freeze–thaw cycles, the advantages of BFRC’s mechanical properties can be further exploited in order to expand its application scope. The effects of the fiber volume fraction, temperature gradient, and number of freeze–thaw cycles on the compressive strength, toughness index, splitting tensile strength, flexural strength, etc., of BFRC were investigated. Additionally, the damage mechanism of BFRC after freeze–thaw cycles was analyzed via scanning electron microscopy (SEM). The results show that the compressive strength of BFRC reaches its peak value when the fraction reaches 0.1% under the conditions of freezing and thawing cycles from room temperature to −80 °C. When the fraction of BFRC is 0.1%, and the maximum reduction is 17.1%, the splitting tensile strength decreased most sharply when the fraction was 0.1%, and the decrease amplitude was 40.9%, and the flexural strength decreased most acutely when the fraction was 0.3%, and the maximum decrease was 44.62%. The addition of basalt fibers can reduce the damage to the microstructure of concrete and improve its plastic degradation characteristics to a certain extent. With a decrease in the minimum temperature of the cryogenic freeze–thaw cycle, the optimal fiber content for compressive strength increases. Nevertheless, the splitting tensile strength and flexural strength of BFRC is improved as the fiber content increases under the cryogenic freeze–thaw environment. Full article
(This article belongs to the Special Issue Structure and Mechanical Properties of Polymer Composites)
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14 pages, 4845 KiB  
Article
A Study on Hot Stamping Formability of Continuous Glass Fiber Reinforced Thermoplastic Composites
by Feng Zhao, Wei Guo, Wei Li, Huajie Mao, Hongxu Yan and Jingwen Deng
Polymers 2022, 14(22), 4935; https://doi.org/10.3390/polym14224935 - 15 Nov 2022
Cited by 3 | Viewed by 1761
Abstract
In this study, hot stamping tests on continuous glass fiber (GF)-reinforced thermoplastic (PP) composites were conducted under different process parameters using a self-designed hemispherical hot stamping die with a heating system. The effects of parameters such as preheating temperature, stamping depth, and stamping [...] Read more.
In this study, hot stamping tests on continuous glass fiber (GF)-reinforced thermoplastic (PP) composites were conducted under different process parameters using a self-designed hemispherical hot stamping die with a heating system. The effects of parameters such as preheating temperature, stamping depth, and stamping speed on the formability of the fabricated parts were analyzed using optical microscopy and scanning electron microscopy (SEM). The test results show that the suitable stamping depth should be less than 15 mm, the stamping speed should be less than 150 mm/min, and the preheating temperature should be about 200 °C. From the edge of the formed parts to their pole area, a thin-thick-thin characteristic in thickness was observed. Under the same preheating temperature, the influence of stamping depth on the thickness variation of the formed parts was more significant than the stamping speed. The primary defects of the formed parts were cracking, wrinkling, delamination, and fiber exposure. Resin poverty often occurred in the defect area of the formed parts and increased with stamping depth and stamping speed. Full article
(This article belongs to the Special Issue Structure and Mechanical Properties of Polymer Composites)
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19 pages, 6030 KiB  
Article
Characterization of Polyurethane Shape Memory Polymer and Determination of Shape Fixity and Shape Recovery in Subsequent Thermomechanical Cycles
by Maria Staszczak, Mana Nabavian Kalat, Karol Marek Golasiński, Leszek Urbański, Kohei Takeda, Ryosuke Matsui and Elżbieta Alicja Pieczyska
Polymers 2022, 14(21), 4775; https://doi.org/10.3390/polym14214775 - 07 Nov 2022
Cited by 17 | Viewed by 2750
Abstract
Multifunctional polyurethane shape memory polymers (PU-SMPs) have been of increasing interest in various applications. Here we report structure characterization, detailed methodology, and obtained results on the identification of functional properties of a thermoset PU-SMP (MP4510) with glass transition temperature of 45 °C. The [...] Read more.
Multifunctional polyurethane shape memory polymers (PU-SMPs) have been of increasing interest in various applications. Here we report structure characterization, detailed methodology, and obtained results on the identification of functional properties of a thermoset PU-SMP (MP4510) with glass transition temperature of 45 °C. The stable, chemically crosslinked network of this thermoset PU-SMP results in excellent shape memory behavior. Moreover, the proximity of the activation temperature range of this smart polymer to room and body temperature enables the PU-SMP to be used in more critical industrial applications, namely fast-response actuators. The thermomechanical behavior of a shape memory polymer determines the engineering applications of the material. Therefore, investigation of the shape memory behavior of this class of commercial PU-SMP is of particular importance. The conducted structural characterization confirms its shape memory properties. The shape fixity and shape recovery properties were determined by a modified experimental approach, considering the polymer’s sensitivity to external conditions, i.e., the temperature and humidity variations. Three thermomechanical cycles were considered and the methodology used is described in detail. The obtained shape fixity ratio of the PU-SMP was approximately 98% and did not change significantly in the subsequent cycles of the thermomechanical loading due to the stability of chemical crosslinks in the thermoset materials structure. The shape recovery was found to be approximately 90% in the first cycle and reached a value higher than 99% in the third cycle. The results confirm the effect of the thermomechanical training on the improvement of the PU-SMP shape recovery after the first thermomechanical cycle as well as the effect of thermoset material stability on the repeatability of the shape memory parameters quantities. Full article
(This article belongs to the Special Issue Structure and Mechanical Properties of Polymer Composites)
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