scholarly journals Self-Healing Polymers and Composite Materials

2021 ◽  
Author(s):  
Allana Azevedo do Nascimento

In order to overcome the challenges and limitations related to conventional maintenance and repair methods in structural composites during service, the concept of self-healing for polymeric materials has been developed in the last decades. Inspired by biological systems, ideal self-healing materials must be able to repair damages continuously during the service life of the component, recovering its performance. Several techniques have been proposed in the last years to manufacture self-healing polymers and fiber-reinforced composites to provide healing of microcracks in the composite structure without or with less intervention, extending service life and safety of the components and reducing maintenance time and cost. This book chapter proposes an overview of the most promising self-healing approaches for thermoset and polymer matrix composites developed in recent year.

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 201
Author(s):  
Stefano Paolillo ◽  
Ranjita K. Bose ◽  
Marianella Hernández Santana ◽  
Antonio M. Grande

This article reviews some of the intrinsic self-healing epoxy materials that have been investigated throughout the course of the last twenty years. Emphasis is placed on those formulations suitable for the design of high-performance composites to be employed in the aerospace field. A brief introduction is given on the advantages of intrinsic self-healing polymers over extrinsic counterparts and of epoxies over other thermosetting systems. After a general description of the testing procedures adopted for the evaluation of the healing efficiency and the required features for a smooth implementation of such materials in the industry, different self-healing mechanisms, arising from either physical or chemical interactions, are detailed. The presented formulations are critically reviewed, comparing major strengths and weaknesses of their healing mechanisms, underlining the inherent structural polymer properties that may affect the healing phenomena. As many self-healing chemistries already provide the fundamental aspects for recyclability and reprocessability of thermosets, which have been historically thought as a critical issue, perspective trends of a circular economy for self-healing polymers are discussed along with their possible advances and challenges. This may open up the opportunity for a totally reconfigured landscape in composite manufacturing, with the net benefits of overall cost reduction and less waste. Some general drawbacks are also laid out along with some potential countermeasures to overcome or limit their impact. Finally, present and future applications in the aviation and space fields are portrayed.


Author(s):  
Brian S. Hayes ◽  
Luther M. Gammon

Optical Microscopy of Fiber-Reinforced Composites discusses the tools and techniques used to examine the microstructure of engineered composites and provides insights that can help improve the quality and performance of parts made from them. It begins with a review of fiber-reinforced polymer-matrix composites and their unique microstructure and morphology. It then explains how to prepare and mount test samples, how to assess lighting, illumination, and contrast needs, and how to use reagents to bring out different phases and areas of interest. It also presents the results of several studies that have been conducted using optical microscopy to gain a better understanding of processing effects, toughening approaches, defects and damage mechanisms, and structural variations. The book includes more than 180 full-color images along with clear and concise explanations of what they reveal about composite materials and processing methods. For information on the print version, ISBN 978-1-61503-044-6, follow this link.


2020 ◽  
Vol 62 (1) ◽  
pp. 63-85
Author(s):  
Rahul Roy ◽  
Emanuele Rossi ◽  
Johan Silfwerbrand ◽  
Henk Jonkers

AbstractCrack formation in concrete structures due to various load and non-load factors leading to degradation of service life is very common. Repair and maintenance operations are, therefore, necessary to prevent cracks propagating and reducing the service life of the structures. Accessibility to affected areas can, however, be difficult as the reconstruction and maintenance of concrete buildings are expensive in labour and capital. Autonomous healing by encapsulated bacteria-based self-healing agents is a possible solution. During this process, the bacteria are released from a broken capsule or triggered by water and oxygen access. However, its performance and reliability depend on continuous water supply, protection against the harsh environment, and densification of the cementitious matrix for the bacteria to act. There are vast methods of encapsulating bacteria and the most common carriers used are: encapsulation in polymeric materials, lightweight aggregates, cementitious materials, special minerals, nanomaterials, and waste-derived biomass. Self-healing efficiency of these encapsulated technologies can be assessed through many experimental methodologies according to the literature. These experimental evaluations are performed in terms of quantification of crackhealing, recovery of durability and mechanical properties (macro-level test) and characterization of precipitated crystals by healing agent (micro-level test). Until now, quantification of crack-healing by light microscopy revealed maximum crack width of 1.80mm healed. All research methods available for assesing self-healing efficiency of bacteria-based healing agents are worth reviewing in order to include a coherent, if not standardized framework testing system and a comparative evaluation for a novel incorporated bacteria-based healing agent.


2018 ◽  
Vol 48 (1) ◽  
pp. 83-106
Author(s):  
Sławomir Augustyn ◽  
Rafał Kowalski

Abstract This publication presented the main issues related to fatigue of polymer composite materials. It was featured a fatigue stress test based on composite sample, made of carbon fiber-reinforced polymer, using the four-point bending method. The test was carried out with the initial load and using positive load cycles. The perspectives of diagnostics and self-healing of composite materials, including intelligent materials, were also presented.


2018 ◽  
Vol 1148 ◽  
pp. 37-42
Author(s):  
Vemu Vara Prasad ◽  
Tanna Eswara Rao

Now a day’s eco-friendly natural fiber used as the reinforcement for the fabrication of the light weight, lower cost and biodegradable polymer matrix composites. One of such available natural reinforcement for the composite material is basalt fiber. The present paper gives a review on how the basalt fiber reinforced polymer matrix composite behave when they are adhesively, riveted and hybrid joined with other reinforcements such as aluminum, which is used for the particular or other applications and which joint gives better efficiency , suited for given application were discussed and the three joining techniques were investigated. Behavior of basalt fiber reinforced composites for the frequencies at which frequencies the failures like adhesive failure, light fiber tear, and mixed failure modes will occur. These three types of failure modes are investigated with the help of acoustic emission monitoring system.


2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Amuthakkannan Pandian ◽  
Manikandan Vairavan ◽  
Winowlin Jappes Jebbas Thangaiah ◽  
Marimuthu Uthayakumar

The study of mechanical properties of fibre reinforced polymeric materials under different environmental conditions is much important. This is because materials with superior ageing resistance can be satisfactorily durable. Moisture effects in fibre reinforced plastic composites have been widely studied. Basalt fibre reinforced unsaturated polyester resin composites were subjected to water immersion tests using both sea and normal water in order to study the effects of water absorption behavior on mechanical properties. Composites specimens containing woven basalt, short basalt, and alkaline and acid treated basalt fibres were prepared. Water absorption tests were conducted by immersing specimens in water at room temperature for different time periods till they reached their saturation state. The tensile, flexural, and impact properties of water immersed specimens were conducted and compared with dry specimens as per the ASTM standard. It is concluded that the water uptake of basalt fibre is considerable loss in the mechanical properties of the composites.


Author(s):  
K. Senthilnathan ◽  
G. Suresh ◽  
T. Srinivasan ◽  
S. Ilaiyavel ◽  
Rajesh Ravi ◽  
...  

Nowadays many of the conventional materials are effectively replaced by composite materials, because of their light weight to stiffness ratio. Gears are the very essential components in mechanical power transmission, and drive in the most industrial rotating machinery. Polymer gears are used in motion and power transmission under different loads and speeds. Gears are generally made from metallic materials but recently advanced polymeric materials were developed because of low cost, light weight, high strength and improved performance of the system. Nylon, polymers, acetal and derlin are the structural polymeric materials used in printing and robotics, mechanical machines such as washing machines, sugarcane crushing machine and gear pump that are used for power and speed transmission. The paper investigates the polymer matrix composites gear with different fiber proportions. The main objective is to make glass fiber reinforced polymer gears using epoxy resin with various proportions of E-glass CSM (5%, 10%, 15%, 20%). The work investigates the wear testing of polymer gears of different proportions with metal gear using gear testing rig. The paper focused on morphology of fractured surfaces of polymer gears using scanning electron microscope. Finally, the gear is modeled in Catia software and imported to Ansys for static structural application.


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