An overview of polymer foam technologies with a focus on polylactic acid, polypropylene, and polyamide 6-based materials

Introduction: hip joint replacement surgery involves replacing the damaged joint with an implant that can re-create the joint's articulation functionality. 3D printing technology is more promising than the traditional manufacturing process when it comes to producing more complex parts and shapes. The goal of the current research project is to determine how quickly biomaterial implant can be manufactured using 3D printing for hip-joint replacement by studying the wear rate of parts manufactured using different printing orientations. Although there are several additive manufacturing technologies, fuse deposition modeling (FDM) technology has had a significant impact on healthcare, automotive industry, etc. This is mainly due to the adaptability of different polymer-based composite materials and its cost-effectiveness. Such 3D printed polymers need to be further studied to evaluate the wear rate depending on different 3D printing orientations. Polylactic acid (PLA) biomaterials were extensively studied to determine its suitability for use as hip joint materials. Purpose of the work: in this work, an experimental study was carried out on the effect of printing orientation on dry sliding wear of a polylactic acid (PLA) material obtained by fused deposition modeling (FDM) technology using the pin-on-disk (SS 316) scheme. In addition, experimental and empirical models are developed to predict the performance taking into account the influence of load and sliding speed. Grey relational analysis was used to determine the optimal parameters. The methods of investigation: the FDM printing was used to manufacture pins using different printing orientations. Printing direction refers to printing at angles of 0°, 45°, and 90°, while all other 3D printing parameters remained unchanged. Wear testing was performed using the pin-on-disk kinematic scheme. During the experiments, the normal pin load and disk rotation speed were varied. The experiments were methodically designed to study the effect of input parameters on the specific wear rate. About 13 experiments were conducted for each printing orientation with a friction path of 4 kilometers, in the load range of 400–800 N, at a sliding speed of 450–750 rpm. Result and discussion: the study provides important results especially regarding the direction of 3D printing of components. It was found that the lowest sliding wear was observed for the pin printed at an angle of 0°, while slightly higher wear was observed for the pin printed at an angle of 90°. The layer bonding in the pin printed at an angle of 45° deformed under higher load, mainly due to an increase in temperature. The low bond strength in the pin printed at an angle of 45° resulted in high sliding wear. The optimal result was achieved at a sliding speed of 451 rpm and a load of 600 N. The results of the study are very useful for choosing materials for 3D printing of biomedical implants, medical and industrial products.

The variations of dielectric properties of epoxyamine polymers and polymer-based composite materials during ground-based tests imitating the influence of space environment factors and under the conditions of long-term active experiments using the ERE instrumentation onboard the Mir station are compared. The influence of space environment factors is shown to result in both reversible and irreversible changes of dielectric properties. The former are related to temperature effects and effects of charged particles. The latter are related to the removal of low-molecular components from the composition of binders in a vacuum, and to increasing density of polymeric lattice under an effect of thermal cycling and various types of radiations. It is established that the influence of ultra-violet radiation reveals itself, first of all, in changing temperature of samples, while the influence of irradiation by a flux of electrons is reduced to charge accumulation and discharges.

Various types of composite materials are becoming an inevitable part of our day-to-day life since these are used for a variety of applications. A better understanding on the various properties of the composites is very helpful in their targeted applications, and hence characterizing the composite materials by different techniques play a major role in the development of long-life, high-quality composite products. The polymer-based composite materials provide large amount of flexibility and lightweight to the final product. The selection of various reinforcements and polymer matrices is very critical in designing a desired product. In this chapter, various techniques used for characterizing the polymer-based composite materials in order to examine their mechanical, thermal, electrical, magnetic, piezoelectric, tribological, rheological, and biological properties are discussed.

Polymer-based composite materials resulted from a combination of a variety of raw materials to form a new composite material. The use of a type of polymer-based composite material, known as the Glass Fibre Reinforced Polymer (GFRP) has been on the increase today. GFRP Industrialised Building System (IBS) has been developed in the form of prefabricated structural beams, slabs, walls, staircases, and trusses for applications in buildings and bridges. For applications of the IBS system especially in areas that are often vulnerable to flooding, special attention needs to be paid to the water/flood-resistant properties of such a system. Most of the existing materials adopted for building construction are not intended to be used in flood environments, as they have a high percentage of water absorption. High water absorption of GFRP will result in the reduction of its mechanical properties. Therefore, the objective of this study is to obtain and improve the GFRP composite properties for use as a flood-resistant structure. The experiments involved materials such as woven fibreglass matrix, polyester resin, fly ash and calcium carbonate. The fly ash and calcium carbonate are introduced as filler materials to study their influence on the mechanical and water absorption properties of the GFRP composite. In total, 21 samples were tested for tensile, compressive and flexural strengths, and also water absorption. The results obtained from tensile tests found that the maximum tensile strength is 172.8 MPa for the composition of 10% of both fly ash and calcium carbonate. Through compression and three-point bending tests, the maximum compressive and flexural strengths are 169.2 MPa and 327.3 MPa, respectively for the composition of 5% fly ash and 15% calcium carbonate. The composition of 5% calcium carbonate and 15% fly ash yielded the lowest water absorption at 0.45%. It was discovered that compared to the conventional concrete, the percentage water absorption of the RHA concrete cured with 5% NaCl absorbs less water with increase in replacement proportions of RHA [9]. In conclusion, calcium carbonate improves mechanical strength while fly ash reduces water absorption.KeywordsGFRPCalcium carbonateFly ashMechanical propertiesWater absorption

Due to the variety of properties of the composites produced, determining the choice of the appropriate cutting technique is demanding. Therefore, it is necessary to know the problems associated with cutting operations, i.e., mechanical cutting (blanking), plasma cutting plasma, water jet cutting, abrasive water jet cutting, laser cutting and electrical discharge machining (EDM). The criterion for choosing the right cutting technique for a specific application depends not only on the expected cutting speed and material thickness, but it is also related to the physico-mechanical properties of the material being processed. In other words, the large variety of composite properties necessitates an individual approach determining the possibility of cutting a composite material with a specific method. This paper presents the achievements gained over the last ten years in the field of non-conventional cutting of metal-based and polymer-based composite materials. The greatest attention is paid to the methods of electrical discharge machining and ultrasonic cutting. The methods of high-energy cutting and water jet cutting are also considered and discussed. Although it is well-known that plasma cutting is not widely used in cutting composites, the authors also took into account this type of cutting treatment. The volume of each chapter depends on the dissemination of a given metal-based and polymer-based composite material cutting technique. For each cutting technique, the paper presents the phenomena that have a direct impact on the quality of the resulting surface and on the formation of the most important defects encountered. Finally, the identified current knowledge gaps are discussed.

Influence of second-phase particles on fracture behavior of PLA and advanced PLA-X material

Polymers play an important role in our everyday life. With the advent of additive manufacturing (AM) technologies, the design and manufacture of new polymer-based composite materials has experienced a significant boost. AM enables precise deposition of printable material(s) with micro scale accuracy to build up a desired structure in three dimensions in a layer-by-layer fashion. In this chapter, recent advances in the use of additive manufacturing for the design of architectured polymer-based materials is discussed. A compendium of the existing AM methods is presented, followed by an overview of applications of AM technology to fabrication of polymer-based materials with engineered inner architecture.

Time-dependent changes of mechanical properties of polymer-based composite materials for adhesive anchor systems

Purpose The purpose of this study is to investigate the influences of extruder temperatures and raster orientations on the mechanical properties of polylactic-acid (PLA) material processed by using fused filament fabrication (FFF). Design/methodology/approach In this research, the PLA specimens were first printed with nozzle or extruder temperatures of 205°C, 215°C and 225°C and then evaluated in terms of their physical, chemical and mechanical properties. An appropriate extruder temperature was then selected based on this experiment and used for the printing of the other PLA specimens having various raster orientations. A series of tensile tests were carried out again to investigate the influence of raster orientations on the tensile strength, tensile strain and elastic modulus of those FFF-processed PLA materials. In the end, the one-way ANOVA was applied for the statistical analysis and the Mohr’s circle was established to aid in the analysis of the data obtained in this experiment. Findings The result of this study shows that the chemistry, porosity, degree of crystallinity and mechanical properties (tensile strength, strain and elastic modulus) of the PLA material printed with a raster angle of 0° were all insensitive to the increasing extruder temperature from 205°C to 225°C. Meanwhile, the mechanical properties of such printed PLA material were obviously influenced by its raster orientation. In this case, a PLA material with a raster orientation parallel to its loading axis, i.e. those with a raster angle of θ = 0°, was found as the strongest material. Meanwhile, the raster configuration-oriented perpendicular to its loading axis or θ = 90° yielded the weakest PLA material. The results of the tensile tests for the PLA material printed with bidirectional raster orientations, i.e. θ = 0°/90° and 45°/−45° demonstrated their strengths with values falling between those of the materials having unidirectional raster θ = 0° and 90°. Furthermore, the result of the analysis by using a well-known Mohr’s circle confirmed the experimental tensile strengths and the failure mechanisms of the PLA material that had been printed with various raster orientations. Originality/value This study presented consistent results on the chemistry, physical, degree of crystallinity and mechanical properties of the FFF-processed PLA in responding to the increasing extruder temperature from 205°C to 225°C applied during the printing process. Unlike the results of the previous studies, all these properties were also found to be insensitive to the increase of extruder temperature. Also, the result of this research demonstrates the usability of Mohr’s circle in the analysis of stresses working on an FFF-processed PLA material in responding to the changes in raster orientation printed in this material.

Lightweight and tough multilayered composite based on poly(aryl ether nitrile)/carbon fiber cloth for electromagnetic interference shielding

Composite microgranular scaffolds with surface modifications for improved initial osteoblastic cell proliferation

3 - Mechanical properties of polymer/graphene composites

Polymer materials are increasingly dominating various engineering fields. Recently, polymer-based composite materials’ surface performances—in particular, surface in relative motion—have been improved markedly by thermal spray coating. Despite this recent progress, the deposition of high-strength materials—producing a coating thickness of the order of more than 500 μm—remains highly challenging. In the present work, a highly dense and thick titanium coating was successfully deposited onto the carbon fiber-reinforced plastic (CFRP) substrate using a newly developed high-pressure warm spray (WS) system. The coating properties, such as hardness (300 ± 20 HV) and adhesion strength (8.1 ± 0.5 MPa), were evaluated and correlated with the microstructures of the coating. In addition, a wipe-test and in situ particle velocity and temperature measurement were performed to validate the particle deposition behavior as a function of the nitrogen flow rate in the WS system. It was found that the microstructures, deposition efficiency, and mechanical properties of the coatings were highly sensitive to nitrogen flow rates. The coating porosity increased with increasing nitrogen flow rates; however, the highest density was observed for nitrogen flow rate of 1000 standard liters per minute (SLM) samples due to the high fraction of semi-molten particles in the spray stream.

Purpose Auxetic structures are one type of mechanical meta-materials mainly used for energy absorption applications because of their unique negative Poisson’s ratio. This study is focused on numerical and experimental investigations of fused deposition modeling (FDM) fabricated re-entrant auxetic structures of acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) materials under compressive loading. Influence of geometric parameters, namely, re-entrant angle, height and arm-length on strength, stiffness and specific energy absorption (SEA) of auxetic structures under compressive loading. Optimization of significant parameters is also performed to maximize these responses and minimize weight and time of fabrication. Further, efforts have also been made to develop predictive models for strength, stiffness and SEA of auxetic structures. Design/methodology/approach A full factorial design of experiment is used for planning experiments. Auxetic structures of ABS and PLA are fabricated by FDM technique of additive manufacturing within the constrained range of geometric parameters. Analysis of variance is performed to identify the influence of geometric parameters on responses. To optimize the geometric parameters Gray relational analysis is used. Deformation of auxetic structures is studied under compressive loading. A numerical investigation is also performed by building nonlinear finite element models of auxetic structures. Findings From the analysis of results, it is found that re-entrant angle, height and arm-length with their interactions are significant parameters influencing responses, namely, strength, stiffness and SEA of the auxetic structures of ABS and PLA materials. Based on the analysis, statistical nonlinear quadratic models are developed to predict these responses. Optimal configurations of auxetic structure of ABS and PLA are determined to maximize strength, stiffness, SEA and minimize weight and time of fabrication. From the study of deformation of auxetic structures, it is found that ABS structures have higher energy absorption, whereas PLA structures have better stiffness. Results of finite element analysis (FEA) are found in good agreement with experimental results. Research limitations/implications The present study is limited to re-entrant type of auxetic structures of ABS and PLA materials only under compressive loading. Also, results from the present study are valid within the selected range of geometric parameters. The findings of the present study are useful in maximizing strength, stiffness and SEA of auxetic structures that have wide applications in the automotive, aerospace, sports and marine sector. Originality/value No literature is available on studying the influence of geometric parameters, namely, re-entrant angle, height and arm-length of auxetic structure on strength, stiffness and SEA under compressive loading. Also, a comparative study of feedstock materials, namely, ABS and PLA, is also not reported. The present work attempts to fulfill the above research gaps.

Active use of polymeric materials has become an integral part of all areas of modern medicine. Wound dressings capable of prolonged release of drugs directly into the lesion occupy a special place among them. The possibility of using such materials in the presence of low-intensity currents without external power supplies in a comprehensive treatment program for patients with burn injuries remains promising. The aim of the work is to study experimentally the antimicrobial efficacy of a new composite polymeric material based on poly(2-hydroxyethyl methacrylate), saturated with the antiseptic decamethoxine, under conditions of low-intensity current without external power supplies. The method of free radical thermal polymerization of a mixture of liquid monomer 2-hydroxyethyl methacrylate, crosslinking agent triethylene glycol dimethacrylate, polymerization initiator azobisisobutyronitrile was used for the synthesis of composite polymeric material. In addition, fourfold volume of distilled water as a pore-forming agent and decamethoxine as an antimicrobial component were administered. Known dressings of synthetic and biological origin were selected for comparison, some of which were pre-soaked in a 0.02% solution of decamethoxine. The study of conductivity of the materials without external power supplies was performed on the surface of a dense nutrient medium in a Petri dish using VITA-01M measuring device. Determination of antibacterial properties was performed by diffusion into agar. The obtained results allowed to establish the ability of the suggested polymeric material to conduct low-intensity currents without external power supplies, exceeding the duration of other traditional dressings. Comparison of antimicrobial activity of the studied samples confirmed the synergism of the action of physical factors and a new polymer-based composite material with the addition of antimicrobial substance to inhibit the growth of the test museum and clinical strains of Staphylococcus aureus. The ability of low-intensity currents without external power supplies to potentiate the antimicrobial properties of a new composite polymeric material based on poly(2-hydroxyethyl methacrylate), modified with a pore-forming agent, with the addition of decamethoxine was experimentally established.