Hengky Eng, Saeed Maleksaeedi, Suzhu Yu, Yu Ying Clarrisa Choong, Florencia Edith Wiria, Ruihua Eugene Kheng, Jun Wei, Pei-Chen Su and Huijun Phoebe Tham
Polymeric parts produced by 3D stereolithography (SL) process have poorer mechanical properties as compared to their counterparts fabricated via conventional methods, such as…
Abstract
Purpose
Polymeric parts produced by 3D stereolithography (SL) process have poorer mechanical properties as compared to their counterparts fabricated via conventional methods, such as injection or compression molding. Adding nanofillers in the photopolymer resin for SL could help improve mechanical properties. This study aims to achieve enhancement in mechanical properties of parts fabricated by SL, for functional applications, by using well-dispersed nanofillers in the photopolymers, together with suitable post-processing.
Design/methodology/approach
Carbon nanotubes (CNTs) have high strength and Young’s modulus, making them attractive nanofillers. However, dispersion of CNTs in photopolymer is a critical challenge, as they tend to agglomerate easily. Achieving good dispersion is crucial to improve the mechanical properties; thus, suitable dispersion mechanisms and processes are examined. Solvent exchange process was found to improve the dispersion of multiwalled carbon nanotubes in the photopolymer. The UV-absorbing nature of CNTs was also discovered to affect the curing properties. With suitable post processing, coupled with thermal curing, the mechanical properties of SL parts made from CNTs-filled resin improved significantly.
Findings
With the addition of 0.25 wt.% CNTs into the photopolymer, tensile stress and elongation of the 3D printed parts increased by 70 and 46 per cent, respectively. With the significant improvement, the achieved tensile strength is comparable to parts manufactured by conventional methods.
Practical implications
This allows functional parts to be manufactured using SL.
Originality/value
In this paper, an improved procedure to incorporate CNTs into the photopolymer was developed. Furthermore, because of strong UV-absorption nature of CNTs, curing properties of photopolymer and SL parts with and without CNT fillers were studied. Optimized curing parameters were determined and additional post-processing step for thermal curing was discovered as an essential step in order to further enhance the mechanical properties of SL composite parts.
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Ramakrishna Vasireddi and Bikramjit Basu
The purpose of this paper is to investigate the possibility to construct tissue-engineered bone repair scaffolds with pore size distributions using rapid prototyping techniques…
Abstract
Purpose
The purpose of this paper is to investigate the possibility to construct tissue-engineered bone repair scaffolds with pore size distributions using rapid prototyping techniques.
Design/methodology/approach
The fabrication of porous scaffolds with complex porous architectures represents a major challenge in tissue engineering and the design aspects to mimic complex pore shape as well as spatial distribution of pore sizes of natural hard tissue remain unexplored. In this context, this work aims to evaluate the three-dimensional printing process to study its potential for scaffold fabrication as well as some innovative design of homogeneously porous or gradient porous scaffolds is described and such design has wider implication in the field of bone tissue engineering.
Findings
The present work discusses biomedically relevant various design strategies with spatial/radial gradient in pore sizes as well as with different pore sizes and with different pore geometries.
Originality/value
One of the important implications of the proposed novel design scheme would be the development of porous bioactive/biodegradable composites with gradient pore size, porosity, composition and with spatially distributed biochemical stimuli so that stem cells loaded into scaffolds would develop into complex tissues such as those at the bone–cartilage interface.
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Emrah Uysal, Mustafa Çakir and Bülent Ekici
Traditional nanocomposite production methods such as in situ polymerization, melt blending and solvent technique, have some deficits. Some of these are non-homogeneous particle…
Abstract
Purpose
Traditional nanocomposite production methods such as in situ polymerization, melt blending and solvent technique, have some deficits. Some of these are non-homogeneous particle distribution, setup difficulties, time-consuming and costly. On the other hand, three-dimensional printing technology is a quite popular method. Especially, Stereolithography (SLA) printing offers some benefits such as fast printing, easy setup and smooth surface specialties. Furthermore, surface modification of Graphene Oxide (GO) and its effects on polymer nanocomposites are quite important. The purpose of this study is to examine the effect of surface modification of GO nanoparticles on the mechanical properties and morphology of epoxy acrylate (BisGMA/1,6 hexane diol diacrylate) matrix nanocomposites.
Design/methodology/approach
In this study, Ultraviolet (UV) curable end groups of synthesized resin were linked to functional groups of graphene oxide, which are synthesized by the Tour method, which is a kind of modified Hummer method. In addition, synthesized GO nanoparticle’s surfaces were modified by 3-(methacryloyloxy) propyl trimethoxysilane. Significant weight percentages of GO were added into the epoxy acrylate resin. Different Wt.% of modified graphene oxide/acrylate resins was used to print test specimens with SLA type three-dimensional printer.
Findings
Surface modification has a significant effect on tensile strength for graphene oxide nanoparticles contained composites. In addition, a specific trend was not observed for tensile test results of non-modified graphene oxide. The tendency of impact and hardness test finding were similar for both surfaces modified and non-modified nanoparticles. Finally, the distribution of particles was homogeneous.
Originality/value
This paper is unique because of the inclusion of both surface modifications of graphene oxide nanoparticles and SLA production of nanocomposites with its own production of three-dimensional printer and photocurable polymer resin.
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Dilpreet Singh, Bhavuk Garg, Pulak Mohan Pandey and Dinesh Kalyanasundaram
The purpose of this paper is to establish a methodology for the design and development of patient-specific elbow implant with an elastic modulus close to that of the human bone…
Abstract
Purpose
The purpose of this paper is to establish a methodology for the design and development of patient-specific elbow implant with an elastic modulus close to that of the human bone. One of the most preferred implant material is titanium alloy which is about 8 to 9 times higher in strength than that of the human bone and is the closest than other metallic biomedical materials.
Design/methodology/approach
The methodology begins with the design of the implant from patient-specific computed tomography information and incorporates the manufacturing of the implant via a novel rapid prototyping assisted microwave sintering process.
Findings
The elastic modulus and the flexural strength of the implant were observed to be comparable to that of human elbow bones. The fatigue test depicts that the implant survives the one million cycles under physiological loading conditions. Other mechanical properties such as impact energy absorption, hardness and life cycle tests were also evaluated. The implant surface promotes human cell growth and adhesion and does not cause any adverse or undesired effects i.e. no cytotoxicity.
Practical implications
Stress shielding, and therefore, aseptic loosening of the implant shall be avoided. In the event of any trauma post-implantation, the implant would not hurt the patient.
Originality/value
The present study describes a methodology for the first time to be able to obtain the strength required for the medical implant without sacrificing the fatigue life requirement.
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Yee Ling Yap, Swee Leong Sing and Wai Yee Yeong
Soft robotics is currently a rapidly growing new field of robotics whereby the robots are fundamentally soft and elastically deformable. Fabrication of soft robots is currently…
Abstract
Purpose
Soft robotics is currently a rapidly growing new field of robotics whereby the robots are fundamentally soft and elastically deformable. Fabrication of soft robots is currently challenging and highly time- and labor-intensive. Recent advancements in three-dimensional (3D) printing of soft materials and multi-materials have become the key to enable direct manufacturing of soft robots with sophisticated designs and functions. Hence, this paper aims to review the current 3D printing processes and materials for soft robotics applications, as well as the potentials of 3D printing technologies on 3D printed soft robotics.
Design/methodology/approach
The paper reviews the polymer 3D printing techniques and materials that have been used for the development of soft robotics. Current challenges to adopting 3D printing for soft robotics are also discussed. Next, the potentials of 3D printing technologies and the future outlooks of 3D printed soft robotics are presented.
Findings
This paper reviews five different 3D printing techniques and commonly used materials. The advantages and disadvantages of each technique for the soft robotic application are evaluated. The typical designs and geometries used by each technique are also summarized. There is an increasing trend of printing shape memory polymers, as well as multiple materials simultaneously using direct ink writing and material jetting techniques to produce robotics with varying stiffness values that range from intrinsically soft and highly compliant to rigid polymers. Although the recent work is done is still limited to experimentation and prototyping of 3D printed soft robotics, additive manufacturing could ultimately be used for the end-use and production of soft robotics.
Originality/value
The paper provides the current trend of how 3D printing techniques and materials are used particularly in the soft robotics application. The potentials of 3D printing technology on the soft robotic applications and the future outlooks of 3D printed soft robotics are also presented.