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Article
Publication date: 12 May 2020

Pu Tian, Ruosi Yan, Yabiao Tong, Lixia Jia and Jiming Yao

The purpose of this paper is to investigate the effects of alkali treatment on adhesion of industrial thermoplastic polyurethane elastomer (TPU)/polyester woven fabric inter-ply…

119

Abstract

Purpose

The purpose of this paper is to investigate the effects of alkali treatment on adhesion of industrial thermoplastic polyurethane elastomer (TPU)/polyester woven fabric inter-ply hybrid composites.

Design/methodology/approach

Inter-ply hybrid composites were exposed to varying concentration of sodium hydroxide at different temperature and time and their mechanical properties including differential scanning calorimetry, scanning electron microscope, tensile and peeling strength evaluated to determine optimal treatment parameters.

Findings

Modified polyester fabrics treated with alkali had higher tensile and peeling strengths. Accordingly, alkali treatment roughened the surface of polyester fabric, decreasing warp and weft densities, thus increasing fiber surface energy. The fabric had the highest peeling strength of 3.23 N/mm at treatment of 25% concentration of sodium hydroxide (NaOH). Short-term exposure to ultraviolet had little effect on interfacial adhesion of alkali-treated conveyor belt.

Research limitations/implications

Polyester fabric, applied in reinforcing industrial conveyor belts, is never degreased, roughened, sensitized or activated. In this paper, one-step treatment of polyester fabric was performed to increase its adhesion with polyester inter-ply hybrid composites, providing a reference for practical industrial application.

Practical implications

The method developed in this research is simple and provides a solution to improving the interfacial adhesion of TPU/polyester conveyor belt.

Originality/value

The novel alkali treatment technology has many applications in the interfacial performance of composite materials.

Details

Pigment & Resin Technology, vol. 49 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 9 July 2021

Xinjie Wang, Yan Cheng, Huadong Zheng, Yihao Li and Caidong Wang

Currently, rehabilitation medical care is expensive, requires a large number of rehabilitation therapist and which can only limit in the fixed location. In addition, there is a…

Abstract

Purpose

Currently, rehabilitation medical care is expensive, requires a large number of rehabilitation therapist and which can only limit in the fixed location. In addition, there is a lack of research on the structure optimization and theoretical analysis of soft actuators for hand rehabilitation. In view of the problems above, this paper aims to propose a cheap, portable, wearable soft multiple joints rehabilitation glove.

Design/methodology/approach

First, this paper determined the hyperelastic constitutive model by material tensile test. Second, the soft actuator’s internal longitudinal section shape was optimized through the comparison of three diverse chamber structures. Meanwhile, the motion model of the soft actuator is established by the finite element model analysis method. Then, this paper established the constitutive model of the soft actuator according to the torque equilibrium equation and analyzed the relationship between the soft actuator’s bending angle and the input air pressure. This paper has verified that the theoretical model is correct through the soft actuator bending test. Finally, rehabilitation gloves were manufactured according to the model and the rehabilitation performance and grasping ability of gloves were verified through experiments.

Findings

The optimization results show that the internal semicircular cavity has better performance. Then, the actuator performance is better after adding the external arc structure and optimizing the physical dimension. The experimental results show that the trajectory of the actuator conforms to the mathematical model and rehabilitation gloves can meet the needs of rehabilitation treatment.

Practical implications

Rehabilitation gloves made of actuators can help patients with hand dysfunction in daily rehabilitation training. Then, it can also assist patients with some fine and complicated hand movements.

Originality/value

This paper proposes a new type of soft rehabilitation glove, which is composed of new soft actuators and adapting pieces. The new actuator is small enough to be fitted to the knuckle of the glove to move each joint of the finger.

Details

Industrial Robot: the international journal of robotics research and application, vol. 48 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 25 November 2021

Samir Kasmi, Geoffrey Ginoux, Eric Labbé and Sébastien Alix

The purpose of this study is to test a flexible polymer with different characteristics compared to other classical polymers mostly used in the additive manufacturing process, and…

Abstract

Purpose

The purpose of this study is to test a flexible polymer with different characteristics compared to other classical polymers mostly used in the additive manufacturing process, and to improve its mechanical properties and microstructure, by modifying different printing parameters, to make it more suitable for various industrial applications.

Design/methodology/approach

Seven parameters were tested, namely, nozzle temperature, bed temperature, layer thickness, printing speed, flow rate, printing time gap between two successive printed layers and raster orientation. Rheological characterizations were conducted to evaluate the influence of nozzle temperature on the melt viscosity of thermoplastic polyurethane (TPU). The effect of thermal printing parameters on the crystallinity behavior was explored. Tomographic characterizations were realized to measure the porosity and evaluate the internal structure quality of printed specimens.

Findings

Increases of the nozzle temperature, bed temperature, layer thickness and flow rate had a positive influence on the tensile strength properties of TPU with a reduction of porosity. Higher printing speeds created defects and negatively influenced the strength properties of TPU. An increase in the printing time gap between layers led to poor interlayer adhesion and decreased the tensile strength. Specimens with layers all oriented parallel to the loading direction exhibited superior mechanical properties compared to other raster orientations.

Originality/value

Thermoplastic elastomers are a unique class of polymers characterized by the combined thermal, chemical and mechanical properties of their elastomer and thermoplastic parts. TPU elastomer, as one of the elastomer families, has found an important position in the bioengineering and three-dimensional printing industry. This study reports a comprehensive study of the impact of additive manufacturing parameters on the properties of TPU.

Details

Rapid Prototyping Journal, vol. 28 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 25 April 2022

Tao Xu, Wei Shen, Xiaoshan Lin and Yi Min Xie

Irregularly shaped architectural designs with surfaces curved in multiple directions, known as free-form designs, have gained significant public interest in recent decades…

Abstract

Purpose

Irregularly shaped architectural designs with surfaces curved in multiple directions, known as free-form designs, have gained significant public interest in recent decades. However, it is challenging to convert complex designs into real structures. This paper aims to realize free-form construction by developing a novel workflow in which additively manufactured thermoplastic polyurethane (TPU) molds are used.

Design/methodology/approach

The workflow is developed through mechanical tests on additively manufactured TPU specimens, determination of TPU mold design criteria and exploration of mold preparation methods. Two concrete elements with free-form geometries are fabricated using the proposed workflow.

Findings

TPU is a thermoplastic elastomer that is strong and inexpensive, making it an ideal mold material for casting complex concrete structures. An innovative workflow is developed in which TPU molds are used, appropriate release agents are selected for different concrete casting conditions and a mold subdivision method is proposed to facilitate the demolding process. Furthermore, the integrity of TPU molds can be maintained by following the proposed workflow, enabling repetitive use of molds. The fabrication of the two free-form structures shows that complex concrete members with high dimensional accuracy and excellent surface quality can be manufactured using the proposed method.

Originality/value

To the best of the authors’ knowledge, this is the first systematic study on using additively manufactured TPU molds for concrete casting of complex structures. The new techniques developed in this research can be applied to large-scale architectural, engineering and construction projects.

Details

Rapid Prototyping Journal, vol. 28 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 23 February 2021

Paschalis Charalampous, Ioannis Kostavelis, Theodora Kontodina and Dimitrios Tzovaras

Additive manufacturing (AM) technologies are gaining immense popularity in the manufacturing sector because of their undisputed ability to construct geometrically complex…

Abstract

Purpose

Additive manufacturing (AM) technologies are gaining immense popularity in the manufacturing sector because of their undisputed ability to construct geometrically complex prototypes and functional parts. However, the reliability of AM processes in providing high-quality products remains an open and challenging task, as it necessitates a deep understanding of the impact of process-related parameters on certain characteristics of the manufactured part. The purpose of this study is to develop a novel method for process parameter selection in order to improve the dimensional accuracy of manufactured specimens via the fused deposition modeling (FDM) process and ensure the efficiency of the procedure.

Design/methodology/approach

The introduced methodology uses regression-based machine learning algorithms to predict the dimensional deviations between the nominal computer aided design (CAD) model and the produced physical part. To achieve this, a database with measurements of three-dimensional (3D) printed parts possessing primitive geometry was created for the formulation of the predictive models. Additionally, adjustments on the dimensions of the 3D model are also considered to compensate for the overall shape deviations and further improve the accuracy of the process.

Findings

The validity of the suggested strategy is evaluated in a real-life manufacturing scenario with a complex benchmark model and a freeform shape manufactured in different scaling factors, where various sets of printing conditions have been applied. The experimental results exhibited that the developed regressive models can be effectively used for printing conditions recommendation and compensation of the errors as well.

Originality/value

The present research paper is the first to apply machine learning-based regression models and compensation strategies to assess the quality of the FDM process.

Details

Rapid Prototyping Journal, vol. 27 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 26 January 2024

Silvia Badini, Serena Graziosi, Michele Carboni, Stefano Regondi and Raffaele Pugliese

This study evaluates the potential of using the material extrusion (MEX) process for recycling waste tire rubber (WTR). By investigating the process parameters, mechanical…

Abstract

Purpose

This study evaluates the potential of using the material extrusion (MEX) process for recycling waste tire rubber (WTR). By investigating the process parameters, mechanical behaviour and morphological characterisation of a thermoplastic polyurethane-waste tire rubber composite filament (TPU-WTR), this study aims to establish a framework for end-of-life tire (ELT) recycling using the MEX technology.

Design/methodology/approach

The research assesses the impact of various process parameters on the mechanical properties of the TPU-WTR filament. Hysteresis analysis and Poisson’s ratio estimation are conducted to investigate the material’s behaviour. In addition, the compressive performance of diverse TPU-WTR triply periodic minimal surface lattices is explored to test the filament suitability for printing intricate structures.

Findings

Results demonstrate the potential of the TPU-WTR filament in developing sustainable structures. The MEX process can, therefore, contribute to the recycling of WTR. Mechanical testing has provided insights into the influence of process parameters on the material behaviour, while investigating various lattice structures has challenged the material’s capabilities in printing complex topologies.

Social implications

This research holds significant social implications addressing the growing environmental sustainability and waste management concerns. Developing 3D-printed sustainable structures using recycled materials reduces resource consumption and promotes responsible production practices for a more environmentally conscious society.

Originality/value

This study contributes to the field by showcasing the use of MEX technology for ELT recycling, particularly focusing on the TPU-WTR filament, presenting a novel approach to sustainable consumption and production aligned with the United Nations Sustainable Development Goal 12.

Open Access
Article
Publication date: 22 July 2021

Susan Erica Nace, John Tiernan, Donal Holland and Aisling Ni Annaidh

Most support surfaces in comfort applications and sporting equipment are made from pressure-relieving foam such as viscoelastic polyurethane. However, for some users, foam is not…

3347

Abstract

Purpose

Most support surfaces in comfort applications and sporting equipment are made from pressure-relieving foam such as viscoelastic polyurethane. However, for some users, foam is not the best material as it acts as a thermal insulator and it may not offer adequate postural support. The additive manufacturing of such surfaces and equipment may alleviate these issues, but material and design investigation is needed to optimize the printing parameters for use in pressure relief applications. This study aims to assess the ability of an additive manufactured flexible polymer to perform similarly to a viscoelastic foam for use in comfort applications.

Design/methodology/approach

Three-dimensional (3D) printed samples of thermoplastic polyurethane (TPU) are tested in uniaxial compression with four different infill patterns and varying infill percentage. The behaviours of the samples are compared to a viscoelastic polyurethane foam used in various comfort applications.

Findings

Results indicate that TPU experiences an increase in strength with an increasing infill percentage. Findings from the study suggest that infill pattern impacts the compressive response of 3D printed material, with two-dimensional patterns inducing an elasto-plastic buckling of the cell walls in TPU depending on infill percentage. Such buckling may not be a beneficial property for comfort applications. Based on the results, the authors suggest printing from TPU with a low-density 3D infill, such as 5% gyroid.

Originality/value

Several common infill patterns are characterised in compression in this work, suggesting the importance of infill choices when 3D printing end-use products and design for manufacturing.

Details

Rapid Prototyping Journal, vol. 27 no. 11
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 28 January 2020

John Carrell, Garrett Gruss and Elizabeth Gomez

This paper aims to provide a review of four-dimensional (4D) printing using fused-deposition modeling (FDM). 4D printing is an emerging innovation in (three-dimensional) 3D…

1278

Abstract

Purpose

This paper aims to provide a review of four-dimensional (4D) printing using fused-deposition modeling (FDM). 4D printing is an emerging innovation in (three-dimensional) 3D printing that encompasses active materials in the printing process to create not only a 3D object but also a 3D object that can perform an active function. FDM is the most accessible form of 3D printing. By providing a review of 4D printing with FDM, this paper has the potential in educating the many FDM 3D printers in an additional capability with 4D printing.

Design/methodology/approach

This is a review paper. The approach was to search for and review peer-reviewed papers and works concerning 4D printing using FDM. With this discussion of the shape memory effect, shape memory polymers and FDM were also made.

Findings

4D printing has become a burgeoning area in addivitive manufacturing research with many papers being produced within the past 3-5 years. This is especially true for 4D printing using FDM. The key findings from this review show the materials and material composites used for 4D printing with FDM and the limitations with 4D printing with FDM.

Research limitations/implications

Limitations to this paper are with the availability of papers for review. 4D printing is an emerging area of additive manufacturing research. While FDM is a predominant method of 3D printing, it is not a predominant method for 4D printing. This is because of the limitations of FDM, which can only print with thermoplastics. With the popularity of FDM and the emergence of 4D printing, however, this review paper will provide key resources for reference for users that may be interested in 4D printing and have access to a FDM printer.

Practical implications

Practically, FDM is the most popular method for 3D printing. Review of 4D printing using FDM will provide a necessary resource for FDM 3D printing users and researchers with a potential avenue for design, printing, training and actuation of active parts and mechanisms.

Social implications

Continuing with the popularity of FDM among 3D printing methods, a review paper like this can provide an initial and simple step into 4D printing for researchers. From continued research, the potential to engage general audiences becomes more likely, especially a general audience that has FDM printers. An increase in 4D printing could potentially lead to more designs and applications of 4D printed devices in impactful fields, such as biomedical, aerospace and sustainable engineering. Overall, the change and inclusion of technology from 4D printing could have a potential social impact that encourages the design and manufacture of such devices and the treatment of said devices to the public.

Originality/value

There are other 4D printing review papers available, but this paper is the only one that focuses specifically on FDM. Other review papers provide brief commentary on the different processes of 4D printing including FDM. With the specialization of 4D printing using FDM, a more in-depth commentary results in this paper. This will provide many FDM 3D printing users with additional knowledge that can spur more creative research in 4D printing. Further, this paper can provide the impetus for the practical use of 4D printing in more general and educational settings.

Details

Rapid Prototyping Journal, vol. 26 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 2 January 2018

Changchun Wang, Bo Kou, Zusheng Hang, Xuejuan Zhao, Tianxuan Lu, Ziqi Wu and Jin-Peng Zhang

This study aims to present that the chemo-responsive shape recovery of thermoplastic polyurethane (TPU) is tunable by solvents with different solubility parameters, and it is…

Abstract

Purpose

This study aims to present that the chemo-responsive shape recovery of thermoplastic polyurethane (TPU) is tunable by solvents with different solubility parameters, and it is generic for chemo-responsive shape-memory polymer and its composites.

Design/methodology/approach

Two kinds of commercial TPU samples with different thicknesses were prepared by panel vulcanizer and injection molding (an industrial manner) to investigate their chemo-responsive shape memory properties in acetic ether and acetone.

Findings

Results showed that all of TPU films with different thicknesses can fully recover their original shapes weather they recover in acetic ether or acetone. But the recovery time of TPU films in acetone is greatly reduced, especially for the twisting samples. The residual strains of recovery TPU samples after extension reduce obviously.

Research limitations/implications

The great decrement of recovery time is related to two factors. One is due to the bigger solubility parameter of acetone with higher dipole moment compared with those of acetic ether, and the other is the remained internal stress of TPU films after preparation. The internal stress is identified to have an effect on the shape-memory properties by comparing the recovery process of samples with/without annealing. The reduced residual strains of recovery TPU samples after extension is due to the increasing mobility of polymer segments after molecules of acetic ether penetrates into the polymeric chains.

Originality/value

This is a universal strategy to control the recovery process of shape-memory materials or composites. The underlying mechanism is generic and should be applicable to chemo-responsive shape-memory polymers or their composites.

Details

Pigment & Resin Technology, vol. 47 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 2 July 2020

Marek Pagac, David Schwarz, Jana Petru and Stanislav Polzer

Mechanical properties testing of the hyperelastic thermoplastic polyurethane (TPU) produced by the continuous digital light processing (CDLP) method of additive manufacturing…

Abstract

Purpose

Mechanical properties testing of the hyperelastic thermoplastic polyurethane (TPU) produced by the continuous digital light processing (CDLP) method of additive manufacturing. Primarily, this paper aims to verify that 3D printed TPU still satisfies commonly assumed volumetric incompressibility and material isotropy in elastic range. The secondary aim is to investigate the accuracy and reproducibility of the CDLP method.

Design/methodology/approach

Cylindrical samples were printed and subjected to a volumetric compression test to reveal their bulk modulus K and maximal theoretical porosity (MTP). Dog bone specimens were oriented along different axes and printed. Their dimensions were measured, and they were subjected to cyclic uniaxial tests up to 100% strain to reveal the level of stress softening and possible anisotropy. The hyperelastic Yeoh model was fitted to the mean response.

Findings

The authors measured the bulk modulus of K = 1851 ± 184 MPa. The mean MTP was 0.9 ± 0.5%. The mean response was identical in both directions and the data could be fitted by the isotropic third order Yeoh function with R^2 = 0.996. The dimensions measurement revealed the largest error (above 5%) in the direction perpendicular to the direction of the digital light projection while the dimensions in other two dimensions were much more accurate (0.75 and 1%, respectively).

Practical implications

The TPU printed by CDLP can be considered and modelled as isotropic and practically volumetrically incompressible. The parts in the printing chamber should be positioned in a way that the important dimensions are not parallel to the direction of the digital light projection.

Originality/value

The authors experimentally confirmed the volumetric incompressibility and mechanical isotropy of the TPU printed using the CDLP method.

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