Polymers

Research

17 pages, 15359 KiB

Open AccessArticle

Characterization of the Polyetheretherketone Weldment Fabricated via Rotary Friction Welding

by Chil-Chyuan Kuo, Hua-Xhin Liang and Song-Hua Huang

Polymers 2023, 15(23), 4552; https://doi.org/10.3390/polym15234552 - 27 Nov 2023

Viewed by 758

Polyether ether ketone (PEEK) is frequently employed in biomedical engineering due to its biocompatibility. Traditionally, PEEK manufacturing methods involve injection molding, compression molding, additive manufacturing, or incremental sheet forming. Few studies have focused on rotational friction welding (RFW) with PEEK plastics. Based on [...] Read more.

Polyether ether ketone (PEEK) is frequently employed in biomedical engineering due to its biocompatibility. Traditionally, PEEK manufacturing methods involve injection molding, compression molding, additive manufacturing, or incremental sheet forming. Few studies have focused on rotational friction welding (RFW) with PEEK plastics. Based on years of RFW practical experience, the mechanical properties of the weldment are related to the burn-off length. However, few studies have focused on this issue. Therefore, the main objective of this study is to assess the effects of burn-off length on the mechanical properties of the welded parts using PEEK polymer rods. The welding pressure can be determined by the rotational speed according to the proposed prediction equation. The burn-off length of 1.6 mm seems to be an optimal burn-off length for RFW. For the rotational speed of 1000 rpm, the average bending strength of the welded parts was increased from 108 MPa to 160 Mpa, when the burn-off length was increased from 1 mm to 1.6 mm and the cycle time of RFW was reduced from 80 s to 76 s. A saving in the cycle time of RFW of about 5% can be obtained. The bending strength of the welded part using laser welding is lower than that using RFW, because only the peripheral material of the PEEK cylinder was melted by the laser. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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22 pages, 8270 KiB

Open AccessArticle

Optimization of Dimensional Accuracy and Surface Roughness of SLA Patterns and SLA-Based IC Components

by Aishabibi Mukhangaliyeva, Damira Dairabayeva, Asma Perveen and Didier Talamona

Polymers 2023, 15(20), 4038; https://doi.org/10.3390/polym15204038 - 10 Oct 2023

Cited by 1 | Viewed by 1108

Abstract

Rapid investment casting is a casting process in which the sacrificial patterns are fabricated using additive manufacturing techniques, making the creation of advanced designs possible. One of the popular 3D printing methods applied in rapid investment casting is stereolithography because of its high [...] Read more.

Rapid investment casting is a casting process in which the sacrificial patterns are fabricated using additive manufacturing techniques, making the creation of advanced designs possible. One of the popular 3D printing methods applied in rapid investment casting is stereolithography because of its high dimensional precision and surface quality. Printing parameters of the used additive manufacturing method can influence the surface quality and accuracy of the rapid investment cast geometries. Hence, this study aims to investigate the effect of stereolithography printing parameters on the dimensional accuracy and surface roughness of printed patterns and investment cast parts. Castable wax material was used to print the sacrificial patterns for casting. A small-scale prosthetic biomedical implant for total hip replacement was selected to be the benchmark model due to its practical significance. The main results indicate that the most significant stereolithography printing parameter affecting surface roughness is build angle, followed by layer thickness. The optimum parameters that minimize the surface roughness are 0.025 mm layer thickness, 0° build angle, 1.0 support density index, and across the front base orientation. As for the dimensional accuracy, the optimum stereolithography parameters are 0.025 mm layer thickness, 30° build angle, 0.6 support density index, and diagonal to the front base orientation. The optimal printing parameters to obtain superior dimensional accuracy of the cast parts are 0.05 mm layer thickness, 45° build angle, 0.8 support density index, and diagonal to the front model base orientation. With respect to the surface roughness, lower values were obtained at 0.025 mm layer thickness, 0° build angle, 1.0 support density index, and parallel to the front base orientation. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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15 pages, 5162 KiB

Open AccessArticle

Optimization of Printing Parameters to Enhance Tensile Properties of ABS and Nylon Produced by Fused Filament Fabrication

by Andrei Yankin, Yerassyl Alipov, Ali Temirgali, Gaini Serik, Saniya Danenova, Didier Talamona and Asma Perveen

Polymers 2023, 15(14), 3043; https://doi.org/10.3390/polym15143043 - 14 Jul 2023

Cited by 3 | Viewed by 1754

Abstract

This study aimed to identify the optimum printing parameters for the fused filament fabrication (FFF) of acrylonitrile butadiene styrene (ABS) and polyamide (nylon), to improve strength properties. For this purpose, the methodology of the paper involves an experimental study that used Taguchi’s method [...] Read more.

This study aimed to identify the optimum printing parameters for the fused filament fabrication (FFF) of acrylonitrile butadiene styrene (ABS) and polyamide (nylon), to improve strength properties. For this purpose, the methodology of the paper involves an experimental study that used Taguchi’s method to identify the effects of the infill pattern, infill density, and printing speed on the mechanical properties of the materials. ABS and nylon plastic parts were tested in tension to failure. Based on the results of the tensile tests, it was found that ABS material produced the highest ultimate tensile strength when printed using a tri-hexagonal infill pattern, 100% infill density, and a printing speed of 65 mm/s. On the other hand, nylon material exhibited a better performance when printed using an octet geometric structure, with identical other parameters. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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12 pages, 3077 KiB

Open AccessArticle

Evaluation of Organofunctionalized Polydimethylsiloxane Films for the Extraction of Furanic Compounds

by Yamile Pérez-Padilla, Manuel Aguilar-Vega, Erbin Guillermo Uc-Cayetano, Adriana Esparza-Ruiz, Marcial Alfredo Yam-Cervantes and David Muñoz-Rodríguez

Polymers 2023, 15(13), 2851; https://doi.org/10.3390/polym15132851 - 28 Jun 2023

Viewed by 1006

Abstract

Hybrid membranes with three different thicknesses, PMDS_C1, PMDS_C2, and PMDS_C3 (0.21 ± 0.03 mm, 0.31 ± 0.05 mm, and 0.48 ± 0.07 mm), were synthesized by the sol–gel method using polydimethylsiloxane, hydroxy-terminated, and cyanopropyltriethoxysilane. The presence of cyano, methyl, and silicon-methyl groups was [...] Read more.

Hybrid membranes with three different thicknesses, PMDS_C1, PMDS_C2, and PMDS_C3 (0.21 ± 0.03 mm, 0.31 ± 0.05 mm, and 0.48 ± 0.07 mm), were synthesized by the sol–gel method using polydimethylsiloxane, hydroxy-terminated, and cyanopropyltriethoxysilane. The presence of cyano, methyl, and silicon-methyl groups was confirmed by FTIR analysis. Contact angle analysis revealed the membranes’ hydrophilic nature. Solvent resistance tests conducted under vortex and ultrasonic treatments (45 and 60 min) demonstrated a preference order of acetonitrile > methanol > water. Furthermore, the membranes exhibited stability over 48 h when exposed to different pH conditions (1, 3, 6, and 9), with negligible mass losses below 1%. The thermogravimetric analysis showed that the material was stable until 400 °C. Finally, the sorption analysis showed its capacity to detect furfural, 2-furylmethylketone, 5-methylfurfural, and 2-methyl 2-furoate. The thicker membrane was able to adsorb and slightly desorb a higher concentration of furanic compounds due to its high polarity provided by the addition of the cyano groups. The results indicated that the membranes may be suitable for sorbent materials in extracting and enriching organic compounds. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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19 pages, 5381 KiB

Open AccessArticle

UV Irradiation of Wood Surface: Bonding Properties

by Tomislav Gržan, Lucianna Grieco, Vjekoslav Živković and Goran Mihulja

Polymers 2023, 15(11), 2552; https://doi.org/10.3390/polym15112552 - 31 May 2023

Viewed by 1470

Abstract

Various surface modification techniques have been developed to improve synthetic polymer surfaces’ wetting, adhesion, and printing by adding various functional (polar) groups. UV irradiation has been proposed as a suitable procedure to achieve adequate surface modifications of such polymers, which can be of [...] Read more.

Various surface modification techniques have been developed to improve synthetic polymer surfaces’ wetting, adhesion, and printing by adding various functional (polar) groups. UV irradiation has been proposed as a suitable procedure to achieve adequate surface modifications of such polymers, which can be of further use to bond many compounds of interest. The activation of the surface, the favourable wetting properties, and the increased micro tensile strength of the substrate after short-term UV irradiation suggest that such pretreatment can also improve the bonding of the wood-glue system. Thus, this study aims to determine the feasibility of UV irradiation for pretreatment of wood surfaces before gluing and to determine the properties of wooden glued joints prepared in this way. UV irradiation was used to modify variously machined pieces of beech wood (Fagus sylvatica L.) before gluing. Six sets of samples were prepared for each machining process. Samples prepared in this manner were exposed to irradiation on a UV line. Each radiation level had a certain number of passes through the UV line, the more passes, the stronger the irradiation. Thus, the radiation levels were as follows: 1, 5, 10, 20, and 50 passes. The dose (energy delivered on the wood surface) in one pass was 2.36 J/cm². A wetting angle test with glue, a compressive shear strength test of lap joints, and designation of main failure patterns were used to evaluate the properties of wooden glued joints. Wetting angle test was performed according to EN 828, while the compressive shear strength test samples were prepared and tested following the ISO 6238 standard. The tests were conducted using a polyvinyl acetate adhesive. The study found that UV irradiation before gluing improved the bonding properties of variously machined wood. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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16 pages, 6262 KiB

Open AccessArticle

Crazing Initiation and Growth in Polymethyl Methacrylate under Effects of Alcohol and Stress

by Ying Yan, Yujia Sun, Jiyang Su, Bo Li and Ping Zhou

Polymers 2023, 15(6), 1375; https://doi.org/10.3390/polym15061375 - 9 Mar 2023

Cited by 3 | Viewed by 2938

Abstract

Polymer crazing is typically a precursor to damage and considerably reduces the mechanical performance of polymer materials. The concentrated stress caused by machines and the solvent atmosphere created during machining exacerbates the formation of crazing. In this study, the tensile test method was [...] Read more.

Polymer crazing is typically a precursor to damage and considerably reduces the mechanical performance of polymer materials. The concentrated stress caused by machines and the solvent atmosphere created during machining exacerbates the formation of crazing. In this study, the tensile test method was employed to examine the initiation and progression of crazing. The research focused on polymethyl methacrylate (PMMA), both regular and oriented, and the impact of machining and alcohol solvents on the formation of crazing. The results showed that the alcohol solvent influenced PMMA through physical diffusion, whereas machining primarily affected crazing growth via residual stress. Treatment reduced the crazing stress threshold of PMMA from 20% to 35% and produced a threefold increase in its sensitivity to stress. The findings revealed that oriented PMMA exhibited 20 MPa higher resistance to crazing stress compared with regular PMMA. The results also indicated that the extension of the crazing tip and thickening were in conflict, with the crazing tip of regular PMMA severely bending under tensile stress. This study provides valuable insight into the initiation of crazing and the methods of its prevention. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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16 pages, 4768 KiB

Open AccessArticle

Multi-Material Additive Manufacturing of High Temperature Polyetherimide (PEI)–Based Polymer Systems for Lightweight Aerospace Applications

by Ved S. Vakharia, Hunter Leonard, Mrityunjay Singh and Michael C. Halbig

Polymers 2023, 15(3), 561; https://doi.org/10.3390/polym15030561 - 21 Jan 2023

Cited by 4 | Viewed by 1875

Abstract

Rapid innovations in 3-D printing technology have created a demand for multifunctional composites. Advanced polymers like amorphous thermoplastic polyetherimide (PEI) can create robust, lightweight, and efficient structures while providing high-temperature stability. This work manufactured ULTEM, a PEI-based polymer, and carbon-fiber-infused ULTEM multi-material composites [...] Read more.

Rapid innovations in 3-D printing technology have created a demand for multifunctional composites. Advanced polymers like amorphous thermoplastic polyetherimide (PEI) can create robust, lightweight, and efficient structures while providing high-temperature stability. This work manufactured ULTEM, a PEI-based polymer, and carbon-fiber-infused ULTEM multi-material composites with varying layering patterns (e.g., AAABBB vs. ABABAB) using fused filament fabrication (FFF). The microstructure of fractured surfaces and polished cross-sections determined that the print quality of layers printed closer to the heated bed was higher than layers closer to the top surface, primarily due to the thermal insulating properties of the material itself. Mechanical properties of the multi-material parts were between those of the single-material parts: an ultimate tensile strength and elastic modulus of 59 MPa and 3.005 GPa, respectively. Multi-material parts from the same filaments but with different layering patterns showed different mechanical responses. Prints were of higher quality and demonstrated a higher elastic modulus (3.080 GPa) when consecutive layers were printed from the same filament (AAABBB) versus parts with printed layers of alternating filaments (ABABAB), which showed a higher ultimate strength (62.04 MPa). These results demonstrate the potential for creatively designing multi-material printed parts that may enhance mechanical properties. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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18 pages, 2346 KiB

Open AccessArticle

Static Mixers Producible by Additive Manufacturing: Novel Rapid Automatic Optimisation and Practical Evaluation

by Jana Sasse, Malte Schön and Christian Hopmann

Polymers 2022, 14(21), 4646; https://doi.org/10.3390/polym14214646 - 1 Nov 2022

Cited by 1 | Viewed by 2329

Abstract

In the extrusion of plastics, the thermal and material homogeneity of the plastic melt at the die entry are of high importance for the extrudate quality. While static mixers are widely used to improve the melt homogeneity, previous attempts at optimisation for reduced [...] Read more.

In the extrusion of plastics, the thermal and material homogeneity of the plastic melt at the die entry are of high importance for the extrudate quality. While static mixers are widely used to improve the melt homogeneity, previous attempts at optimisation for reduced pressure loss and improved mixing had to be performed by hand and human experience, limiting the degrees of freedom and efficiency. A new automatic optimisation method based on the open source software OpenFOAM was developed. Using immersed boundary methods, new target functions in the pre-existing routine adjointShapeOptimizationFoam and an additional algorithm checking the suitability for additive manufacturing and fixing the geometry during run-time is presented. The new algorithm is used to optimise an existing static mixer based on an X-type geometry with integrated oil channels, maximising the heat exchange between oil and melt. Based on the results of these simulative optimisations, the best candidates were manufactured using selective laser melting and experimental trials were run. Experimental validation shows that with our optimisation algorithm, a pressure loss reduction of 10% could be achieved. The core melt temperature was reduced by 6

^{\circ}

C, improving the thermal homogenisation as well. While the main advantage of this method is the rapid optimisation taking the operating point into account, the trials also showed positive results in off-design operating points. This allows the low-cost design and manufacture of individualised static mixers. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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25 pages, 5506 KiB

Open AccessArticle

Experimental Investigation and Optimization of Turning Polymers Using RSM, GA, Hybrid FFD-GA, and MOGA Methods

by Abdulrahman I. Alateyah, Yasmine El-Taybany, Samar El-Sanabary, Waleed H. El-Garaihy and Hanan Kouta

Polymers 2022, 14(17), 3585; https://doi.org/10.3390/polym14173585 - 30 Aug 2022

Cited by 7 | Viewed by 1352

Abstract

The machining of polymers has become widely common in several components of industry 4.0 technology, i.e., mechanical and structural components and chemical and medical instruments, due to their unique characteristics such as: being strong and light-weight with high stiffness, chemical resistance, and heat [...] Read more.

The machining of polymers has become widely common in several components of industry 4.0 technology, i.e., mechanical and structural components and chemical and medical instruments, due to their unique characteristics such as: being strong and light-weight with high stiffness, chemical resistance, and heat and electricity insolation. Along with their properties, there is a need to attain a higher quality surface finish of machined parts. Therefore, this research concerns an experimental and analytical study dealing with the effect of process parameters on process performance during the turning two different types of polymers: high-density polyethylene (HDPE) and unreinforced polyamide (PA6). Firstly, the machining output responses (surface roughness (Ra), material removal rate (MRR), and chip formation (λc)) are experimentally investigated by varying cutting speed (v_c), feed rate (f), and depth of cut (d) using the full factorial design of experiments (FFD). The second step concerns the statistical analysis of the input parameters’ effect on the output responses based on the analysis of variance and 3D response surface plots. The last step is the application of the RSM desirability function, genetic algorithm (GA), and hybrid FFD-GA techniques to determine the optimum cutting conditions of each output response. The lowest surface roughness for HDPE was obtained at v_c = 50 m/min, f = 0.01 mm/rev, and d = 1.47 mm and for PA6 it was obtained at v_c = 50 m/min, f = 0.01 mm/rev, and d = 1 mm. The highest material removal rate was obtained at v_c = 150 m/min, f = 0.01 mm/rev, and d = 1.5 mm for both materials. At f = 0.01 mm/rev, d = 1.5 mm, and v_c = 100 for HDPE, and v_c = 77 m/min for PA6, the largest chip thickness ratios were obtained. Finally, the multi-objective genetic algorithm (MOGA) methodology was used and compared. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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18 pages, 1551 KiB

Open AccessArticle

Effects of Melt Temperature and Non-Isothermal Flow in Design of Coat Hanger Dies Based on Flow Network of Non-Newtonian Fluids

by Amin Razeghiyadaki, Dongming Wei, Asma Perveen, Dichuan Zhang and Yanwei Wang

Polymers 2022, 14(15), 3161; https://doi.org/10.3390/polym14153161 - 3 Aug 2022

Cited by 3 | Viewed by 1616

Abstract

In the design of coat hanger extrusion dies, the main objective is to provide a uniform flow rate at the die exit. Previously, a multi-rheology isothermal method model for coat hanger extrusion dies was developed to reach this objective. Polymer melts in extrusion [...] Read more.

In the design of coat hanger extrusion dies, the main objective is to provide a uniform flow rate at the die exit. Previously, a multi-rheology isothermal method model for coat hanger extrusion dies was developed to reach this objective. Polymer melts in extrusion dies commonly experience high shear rates. Viscous dissipation rooted by high shear rate may lead to significant temperature differences across the die. Due to temperature-dependency of viscosity, temperature differences may lead to nonuniform flow rates, which may significantly affect the flow rate at the die exit. As a result, a new design method is proposed to take into account the effects of temperature and viscous dissipation in the design of coat hanger dies. Although more non-Newtonian fluid rheology models can be adapted in the proposed study, as demonstration, temperature-dependent power-law and Carreau–Yasuda models are adapted in this study. Performances are compared with our isothermal method published earlier. In addition, the novel nonisothermal method is comprehensively examined where the effect of viscous dissipation is studied through Brinkman number of extrusion die. It is demonstrated that, for a low Brinkman number, both isothermal and nonisothermal design give similar flow uniformity level. However, for higher Brinkman numbers, the proposed nonisothermal method produces a design with more desirable velocity uniformity level along with a maximum improvement of

5.24 %

over the isothermal method. In addition, dependency of flow field on temperature, due to temperature-dependent viscosity, is studied, and it is demonstrated that fully-developed velocity profile changes as temperature increases along the flow channel. Moreover, the effect of the temperature sensitivity parameter in temperature-dependent non-Newtonian models is considered. It is demonstrated that the temperature boundary condition with the Biot number of 1.0 gives adequate results for lower values of the temperature sensitivity parameter. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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13 pages, 4473 KiB

Open AccessArticle

Simulation of Cone-Jet and Micro-Drip Regimes and Printing of Micro-Scale Patterns on PET Substrate

by Dazhi Wang, Zeshan Abbas, Liangkun Lu, Shiwen Liang, Xiangyu Zhao, Pengfei Xu, Kuipeng Zhao, Liujia Suo, Yan Cui, Penghe Yin, Bin Tang, Jin Xie, Yong Yang and Junsheng Liang

Polymers 2022, 14(13), 2683; https://doi.org/10.3390/polym14132683 - 30 Jun 2022

Cited by 6 | Viewed by 1798

Abstract

The fabrication of various micro-patterns on polymer insulating substrates is a current requirement in micro-electromechanical system (MEMS) and packaging sectors. In this paper, we use electrohydrodynamic jet (E-Jet) printing to create multifaceted and stable micro-patterns on a polyethylene terephthalate (PET) substrate. Initially, simulation [...] Read more.

The fabrication of various micro-patterns on polymer insulating substrates is a current requirement in micro-electromechanical system (MEMS) and packaging sectors. In this paper, we use electrohydrodynamic jet (E-Jet) printing to create multifaceted and stable micro-patterns on a polyethylene terephthalate (PET) substrate. Initially, simulation was performed to investigate optimized printing settings in phase field physics for the usage of two distinct functional inks. A series of simulation experiments was conducted, and it was determined that the following parameters are optimised: applied pressure of 40 kPa, high pulse voltage of 1.95 kV, low dc voltage of 1.60 kV, duty cycle of 80%, pulse frequency of 60 Hz, printing height of 0.25 mm, and printing speed of 1 mm/s. Then, experiments showed that adjusting a pressure value of 40 kPa and regulating the SEMICOSIL988/1 K ink to print micro-drops on a polymer substrate with a thickness of 1 mm prevents coffee staining. The smallest measured droplet size was 200 μm. Furthermore, underfill (UF 3808) ink was driven with applied pressure to 50 kPa while other parameters were left constant, and the minimum size of linear patterns was printed to 105 μm on 0.5-mm-thick PET substrate. During the micro-drip and cone-jet regimes, the consistency and diameter of printed micro-structures were accurately regulated at a pulse frequency of 60 Hz and a duty cycle of 80%. Full article

(This article belongs to the Special Issue Recent Advances in Polymer Processing)

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