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18. A state-of-the-art review of polyimide foams research

Author

Liu, Haiming, Wang, Xiangdong, Antwi-Afari, Maxwell Fordjour, Mi, Hao-Yang, Liu, Chuntai, Liu, Haiming, Wang, Xiangdong, Antwi-Afari, Maxwell Fordjour, Mi, Hao-Yang, and Liu, Chuntai

Abstract

Polyimide foams (PIFs), renowned as some of the best materials for excellent performance in harsh temperature environments, have been developed to meet the increasing demands of high-tech industries. A state-of-the-art review of advanced PIFs research was conducted, covering the general research profiles and trends, institutions and scholars, major journals, research categories, and application fields through a bibliometric analysis of publications.Research on polyimide-based foam has increased approximately 30-fold over the past 40 years. One hundred forty-two research institutions from 20 countries have conducted research related to PIFs. Literature co-citation analysis reveals that the knowledge base of the PIFs research field primarily focuses on chemical synthesis foaming. This spotlight on engineering applications systematically describes the synthesis mechanisms, various typical fabrication methods, and the microstructure of PIFs. The advantages and disadvantages of this methods have been compared. Representative functions and corresponding mechanism models, which include thermal, mechanical, sensing, electromagnetic, flame retardant, oil-water separation, and other fields, have been outlined. This review offers insights into the technological development prospects and opportunities. Finally, the arduous tasks and challenges of PIFs research are summarized, providing valuable guidance for researchers interested in this field.

Published
2024

24. Preparation of Fast-Degrading Poly(Lactic Acid)/Soy Protein Concentrate Biocomposite Foams via Supercritical C[O.sub.2] Foaming

Author

Liu, Tong, Peng, Xiang-Fang, Mi, Hao-Yang, Li, Heng, Turng, Lih-Sheng, and Xu, Bai-Ping

Subjects
Soy protein -- Production processes -- Composition, Foams (Chemistry) -- Properties -- Composition, Biodegradation -- Analysis, Biphenyl (Compound), Isocyanates, Surface science, Methane, Density, Engineering and manufacturing industries, Science and technology
Abstract

To increase the degradation rate of poly(lactic acid) (PLA), soy protein concentrate (SPC) was introduced via melt compounding using a self-developed, co-rotating, non-twin-screw extruder. Poly(2-ethyl-2-oxazoline) (PEOX) and diphenyl methane diisocyanate (MDI) were added to plasticize the melt and improve the compatibility between PLA and SPC. The PLA/SPC blends were subsequently foamed using supercritical carbon dioxide (C[O.sub.2]) as a blowing agent to produce porous composites. The involvement of SPC promoted cold crystallization of PLA but reduced the thermal stability of the blends. PLA showed a strong interfacial bonding with modified SPC, and the SPC formed continuous three-dimensional networks when its proportion reached 30 wt%. In the foaming process, SPC domains acted as heterogeneous nucleation sites, which resulted in enhanced cell densities and reduced cell diameters. The PLA/SPC (70:30) sample showed the finest cell structure due to the presence of the SPC network. For the same blends, increasing the foaming pressure from 16 to 20 MPa enhanced the cell density by about 5 times. The water absorption rate and the biodegradation rate of the PLA/SPC foams were much higher than that of neat PLA due to the hydrophilicity of SPC and the porous structure of the foams., INTRODUCTION In the recent years, biobased polymers have received great interest as renewable plastics because of their biodegradability and biocompatibility [1-4]. PLA, which is a compostable polymer derived from renewable [...]

Published
2019
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25. Microcellular injection molding of foamed engineering plastic parts with high dimensional accuracy

Author

Feng, Yu‐Teng, Zhan, Haiying, Mi, Hao‐Yang, Antwi‐Afari, Maxwell Fordjour, Chen, Youfu, Gu, Laifa, Dong, Binbin, Liu, Chuntai, Shen, Changyu, Feng, Yu‐Teng, Zhan, Haiying, Mi, Hao‐Yang, Antwi‐Afari, Maxwell Fordjour, Chen, Youfu, Gu, Laifa, Dong, Binbin, Liu, Chuntai, and Shen, Changyu

Abstract

Polyformaldehyde (POM) and Polyamide 66 (PA66) are engineering plastics with excellent mechanical properties and thermal stability. Producing microcellular injection molded POM and PA66 parts with high dimensional accuracy would be beneficial to reduce material cost and product quality. In this research, foamed POM and PA66 gear parts were fabricated by using microcellular injection molding with supercritical nitrogen as the blowing agent. Compared to conventional injection molded parts (parts that foaming is not involved), the foamed POM and PA66 gear parts achieved 5% and 10% average weight reduction, respectively. The foamed parts displayed a lower shrinkage ratio when compared to the solid counterparts, which was attributed to the cell expansion that offset part of the inward shrinkage stress. Moreover, POM gear parts with a higher crystallinity degree presented more serious shrinkage ratio compared to the PA66 gear parts, which contributed to the denser polymer molecular chains arrangement. The shrinkage ratio in both directions of PA66 foamed gear parts depended on the injection volume, and the lowest shrinkage ratio of 0.043‰ was obtained at the injection volume of 74 mm, when the polymer reached the maximum foaming ratio. The findings from this study could provide practical guidance for preparing microcellular injection molded products with high dimensional accuracy.

Published
2023

27. Self-Reinforced Thermoplastic Polyurethane Wrinkled Foams with High Energy Absorption Realized by Gas Cooling Assisted Supercritical CO2 Foaming

Author

Hu, Jiashun, Gu, Ruixing, Mi, Hao-Yang, Jing, Xin, Antwi-Afari, Maxwell Fordjour, Dong, Binbin, Liu, Chuntai, and Shen, Changyu

Abstract

Self-reinforcement of polymer foams by cellular structure manipulation is a cost-effective approach to boost the performance and extend the applicable fields of the foams. Herein, thermoplastic polyurethane (TPU) foams with special wrinkly structures were fabricated via a gas cooling assisted scCO2 foaming process which employed a CO2 flow to rapidly reduce the temperature of the foam and trigger the release of intramolecular stress in the form of macroscopic distortion via the formation of wrinkles on the cell surface. The wrinkly structure could be regulated in the range of 1.61 to 2.16 μm by the key processing parameters, including foaming temperature (T), foaming pressure (P), waiting time (Δt), and temperature drop (ΔT). The wrinkled foams demonstrated superior compressive properties, recoverability, and energy absorption in cyclic compression tests compared with conventional foams with the same cell size. The wrinkled foam with a wrinkle wavelength of 1.77 μm achieved 153.0%, 2.83%, and 99.0% improvement in compressive modulus, recovery rate, and energy absorption, respectively. It also displayed a low energy loss coefficient of 3.50% which was only 31.48% of that of the conventional foam. This work provides a feasible approach to realize the self-reinforcement of TPU foams by creating wrinkly structures on the cell surface, and extends potential applications of wrinkled TPU foams in cushioning and buffering.

Published
2022

28. Carbon black and polydopamine modified non-woven fabric enabling efficient solar steam generation towards seawater desalination and wastewater purification

Author

Sun, Shuangjie, Sun, Binbin, Wang, Yameng, Fordjour Antwi-Afari, Maxwell, Mi, Hao-yang, Guo, Zhanhu, Liu, Chuntai, Shen, Changyu, Sun, Shuangjie, Sun, Binbin, Wang, Yameng, Fordjour Antwi-Afari, Maxwell, Mi, Hao-yang, Guo, Zhanhu, Liu, Chuntai, and Shen, Changyu

Abstract

The utilization of solar energy for steam generation is a highly efficient and sustainable technology for seawater desalination to solve the long-standing water crisis. Carbon-based materials have shown promising thermal-heat conversion efficiency due to their broadband solar absorption. Herein, carbon black (CB) was combined with polydopamine (PDA) to develop a high-performance, low-cost, and scalable PDA/CB@PP composite non-woven fabric was fabricated by dip-coating of CB and in situ polymerization of PDA. The hierarchical structure constructed on the fiber surface and the synergetic effects of CB and PDA contributed to the high light absorbance (>95%), superhydrophilicity, and high energy conversion efficiency. The one-way fluidic PDA/CB@PP photothermal based solar steam evaporator demonstrated a high evaporation rate of 1.68 kg m-2 h-1 with a solar steam efficiency of 91.5%. Moreover, the PDA/CB@PP fabric shows remarkable salt resistance when purifying seawater because of the water channel preserved by the hydrophilic porous structure of the fabric which could provide sustained water supply. Besides, the PDA/CB@PP fabric possesses excellent purification capability to wastewaters contaminated by heavy-metal and chemical dyes. This study provides insights into the design and development of low-cost, scalable, highly stable, and efficient solar steam generators for seawater desalination and wastewater purification.

Published
2022

29. Fabrication of polylactic acid/polyethylene glycol (PLA/PEG) porous scaffold by supercritical C[O.sub.2] foaming and particle leaching

Author

Chen, Bin-Yi, Jing, Xin, Mi, Hao-Yang, Zhao, Haibin, Zhang, Wen-Hao, Peng, Xiang-Fang, and Turng, Lih-Sheng

Subjects
Porous materials -- Chemical properties -- Production processes, Polyethylene glycol -- Usage, Leaching -- Models, Chemical synthesis -- Methods, Lactic acid -- Usage, Carbon dioxide -- Usage, Engineering and manufacturing industries, Science and technology
Abstract

PLA/PEG/NaCl blends were melt-blended followed by gas foaming and particle leaching process to fabricate porous scaffold with high porosity and interconnectivity. A homemade triple-screw compounding extruder was used to intensify the mixability and dispersion of NaCl and PEG in the PLA matrix. Supercritical carbon dioxide was used as physical blowing agent for the microcellular foaming process. Sodium chloride (NaCl) was used as the porogen to further improve the porosity of PLA scaffold. This study investigated the effects of PEG and NaCl on the structure and properties of the PLA-based blend, as well as the porosity, pore size, interconnectivity, and hydrophilicity of porous scaffolds. It was found that the incorporation of PEG and NaCl significantly improved the crystallization rate and reduced viscoelasticity of PLA. Moreover, scaffolds obtained from PLA/PEG/NaCl blends had an interconnected bimodal porous structure with the open-pore content about 86% and the highest porosity of 80%. And the presence of PEG in PLA/NaCl composite improved the extraction ability of NaCl particles during leaching process, which resulted in a well-interconnected structure. The biocompatibility of the porous scaffolds fabricated was verified by culturing fibroblast cells for 10 days., INTRODUCTION Tissue engineering, an interdisciplinary field that aims to provide therapeutic treatments to maintain, restore, or replace damaged tissues and organs, has been a focus of intense research over the [...]

Published
2015
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30. The morphology, properties, and shape memory behavior of polylactic acid/thermoplastic polyurethane blends

Author

Jing, Xin, Mi, Hao-Yang, Peng, Xiang-Fang, and Turng, Lih-Sheng

Subjects
Polyurethanes -- Mechanical properties, Polymeric composites -- Mechanical properties, Plastics -- Biodegradation, Engineering and manufacturing industries, Science and technology
Abstract

Biodegradable polylactic acid (PLA) was compounded with thermoplastic polyurethane (TPU) by twin-screw extrusion at weight ratios of 90/10, 80/20, 70/30, and 60/ 40. The blends were investigated based on their phase morphology, thermal and mechanical properties, and shape memory properties. The tensile results showed that PLA was successfully toughened by TPU. When the TPU content was 40%, the elongation-at-break increased to 400%. The SEM morphology showed that TPU was dispersed uniformly in the PLA matrix; DMA and DSC results indicated that the two polymers were immiscible. Most interestingly, it was found that the blends exhibited a shape memory behavior and, unlike most of the existing shape memory polymers (SMPs), the PLA/TPU blends could be deformed at room temperature without an extra heating and cooling step. During the deformation process, TPU acted as a toughening agent that prevented the PLA/ TPU blends from breaking; thus, the temporary shape could be kept and internal stress was stored in the blends. Upon heating to above the glass transition temperature of PLA (about 60°C), the deformed parts regained their original shapes quickly along with the release of the stress., INTRODUCTION Polylactic acid (PLA), an aliphatic polyester, is a biodegradable polymer derived from renewable resources such as com and sugar beets. It has attracted great interest in both academia and [...]

Published
2015
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32. A novel thermoplastic polyurethane scaffold fabrication method based on injection foaming with water and supercritical carbon dioxide as coblowing agents

Author

Mi, Hao-Yang, Jing, Xin, Salick, Max R., Peng, Xiang-Fang, and Turng, Lih-Sheng

Subjects
Tissue engineering -- Analysis, Polyurethanes -- Mechanical properties, Engineering and manufacturing industries, Science and technology
Abstract

Injection foaming is an method for mass producing lightweight, foamed plastic components with excellent dimensional stability while using less material and energy. In this study, a novel injection foaming method employing supercritical C[O.sub.2] (scC[O.sub.2]) and water as coblowing agents was developed to produce thermoplastic polyurethane (TPU) components with a uniform porous structure and no solid skin. Various characterization techniques were employed to investigate the cell morphology, crystallization behavior, and static and dynamic mechanical properties of solid injection molded samples, foamed samples using C[O.sub.2] or water as a single blowing agent, and foamed samples using both C[O.sub.2] and water as coblowing agents. When compared with C[O.sub.2] foamed samples, samples produced by the coblowing method exhibited much more uniform cell morphologies without a noticeable reduction in mechanical properties. Moreover, these TPU samples had almost no skin layer, which permitted the free transport of nutrients and waste throughout the samples. Such a mass-produced, skin-free structure is desirable in tissue engineering. In this study, the biocompatibility of the scaffolds was confirmed and the effect of these blowing agents on the TPU foaming behavior was studied., INTRODUCTION Synthetic and natural polymers have been used in tissue engineering to prepare temporary scaffolds for transplanted cells for tissue recovery and organ replacement. A wide variety of fabrication methods [...]

Published
2014
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36. Synthesis and Fabrication of Supramolecular Polydimethylsiloxane-Based Nanocomposite Elastomer for Versatile and Intelligent Sensing

Author

Jing, Xin, Ma, Zhenping, Antwi-Afari, Maxwell Fordjour, Wang, Lin, Li, Heng, Mi, Hao-Yang, Feng, Pei-Yong, and Liu, Yuejun

Abstract

High-performance strain sensors featuring self-healing ability and high stretchability are desired for human motion detection, soft robotics, and diver intelligent applications. Herein, a novel self-healing elastomer was synthesized via a facile one-pot polycondensation reaction between bis(3-aminopropyl) terminated polydimethylsiloxane and 2,4’-tolylene diisocyanate, followed by introducing carboxyl-functionalized multiwalled carbon nanotubes (CNTs). The physically entangled linear molecular chains and multiple hydrogen bonds endowed elastomer with a remarkable healing efficiency of 98.1% and outstanding stretchability of over 1000%. Owing to the conductive network constructed by the uniformly dispersed CNT, the nanocomposite elastomer-based strain sensor achieved a high gauge factor of 2.43 and its sensing performance could be well regained after self-healing. The strain sensor was successfully used for detecting various human motions and distinguishing facial microexpressions. Moreover, the nanocomposite elastomer applied on a grip ball and woolen glove as sensing units rendered them with the ability of grip force detection and sign language recognition. This work offers a new route and a promising self-healing nanocomposite elastomer for the development of recyclable and sustainable high-performance strain sensors and prospects its advanced intelligent applications.

Published
2021

37. Assessment of a passive exoskeleton system on spinal biomechanics and subjective responses during manual repetitive handling tasks among construction workers

Author

Antwi-afari, Maxwell Fordjour, Li, Heng, Anwer, Shahnawaz, Li, Dawei, Yu, Yi, Mi, Hao-yang, Wuni, Ibrahim Yahaya, Antwi-afari, Maxwell Fordjour, Li, Heng, Anwer, Shahnawaz, Li, Dawei, Yu, Yi, Mi, Hao-yang, and Wuni, Ibrahim Yahaya

Abstract

An exoskeleton system can be an effective ergonomic intervention for mitigating the risks of developing work-related musculoskeletal disorders, yet little attention is given to the effects of its application on physical risk factors and subjective responses. Therefore, the objective of this study was to examine the effects of a passive exoskeleton system on spinal biomechanics and subjective responses during manual repetitive handling tasks among construction workers. Muscle activity of the Thoracic Erector Spinae (TES), Lumbar Erector Spinae (LES) at L3 vertebrae level, Rectus Abdominis (RA), and External Oblique (EO) during the repetitive handling tasks were measured by surface electromyography (sEMG). Additionally, the Borg categorical rating scale (Borg CR 10), local perceived pressure (LPP), and system usability scale (SUS) were used to measure the ratings of perceived discomfort, perceived musculoskeletal pressure, and system usability, respectively. Our results found that: (1) the use of the passive exoskeleton system significantly reduced LES muscle activity (11–33% MVC), with a greater reduction in LES muscle activity (32.71% MVC) for the heaviest lifting load; (2) the use of the passive exoskeleton system significantly reduced perceived discomfort scores (42.40%) of the lower back for the heaviest lifting load; (3) increased lifting load significantly increased LPP scores of the shoulder, lower back, and leg body parts; and (4) majority of the participants rated the passive exoskeleton system as having acceptable usability. The findings of these results indicate that the developed passive exoskeleton system could reduce the internal muscle force, extensor moments, and spinal forces in the lumbar region.

Published
2021

41. Development of Biomimetic Thermoplastic Polyurethane/Fibroin Small-Diameter Vascular Grafts via a Novel Electrospinning Approach

Author

Yu, Emily, Mi, Hao-Yang, Zhang, Jue, Thomson, James A., and Turng, Lih-Sheng

Subjects
Tissue Engineering, Polyurethanes, Temperature, Endothelial Cells, Water, Bombyx, Article, Blood Vessel Prosthesis, Biomimetic Materials, Tensile Strength, Solvents, Wettability, Animals, Humans, Fibroins, Plastics
Abstract

A new electrospinning approach for fabricating vascular grafts with a layered, circumferentially aligned, and micro-wavy fibrous structure similar to natural elastic tissues has been developed. The customized electrospinning collector was able to generate wavy fibers using the dynamic "jump rope" collecting process, which also solved the sample removal problem for mandrel-type collectors. In this study, natural silk fibroin and synthetic thermoplastic polyurethane (TPU) were combined at different weight ratios to produce hybrid small-diameter vascular grafts. The purpose of combining these two materials was to leverage the bioactivity and tunable mechanical properties of these natural and synthetic materials. Results showed that the electrospun fiber morphology was highly influenced by the material compositions and solvents employed. All of the TPU/fibroin hybrid grafts had mechanical properties comparable to natural blood vessels. The circumferentially aligned and wavy biomimetic configuration provided the grafts with a sufficient toe region and the capacity for long-term usage under repeated dilatation and contraction. Cell culture tests with human endothelial cells (EC) also revealed high cell viability and good biocompatibility for these grafts. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 985-996, 2018.

Published
2017

42. Highly chlorine resistant polyamide reverse osmosis membranes realized by interfacial polymerization at a free interface with a buffer layer

Author

Zhang, Qing, Ma, Zhenping, Jing, Xin, Mi, Hao-Yang, Liu, Yuejun, and Li, Songwei

Abstract

The polyamide (PA) reverse osmosis (RO) membranes prepared by interfacial polymerization at a free aqueous–organic interface always suffer from polymerization instability on the free-interface and low chlorine resistance. Focusing on these problems, in this study, a new approach was proposed which introduced an additional buffer layer to assist the free-interfacial polymerization (BLFIP). And due to the adjustment of the mitigation of the organic phase and water phase on the free-interface, defect-free PA membranes with significantly improved surface smoothness were successfully prepared by the proposed BLFIP process and the resultant membranes demonstrated superior desalination performance compared to the PA membranes prepared with the previous technique. With the optimized concentration of 0.3 wt.% trimesoyl chloride (TMC) and 0.6 wt.%, m-xylylenediamine, the prepared BLFIP PA membrane showed salt rejection rate of 92.55%, 92.01%, 83.99% and 95.16%, to Na2SO4, MgSO4, NaCl and methyl orange, respectively at 5 bar, while maintained a water flux of about 2 Lm–2h–1bar–1. More importantly, the BLFIP PA membrane possesses excellent long-term stability, and chlorine resistance comparing with traditional PA membranes based on TMC and m-phenylenediamine, which demonstrated the new method in this study paved a facile way for preparing RO filtration membranes with outstanding performance in seawater desalination.

Published
2021
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43. Preparation of fast‐degrading poly(lactic acid)/soy protein concentrate biocomposite foams via supercritical CO2 foaming.

Author

Liu, Tong, Peng, Xiang‐Fang, Mi, Hao‐Yang, Li, Heng, Turng, Lih‐Sheng, and Xu, Bai‐Ping

Subjects
FOAM, LACTIC acid, SUPERCRITICAL carbon dioxide, BLOWING agents, SOY proteins, INTERFACIAL bonding, HETEROGENOUS nucleation
Abstract

To increase the degradation rate of poly(lactic acid) (PLA), soy protein concentrate (SPC) was introduced via melt compounding using a self‐developed, co‐rotating, non‐twin‐screw extruder. Poly(2‐ethyl‐2‐oxazoline) (PEOX) and diphenyl methane diisocyanate (MDI) were added to plasticize the melt and improve the compatibility between PLA and SPC. The PLA/SPC blends were subsequently foamed using supercritical carbon dioxide (CO2) as a blowing agent to produce porous composites. The involvement of SPC promoted cold crystallization of PLA but reduced the thermal stability of the blends. PLA showed a strong interfacial bonding with modified SPC, and the SPC formed continuous three‐dimensional networks when its proportion reached 30 wt%. In the foaming process, SPC domains acted as heterogeneous nucleation sites, which resulted in enhanced cell densities and reduced cell diameters. The PLA/SPC (70:30) sample showed the finest cell structure due to the presence of the SPC network. For the same blends, increasing the foaming pressure from 16 to 20 MPa enhanced the cell density by about 5 times. The water absorption rate and the biodegradation rate of the PLA/SPC foams were much higher than that of neat PLA due to the hydrophilicity of SPC and the porous structure of the foams. POLYM. ENG. SCI., 59:1753–1762, 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Published
2019
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47. Hierarchically decorated electrospun poly( $$ \varepsilon $$ -caprolactone)/nanohydroxyapatite composite nanofibers for bone tissue engineering.

Author

Jing, Xin, Jin, Elizabeth, Mi, Hao-Yang, Li, Wan-Ju, Peng, Xiang-Fang, and Turng, Lih-Sheng

Subjects
CAPROLACTONES, HYDROXYAPATITE, COMPOSITE materials, NANOFIBERS, TISSUE engineering, NANOCOMPOSITE materials
Abstract

Bone is a nanocomposite comprised of two main components, nanohydroxyapatite (nHA) and Type I collagen. The aim of this study is to mimic the nanotopography of collagen fibrils in bone tissue and to modulate their cellular functions by nanoscale stimulation. Three-dimensional structures consisting of electrospun poly( $$ \varepsilon $$ -caprolactone) (PCL) and PCL/nHA composite nanofibers decorated by periodically spaced PCL crystal lamellae (shish-kebab structure) were created. It was found that the hierarchically decorated nanostructure not only enhanced the mechanical properties of the scaffolds but also changed the surface wettability behavior of the scaffolds. The enhanced surface wettability facilitated biomimetic mineralization through apatite deposition when exposed to simulated body fluids (SBF). MG-63, an osteosarcoma cell line which behaves similarly to osteoblasts, was used to study the cellular response to the scaffolds. Data suggest kebab crystal nanotopography facilitating cell attachment and proliferation. Functional assays, which quantify alkaline phosphatase (ALP) and calcium expression, revealed increased ALP activity and increased calcium expression on decorated nanofibers. In addition, compared with other scaffolds, the cells on PCL/nHA nanofibrous shish-kebab-structured scaffolds showed obvious extended pseudopodia of the filaments in the cytoskeleton study, demonstrating better interactions between cells and scaffolds. [ABSTRACT FROM AUTHOR]

Published
2015
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48. Fabrication of polylactic acid/polyethylene glycol ( PLA/ PEG) porous scaffold by supercritical CO2 foaming and particle leaching.

Author

Chen, Bin‐Yi, Jing, Xin, Mi, Hao‐Yang, Zhao, Haibin, Zhang, Wen‐Hao, Peng, Xiang‐Fang, and Turng, Lih‐Sheng

Subjects
POLYLACTIC acid, POLYETHYLENE glycol, SCAFFOLDING, VISCOELASTICITY, POROSITY, CHEMICAL engineering, POLYMERS
Abstract

PLA/PEG/NaCl blends were melt-blended followed by gas foaming and particle leaching process to fabricate porous scaffold with high porosity and interconnectivity. A home-made triple-screw compounding extruder was used to intensify the mixability and dispersion of NaCl and PEG in the PLA matrix. Supercritical carbon dioxide was used as physical blowing agent for the microcellular foaming process. Sodium chloride (NaCl) was used as the porogen to further improve the porosity of PLA scaffold. This study investigated the effects of PEG and NaCl on the structure and properties of the PLA-based blend, as well as the porosity, pore size, interconnectivity, and hydrophilicity of porous scaffolds. It was found that the incorporation of PEG and NaCl significantly improved the crystallization rate and reduced viscoelasticity of PLA. Moreover, scaffolds obtained from PLA/PEG/NaCl blends had an interconnected bimodal porous structure with the open-pore content about 86% and the highest porosity of 80%. And the presence of PEG in PLA/NaCl composite improved the extraction ability of NaCl particles during leaching process, which resulted in a well-interconnected structure. The biocompatibility of the porous scaffolds fabricated was verified by culturing fibroblast cells for 10 days. POLYM. ENG. SCI., 55:1339-1348, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Published
2015
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