Microcellular Injection Molding of Thermoplastic Polyurethane (TPU) Scaffolds Using Carbon Dioxide and Water as Co-Blowing Agents

2013 ◽  
Author(s):  
Hao-Yang Mi ◽  
Xin Jing ◽  
Lih-Sheng Turng ◽  
Xiang-Fang Peng
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Thermoplastic Polyurethane ◽  
Dynamic Mechanical Properties ◽  
Skin Layer ◽  
Tissue Engineering Scaffolds ◽  
Blowing Agents ◽  
Microcellular Injection Molding ◽  
Noticeable Reduction ◽  
Free Transport

In this study, a novel microcellular injection foaming method employing supercritical CO2 (scCO2) and water as co-blowing agents was developed to produce thermoplastic polyurethane (TPU) tissue engineering scaffolds with a uniform porous structure and no solid skin layer. Various characterization techniques were applied to investigate the cell morphology, crystallization behavior, and static and dynamic mechanical properties of solid molded samples, foamed samples using CO2 or water as a single blowing agent, and foamed samples using both CO2 and water as co-blowing agents. Compared with CO2 foamed scaffolds, scaffolds produced by the co-blowing method exhibit much more uniform cell morphologies without a noticeable reduction in mechanical properties. Moreover, these TPU scaffolds have almost no skin layer, which permits free transport of nutrients and waste throughout the samples, which is highly desirable in tissue engineering. The effect of these blowing agents on the shear viscosity of various samples is also reported.

A novel biocompatible double network hydrogel consisting of konjac glucomannan with high mechanical strength and ability to be freely shaped

2015 ◽  
Vol 3 (9) ◽  
pp. 1769-1778 ◽  
Author(s):  
Zhiyong Li ◽  
Yunlan Su ◽  
Baoquan Xie ◽  
Xianggui Liu ◽  
Xia Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Cell Adhesion ◽  
Mechanical Strength ◽  
Synthetic Polymer ◽  
Natural Polymer ◽  
Tissue Engineering Scaffolds ◽  
Adhesion Properties ◽  
High Mechanical Strength ◽  
Double Network

A novel physically linked double-network (DN) hydrogel was prepared by natural polymer KGM and synthetic polymer PAAm. The DN hydrogels exhibit good mechanical properties, cell adhesion properties, and can be freely shaped, making such hydrogels promising for tissue engineering scaffolds.

Comparative study of chemical and physical foaming methods for injection-molded thermoplastic polyurethane

2016 ◽  
Vol 53 (4) ◽  
pp. 373-388 ◽  
Author(s):  
Hrishikesh A Kharbas ◽  
Jason D McNulty ◽  
Thomas Ellingham ◽  
Cyrus Thompson ◽  
Mihai Manitiu ◽  
...  
Keyword(s):  
Injection Molding ◽  
Thermoplastic Polyurethane ◽  
Polyurethane Foams ◽  
Average Cell Size ◽  
Average Cell ◽  
Blowing Agents ◽  
Blowing Agent ◽  
Microcellular Injection Molding ◽  
Injection Molded ◽  
Commercial Applications

Thermoplastic polyurethane is one of the most versatile thermoplastic materials being used in a myriad of industrial and commercial applications. Thermoplastic polyurethane foams are finding new applications in various industries including the furniture, automotive, sportswear, and packaging industries because of their easy processability and desirable customizable properties. In this study, three methods of manufacturing injection molded low density foams were investigated and compared: (1) using chemical blowing agents, (2) using microcellular injection molding with N2 as the blowing agent, and (3) using a combination of supercritical gas-laden pellets injection molding foaming technology and microcellular injection molding processes using co-blowing agents CO2 and N2. Thermal, rheological, microscopic imaging, and mechanical testing were carried out on the molded samples with increasing amounts of blowing agents. The results showed that the use of physical blowing agents yielded softer foams, while the use of CO2 and N2 as co-blowing agents helped to manufacture foams with lower bulk densities, better microstructures, and lower hysteresis loss ratios. Chemical blowing agent-foamed thermoplastic polyurethane showed an earlier onset of degradation. The average cell size decreased and the cell density increased with the use of co-blowing agents. A further increase in gas saturation levels showed a degradation of microstructure by cell coalescence.

Microscopic Methods for Characterization of Selected Surface Properties of Biodegradable, Nanofibrous Tissue Engineering Scaffolds

2017 ◽  
Vol 890 ◽  
pp. 213-216 ◽  
Author(s):  
Adrian Chlanda ◽  
Ewa Kijeńska ◽  
Wojciech Święszkowski
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Force Spectroscopy ◽  
Operating Mode ◽  
Tissue Engineering Scaffolds ◽  
Force Microscopy ◽  
Atomic Force

Biodegradable polymeric fibers with nanoand submicron diameters, produced by electrospinning can be used as scaffolds in tissue engineering. It is necessary to characterize their mechanical properties especially at the nanoscale. The Force Spectroscopy is suitable atomic force microscopy mode, which allows to probe mechanical properties of the material, such as: reduced Young's modulus, deformation, adhesion, and dissipation. If combined with standard operating mode: contact or semicontact, it will also provide advanced topographical analysis. In this paper we are presenting results of Force Spectroscopy characterization of two kinds of electrospun fibers: polycaprolactone and polycaprolactone with hydroxyapatite addition. The average calculated from Johnson-Kendall-Roberts theory Young's modulus was 4 ± 1 MPa for pure polymer mesh and 20 ± 3 MPa for composite mesh.

Effects of EVA-g-MAH on Mechanical Properties and Morphological Structure of TPU/PVC Blends

2012 ◽  
Vol 602-604 ◽  
pp. 656-659
Author(s):  
Gao Shuang Huang ◽  
Song Bai Lin ◽  
Qing Hai Zhang ◽  
Da Gang Li ◽  
Yun Long Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Thermoplastic Polyurethane ◽  
Phase Interface ◽  
Morphological Structure ◽  
Ethylene Vinyl Acetate ◽  
Dynamic Mechanical Properties ◽  
Poly Vinyl Chloride ◽  
Thermal Stability Of ◽  
Scanning Electron

The effects of ethylene vinyl acetate grafting maleic anhydride (EVA-g-MAH )as a compatilizer on the mechanical properties, compatibility and morphological structure of thermoplastic Polyurethane and poly(vinyl chloride) blends were studied. The blends were prepared and characterized by mechanics properties test, scanning electron microscopy(SEM,)dynamic mechanical properties (DMA) and thermogravimetry(TG) . Mechanical properties indicate that the hardness, tensile strength, breaking elongation of the blends are greatly improved by EVA-g-MAH, when the critical EVA-g-MAH content at about 4 wt%.SEM micrographs reveal that EVA-g-MAH could bring down the diameter of dispersed , change brittle fracture into ductile fracture, and promote adhesion of phase interface. The glass transition temperature change by DMA proves that the addition of the EVA-g-MAH improved the compatibilization of blends. And the results of TG experiment show that EVA-g-MAH greatly improve the thermal stability of the blends.

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