Mechanical properties and shape memory effect of 3D-printed PLA-based porous scaffolds.
01 Apr 2016-Journal of The Mechanical Behavior of Biomedical Materials (Elsevier)-Vol. 57, pp 139-148
TL;DR: PLA/15%HA porous scaffolds obtained by 3D-printing with shape recovery of 98% may be used as self-fitting implant for small bone defect replacement owing to SME and were found to withstand up to three compression-heating-compression cycles without delamination.
Abstract: In the present work polylactide (PLA)/15wt% hydroxyapatite (HA) porous scaffolds with pre-modeled structure were obtained by 3D-printing by fused filament fabrication. Composite filament was obtained by extrusion. Mechanical properties, structural characteristics and shape memory effect (SME) were studied. Direct heating was used for activation of SME. The average pore size and porosity of the scaffolds were 700μm and 30vol%, respectively. Dispersed particles of HA acted as nucleation centers during the ordering of PLA molecular chains and formed an additional rigid fixed phase that reduced molecular mobility, which led to a shift of the onset of recovery stress growth from 53 to 57°C. A more rapid development of stresses was observed for PLA/HA composites with the maximum recovery stress of 3.0MPa at 70°C. Ceramic particles inhibited the growth of cracks during compression-heating-compression cycles when porous PLA/HA 3D-scaffolds recovered their initial shape. Shape recovery at the last cycle was about 96%. SME during heating may have resulted in "self-healing" of scaffold by narrowing the cracks. PLA/HA 3D-scaffolds were found to withstand up to three compression-heating-compression cycles without delamination. It was shown that PLA/15%HA porous scaffolds obtained by 3D-printing with shape recovery of 98% may be used as self-fitting implant for small bone defect replacement owing to SME.
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01 Jan 2007
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TL;DR: The novelty of this new method is that the PLLA paste containing ammonium bicarbonate salt particles can be easily handled and molded into any shape, allowing for fabricating a wide range of temporal tissue scaffolds requiring a specific shape and geometry.
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471 citations
TL;DR: In this literature review the biologically inspired scaffolds, bone substitutes, implants characterized by mechanical strength and biocompatibility, as well the drug delivery systems, based on hydroxyapatite are discussed.
429 citations
References
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TL;DR: A very broad, additional spectrum of possible applications for intelligent polymers that covers an area from minimally invasive surgery, through high-performance textiles, up to self-repairing plastic components in every kind of transportation vehicles.
Abstract: Shape memory polymer compositions, articles of manufacture thereof, and methods of preparation and use thereof are described. The shape memory polymer compositions can hold more than one shape in memory. Suitable compositions include at least one hard segment and at least one soft segment. The Ttrans of the hard segment is preferably between -30 and 270 °C. At least one of the hard or soft segments can contain a cross-linkable group, and the segments can be linked by formation of an interpenetrating network or a semi-interpenetrating network, or by physical interactions of the blocks. Objects can be formed into a given shape at a temperature above the Ttrans of the hard segment, and cooled to a temperature below the Ttrans of the soft segment. If the object is subsequently formed into a second shape, the object can return to its original shape by heating the object above the Ttrans of the soft segment and below the Ttrans of the hard segment. The compositions can also include two soft segments which are linked via functional groups which are cleaved in response to application of light, electric field, magnetic field or ultrasound. The cleavage of these groups causes the object to return to its original shape.
2,837 citations
"Mechanical properties and shape mem..." refers background in this paper
...Such a transformation can be activated by external stimulation through heat, electric or magnetic field, light, moisture, etc. (Lendlein and Kelch 2002a, 2002b) SMPs require coexistence of a fixed phase (crosslinks, entanglements or intermolecular interactions) and a soft phase (Liu et al., 2004;…...
[...]
01 Jan 2007
TL;DR: The Third edition of the Kirk-Othmer encyclopedia of chemical technology as mentioned in this paper was published in 1989, with the title "Kirk's Encyclopedia of Chemical Technology: Chemical Technology".
Abstract: 介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。
2,666 citations
"Mechanical properties and shape mem..." refers background in this paper
...Such a transformation can be activated by external stimulation through heat, electric or magnetic field, light, moisture, etc. (Lendlein and Kelch 2002a, 2002b) SMPs require coexistence of a fixed phase (crosslinks, entanglements or intermolecular interactions) and a soft phase (Liu et al., 2004;…...
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Book•
01 Jan 1995
TL;DR: In this paper, Free-Radical Chain-Growth Polymerization (FRCG) and Ionic chain-growth polymers (Ionic chain growth polymers) are discussed.
Abstract: Physical Properties and Physical Chemistry of Polymers.- Free-Radical Chain-Growth Polymerization.- Ionic Chain-Growth Polymerization.- Ring-Opening Polymerizations.- Common Chain-Growth Polymers.- Step-Growth Polymerization and Step-Growth Polymers.- Naturally Occurring Polymers.- Reactivity and Chemical Modifications of Polymers.- Polymeric Materials for Special Applications.
2,239 citations
"Mechanical properties and shape mem..." refers background in this paper
...SME in polymers was first described in 1953 (Flory, 1953) and has since been actively studied in different polymers (Xu and Song, 2015; Behl et al., 2010; Liu et al., 2007)....
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TL;DR: A group of degradable thermoplastic polymers that are able to change their shape after an increase in temperature enables bulky implants to be placed in the body through small incisions or to perform complex mechanical deformations automatically.
Abstract: The introduction of biodegradable implant materials as well as minimally invasive surgical procedures in medicine has substantially improved health care within the past few decades. This report describes a group of degradable thermoplastic polymers that are able to change their shape after an increase in temperature. Their shape-memory capability enables bulky implants to be placed in the body through small incisions or to perform complex mechanical deformations automatically. A smart degradable suture was created to illustrate the potential of these shape-memory thermoplastics in biomedical applications.
2,145 citations
Additional excerpts
...Shape memory properties of PLA such as recovery stress and strain may be improved by crosslinking, chemical modification, addition of co-polymers, which was studied in detail by Lendlein et al. (Lendlein and Langer, 2002; Wischke et al., 2009; Pierce et al., 2011)....
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