Open porous morphology evolution in poly (butylene succinate)/chitin nanocrystal nanocomposite foams

In recent decades, biodegradable polymeric open-porous foams have been engaging increasing interests owing to their biodegradability, porosity and biocompatibility. In this work, biodegradable poly (butylene succinate) (PBS)/chitin nanocrystals (ChNCs) nanocomposite foams with open porous structure were successful fabricated by a solid-state batch foaming method. ChNCs were obtained from chitin by using sulfuric acid treatment and then introduced into PBS. The incorporation of ChNCs had a positive effect on the crystallization behaviors, melt viscoelasticity and thermal stability of diverse PBS specimens. Compared with the change of foaming temperature, the addition of ChNCs would cause a prominent influence on the open porous structure of diverse PBS foams. The probable explanation was that during the foaming process, the spherulites and/or ChNCs as the hard region in PBS could be served as pore wall and the amorphous area as the soft region was acted as pore, leading to open porous PBS foams. The reported strategy in this work could provide the guidelines to regulate and control open porous foams in other semi-crystalline polymer matrices.

Open Porous α + β Titanium Alloy by Liquid Metal Dealloying for Biomedical Applications

Open porous dendrite-reinforced TiMo alloy was synthesized by liquid metal dealloying of the precursor Ti47.5Mo2.5Cu50 (at.%) alloy in liquid magnesium (Mg). The porous TiMo alloy consists of α-titanium and β-titanium phases and possesses a complex microstructure. The microstructure consists of micrometer scale β-titanium dendrites surrounded by submicrometer scale α-titanium ligaments. Due to the dendrite-reinforced microstructure, the porous TiMo alloy possesses relatively high yield strength value of up to 180 MPa combined with high deformability probed under compression loading. At the same time, the elastic modulus of the porous TiMo alloy (below 10 GPa) is in the range of that found for human bone. This mechanical behavior along with the open porous structure is attractive for biomedical applications and suggests opportunities for using the porous TiMo alloy in implant applications.

Super Porous Hydrogels: A Review

Super porous hydrogels (SPHs) basically developed initially create as a novel drug delivery system to absorb and continue to hold the drugs in the gastric medium which allows absorption in stomach and upper part of the gastrointestinal tract. These systems get swollen in the stomach instantly and in the harsh stomach environment they maintain their integrity, while the pharmaceutical active ingredient is being released. Instant and fast swelling property of hydrogel is based on water absorption through open porous structure by capillary force. SPHs have the poor mechanical strength which has got over by developing the second-generation SPH composites (SPHCs) and the third-generation SPH hybrids (SPHHs). The present review has been focused on the preparation, characterization and application of SPHs.

Superconducting YBCO Foams as Trapped Field Magnets

Superconducting foams of YBa 2 Cu 3 O y (YBCO) are proposed as trapped field magnets or supermagnets. The foams with an open-porous structure are light-weight, mechanically strong and can be prepared in large sample sizes. The trapped field distributions were measured using a scanning Hall probe on various sides of an YBCO foam sample after field-cooling in a magnetic field of 0.5 T produced by a square Nd-Fe-B permanent magnet. The maximum trapped field (TF) measured is about 400 G (77 K) at the bottom of the sample. Several details of the TF distribution, the current flow and possible applicatons of such superconducting foam samples in space applications, e.g., as active elements in flux-pinning docking interfaces (FPDI) or as portable strong magnets to collect debris in space, are outlined.

Superconducting YBCO Foams as Trapped Field Magnets

Superconducting foams of YBa$_2$Cu$_3$O$_y$ (YBCO) are proposed as trapped field magnets or supermagnets. The foams with an open-porous structure are light-weight, mechanically strong and can be prepared in large sample sizes. The trapped field distributions were measured using a scanning Hall probe on various sides of an YBCO foam sample after field-cooling in a magnetic field of 0.5 T produced by a square Nd-Fe-B permanent magnet. The maximum trapped field (TF) measured is about 400 G (77 K) at the bottom of the sample. Several details of the TF distribution, the current flow and possible applicatons of such superconducting foam samples in space applications, e.g., as active elements in flux-pinning docking interfaces (FPDI) or as portable strong magnets to collect debris in space, are outlined.

Fabrication of three dimensional open porous regular structure of PA-2200 for enhanced strength of scaffold using selective laser sintering

Purpose Scaffolds are essentially required to have open porous structure for facilitating bone to grow. They are generally placed on those bone defective/fractured sites which are more prone to compressive loading. Open porous structure lacks in strength in comparison to solid. Selective laser sintering (SLS) process is prominently used for fabrication of polymer/composite scaffolds. So, this paper aims to study for fabrication of three-dimensional open porous scaffolds with enhanced strength, process parameters of SLS of a biocompatible material are required to be optimized. Design/methodology/approach Regular open porous structures with suitable pore size as per computer-aided design models were fabricated using SLS. Polyamide (PA-2200) was used to fabricate the specimen/scaffold. To optimize the strength of the designed structure, response surface methodology was used to design the experiments. Specimens as per ASTM D695 were fabricated using SLS and compressive testing was carried out. Analysis of variance was done for estimating contribution of individual process parameters. Optimized process parameters were obtained using a trust region algorithm and correlated with experimental results. Accuracy of the fabricated specimen/scaffold was also assessed in terms of IT grades. In vitro cell culture on the fabricated structures confirmed the biocompatibility of polyamide (PA-2200). Findings Optimized process parameters for open cell process structures were obtained and confirmed experimentally. Laser power, hatch spacing and layer thickness have contributed more in the porous part’s strength than scan speed. The accuracy of the order of IT16 has been found for all functional dimensions. Cell growth and proliferation confirmed biocompatibility of polyamide (PA-2200) for scaffold applications. Originality/value This paper demonstrates the biocompatibility of PA-2200 for scaffold applications. The optimized process parameters of SLS process for open cell structure having pore size 1.2 × 1.2 mm2 with strut diameter of 1 mm have been obtained. The accuracy of the order of IT16 was obtained at the optimized process factors.