scholarly journals Mechanical Properties of Architectured Gelatin-Based Hydrogels on Different Hierarchical Levels

MRS Advances ◽  
2016 ◽  
Vol 1 (27) ◽  
pp. 1995-2001 ◽  
Author(s):  
Radovan Vukićević ◽  
Axel T. Neffe ◽  
Tim Gebauer ◽  
Oliver Frank ◽  
Michael Schossig ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ethyl Ester ◽  
Tensile Tests ◽  
Step Process ◽  
Afm Indentation ◽  
Opposite Trend ◽  
Hierarchical Levels ◽  
One Step ◽  
Micro Level ◽  
Porous Biomaterials

ABSTRACTPreparation of three-dimensionally architectured porous biomaterials can be achieved in a one-step process by stabilizing gelatin with L-lysine diisocyanate ethyl ester (LDI) in water. The reaction of gelatin with LDI in presence of water leads to the formation of oligourea bridges between gelatin molecules and oligourea chains grafted on gelatin. The number and the length of the bridges, as well as of the grafted chains strongly depend on the concentration of the LDI used for the stabilization, and this has huge influence on the mechanical properties of the material on different hierarchical levels. Higher LDI concentrations yield materials with increased deformation resistance in tensile tests due to the higher number of covalent and physical netpoints in the material. However, mechanical properties determined on the micro-level by AFM indentation showed the opposite trend, i.e. a decrease of Young’s modulus with increasing LDI content. This was interpreted by a decreasing number of shorter oligourea bridges between gelatin chains with decreasing LDI content.

Synergistic Toughening Effects of Nano-CaCO3 and POE on Ternary-Phase Polypropylene Nanocomposites

2007 ◽  
Vol 334-335 ◽  
pp. 553-556 ◽  
Author(s):  
Min Zhi Rong ◽  
Ming Qiu Zhang ◽  
Chuan Guo Ma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Synergistic Effect ◽  
Ternary Phase ◽  
Binary Blends ◽  
Step Process ◽  
Phase Structures ◽  
Polypropylene Nanocomposites ◽  
One Step ◽  
The One

Microstructure and mechanical properties of ternary PP/POE/nano-CaCO3 composites were investigated. Two different phase structures were obtained mainly by adjusting processing sequence. The one-step process led to the isolated distribution of elastomer and CaCO3 particles in PP matrix, while the two-step one attained an encapsulated microstructure. In comparison with binary blends of PP/POE or pure PP, toughness of the ternary composites was significantly increased. Meanwhile, their stiffness and tensile strength kept nearly unchanged or slightly enhanced, implying that there is a synergistic effect between nano-CaCO3 and POE components.

scholarly journals 2D Rigid Benzoxazole-Linked Covalent Organic Framework Films with High-Strength, High-Modulus Mechanical Behavior

2020 ◽  
Author(s):  
Kristen Miller ◽  
Lawrence B. Alemany ◽  
Edwin L. Thomas ◽  
Eilaf Egap
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Single Step ◽  
Two Dimensions ◽  
Free Standing ◽  
Step Process ◽  
Axial Tensile ◽  
Solution Cast ◽  
One Step ◽  
Rigid Rod

<p>Two-dimensional (2D) benzoxazole-linked covalent organic frameworks (COFs) provide an opportunity to incorporate the strength and modulus of corresponding 1D rigid-rod polymers into multiple directions by extending covalent bonding into two dimensions while simultaneously reducing density. Thus far, this potential has been elusive because of the challenge of producing high-quality COF films, particularly those with irreversible, rigid benzazole linkages. The majority of COF syntheses use a single-step process approach where polymerization occurs faster than crystallization and typically result in a poorly ordered and insoluble powder. Here, we present a one-step synthesis and two-step process that allows the deposition of a uniform intermediate film via reversible, non-covalent interactions. This network then undergoes an annealing step that facilitates the irreversible conversion to 2D covalently-bonded polymer product. The resulting films are semi-crystalline with platelet-like crystals embedded in an amorphous matrix with sharp crystal-amorphous interfaces. By this approach, we achieve free-standing films for which we demonstrate the first example of mechanical testing of benzazole-linked COFs. These initial films have promising mechanical properties with an in-plane ultimate tensile strength of nearly 50 MPa and axial tensile and transverse compressive elastic moduli on the scale of several GPa. These mechanical properties already rival the performance of solution-cast films of 1D polybenzoxazole (PBO).<i></i></p>

scholarly journals Structure and Mechanical Properties of AlMg4.5 And AlMg4.5Mn Wires Extruded by Kobo Method

2014 ◽  
Vol 59 (2) ◽  
pp. 473-479 ◽  
Author(s):  
M. Jaskowski ◽  
K. Pieła ◽  
L. Błaz
Keyword(s):  
Mechanical Properties ◽  
Work Hardening ◽  
Flow Instability ◽  
Cold Deformation ◽  
Tensile Tests ◽  
Strength Properties ◽  
Extrusion Ratio ◽  
Groove Rolling ◽  
One Step ◽  
Lüders Bands

Abstract The influence of the number of extrusion steps in KoBo method (at the same total extrusion ratio of λ = 100) on structure, mechanical properties and work hardening characteristics of AlMg4.5 and AlMg4.5Mn (AA5083) alloys was investigated. It was found that one-step extrusion leads to the formation of recrystallised structure of the material, while the use of two-step extrusion yields a fibrous structure of a “mixed” type, i.e. containing areas where the intensive recovery effects are associated with partially recrystallised structure. As a consequence, the strength properties of the latter extrudate are much higher in both as extruded state and after the subsequent cold rolling. In all cases, the tensile stress-strain curves of the extrudates show the flow stress serrations that are typical for the Portevin - LeChatelier (P-L) effect. In a few tensile tests, the P-L effect was preceded by the plastic flow instability being typical for the occurrence of Lüders bands. Both AlMg4.5 and AlMg4.5Mn extruded wires show a monotonic increase of the work hardening that results from the following cold deformation in the groove rolling.

scholarly journals 2D Rigid Benzoxazole-Linked Covalent Organic Framework Films with High-Strength, High-Modulus Mechanical Behavior

2020 ◽  
Author(s):  
Kristen Miller ◽  
Lawrence B. Alemany ◽  
Edwin L. Thomas ◽  
Eilaf Egap
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Single Step ◽  
Two Dimensions ◽  
Free Standing ◽  
Step Process ◽  
Axial Tensile ◽  
Solution Cast ◽  
One Step ◽  
Rigid Rod

<p>Two-dimensional (2D) benzoxazole-linked covalent organic frameworks (COFs) provide an opportunity to incorporate the strength and modulus of corresponding 1D rigid-rod polymers into multiple directions by extending covalent bonding into two dimensions while simultaneously reducing density. Thus far, this potential has been elusive because of the challenge of producing high-quality COF films, particularly those with irreversible, rigid benzazole linkages. The majority of COF syntheses use a single-step process approach where polymerization occurs faster than crystallization and typically result in a poorly ordered and insoluble powder. Here, we present a one-step synthesis and two-step process that allows the deposition of a uniform intermediate film via reversible, non-covalent interactions. This network then undergoes an annealing step that facilitates the irreversible conversion to 2D covalently-bonded polymer product. The resulting films are semi-crystalline with platelet-like crystals embedded in an amorphous matrix with sharp crystal-amorphous interfaces. By this approach, we achieve free-standing films for which we demonstrate the first example of mechanical testing of benzazole-linked COFs. These initial films have promising mechanical properties with an in-plane ultimate tensile strength of nearly 50 MPa and axial tensile and transverse compressive elastic moduli on the scale of several GPa. These mechanical properties already rival the performance of solution-cast films of 1D polybenzoxazole (PBO).<i></i></p>

Experimental investigation on fabrication and thermal-stamping of woven jute/polylactic acid biocomposites

2018 ◽  
Vol 53 (7) ◽  
pp. 851-861 ◽  
Author(s):  
Siqi Du ◽  
Xiongqi Peng ◽  
Hailin Gu
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Alkali Treatment ◽  
Tensile Tests ◽  
Woven Fabrics ◽  
Scanning Calorimetry ◽  
Biodegradable Composites ◽  
One Step ◽  
Jute Fabrics ◽  
Complicated Geometries

Jute woven fabrics in as-received and alkali-treated conditions were respectively combined with polylactic acid resin to fabricate completely biodegradable composites by compression molding in one step. Scanning electron microscopy and differential scanning calorimetry and tensile tests were conducted to estimate the surface morphology, thermal, and mechanical properties of jute fabrics and the composites manufactured. The formability of the composites was evaluated by a thermal-stamping experiment. The results demonstrate that alkali treatment removes the surface impurities of fabrics and refine the fiber structures, lifting the thermal property of composites. As for the mechanical properties, the strength of the fabrics and composites declines while the modulus increases after alkali treatment of fabrics. Although some defects occur, the thermal-stamping experiments confirm the possibility of shaping jute/polylactic acid composite into complicated geometries. And the formability of the composites is influenced by many factors including sample sizes, the holding time of temperature, layup sequence, and so on while the number of layer makes no obvious difference to it.

scholarly journals Preparation and Characterization of Polybutylene Succinate Reinforced with Pure Cellulose Nanofibril and Lignocellulose Nanofibril Using Two-Step Process

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3945
Author(s):  
Azelia Wulan Cindradewi ◽  
Rajkumar Bandi ◽  
Chan-Woo Park ◽  
Ji-Soo Park ◽  
Eun-Ah Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lignin Content ◽  
Deep Eutectic Solvent ◽  
Cellulose Nanofibril ◽  
Twin Screw Extrusion ◽  
Step Process ◽  
Pure Cellulose ◽  
Twin Screw ◽  
One Step ◽  
Polybutylene Succinate

This study reports the preparation of a polybutylene succinate (PBS) film reinforced with pure cellulose nanofibril (PCNF) and lignocellulose nanofibril (LCNF) by a two-step process that consists of solvent dispersion and twin-screw extrusion. Compared to the conventional one-step process, this method offered improved mechanical properties. The addition of 5% CNF increased the tensile properties up to 18.8%. Further, the effect of the lignin content was also studied by using LCNF as a reinforcement. The LCNF was prepared with and without a deep eutectic solvent (DES) pretreatment to gain LCNF with a lignin content that varied between 5, 19, and 30%. The mechanical properties results show that a 5% addition of LCNF to the PBS matrix increased its tensile strength and elastic modulus. Further, the morphological and thermal properties of the composites were also studied in detail.

Effect of Dynamic Crosslinking on Mechanical Properties of PP/EPDM Blends

1993 ◽  
Vol 58 (11) ◽  
pp. 2642-2650 ◽  
Author(s):  
Zdeněk Kruliš ◽  
Ivan Fortelný ◽  
Josef Kovář
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Shear Modulus ◽  
High Impact ◽  
Necessary Condition ◽  
Step Method ◽  
Melt Mixing ◽  
One Step ◽  
High Impact Strength ◽  
Dynamic Curing

The effect of dynamic curing of PP/EPDM blends with sulfur and thiuram disulfide systems on their mechanical properties was studied. The results were interpreted using the knowledge of the formation of phase structure in the blends during their melt mixing. It was shown, that a sufficiently slow curing reaction is necessary if a high impact strength is to be obtained. Only in such case, a fine and homogeneous dispersion of elastomer can be formed, which is the necessary condition for high impact strength of the blend. Using an inhibitor of curing in the system and a one-step method of dynamic curing leads to an increase in impact strength of blends. From the comparison of shear modulus and impact strength values, it follows that, at the stiffness, the dynamically cured blends have higher impact strength than the uncured ones.

scholarly journals Is Dialdehyde Chitosan a Good Substance to Modify Physicochemical Properties of Biopolymeric Materials?

2021 ◽  
Vol 22 (7) ◽  
pp. 3391
Author(s):  
Sylwia Grabska-Zielińska ◽  
Alina Sionkowska ◽  
Ewa Olewnik-Kruszkowska ◽  
Katarzyna Reczyńska ◽  
Elżbieta Pamuła
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Physicochemical Properties ◽  
Silk Fibroin ◽  
Three Dimensional ◽  
Microscopy Imaging ◽  
Maximum Deformation ◽  
One Step ◽  
Chitosan Blends ◽  
Fourier Transfer Infrared Spectroscopy

The aim of this work was to compare physicochemical properties of three dimensional scaffolds based on silk fibroin, collagen and chitosan blends, cross-linked with dialdehyde starch (DAS) and dialdehyde chitosan (DAC). DAS was commercially available, while DAC was obtained by one-step synthesis. Structure and physicochemical properties of the materials were characterized using Fourier transfer infrared spectroscopy with attenuated total reflectance device (FTIR-ATR), swelling behavior and water content measurements, porosity and density observations, scanning electron microscopy imaging (SEM), mechanical properties evaluation and thermogravimetric analysis. Metabolic activity with AlamarBlue assay and live/dead fluorescence staining were performed to evaluate the cytocompatibility of the obtained materials with MG-63 osteoblast-like cells. The results showed that the properties of the scaffolds based on silk fibroin, collagen and chitosan can be modified by chemical cross-linking with DAS and DAC. It was found that DAS and DAC have different influence on the properties of biopolymeric scaffolds. Materials cross-linked with DAS were characterized by higher swelling ability (~4000% for DAS cross-linked materials; ~2500% for DAC cross-linked materials), they had lower density (Coll/CTS/30SF scaffold cross-linked with DAS: 21.8 ± 2.4 g/cm3; cross-linked with DAC: 14.6 ± 0.7 g/cm3) and lower mechanical properties (maximum deformation for DAC cross-linked scaffolds was about 69%; for DAS cross-linked scaffolds it was in the range of 12.67 ± 1.51% and 19.83 ± 1.30%) in comparison to materials cross-linked with DAC. Additionally, scaffolds cross-linked with DAS exhibited higher biocompatibility than those cross-linked with DAC. However, the obtained results showed that both types of scaffolds can provide the support required in regenerative medicine and tissue engineering. The scaffolds presented in the present work can be potentially used in bone tissue engineering to facilitate healing of small bone defects.

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