scholarly journals Options to Improve the Mechanical Properties of Protein-Based Materials

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 446
Author(s):  
Anne Lamp ◽  
Martin Kaltschmitt ◽  
Jan Dethloff
Keyword(s):  
Mechanical Properties ◽  
Polymer Matrix ◽  
Weak Interactions ◽  
Complex Structure ◽  
High Potential ◽  
Cross Linking ◽  
Reaction Conditions ◽  
Polymer Backbone ◽  
Heat Curing ◽  
Major Bottleneck

While bio-based but chemically synthesized polymers such as polylactic acid require industrial conditions for biodegradation, protein-based materials are home compostable and show high potential for disposable products that are not collected. However, so far, such materials lack in their mechanical properties to reach the requirements for, e.g., packaging applications. Relevant measures for such a modification of protein-based materials are plasticization and cross-linking; the former increasing the elasticity and the latter the tensile strength of the polymer matrix. The assessment shows that compared to other polymers, the major bottleneck of proteins is their complex structure, which can, if developed accordingly, be used to design materials with desired functional properties. Chemicals can act as cross-linkers but require controlled reaction conditions. Physical methods such as heat curing and radiation show higher effectiveness but are not easy to control and can even damage the polymer backbone. Concerning plasticization, effectiveness and compatibility follow opposite trends due to weak interactions between the plasticizer and the protein. Internal plasticization by covalent bonding surpasses these limitations but requires further research specific for each protein. In addition, synergistic approaches, where different plasticization/cross-linking methods are combined, have shown high potential and emphasize the complexity in the design of the polymer matrix.

Effect of fibre content on the mechanical properties of hemp fibre woven fabrics/polypropylene composite laminates

2021 ◽  
pp. 096739112110239
Author(s):  
Sheedev Antony ◽  
Abel Cherouat ◽  
Guillaume Montay
Keyword(s):  
Mechanical Properties ◽  
Polymer Matrix ◽  
Composite Laminates ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Woven Fabrics ◽  
Fibre Content ◽  
Viscoelastic Behaviour ◽  
Hemp Fibre

Nowadays natural fibre composites have gained great significance as reinforcements in polymer matrix composites. Composite material based on a polymer matrix reinforced with natural fibres is extensively used in industry due to their biodegradability, recyclability, low density and high specific properties. A study has been carried out here to investigate the fibre volume fraction effect of hemp fibre woven fabrics/PolyPropylene (PP) composite laminates on the tensile properties and impact hammer impact test. Initially, composite sheets were fabricated by the thermal-compression process with desired number of fabric layers to obtain composite laminates with different fibre volume fraction. Uniaxial, shear and biaxial tensile tests were performed and mechanical properties were calculated. Impact hammer test was also carried out to estimate the frequency and damping parameters of stratified composite plates. Scanning Electron Microscope (SEM) analysis was performed to observe the matrix and fibre constituent defects. Hemp fabrics/PP composite laminates exhibits viscoelastic behaviour and as the fibre volume fraction increases, the viscoelastic behaviour decreases to elastic behaviour. Due to this, the tensile strength increases as the fibre content increases. On the other hand, the natural frequency increases and damping ratio decrease as the fibre volume fraction increases.

scholarly journals Influence of Rhamnolipids and Ionic Cross-Linking Conditions on the Mechanical Properties of Alginate Hydrogels as a Model Bacterial Biofilm

2021 ◽  
Vol 22 (13) ◽  
pp. 6840
Author(s):  
Natalia Czaplicka ◽  
Szymon Mania ◽  
Donata Konopacka-Łyskawa
Keyword(s):  
Mechanical Properties ◽  
Pure Water ◽  
Testing Machine ◽  
Bacterial Biofilm ◽  
Ion Trapping ◽  
Cross Linking ◽  
Box Behnken Design ◽  
Compression Load ◽  
Alginate Hydrogels ◽  
Biofilm Structure

The literature indicates the existence of a relationship between rhamnolipids and bacterial biofilm, as well as the ability of selected bacteria to produce rhamnolipids and alginate. However, the influence of biosurfactant molecules on the mechanical properties of biofilms are still not fully understood. The aim of this research is to determine the effect of rhamnolipids concentration, CaCl2 concentration, and ionic cross-linking time on the mechanical properties of alginate hydrogels using a Box–Behnken design. The mechanical properties of cross-linked alginate hydrogels were characterized using a universal testing machine. It was assumed that the addition of rhamnolipids mainly affects the compression load, and the value of this parameter is lower for hydrogels produced with biosurfactant concentration below CMC than for hydrogels obtained in pure water. In contrast, the addition of rhamnolipids in an amount exceeding CMC causes an increase in compression load. In bacterial biofilms, the presence of rhamnolipid molecules does not exceed the CMC value, which may confirm the influence of this biosurfactant on the formation of the biofilm structure. Moreover, rhamnolipids interact with the hydrophobic part of the alginate copolymer chains, and then the hydrophilic groups of adsorbed biosurfactant molecules create additional calcium ion trapping sites.

scholarly journals Comparison of Mechanical Properties of PMMA Disks for Digitally Designed Dentures

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1745
Author(s):  
Tamaki Hada ◽  
Manabu Kanazawa ◽  
Maiko Iwaki ◽  
Awutsadaporn Katheng ◽  
Shunsuke Minakuchi
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Water Sorption ◽  
Water Solubility ◽  
Flexural Modulus ◽  
Manufacturing Method ◽  
Heat Curing ◽  
Significant Difference ◽  
Cad Cam ◽  
Curing Method

In this study, the physical properties of a custom block manufactured using a self-polymerizing resin (Custom-block), the commercially available CAD/CAM PMMA disk (PMMA-disk), and a heat-polymerizing resin (Conventional PMMA) were evaluated via three different tests. The Custom-block was polymerized by pouring the self-polymerizing resin into a special tray, and Conventional PMMA was polymerized with a heat-curing method, according to the manufacturer’s recommended procedure. The specimens of each group were subjected to three-point bending, water sorption and solubility, and staining tests. The results showed that the materials met the requirements of the ISO standards in all tests, except for the staining tests. The highest flexural strength was exhibited by the PMMA-disk, followed by the Custom-block and the Conventional PMMA, and a significant difference was observed in the flexural strengths of all the materials (p < 0.001). The Custom-block showed a significantly higher flexural modulus and water solubility. The water sorption and discoloration of the Custom-block were significantly higher than those of the PMMA-disk, but not significantly different from those of the Conventional PMMA. In conclusion, the mechanical properties of the three materials differed depending on the manufacturing method, which considerably affected their flexural strength, flexural modulus, water sorption and solubility, and discoloration.

scholarly journals Hyperbranched polyamide modified graphene oxide-reinforced polyurethane nanocomposites with enhanced mechanical properties

RSC Advances ◽  
2021 ◽  
Vol 11 (24) ◽  
pp. 14484-14494
Author(s):  
Yahao Liu ◽  
Jian Zheng ◽  
Xiao Zhang ◽  
Yongqiang Du ◽  
Guibo Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
High Performance ◽  
Cross Linking ◽  
Elongation At Break ◽  
Modified Graphene Oxide ◽  
High Performance Composite ◽  
Modified Graphene ◽  
Polyurethane Nanocomposites ◽  
Hyperbranched Polyamide

We successfully modified graphene oxide with amino-terminated hyperbranched polyamide (HGO), and obtained a high-performance composite with enhanced strength and elongation at break via cross-linking hydroxyl-terminated polybutadiene chains with HGO.

scholarly journals Smart Hydrogel Bilayers Prepared by Irradiation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1753
Author(s):  
Weixian Huo ◽  
Heng An ◽  
Shuquan Chang ◽  
Shengsheng Yang ◽  
Yin Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gamma Radiation ◽  
Antibacterial Properties ◽  
Cross Linking ◽  
Temperature Sensitive ◽  
Temperature Changes ◽  
Smart Hydrogel ◽  
Isopropyl Acrylamide ◽  
Hydrogel Synthesis ◽  
Potential Applications

Environment-responsive hydrogel actuators have attracted tremendous attention due to their intriguing properties. Gamma radiation has been considered as a green cross-linking process for hydrogel synthesis, as toxic cross-linking agents and initiators were not required. In this work, chitosan/agar/P(N-isopropyl acrylamide-co-acrylamide) (CS/agar/P(NIPAM-co-AM)) and CS/agar/Montmorillonite (MMT)/PNIPAM temperature-sensitive hydrogel bilayers were synthesized via gamma radiation at room temperature. The mechanical properties and temperature sensitivity of hydrogels under different agar content and irradiation doses were explored. The enhancement of the mechanical properties of the composite hydrogel can be attributed to the presence of agar and MMT. Due to the different temperature sensitivities provided by the two layers of hydrogel, they can move autonomously and act as a flexible gripper as the temperature changes. Thanks to the antibacterial properties of the hydrogel, their storage time and service life may be improved. The as prepared hydrogel bilayers have potential applications in control devices, soft robots, artificial muscles and other fields.

scholarly journals Double-Cross-Linked Networks Based on Methacryloyl Mucin

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1706
Author(s):  
Elena Olăreț ◽  
Brîndușa Bălănucă ◽  
Andra Mihaela Onaș ◽  
Jana Ghițman ◽  
Horia Iovu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aqueous Solution ◽  
Chemical Modification ◽  
Structural Modification ◽  
Aqueous Media ◽  
Cross Linking ◽  
Ph Values ◽  
Acid Aqueous Solution ◽  
Reaction Media ◽  
Double Cross

Mucin is a glycoprotein with proven potential in the biomaterials field, but its use is still underexploited for such applications. The present work aims to produce a synthesis of methacryloyl mucin single-network (SN) hydrogels and their double-cross-linked-network (DCN) counterparts. Following the synthesis of the mucin methacryloyl derivative, various SN hydrogels are prepared through the photopolymerization of methacrylate bonds, using reaction media with different pH values. The SN hydrogels are converted into DCN systems via supplementary cross-linking in tannic acid aqueous solution. The chemical modification of mucin is described, and the obtained product is characterized; the structural modification of mucin is assessed through FTIR spectroscopy, and the circular dichroism and the isoelectric point of methacryloyl mucin is evaluated. The affinity for aqueous media of both SN and DCN hydrogels is estimated, and the mechanical properties of the systems are assessed, both at macroscale through uniaxial compression and rheology tests and also at microscale through nanoindentation tests.

scholarly journals Cellular Orientation on Repeatedly Stretching Gelatin Hydrogels with Supramolecular Cross-Linkers

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2095
Author(s):  
Dae Hoon Lee ◽  
Yoshinori Arisaka ◽  
Asato Tonegawa ◽  
Tae Woong Kang ◽  
Atsushi Tamura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Cellular Response ◽  
Linear Polymer ◽  
Cross Linking ◽  
Adherent Cells ◽  
Cell Cultivation ◽  
Supramolecular Compound ◽  
Synthetic Materials ◽  
Cyclic Molecules

The cytocompatibility of biological and synthetic materials is an important issue for biomaterials. Gelatin hydrogels are used as biomaterials because of their biodegradability. We have previously reported that the mechanical properties of gelatin hydrogels are improved by cross-linking with polyrotaxanes, a supramolecular compound composed of many cyclic molecules threaded with a linear polymer. In this study, the ability of gelatin hydrogels cross-linked by polyrotaxanes (polyrotaxane–gelatin hydrogels) for cell cultivation was investigated. Because the amount of polyrotaxanes used for gelatin fabrication is very small, the chemical composition was barely altered. The structure and wettability of these hydrogels are also the same as those of conventional hydrogels. Fibroblasts adhered on polyrotaxane–gelatin hydrogels and conventional hydrogels without any reduction or apoptosis of adherent cells. From these results, the polyrotaxane–gelatin hydrogels have the potential to improve the mechanical properties of gelatin without affecting cytocompatibility. Interestingly, when cells were cultured on polyrotaxane–gelatin hydrogels after repeated stress deformation, the cells were spontaneously oriented to the stretching direction. This cellular response was not observed on conventional hydrogels. These results suggest that the use of a polyrotaxane cross-linking agent can not only improve the strength of hydrogels but can also contribute to controlling reorientation of the gelatin.

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