Tuning the mechanical properties of cellulose nanofibrils reinforced polyvinyl alcohol composites via altering the cellulose polymorphs

RSC Advances ◽  
2016 ◽  
Vol 6 (86) ◽  
pp. 83356-83365 ◽  
Author(s):  
Xiaran Miao ◽  
Feng Tian ◽  
Jinyou Lin ◽  
Hui Li ◽  
Xiuhong Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Polyvinyl Alcohol ◽  
Polymer Composites ◽  
Functional Groups ◽  
Cellulose Nanofibrils ◽  
Reinforcement Effect ◽  
Cellulose I

Cellulose nanofibrils (CNF) with polymorphs of cellulose I and II are different in morphology, aspect ratio, density of functional groups and mechanical properties, which influence the reinforcement effect for polymer composites.

Influence of the Composition of Cement Mortars Modified by Lime or Polymers on the Mechanical Properties and Microstructure of Mortars

2013 ◽  
Vol 592-593 ◽  
pp. 647-650 ◽  
Author(s):  
Małgorzata Lenart
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Reinforced Concrete ◽  
Flexural Strength ◽  
Polyvinyl Alcohol ◽  
Polymer Composites ◽  
Adhesion Strength ◽  
Hardened Cement ◽  
Cement Mortars ◽  
Styrene Butadiene

Cement – polymer composites are nowadays widely used in repair systems not only in case of concrete or reinforced concrete constructions but also in masonry. Polymers addition for example already at 5% m.c. modifies the structure of the cement – polymer composite in a way that many of the mechanical properties such as flexural strength, tensile strength or adhesion to substrates are improved. The paper presents the results of tests such as flexural, compressive or adhesion strength to ceramic substrate of hardened cement mortars with different composition, as well as selected cement mortars modified by two polymers: polyvinyl alcohol and styrene – butadiene polymer dosed at 5 % m.c. Four types of cement mortars modified by lime (component used in historical constructions as well as in contemporary masonry mortars) are also examined for comparison.

scholarly journals Synthesis of Nanofiber from Polyvinyl Alcohol (PVA)-Collagen Using Electrospinning Methods

2020 ◽  
Vol 21 (2) ◽  
pp. 55-65
Author(s):  
Sudirman Sudirman ◽  
Aloma Karo Karo ◽  
Sulistiyoso Giat Sukaryo ◽  
Karina Dwi Adistiana ◽  
Kiagus Dahlan
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Alcohol ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Wound Dressing ◽  
Collagen Fiber ◽  
Tissue Formation ◽  
Collagen Concentration ◽  
Electrospinning Method ◽  
Growth Of Bacteria

Polyvinil alcohol (PVA) polymer can be used as matrix to be mixed with collagen in the subtance of primary wound dressing material to cover wound that prevents growth of bacteria and enhanced tissue formation. Collagen fiber is fragile, so important to combined with PVA to obtain better mechanical properties. The PVA-collagen fibers are prepared in aqueous solutions with PVA (10%) and collagen concentration (1% and 2%) using electrospinning method and the effect of voltage 15 kV, 19 kV, and 23 kV. Analysis of functional groups show that the presence of identical compounds produced and new functional groups are not formed. SEM data show that the effect of variation of voltage and collagen concentration on the resulting morphology of fiber. PVA-collagen 2% fibers produce continuous fibers, has a diameter 284-426 nm, thickness 0.0324-0.0483 mm and has a high percent of elongation so it can be used as a wound dressing material.

scholarly journals Impact of the Enzyme Charge on the Production and Morphological Features of Cellulose Nanofibrils

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3238
Author(s):  
Sergio Henríquez-Gallegos ◽  
Gregory Albornoz-Palma ◽  
Andrea Andrade ◽  
Carolina Soto ◽  
Miguel Pereira
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cell Wall ◽  
Aspect Ratio ◽  
Linear Relationship ◽  
Mechanical Treatment ◽  
Essential Role ◽  
Cellulose Nanofibrils ◽  
Degree Of Polymerization ◽  
Cnf Films

The available research does not allow specific relationships to be established between the applied enzymatic-mechanical treatment, the degree of polymerization, and the characteristics of the cellulose nanofibrils (CNFs) produced. This work aims to establish specific relationships between the intensity of enzymatic treatment, the degree of polymerization of the cellulose, the morphology of CNFs, and the tensile strength of the CNF films. It is determined that the decrease in the degree of polymerization plays an essential role in the fibrillation processes of the cell wall to produce CNFs and that there is a linear relationship between the degree of polymerization and the length of CNFs, which is independent of the type of enzyme, enzyme charge, and intensity of the applied mechanical treatment. In addition, it is determined that the percentage of the decrease in the degree of polymerization of CNFs due to mechanical treatment is irrespective of the applied enzyme charge. Finally, it is shown that the aspect ratio is a good indicator of the efficiency of the fibrillation process, and is directly related to the mechanical properties of CNF films.

Mechanical Properties of Graphene Oxide/Polyvinyl Alcohol Composite Film

2017 ◽  
Vol 25 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Tao Cheng-an ◽  
Zhang Hao ◽  
Wang Fang ◽  
Zhu Hui ◽  
Zou Xiaorong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Graphene Oxide ◽  
Hydrogen Bonds ◽  
Polyvinyl Alcohol ◽  
Composite Film ◽  
Functional Groups ◽  
Failure Strain ◽  
Oh Groups ◽  
Enhancement Mechanism

Graphene oxide (GO) was served as mechanical strengthening to prepare GO/Polyvinyl Alcohol(PVA) composite film. This was accomplished in order to explore the influence of contents of GO on the tensile strength and failure strain of GO/PVA composite film. The results showed that as the GO content increased, the tensile strength of the composite film became greater rapidly at first, and then decreased gradually. When the GO content was 20%, the film had its maximum tensile strength (59.6 MPa). This is over 500% of the tensile strength of pure PVA film. The failure strain of GO/PVA composite film decreased rapidly as the GO content increased. The enhancement mechanism of the composite can be explained by the existence of multi-hydrogen bonds between the hydroxyl (-OH) groups of PVA and oxygen-containing functional groups of GO.

scholarly journals Utilization of Recycled Material Sources for Wood-Polypropylene Composites: Effect on Internal Composite Structure, Particle Characteristics and Physico-Mechanical Properties

Fibers ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 86 ◽  
Author(s):  
Kim Krause ◽  
Philipp Sauerbier ◽  
Tim Koddenberg ◽  
Andreas Krause
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Polymer Composites ◽  
Wood Material ◽  
Polypropylene Composites ◽  
Material Sources ◽  
Aspect Ratios ◽  
Wood Polymer ◽  
Before And After ◽  
Wood Polymer Composites

In this study, various wood material sources were used for the manufacture of wood-polymer composites (WPC). The materials were categorised as virgin wood particles (VWP), reprocessed WPC particles (RWP) and recycled thermoset composite particles (RCP) and derived from two virgin wood sources, three-layer particleboards, medium-density fibreboards (MDF) boards, or two different wood/polypropylene composites. All produced wood-polypropylene compounds contained 60% wood material and were manufactured using a co-rotating extruder. Malleated polypropylene was used as a coupling agent. Specimens were injection moulded and subsequently tested for their physico-mechanical properties. To characterize particles before and after processing, dynamic image analysis (DIA) measurement were performed. Additionally, X-ray micro-computed tomography (XµCT) was used to characterize the internal structure of the composites and to verify the obtained particle’s characteristics. It was found that length and aspect ratio of particles were remarkably different before and after processing (loss in length of 15–70% and aspect ratio of 10–40%). Moreover, there were notably differences between the particle sources (RCP retained the highest length and aspect ratio values, followed by VWP and RWP). The results suggest that increased aspect ratios can indeed significantly improve mechanical properties (up to 300% increase in impact bending strength and 75% increase in tensile strength, comparing WPC based either on virgin spruce or MDF material). This phenomenon is suggested to be partially superimposed by improved dispersion of particles, which is expected due to lower variance and increased mechanical properties of RWP composites. However, no notable alterations were observed for composite density. Reprocessed WPC and, particularly, RCP material have proved to be an appealing raw material substitute for the manufacturing of wood–polymer composites.

Cellulose Nanofibrils-based Hydrogels for Biomedical Applications: Progresses and Challenges

2020 ◽  
Vol 27 (28) ◽  
pp. 4622-4646 ◽  
Author(s):  
Huayu Liu ◽  
Kun Liu ◽  
Xiao Han ◽  
Hongxiang Xie ◽  
Chuanling Si ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Metal Ion ◽  
Biomedical Applications ◽  
Biomedical Application ◽  
Cellulose Nanofibrils ◽  
Wound Dressings ◽  
Preparation Methods ◽  
Tissue Scaffold ◽  
Surface Areas ◽  
Mechanical Methods

Background: Cellulose Nanofibrils (CNFs) are natural nanomaterials with nanometer dimensions. Compared with ordinary cellulose, CNFs own good mechanical properties, large specific surface areas, high Young's modulus, strong hydrophilicity and other distinguishing characteristics, which make them widely used in many fields. This review aims to introduce the preparation of CNFs-based hydrogels and their recent biomedical application advances. Methods: By searching the recent literatures, we have summarized the preparation methods of CNFs, including mechanical methods and chemical mechanical methods, and also introduced the fabrication methods of CNFs-based hydrogels, including CNFs cross-linked with metal ion and with polymers. In addition, we have summarized the biomedical applications of CNFs-based hydrogels, including scaffold materials and wound dressings. Results: CNFs-based hydrogels are new types of materials that are non-toxic and display a certain mechanical strength. In the tissue scaffold application, they can provide a micro-environment for the damaged tissue to repair and regenerate it. In wound dressing applications, it can fit the wound surface and protect the wound from the external environment, thereby effectively promoting the healing of skin tissue. Conclusion: By summarizing the preparation and application of CNFs-based hydrogels, we have analyzed and forecasted their development trends. At present, the research of CNFs-based hydrogels is still in the laboratory stage. It needs further exploration to be applied in practice. The development of medical hydrogels with high mechanical properties and biocompatibility still poses significant challenges.

scholarly journals Effects of Steel Fiber Percentage and Aspect Ratios on Fresh and Harden Properties of Ultra-High Performance Fiber

2021 ◽  
Vol 2 (3) ◽  
pp. 501-515
Author(s):  
Rajib Kumar Biswas ◽  
Farabi Bin Ahmed ◽  
Md. Ehsanul Haque ◽  
Afra Anam Provasha ◽  
Zahid Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Performance ◽  
Steel Fiber ◽  
Setting Time ◽  
Fiber Reinforced Concrete ◽  
Future Research ◽  
Manufacturing Cost ◽  
Aspect Ratios ◽  
High Performance Fiber

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

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