scholarly journals Solvent Retention in Electrospun Fibers Affects Scaffold Mechanical Properties

2018 ◽  
Vol 2 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Anthony R. D’Amato ◽  
Michael T. K. Bramson ◽  
David T. Corr ◽  
Devan L. Puhl ◽  
Ryan J. Gilbert ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrospun Fiber ◽  
Ambient Air ◽  
Yield Strain ◽  
Scanning Calorimetry ◽  
Young’S Moduli ◽  
Solvent Retention ◽  
Fine Control ◽  
Fiber Scaffolds ◽  
The Impact

Abstract Electrospinning is a robust material fabrication method allowing for fine control of mechanical, chemical, and functional properties in scaffold manufacturing. Electrospun fiber scaffolds have gained prominence for their potential in a variety of applications such as tissue engineering and textile manufacturing, yet none have assessed the impact of solvent retention in fibers on the scaffold’s mechanical properties. In this study, we hypothesized that retained electrospinning solvent acts as a plasticizer, and gradual solvent evaporation, by storing fibers in ambient air, will cause significant increases in electrospun fiber scaffold brittleness and stiffness, and a significant decrease in scaffold toughness. Thermogravimetric analysis indicated solvent retention in PGA, PLCL, and PET fibers, and not in PU and PCL fibers. Differential scanning calorimetry revealed that polymers that were electrospun below their glass transition temperature (Tg) retained solvent and polymers electrospun above Tg did not. Young’s moduli increased and yield strain decreased for solventretaining PGA, PLCL, and PET fiber scaffolds as solvent evaporated from the scaffolds over a period of 14 days. Toughness and failure strain decreased for PGA and PET scaffolds as solvent evaporated. No significant differences were observed in the mechanical properties of PU and PCL scaffolds that did not retain solvent. These observations highlight the need to consider solvent retention following electrospinning and its potential effects on scaffold mechanical properties.

Effect of toughened polyamide-coated carbon fiber fabric on the mechanical performance and fracture toughness of CFRP

2021 ◽  
pp. 002199832199945
Author(s):  
Jong H Eun ◽  
Bo K Choi ◽  
Sun M Sung ◽  
Min S Kim ◽  
Joon S Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Photoelectron Spectroscopy ◽  
Mechanical Performance ◽  
Epoxy Composites ◽  
Scanning Calorimetry ◽  
Internal Damage ◽  
Impact Tests ◽  
Flexural Tests ◽  
The Impact

In this study, carbon/epoxy composites were manufactured by coating with a polyamide at different weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to improve their impact resistance and fracture toughness. The chemical reaction between the polyamide and epoxy resin were examined by fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy. The mechanical properties and fracture toughness of the carbon/epoxy composites were analyzed. The mechanical properties of the carbon/epoxy composites, such as transverse flexural tests, longitudinal flexural tests, and impact tests, were investigated. After the impact tests, an ultrasonic C-scan was performed to reveal the internal damage area. The interlaminar fracture toughness of the carbon/epoxy composites was measured using a mode I test. The critical energy release rates were increased by 77% compared to the virgin carbon/epoxy composites. The surface morphology of the fractured surface was observed. The toughening mechanism of the carbon/epoxy composites was suggested based on the confirmed experimental data.

scholarly journals Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1242
Author(s):  
Olga Mysiukiewicz ◽  
Paulina Kosmela ◽  
Mateusz Barczewski ◽  
Aleksander Hejna
Keyword(s):  
Mechanical Properties ◽  
Melt Flow Index ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Metal Composites ◽  
Pre Treatment ◽  
The Impact ◽  
Properties Of Composites

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

scholarly journals Simultaneous Enhancement of Strength and Toughness of PLA Induced by Miscibility Variation with PVA

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1178 ◽  
Author(s):  
Yanping Liu ◽  
Hanghang Wei ◽  
Zhen Wang ◽  
Qian Li ◽  
Nan Tian
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Fracture Strain ◽  
Electrospun Fiber ◽  
Structural Evolution ◽  
Amorphous Structure ◽  
Poly Lactic Acid ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
Strength And Toughness

The mechanical properties of poly (lactic acid) (PLA) nanofibers with 0%, 5%, 10%, and 20% (w/w) poly (vinyl alcohol) (PVA) were investigated at the macro- and microscale. The macro-mechanical properties for the fiber membrane revealed that both the modulus and fracture strain could be improved by 100% and 70%, respectively, with a PVA content of 5%. The variation in modulus and fracture strain versus the diameter of a single electrospun fiber presented two opposite trends, while simultaneous enhancement was observed when the content of PVA was 5% and 10%. With a diameter of 1 μm, the strength and toughness of the L95V5 and L90V10 fibers were enhanced to over 3 and 2 times that of pure PLA, respectively. The structural evolution of electrospun nanofiber was analyzed by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Although PLA and PVA were still miscible in the concentration range used, the latter could crystallize independently after electrospinning. According to the crystallization behavior of the nanofibers, a double network formed by PLA and PVA—one microcrystal/ordered structure and one amorphous structure—is proposed to contribute to the simultaneous enhancement of strength and toughness, which provides a promising method for preparing biodegradable material with high performance.

scholarly journals Characteristics and mechanical properties changes due to incorporation of aloe vera in polyethylene-based film

2020 ◽  
Vol 17 (2) ◽  
pp. 61
Author(s):  
Siti Fatma Abd Karim ◽  
Junaidah Binti Jai ◽  
Ku Halim Ku Hamid ◽  
Abdul Wafi Abdul Jalil
Keyword(s):  
Mechanical Properties ◽  
Thermal Degradation ◽  
Aloe Vera ◽  
Functional Materials ◽  
Chain Structure ◽  
Substantial Effect ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
And Performance ◽  
The Impact

Non-degradable properties of polyethylene (PE) films due to long-chain structure cause increment of solid waste plastic. Many researchers, with different purposes, have studied the incorporation of functional materials to PE. Studying the impact of incorporation of aloe vera (AV) into PE films in terms of its characteristic and mechanical properties is the main objective of this paper. The films were prepared using melt-blending and hot press technique. The characterization assessed for the PE and PE-AV films were spectroscopy, crystalline phase, thermal analysis and performance of mechanical properties of the sample.  The functional group detected in spectroscopy studied did not show any changes for PE film or PE with the presence of AV. Lower thermal degradation temperature (Td) obtained for PE-AV3 while others film found no significant changes of Td value and only one peak of thermal degradation occurred for all film. The same goes to the analysis obtained from differential scanning calorimetry (DSC) data. However, the crystalline structure displayed momentous peak changes for PE with AV. The highest tensile strength (TS) obtained by PE-AV3, at once developing highest value of Young’s modulus (YM), modulus of resilience (UE) and modulus of toughness (UT). A certain amount of AV has substantial effect on changing the polymeric structure especially improving the mechanical properties of PE film. Therefore, AV has potential to become an additive for developing a new partially degradable PE film.

scholarly journals The Effects of Silica-Based Fillers on the Properties of Epoxy Molding Compounds

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1811 ◽  
Author(s):  
Mitja Linec ◽  
Branka Mušič
Keyword(s):  
Mechanical Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Fused Silica ◽  
Spiral Flow ◽  
Scanning Calorimetry ◽  
Molding Compounds ◽  
Material Development ◽  
The Impact

Global design and manufacturing of the materials with superb properties remain one of the greatest challenges on the market. The future progress is orientated towards researches into the material development for the production of composites of better mechanical properties to the existing materials. In the field of advanced composites, epoxy molding compounds (EMCs) have attained dominance among the common materials due to their excellent properties that can be altered by adding different fillers. One of the main fillers is often based on silicon dioxide (SiO2). The concept of this study was to evaluate the effects of the selected silica-based fillers on the thermal, rheological, and mechanical properties of EMCs. Various types of fillers with SiO2, including crystalline silica and fused silica, were experimentally studied to clarify the impact of filler on final product. Fillers with different shape (scanning electron microscope, SEM), along with different specific surface area (specific surface area analyzer, BET method) and different chemical structure, were tested to explore their modifications on the EMCs. The influence of the fillers on the compound materials was determined with the spiral flow length (spiral flow test, EMMI), glass transition temperature (differential scanning calorimetry, DSC), and the viscosity (Torque Rheometer) of the composites.

scholarly journals Bio-Based Packaging Materials Containing Substances Derived from Coffee and Tea Plants

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5719
Author(s):  
Olga Olejnik ◽  
Anna Masek
Keyword(s):  
Mechanical Properties ◽  
Caffeic Acid ◽  
Green Tea ◽  
Chemical Structure ◽  
Green Tea Extract ◽  
Packaging Materials ◽  
Scanning Calorimetry ◽  
Spectra Analysis ◽  
Tea Extract ◽  
The Impact

The aim of the research was to obtain intelligent and eco-friendly packaging materials by incorporating innovative additives of plant origin. For this purpose, natural substances, including green tea extract (polyphenon 60) and caffeic acid, were added to two types of biodegradable thermoplastics (Ingeo™ Biopolymer PLA 4043D and Bioplast GS 2189). The main techniques used to assess the impact of phytocompounds on materials’ thermal properties were differential scanning calorimetry (DSC) and thermogravimetry (TGA), which confirmed the improved resistance to thermo-oxidation. Moreover, in order to assess the activity of applied antioxidants, the samples were aged using a UV aging chamber and a weathering device, then retested in terms of dynamic mechanical properties (DMA), colour changing, Vicat softening temperature, and chemical structure, as studied using FT-IR spectra analysis. The results revealed that different types of aging did not cause significant differences in thermo-mechanical properties and chemical structure of the samples with natural antioxidants but induced colour changing. The obtained results indicate that polylactide (PLA) and Bioplast GS 2189, the plasticizer free thermoplastic biomaterial containing polylactide and starch (referred to as sPLA in the present article), both with added caffeic acid and green tea extract, can be applied as smart and eco-friendly packaging materials. The composites reveal better thermo-oxidative stability with reference to pure materials and are able to change colour as a result of the oxidation process, especially after UV exposure, providing information about the degree of material degradation.

scholarly journals Morpho-Structural, Thermal and Mechanical Properties of PLA/PHB/Cellulose Biodegradable Nanocomposites Obtained by Compression Molding, Extrusion, and 3D Printing

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 51 ◽  
Author(s):  
Adriana Nicoleta Frone ◽  
Dan Batalu ◽  
Ioana Chiulan ◽  
Madalina Oprea ◽  
Augusta Raluca Gabor ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Interfacial Adhesion ◽  
Compression Molding ◽  
Processing Technique ◽  
Single Step ◽  
Thermal And Mechanical Properties ◽  
Reactive Blending ◽  
Scanning Calorimetry ◽  
The Impact

Biodegradable blends and nanocomposites were produced from polylactic acid (PLA), poly(3-hydroxybutyrate) (PHB) and cellulose nanocrystals (NC) by a single step reactive blending process using dicumyl peroxide (DCP) as a cross-linking agent. With the aim of gaining more insight into the impact of processing methods upon the morphological, thermal and mechanical properties of these nanocomposites, three different processing techniques were employed: compression molding, extrusion, and 3D printing. The addition of DCP improved interfacial adhesion and the dispersion of NC in nanocomposites as observed by scanning electron microscopy and atomic force microscopy. The carbonyl index calculated from Fourier transform infrared spectroscopy showed increased crystallinity after DCP addition in PLA/PHB and PLA/PHB/NC, also confirmed by differential scanning calorimetry analyses. NC and DCP showed nucleating activity and favored the crystallization of PLA, increasing its crystallinity from 16% in PLA/PHB to 38% in DCP crosslinked blend and to 43% in crosslinked PLA/PHB/NC nanocomposite. The addition of DCP also influenced the melting-recrystallization processes due to the generation of lower molecular weight products with increased mobility. The thermo-mechanical characterization of uncross-linked and cross-linked PLA/PHB blends and nanocomposites showed the influence of the processing technique. Higher storage modulus values were obtained for filaments obtained by extrusion and 3D printed meshes compared to compression molded films. Similarly, the thermogravimetric analysis showed an increase of the onset degradation temperature, even with more than 10 °C for PLA/PHB blends and nanocomposites after extrusion and 3D-printing, compared with compression molding. This study shows that PLA/PHB products with enhanced interfacial adhesion, improved thermal stability, and mechanical properties can be obtained by the right choice of the processing method and conditions using NC and DCP for balancing the properties.

Effect of Co Addition on the Glass-Forming Ability and Mechanical Properties of Ti-Zr-Be-Cu-Co Bulk Amorphous Alloys

2012 ◽  
Vol 182-183 ◽  
pp. 203-207
Author(s):  
Zhong Yuan Suo ◽  
Yan Ling Song ◽  
Ke Qiang Qiu
Keyword(s):  
Mechanical Properties ◽  
Glassy Alloy ◽  
Glass Forming Ability ◽  
Yield Strain ◽  
Scanning Calorimetry ◽  
High Fracture ◽  
Glass Forming ◽  
Transmission Electron ◽  
Bulk Glassy Alloy ◽  
Co Addition

The effect of Co substitution for Be on the glass-forming ability and mechanical properties was investigated in Ti35Zr30Be27.5-xCu7.5Cox (x=0, 3.5, 7.5, 11.5 at.%) alloys by using X-ray diffractometry (XRD), differential scanning calorimetry (DSC), high-resolution transmission electron microscopy (HRTEM) and compression test. With the substitution of Co for Be, glass-forming ability (GFA) is significantly enhanced and fully amorphous rods with a diameter of up to 12 mm were produced in the alloy with 3.5 and 7.5 at.% Co. The Ti35Zr30Be24Cu7.5Co3.5 bulk glassy alloy exhibits good plasticity of 4% during compressive applied load at ambient temperature in conjunction with distinct yield strain of 2% and high fracture strength of 2196 MPa. The effect of the addition of Co on the structure and deformation behavior of the Ti35Zr30Be27.5-xCu7.5Cox (x=0, 3.5, 7.5, 11.5 at.%) alloys is discussed.

CONNECTION BETWEEN STRUCTURAL CHANGES OF IRRIADIATED POLYETHER ETHER KETONE AND MECHANICAL PROPERTIES

Tribologia ◽  
2018 ◽  
Vol 278 (2) ◽  
pp. 95-101
Author(s):  
Aneta NIEMIEC
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Structural Changes ◽  
Radiation Energy ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polyether Ether Ketone ◽  
Ether Ketone ◽  
The Impact ◽  
The Degree Of Crystallinity

The article presents the results of research on the impact of structural changes in polyether ether ketone (PEEK) on its mechanical properties. The polymer was exposed to gamma radiation at a dose of 50 and 150 kGy, and the radiation energy was 4 MeV. Changes in the degree of crystallinity and the related changes in the glass transition and melting temperature for the polymer were determined by differential scanning calorimetry (DSC). Mechanical properties were determined using the micro-mentoring method. The tests showed a change in the degree of crystallinity in the range of several degrees and a significant increase in the glass transition temperature. In terms of mechanical properties, the reduction of hardness and Young’s modulus was observed. Observed changes, especially in terms of changes in the structure of the polymer under the influence of radiation, are difficult to explain, which requires conducting further research, especially in the range of irradiation parameters used. Further research is important because PEEK is used in many fields, especially in conditions conducive to corrosion and the influence of radiation.

scholarly journals Reinforcing polypropylene with calcium carbonate of different morphologies and polymorphs

2018 ◽  
Vol 25 (4) ◽  
pp. 745-751 ◽  
Author(s):  
Yanwei Jing ◽  
Xueying Nai ◽  
Li Dang ◽  
Donghai Zhu ◽  
Yabin Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Calcium Carbonate ◽  
Mechanical Tests ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystallization Property ◽  
Reinforced Composite ◽  
Treated Sample ◽  
The Impact

Abstract The influence of calcium carbonate (CaCO3) with different polymorphs (calcite and aragonite) and morphologies (granular and rod-like) on mechanical and crystallization properties of polypropylene (PP) was investigated. Meanwhile, these CaCO3 fillers coated with oleic acid were added in different contents to PP. The results indicate that the tensile strength, flexural strength, modulus, and crystallization property of the filler-treated samples are improved, but the impact strength decreased. The crystallinity of the composites is higher than that of neat PP. Moreover, in the rod shape filler-treated sample, in both whisker species, the mechanical properties of composites are superior to the particles filled. Differential scanning calorimetry, X-ray diffraction, and mechanical tests display that calcite whisker-reinforced composite has higher crystallization enthalpy, melting enthalpy, degree of crystallinity, and mechanical properties than aragonite whiskers and calcite particles filled composites.

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