scholarly journals Electrospinning of PCL-Based Blends: Processing Optimization for Their Scalable Production

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3853
Author(s):  
Marina P. Arrieta ◽  
Adrián Leonés Gil ◽  
Maysa Yusef ◽  
José M. Kenny ◽  
Laura Peponi
Keyword(s):  
Thermal Stability ◽  
Mechanical Response ◽  
Bulk Material ◽  
Processing Parameters ◽  
Industrial Sector ◽  
Industrial Applications ◽  
Elongation At Break ◽  
Processing Optimization ◽  
Scalable Production

In this work poly(ε-caprolactone) (PCL) based electrospun mats were prepared by blending PCL with microcrystalline cellulose (MCC) and poly(3-hydroxybutyrate) (PHB). The electrospinning processing parameters were firstly optimized with the aim to obtain scalable PCL-based electrospun mats to be used in the industrial sector. Neat PCL as well as PCL-MCC and PCL-PHB based mats in different proportions (99:1; 95:5; 90:10) were prepared. A complete morphological, thermal and mechanical characterization of the developed materials was carried out. Scanning electron microscopy (SEM) observations showed that the addition of PHB to the PCL matrix considerably reduced the formation of beads. Both the addition of MCC and PHB reduced the thermal stability of PCL, but obtained materials with enough thermal stability for the intended use. The electrospun PCL fibers show greatly reduced flexibility with respect to the PCL bulk material, however when PCL is blended with PHB their stretchability is increased, changing their elongation at break from 35% to 70% when 10 wt% of PHB is blended with PCL. However, the mechanical response of the different blends increases with respect to the neat electrospun PCL, offering the possibility to modulate their properties according to the required industrial applications.

Mechanical Response of Porous and Dense NiTi-TiC Composites

2004 ◽  
Vol 844 ◽  
Author(s):  
Douglas E. Burkes ◽  
Guglielmo Gottoli ◽  
John J. Moore ◽  
Reed A. Ayers
Keyword(s):  
Material Properties ◽  
Mechanical Response ◽  
Bulk Material ◽  
Processing Parameters ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Matrix Composites ◽  
Compression Tests ◽  
Commercial Applications ◽  
Micro Indentation

ABSTRACTThe Center for Commercial Applications of Combustion in Space (CCACS) at the Colorado School of Mines is currently using combustion synthesis to produce several advanced materials. These materials include ceramic, intermetallic, and metal-matrix composites in both porous and dense form. Currently, NiTi – TiC intermetallic ceramic composites are under investigation for use as a bone replacement material. The NiTi intermetallic has the potential to provide a surface that is capable of readily producing an oxide layer for corrosion resistance. The TiC ceramic has the potential to increase the hardness and wear resistance of the bulk material that can improve the performance lifetime of the implant. Processing parameters are critical to the production of the NiTi – TiC composite and will be discussed. These parameters can lead to the formation of substoichiometric TiC and nickel rich NiTi that changes the overall mechanical and material properties. In addition, the size of the TiC particles present within the bulk product varies with porosity. Both porous and dense samples have been mechanically analyzed employing micro-indentation techniques as well as compression tests in an attempt to characterize the mechanical response of these composites. The effects of the TiC particles, the formation of Ni3Ti intermetallic and the effects of porosity on the overall mechanical and material properties will be discussed.

scholarly journals Synthesis and Characterization of Biodegradable Polyester/Polyether WPU As The Environmental Protection Coating

2021 ◽  
Author(s):  
Guangfeng Wu ◽  
Xin Song ◽  
ZhiHui Yang ◽  
Ying Chun Li ◽  
HuiXuan Zhang
Keyword(s):  
Thermal Stability ◽  
Contact Angle ◽  
Water Contact Angle ◽  
Degradation Rate ◽  
Soft Segment ◽  
Buffer Solution ◽  
Water Contact ◽  
Elongation At Break ◽  
Protection Coating

Abstract Polyester diol PCL and PBA, polyether diol PTMG and polycarbonate diol PCDL were used as components of WPU soft segment, respectively. Polyether PTMG-WPU has the worst hydrolytic property and the highest thermal stability. The maximum degradation rate temperature Tmax is 407.8°C, the water contact angle reaches 89.5°. Traditional polyester PCL-WPU shows the strongest hydrolysis performance, the smallest water contact angle, only 71.7°, the water absorption rate of 72 hours at room temperature is as high as 26.7%. However, the thermal stability of PCL-WPU is lower, the soft segment Tg is -52.3°C, and Tmax is only 333.7°C, but the mechanical propertie of which is the best, the tensile strength is 58.3 MPa, and the elongation at break reaches 857.9%. The most important thing is that the structure of polyester PCL-WPU is more easily destroyed by lipase and water molecules. The acidic products produced after hydrolysis will further promote the degradation of polyester. Therefore, compared with other WPUs, PCL -WPU has the best biodegradability and the most obvious degradation effect under the same conditions. The degradation rate of PTMG-WPU after 30 days of degradation in 0.6% lipase PBS buffer solution and soil was only 4.2% and 2.3%, while the highest degradation rate of traditional polyester PCL-WPU reached 41.7% and 32.0%, respectively. In addition, polycarbonate PCDL-WPU has the highest hardness, reaching 95.5 HD. But its other performances are lower than PCl-WPU.

High Temperature Dynamic Mechanical Properties Characterization of Polymer Coatings via Nanoindentation

2021 ◽  
pp. 1-17
Author(s):  
Yusuke Matsuda ◽  
Aref Samadi-Dooki ◽  
Yinjie Cen ◽  
Gisela Vazquez ◽  
Luke Bu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Mechanical Response ◽  
Polymer Coatings ◽  
Dynamic Mechanical Properties ◽  
Industrial Applications ◽  
Dynamic Mechanical ◽  
Mechanical Properties Characterization

Abstract Polymer coatings are widely used in industrial applications. The mechanical properties of these polymer coatings are known to vary with temperature and deformation rate. The characterization of the dynamic mechanical properties of these coatings at high temperatures via traditional uniaxial testing is challenging due often to their brittleness and small size. In this paper, the mechanical properties of polymer coatings are reported with emphasis on their dynamic mechanical properties at temperatures up to 280 °C characterized by a dynamic nanoindentation technique with a sharp indenter tip. Nanoindentation was used to characterize the mechanical response with emphasis on dynamic mechanical properties of polymer coatings enclosed in a high-temperature stage. To verify the method, the viscoelastic properties of a reference PET were also characterized by uniaxial cyclic tensile testing which exhibited an excellent agreement with the proposed technique. The proposed nanoindentation method can be applied to other polymer coatings and thin films that are used in applications at high temperatures.

scholarly journals Preparation and characterization of thermoplastic elastomers (TPEs) based on waste polypropylene and waste ground rubber tire powder

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Shu Ling Zhang ◽  
Zhen Xiu Zhang ◽  
Dong jin Kang ◽  
Dae Suk Bang ◽  
Jin Kuk Kim
Keyword(s):  
Thermal Stability ◽  
Testing Machine ◽  
Thermoplastic Elastomers ◽  
Elongation At Break ◽  
Rubber Tire ◽  
Ground Rubber ◽  
Waste Polypropylene ◽  
Better Than ◽  
Recycled Material

AbstractIn this article, the possibility of obtaining the recycled material based on waste polypropylene (WPP) and waste ground rubber tire powder (WGRT) has been studied. It has been proved that partially replacing WPP with PP-g-MA increased the elongation at break of WPP/WGRT blends, whereas decreased the thermal stability. The presence of compatibilizer increased the elongation at break and thermal stability of WPP/WGRT blends, whereas decreased the processing flowability, as revealed by using universal testing machine (UTM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and capillary rheometer. Moreover, the tendency of the change became more obvious with the content of PP-g-MA and compatibilizer or with the combination of PP-g-MA and compatibilizer. In addition, the improvement of the nonpolar compatibilizer (SEBS) in properties of WPP/WGRT blends was better than that of the polar compatibilizer (SEBS-g-MA).

Preparation and Characterization of Cassava Starch-Chitosan/Montmorillonite Nanocomposites

2011 ◽  
Vol 194-196 ◽  
pp. 484-487 ◽  
Author(s):  
Xian Zhong Mo ◽  
Chen Mo ◽  
Xiang Qi ◽  
Ren Huan Li
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Cassava Starch ◽  
Elongation At Break ◽  
The Matrix ◽  
Mechanical Properties Testing ◽  
Thermal Stability Of ◽  
Xrd And Tem

Biopolymer cassava starch(ST)-chitosan(CS)/montmorillonite(MMT) nanocomposites were prepared in which MMT was used as nanofiller and diluted acetic acid was used as solvent for dissolving and dispersing cassava starch, chitosan and MMT. XRD and TEM results indicated the formation of an exfoliated nanostructure of ST-CS/MMT nanocomposites. Mechanical properties testing revealed that at the range of the MMT content from 1wt% to 5wt%, tensile strength of the composites increased from 30MPa to 37.5MPa. But the elongation at break fall from 28% to 22% with the increasing of MMT. Obviously, MMT had an enforced effect to the composites. TGA results showed that the nano-dispersed MMT improved the thermal stability of the matrix systematically with the increasing of MMT.

Constitutive Relationship Development, Modeling and Measurement of Heat Stressing of Micro-SMD Assembly With Sn3.9Ag0.6Cu SAC Alloy

2005 ◽  
Author(s):  
Qiang Xiao ◽  
William D. Armstrong ◽  
James M. Pitarresi ◽  
Satish C. Chaparala ◽  
Brian D. Rogeman ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Solder Joints ◽  
Bulk Material ◽  
Horizontal Displacement ◽  
Processing Parameters ◽  
Constitutive Relationship ◽  
Small Scale ◽  
Cast Material ◽  
Mechanical Models ◽  
Using Data

The Creep and microstructural changes during creep behaviors of bulk and thin cast forms of Sn3.9Ag0.6Cu were compared. The processing parameters of the thin cast material was selected to result in a very fine microstructure analogous to what occurs in very small size solder electronic interconnections. We found that the thin cast material was less creep-resistant than the bulk material. A comparison of Ag element maps between as crept bulk and thin cast material showed that the relevant climb process occurs in a very different environment in the bulk material as compared to the thin cast material. In the bulk material the relevant climb process occurs within a finely dispersed IMC eutectic which covers broad areas within the material. In the thin cast material the relevant climb process occurs primarily in the beta-Sn grains which continuously surround isolated, coarse IMC particles. This resulted in the activation energy of the bulk material being larger than that for the thin cast material. Finally, it is important to note that the strength deficiency of the thin cast material was persistent, once the material is cast in thin cast form it will remain weak in comparison to the bulk material. Therefore, using data obtained from bulk material samples for the construction of thermo-mechanical models of very small scale solder interconnections is likely to result in significant, intrinsic errors. Second, the thermal-mechanical response of electronic packages was simulated using the commercial finite element code ANSYS coupled with the Garofalo model to represent the solder constitutive creep response. The measured properties for bulk and thin-cast Sn3.9Ag0.6Cu SAC alloy were used in the FE modeling. A 36 I/O micro-surface mount device (SMD) package was used as a test vehicle in this work. Moire´ Interferometry was used to measure the horizontal displacements in the solder joints as a result of cooling the package from 100°C to room temperature. Modeling results were found to have good agreement with moire´ measurements on the actual SAC packages. The bulk properties produced a better correlation with the measurement of the horizontal displacement in the solder joints than the thin-cast properties. However, the assemblies that were tested used the Sn3.8Ag0.6Cu alloy rather than the Sn3.9Ag0.6Cu alloy. It is not known if this difference is significant to the thermo-mechanical response.

scholarly journals Kinetic and Thermodynamic Characterization of two Polygalacturonases Isolated from the Digestive Juice of the Snail Limicolaria flammea

2021 ◽  
pp. 54-64
Author(s):  
Bernard Téhi Sea ◽  
Armand Kouassi Kanga ◽  
Djary Michel Koffi ◽  
Lucien Patrice Kouamé
Keyword(s):  
Thermal Stability ◽  
Thermal Inactivation ◽  
Industrial Applications ◽  
Stability Parameters ◽  
Digestive Juice ◽  
Food Industries ◽  
First Order Kinetics ◽  
Thermal Stability Parameters ◽  
D Values

Polygalacturonases are extensively used in food industries for pectic substances degradation. In this paper, we investigate on thermal stability parameters of two Polygalacturonases previously isolated from digestive juice of the snail Limicolaria flammea for several industrial applications such as fruit juice clarification. Thermal inactivation was carried out in the temperature range of 55°C to 80°C from 15 to 120 min. All results were statistically analysed. The results shown that thermal inactivation of studied acid phosphatases follows first order kinetics. At their optimum temperatures, these enzymes showed high half-lives ranging from 462.06 to 630.10 min and D values from 1535.00 to 2093.64 min suggesting that these two enzymes had a large thermal stability. The high values of ΔG# (93.96 to 94.97 kJ/mol) reveal a better resistance to denaturation. The relatively high activation energies (from 120.35 to 129.13 kJ/mol) and average enthalpy values (from 117.67 to 126.44 kJ.mol−1) could corroborate the good stability of these biocatalyst. All these results suggest that Polygalacturonases from digestive juice of the snail Limicolaria flammea may be profitably exploited in future food industrial applications.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

CBED analysis of impurity distributions in AlN

1990 ◽  
Vol 48 (4) ◽  
pp. 214-215
Author(s):  
Daniel Callahan ◽  
G. Thomas
Keyword(s):  
Aluminum Nitride ◽  
Bulk Material ◽  
Strong Dependence ◽  
Lattice Parameter ◽  
Promising Technique ◽  
Nitride Ceramics ◽  
Surface Phases ◽  
Convergent Beam ◽  
Oxygen Impurities

Oxygen impurities may significantly influence the properties of nitride ceramics with a strong dependence on the microstructural distribution of the impurity. For example, amorphous oxygen-rich grain boundary phases are well-known to cause high-temperature mechanical strength degradation in silicon nitride whereas solutionized oxygen is known to decrease the thermal conductivity of aluminum nitride. Microanalytical characterization of these impurities by spectral methods in the AEM is complicated by reactions which form oxygen-rich surface phases not representative of the bulk material. Furthermore, the impurity concentrations found in higher quality ceramics may be too low to measure by EDS or PEELS. Consequently an alternate method for the characterization of impurities in these ceramics has been investigated.Convergent beam electron diffraction (CBED) is a promising technique for the study of impurity distributions in aluminum nitride ceramics. Oxygen is known to enter into stoichiometric solutions with AIN with a consequent decrease in lattice parameter.

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