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1.
This study aimed at assessing and optimizing the influence of printing speed and extrusion temperature in a fused filament fabrication (FFF) process on the tensile properties of a polylactide/layered silicate nanocomposite. Mathematical models using Doehlert designs were formulated to examine factor and interaction effects. The models were corroborated by measurements using capillary rheology, tomographic images, and crystallinity analyses to find physical explanations for the differences in tensile properties. The tensile properties were a non-monotonic function of printing speed, which may be due to various deposition defects that influence the porosity of composite tensile specimens. This study provides new insights into FFF process optimization regarding rheological behavior and mesostructure of nanocomposite by highlighting new modes of deposition defects that originate from process parameter settings and materials. The results contribute to the properties mastery of FFF-processed materials. 相似文献
2.
Guttikatte Kariappa Gowtham Hanumanthappa Somashekarappa Karthik Bharath Rudrappa Somashekar 《应用聚合物科学杂志》2021,138(29):50705
We introduce a novel measure of performance of polymer composites based on physical parameters whose behavior depends on levels of dopant concentration used during their preparation. The performance measure is based on a joint analysis of measurements of the physical parameters exhibiting non-trivial correlations that vary across different levels of dopant concentrations. In contrast to traditional multivariate analysis, we treat data from parameter measurements as being obtained from functional parameters, and develop the performance measure based on the joint average function of parameters that encodes the correlation structure. An optimal level of dopant concentration is then ascertained with respect to the performance measure. While the proposed measure is general enough to be applicable to any chosen physical parameters, we demonstrate its utility in the context of assessing performance using microstructural and nonlinear optical parameters. Computing of the measure and optimal dopant concentration are carried out using Monte Carlo sampling, which further facilitates uncertainty quantification. 相似文献
3.
Pasupuleti Lakshmi Narayana Xiao-Song Wang Jong-Taek Yeom Anoop Kumar Maurya Won-Seok Bang Ommi Srikanth Maddika Harinatha Reddy Jae-Keun Hong Nagireddy Gari Subba Reddy 《应用聚合物科学杂志》2021,138(37):50956
In the present work, we developed an artificial neural networks (ANN) model to predict and analyze the polycaprolactone fiber diameter as a function of 3D melt electrospinning process parameters. A total of 35 datasets having various combinations of electrospinning writing process variables (collector speed, tip to nozzle distance, applied pressure, and voltage) and resultant fiber diameter were considered for model development. The designed stand-alone ANN software extracts relationships between the process variables and fiber diameter in a 3D melt electrospinning system. The developed model could predict the fiber diameter with reasonable accuracy for both train (28) and test (7) datasets. The relative index of importance revealed the significance of process variables on the fiber diameter. Virtual melt spinning system with the mean values of the process variables identifies the quantitative relationship between the fiber diameter and process variables. 相似文献
4.
Segmented polyether soft segment (SS) elastomers with different hard segments (HS) in film and fiber form were studied by birefringence, DSC, and tensile tests. To understand the morphological contributions to property differences, high resolution tapping AFM resolved ribbon-like highly anisotropic hard domain (HD) lamellae in low modulus Pebax (polyamide 12 HS) and polyetherester (PEE), films, while lower HS content high melting poly(urethane urea) (PUU) had much smaller less anisotropic but higher melting HDs, explaining its enhanced thermal and mechanical hysteresis properties. Stress–strain tensile data demonstrate the excellent strength and toughness of PUUs and some spun PEE fibers, and film and fiber birefringence data applied during strain cycling up to very high stresses provided the molecular basis for the varying properties. The parameters from non-Gaussian fits of tensile data provide insight into network properties for these systems exhibiting very high strengths and a large degree of strain hardening. Modeling of PEE and Pebax films also shows the effects of substantial plastic yielding of the HD networks. Tensile data were obtained as a function of strain rate and temperature to help understand the contributions of network restructuring and other factors. For fibers, strain rate data spanning seven decades show and unusual drop in strengths at very high strain rates. Temperature-dependent tensile data also show large differences between PUU materials versus lower melting PEEs. 相似文献
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6.
Poly(phenylene sulfide) (PPS) is a high-performance super-engineering plastic, but is brittle. In this study, super-tough PPS-based blends were successfully generated by melt blending PPS with poly(ethylene-ran-methacrylate-ran-glycidyl methacrylate) (EGMA) and poly(phenylsulfone) (PPSU) at (56/14/30) PPS/EGMA/PPSU composition, and their toughening mechanisms were investigated in detail. It was demonstrated the interfacial reaction between PPS and EGMA and partial miscibility between PPS and PPSU, both play important synergistic roles on the toughening. The interfacial reaction between PPS and EGMA contributes to the reduction of the PPSU domain size by the increased viscosity of the PPS matrix containing EGMA, and the increased mobility of EGMA chains by negative pressure effect. The partial miscibility between PPS and PPSU contributes to the increased interfacial adhesion between PPS and PPSU, resulting in effective propagation of the impact to the domains, and the increased mobility of not only PPSU chains but also PPS chains, causing a reduction in crystallization. 相似文献
7.
The sol–gel or viscous-elastic transitions of the bio-based polyamide 410/POE-g-MA (polyethylene-co-octene copolymer grafted with maleic anhydride) blends have been systematically discussed in the framework of melt rheology as assessed on a parallel plate rheometer set-up in small amplitude oscillatory shear mode and solid state dynamic mechanical relaxation measurements. The viscous response dominated enhancement in elastic moduli of the blends that was characterized by the phase transitions across the composition range of 10–15 wt% of POE-g-MA. A direct correlation between the gel point (estimated from the cross-over of frequency-independent loss tangent curves) and the ultra-toughness (maximized to an extent of ~15-fold increase in notched Izod impact strength) could be established vis-a-vis its corroboration from the morphology of the impact-failed surfaces. The extent of maleic anhydride (−MA) content induced phase interaction with polyamide 410 via the formation of a polyamide-co-(polyoctene-co-ethylene) type copolymer linkage in solid-state and its subsequent impact on solid-state damping was analyzed. The study establishes qualitative correlation between ultra-toughening of polyamide 410 to that parameters based on relaxation dynamics measurements using melt rheology and solid-state dynamic responses conforming to the principles of gelation rheology. 相似文献
8.
Oksana Zholobko Xiang-Fa Wu Zhengping Zhou Ted Aulich Jivan Thakare John Hurley 《应用聚合物科学杂志》2020,137(39):49639
This article reports a comparative experimental study of the hygroscopic and mechanical behaviors of electrospun polybenzimidazole (PBI) nanofiber membranes and solution-cast PBI films. As-electrospun nonwoven PBI nanofiber mats (with the nanofiber diameter of ~250 nm) were heat-pressed under controlled temperature, pressure and duration for the study; lab-made solution-cast PBI films and commercially available PBI films (the PBI Performance Product Inc., Charlotte, NC) were used as the control samples. Thermogravimetric and microtensile tests were utilized to characterize the hygroscopic (moisture absorption) and mechanical properties of the PBI nanofiber membranes at varying heat-pressing conditions, which were further compared to those of solution-cast PBI films. Experimental results indicated that the PBI nanofiber membranes carried slightly higher thermal stability and less hygroscopic properties than those of solution-cast PBI films. In addition, heat-pressing conditions significantly influenced the mechanical properties of the resulting PBI nanofiber membranes. The stiffness and tensile strength increase with increasing either the heat-pressing pressure or duration, and relevant mechanisms were explored. The present study provides a rational understanding of the hygroscopic and mechanical behaviors of electrospun PBI nanofiber membranes and solution-cast PBI films that are beneficial to their reliable cutting-edge applications in high-temperature filtration, polymer electrolyte membranes (PEMs), etc. 相似文献
9.
A core-shell modifier with the cross-linked acrylate and silicone copolymer as the core and polymethyl methacrylate (PMMA) as the shell (PASi-g-PMMA) was used to toughen the brittle polylactide (PLA). In addition, the copolymer of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) (MG) was utilized to further enhance the modification efficiency of the PASi-g-PMMA. The MG copolymer played the double roles of compatibilizer and chain extender, which not only improved the interfacial adhesion between the PLA and PASi-g-PMMA particles, but also increased the molecular weight and chain entanglement of the PLA. Compared with the PASi-g-PMMA toughened PLA blend, the PLA/PASi-g-PMMA/MG blends showed much higher heat-resistance, melt strength, transparency, toughness and stiffness balance. When the PASi-g-PMMA content was 20 wt%, 20 wt% MG increased the glass transition temperature (Tg), complex viscosity (η*), transparency, impact and tensile strength of PLA/PASi-g-PMMA blend from 60.1°C, 1.9 × 103 Pa·s, 76.1%, 748 J/m and 37 MPa to 71.5°C, 0.5 × 104 Pa·s, 78.4%, 860 J/m and 45 MPa for the PLA/PASi-g-PMMA/MG blend. This research provided a facile and practical method to overcome the shortcomings of the PLA and promoted its application in broader fields. 相似文献
10.
With the advance of the thermoplastic plastic elastomer (TPE) technology, there are growing interest and needs for using these materials in the meltblowing process where benefits of small fiber diameters of meltblowns can be combined with rubber-like elastic properties of elastomers. Performances and utilities of wide ranges of meltblown products such as facemask, medical barrier, wound-care, diaper can be drastically improved with additions of TPE. In this study, a new elastomeric meltblown fabric was successfully made with the styrene–ethylene/butylene–styrene (SEBS) block copolymer, and the relationship among structure, tensile properties, and meltblowing process parameters are studied. We found that median fiber diameter increases with the polymer mass throughout and decreases with air pressure, and fabric solidity has significantly influenced by die collector distance (DCD). The pore sizes of the fabrics are directly influenced by fiber diameters at the given DCD, but higher DCD increases the pore size due to their open structures. All SEBS nonwovens exhibit high strain at break, larger than 400%. Processing parameters significantly affect tensile properties, and this can be attributed to the fabric structure changes. The reduction of fiber diameter tends to increase the tensile strength of the fabric as it created more fiber-to-fiber bond points. 相似文献
11.
Ozan Erartsın Stijn A. J. J. Arntz Enrico M. Troisi Leonid V. Pastukhov Martin van Drongelen Laurent Warnet Leon E. Govaert 《应用聚合物科学杂志》2021,138(35):50878
Herein, temperature-dependent long-term behavior of polypropylene and its transversely loaded unidirectional glass fiber reinforced composite is investigated and a lifetime prediction method is proposed, which is based on the observed long-term failure mechanisms. Furthermore, the effect of cooling rate during processing on the time-dependent behavior is addressed. The composite is revealed to exhibit multiple molecular deformation mechanisms, similar to neat polypropylene, which is modeled using the Ree–Eyring approach. Failure kinetics under constant-strain-rate and creep tests are found to be identical and switching from creep to cyclic loading decelerates the failure, which are signs of plasticity-controlled failure. Hence, lifetime is predicted well by using a lifetime prediction methodology for the plasticity-controlled failure which combines the Ree–Eyring approach and the concept of critical strain. A change in the cooling rate alters the deformation and failure kinetics: lower cooling rates promote embrittlement. 相似文献
12.
Zhichao Ma Weizhi Li Siguo Yang Bin Huang Shuai Tong Chaofan Li Hongwei Zhao Luquan Ren 《应用聚合物科学杂志》2021,138(36):50910
This paper focuses on the contributions of diversities of strain rate and orientations for aggravating the diversities of micro failure behaviors on carbon fiber reinforced polymer (CFRP) laminates. A miniature horizontal type tensile tester is employed to conduct experiments with strain rate ranging from 2.6 × 10−6 s−1 to 2.6 × 10−3 s−1. The CFRP laminates are obtained based upon a thermoset toughened epoxy matrix (termed CF/Epoxy) with ply orientations of (0°/0°) and (0°/90°). Significant differences in deformation behaviors of CFRP laminates are determined through tests. The study clearly reveals the strain rate-dependent deformation modes of CFRP laminates, involving pure fiber fracture, epoxy crack with stepped surface and interface failure with residual voids, determines the “low-high-low” variation tendency of Young's modulus and strength as a function of strain rate. Ply orientation-dependent differences in deformation behaviors are also investigated via severe interfacial shearing effect. A unified model consisted of four deformation modes to is clarified to analyze the complexity of CFRP laminates failure mechanism. 相似文献
13.
As an environment-friendly polyester, polylactic acid (PLA) shows great potential market value. While it still faces some obstacles in large-scale practical application due to its brittleness. In this work, a novel strategy to improve the toughness of polylactic acid is developed. By adjusting processing temperature during the melt-blending process, thermoplastic polyurethane/poly (D-lactic) acid/poly (L-lactic) acid (TPU/PDLA/PLLA) ternary blends with different morphology are obtained. The experimental results show that the TPU in ternary blends formed a fibrillated micro-morphology, and the interfacial compatibility between the components is improved when the processing temperature is adjusted to 200°C. Under the synergistic action of in-situ fibrillated TPU and stereocomplex (SC) crystals, the toughness of the ternary blends is improved significantly without sacrificing its own tensile strength. The maximum value of tensile strength, elongation at break, and fracture work of ternary blends are 61.9 MPa, 23.5%, and 1038.9 kJ/m3, respectively. In addition, the melt strength of ternary blends was significantly improved, which is a benefit to their processing application. 相似文献
14.
Nobuyuki Odagiri Keiichi Shirasu Yoshiaki Kawagoe Gota Kikugawa Yutaka Oya Naoki Kishimoto Fumio S. Ohuchi Tomonaga Okabe 《应用聚合物科学杂志》2021,138(23):50542
Epoxy-amine thermosetting resins undergo different reactions depending on the amine/epoxy stoichiometric ratio (r). Although many desirable properties can be achieved by varying the stoichiometric ratio, the effects of the variation on the crosslinked structure and mechanical properties and the contribution of these factors to the ductility of materials have not been fully elucidated. This study investigates the brittle-ductile behavior of epoxies with various stoichiometric ratios and performs curing simulations using molecular dynamics (MD) to evaluate the crosslinked structures. The molecular structure is predominantly branched in low-stoichiometric ratio samples, whereas the chain extension type structure dominates the high-stoichiometric ratio samples. As a result, the higher-stoichiometric ratio samples enhances the ductility of materials and the elongation at break increases form 1.4% (r = 0.6) to 11.4% (r = 1.4). Additionally, the tensile strength (105.4 MPa) and strain energy (7.96 J/cm3) are maximum at r = 0.8 and 1.2, respectively. On the other hand, the Young's modulus is negatively impacted and it decreased from 4.2 to 2.7 GPa with increasing stoichiometric ratio. 相似文献
15.
Y. Nezili;I. El Aboudi;D. He;A. Mdarhri;C. Brosseau;M. Zaghrioui;T. Chartier;A. Ghorbal;R. Ben Arfi;J. Bai; 《应用聚合物科学杂志》2024,141(48):e56282
In this work we use ground tire rubber (GTR) powder obtained by grinding worn tire treads as reinforcer agent in flexible polyurethane (PU). Characterization of the microstructure of the as-received powder is achieved using a series of standard techniques including scanning electron microscopy (SEM), granulometry-laser, Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD). To have complementary physical information the composition and thermal characteristics of the GTR powder, thermogravimetry analysis (TGA) is also performed. The set of these preliminary characterizations shows that the GTR powder particles can be used as reinforcing fillers. For the purpose of good compatibility with the PU matrix, the GTR powder is subjected to chemical treatments for reducing the impurities on the powder particles and to create functional groups at their surface. Subsequently, a series of GTR/PU composite samples are prepared with different weight fractions of GTR using free rising foam method. The GTR/PU composites are then characterized to assess the effect of the GTR content and their chemically pre-treatment on thermal stability, compression mechanical behavior as well as sound attenuation properties. Collectively, these results indicate a significant improvement of both thermal and mechanical properties of the GTR/PU composites compared to the pristine PU matrix. Furthermore, it is also emphasized that the sound absorption response shows a significant shift of the maximum of the absorption coefficient toward lower frequencies resulting from simultaneous increase in air-flow resistivity and tortuosity which can have great potential application in the field of underwater acoustics. The effects of chemical treatments and GTR amount are also discussed. It is also shown that the results show improvement when H2O2 solvent is used in comparison with NaOH, and the optimal properties are reached for PU samples containing 20 wt% of GTR whatever the pre-treatment is. 相似文献
16.
Internal stress analysis is essential to structural design of materials applied in cryogenic engineering. In this contribution, thermomechanical properties including dynamic thermomechanical properties and thermal expansion behavior of four epoxy resins, namely the polyurethane modified epoxy resin (PUE), diglycidyl ether of bisphenol A (DGEBA), tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) and triglycidyl-p-aminophenol (TGPAP) were studied by dynamic thermomechanical analysis. Internal stress of the epoxy layer in the bonded joint was calculated based on the thermomechanical properties. Meanwhile, the structure-cryogenic property relationship of epoxy resins were investigated. Results demonstrate that internal stress in the four epoxies bonded joints is 6 ~ 21 MPa at −150°C, and is positively correlated with the average thermal expansion coefficient (CTE) of epoxy resins. TGDDM and TGPAP showed higher retention of lap shear strength both at −196°C and after temperature cycling due to their lower CTE. Morphology of the fractured surface of bonded joints demonstrated that internal stress is responsible for the severe interface failure at −196°C. It reveals that selection of epoxy resins with low CTE is beneficial for designing high-performance epoxy adhesive systems served at cryogenic temperature. 相似文献
17.
Environmental concerns continue to pose the challenge to replace petroleum-based products with renewable ones completely or at least partially while maintaining comparable properties. Herein, rigid polyurethane (PU) foams were prepared using soy-based polyol for structural and thermal insulation applications. Cell size, density, thermal resistivity, and compression force deflection (CFD) values were evaluated and compared with that of petroleum-based PU foam Baydur 683. The roles of different additives, that is, catalyst, blowing agent, surfactants, and different functionalities of polyol on the properties of fabricated foam were also investigated. For this study, dibutyltin dilaurate was employed as catalyst and water as environment friendly blowing agent. Their competitive effect on density and cell size of the PU foams were evaluated. Five different silicone-based surfactants were employed to study the effect of surface tension on cell size of foam. It was also found that 5 g of surfactant per 100 g of polyol produced a foam with minimum surface tension and highest thermal resistivity (R value: 26.11 m2·K/W). However, CFD values were compromised for higher surfactant loading. Additionally, blending of 5 g of higher functionality soy-based polyol improved the CFD values to 328.19 kPa, which was comparable to that of petroleum-based foam Baydur 683. 相似文献
18.
This study examines the effect of foam thickness on impact damping properties of closed-cell cross-linked polyethylene foams of different densities. Compression tests and falling weight impact tests were performed to detect the most important mechanisms, which affect the mechanical properties of the foams. The results showed that impact damping properties are significantly influenced by foam thickness, while energy-absorbing capability primarily depends on foam density. The average cell diameter was determined with a scanning electron microscope, which proved that the mechanical properties are mostly influenced by cell structure because higher density foams have smaller cells and thicker cell walls. Other important conclusion is that a foam thickness limit can be determined for a given load level to avoid excessive compaction of the cells and maximize the shock absorption of the foam. 相似文献
19.
Mihaela Dascalu Mihail Iacob Codrin Tugui Adrian Bele George-Theodor Stiubianu Carmen Racles Maria Cazacu 《应用聚合物科学杂志》2021,138(14):50161
The first dielectric elastomer actuators based on electroactive nanocomposites with octakis(phenyl)-T8-silsesquioxane (phenyl-T8), obtained ex-situ, used as voltage stabilizer filler for silicone elastomers are reported. The incorporation and homogeneous dispersion of crystalline phenyl-T8 in percentages of 2.5, 3.5, 5, and 10 into the amorphous matrix consisting in a polydimethylsiloxane-α,ω-diol with Mn = 240,000 g/mol was successfully achieved by solution mixing and crosslinking. For the sample with the best actuation performance (that containing 3.5 wt.% filler), an optimized filled elastomer was obtained by dispersing 3.6 wt. % phenyl-T8 in the matrix using a suitable surfactant (Pluronic L81), thus gaining an increased electrical breakdown of 30% compared with the pristine sample. Beside dielectric strength, the matured films were characterized in terms of morphology, mechanical, dielectric and actuation tests. In spite of structural incompatibility between the filler and the matrix, the obtained materials are soft elastomers showing high strain (~800%) and low Young's modulus of 50–100 kPa. The use of phenyl-T8 in a silicone matrix lead to electroactive films with slightly increased lateral actuation strain and electric breakdown strength. 相似文献
20.
Mario Bragaglia Tony McNally Francesca R. Lamastra Valeria Cherubini Francesca Nanni 《应用聚合物科学杂志》2021,138(20):50423
Immiscible blends of ethylene-propylene-diene-monomer (EPDM) and polyoxymethylene (POM), when EPDM is the major phase were compatibilized on the addition of an ionomer, poly(ethylene-co-methacrylic acid). The inclusion of the ionomer reduced the interfacial tension between the two phases, such that the diameter of the POM domains were significantly reduced to between 0.5 and 2 μm, typical of that required to toughen ductile polymers. The mechanical properties of the resultant compatibilized blends were significantly enhanced with increases in Young's modulus (↑54%), tensile strength (σ, ↑139%), elongation at break (ε, ↑97%), and tensile toughness (↑500%) with increasing ionomer content, relative to EPDM rubber alone. The ShoreA hardness of the compatibilized blend was 70.1 compared with 56.8 for the immiscible binary blend and, 50.2 for neat EPDM rubber. 相似文献