共查询到20条相似文献，搜索用时 15 毫秒
1.
Yinglan Zhang Xiaoping Song Ying Kan Mengmeng Huang Cuijie Shi Xiaoping Dai Zhengdong Zhang 《应用聚合物科学杂志》2019,136(48):48230
A twin-bore capillary rheometer is used for the apparent shear viscosity measurement of commercial polyolefin melts based on Ostwald-de Waele model. The effects of stick–slip transition of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) are investigated. The maximum error of apparent shear viscosity calculated by corrected shear rate is 23% when the stick–slip transition occurs. Based on the entanglement‑disentanglement theory, a schematic diagram for shear stress curve containing stick–slip transition is presented to illustrate polymer melt flow in capillary. In this study, the critical stress at the beginning of stick–slip transition at 220 °C is 23.01 kPa higher than that at 190 °C, and why it increases with increasing temperature is discussed with a molecular mechanism in combination with entropy elasticity and entanglement‑disentanglement theory. Through the analysis of ULDPE, PS, EVA, and K-Resin, it can be found that short branches or side groups are helpful to avoid the stick–slip transition. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48230. 相似文献
2.
Loss circulation is one of the major concerns in drilling and well construction. An effective way to control drilling fluid loss and strengthen the wellbore is to plug fractures and holes with loss circulation materials. In this work, a hydrophobic association supramolecular hydrogel GP-A developed by n-dodecylacrylamide, methacrylamide and 2-acrylamide-2-methylpropylsulfonic acid was proposed as a potential lost circulation material for malignant drilling fluid loss. The results show that the initial decomposition temperature of GP-A was 172°C, and the flow characteristics conform to the Herschel-Bulkley model with yield stress. Microstructural analysis shows that GP-A gel with a 3D spatial network, and hydrogen bonds between branched chains form a dynamically recoverable structure. Based on POLYFLOW, the Phan Thien–Tanner model with viscoelastic parameters was used to simulate the viscoelastic flow characteristics of the fluid in fractures. The higher the concentration is, the greater K, and the higher the inlet driving pressure, while the nonlinear relationship between the driving pressure and the gel slug length is evident. The introduction of supramolecular gel polymer as a loss circulation material is an innovative research topic, which provides a new method to simulate the flow of polymer fluid in fractures. 相似文献
3.
Hongfeng Chen Qingsong Lian Weijie Xu Xuqi Hou Yan Li Zhi Wang Dong An Yaqing Liu 《应用聚合物科学杂志》2021,138(21):50484
Toughening epoxy resin (EP) without sacrificing strength, modulus, and processing performance is always a harsh task. Here, a series of epoxy systems containing soft butyl glycidyl ether (BGE) and rigid nano-silica (nano-SiO2) were prepared. Micro-phase separation structures derived from the self-assembly effect of BGE can be observed in atomic force microscopy images by controlling the total amount of BGE and nano-SiO2 at 2 wt% for the EPC:Si-m:n (m + n = 4) systems. Due to the synergistic effect of self-assembly effect of BGE and the rigid effect of well dispersed nano-SiO2, EPC:Si-2:2 system exhibited improvement of tensile strength of 59.3% (92.63 MPa), tensile modulus of 24.8% (3.52 GPa), elongation at break of 78.6% (4.84%), and glass transition temperature of 2.4% (138.4°C) compared with Pure EP system. Besides, due to the low loading of nano-SiO2 (≤2 wt%) and the dilution effect of BGE, the viscosity of all the toughening systems is lower than 600 mPa·s, which can provide this toughening system with superior processing performance for large production of composites by automotive manufacturing methods such as vacuum assistant resin infusion technology. 相似文献
4.
Eduardo Fischer Kerche;Joziel Aparecido da Cruz;Heitor Luiz Ornaghi;Henri Stephan Schrekker;Sandro Campos Amico; 《应用聚合物科学杂志》2024,141(31):e55740
Three ethanolic solutions containing different imidazolium ionic liquids (IL), namely 1-butyl-3-methylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium chloride or 1,3-dicarboxymethylimidazolium chloride), were used for the surface modification of aramid pulp (AP) (5 wt.% of IL in relation to AP mass) to improve its interfacial interaction with triethylene tetramine-cured epoxy resin. Composites were prepared by casting with 0.4 phr of AP. Scanning electron microscopy, mechanical tests, isothermal dynamic mechanical analysis (at 1, 10 and 100 Hz), and conventional non-isothermal analysis were performed. The IL-modified AP (AP-IL) presented greater defibrillation and strengthened interaction with the polymeric matrix, minimizing fiber pullout in the mechanical tests. The AP distribution in the epoxy matrix was assessed, and morphological changes were partly responsible for the improvement in the mechanical and dynamical mechanical response of the AP-IL/epoxy composites. The AP/epoxy composite compatibilized with IL 1-butyl-3-methylimidazolium chloride presented the lowest activation energy and, in turn, the strongest interaction with the epoxy matrix. Normalized DMA curves provided more detailed information on the differences between neat epoxy and the studied composites. 相似文献
5.
Carbonaceous nanoparticles (CNPs), including carbon black, carbon nanotubes, and graphene nanopiece, were selected as nanoadditives for investigating the rheological behavior dependence of their polymer‐based composites on morphological and interfacial structure. Polypropylene (PP) was adopted as matrix and a series of contents of CNPs were used for sample compounding. With identical concentration, the morphological structure of CNPs was emphasized as the dominant effect affecting the shear viscosity and the compressibility of PP/CNPs melts. The viscosity dependence on the CNPs contents and physical structure, such as particle size, aspect ratio, and specific area, was fully discussed in this work. The newly‐introduced inner voids, induced around the interface region between matrix and CNPs during physical mixing, were contributive to the rheological deviation, which was further reflected from the melt compressibility. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46416. 相似文献
6.
Major limitation for use of epoxy thermosets in engineering applications is its sudden brittle failure. In the present study dipropylene glycol dibenzoate (DPGDB) based plasticizer is used to modify diglycidyl ether of bisphenol A (DEGEBA) based epoxy resin system via simple blending technique. Bio-based epoxidized linseed oil was also used to modify epoxy resin system and compared with DPGDB modified resin. For DPGDB modified resin storage modulus and loss modulus of the epoxy system modified with 10% plasticizer increased by 7.54% and 12.24%, respectively. The primary mechanism responsible for such behavior is improved crosslinking density. With 5% plasticizer loading, flexural strength increased by 21%. There was an improvement of 312.74% in strain at failure for 10% plasticizer loading, while preserving its mechanical strength. It was found that DPGDB based modification was better than epoxidized linseed oil modification. 相似文献
7.
In toluene/dimethoxyethane (80/20)v solution, copolymers containing 11, 33, and 51 mol% of oxyethylene residues and having a fixed PS-segment molecular weight of ~60,000 g/mol, are dissolved molecularly. Doping with 10, 20, and 50 mol% of H3PO4 based on the oxyethylene content, induces varying degrees, of micellization in the respective block copolymer solutions. Light scattering and viscometry were used to evaluate the relationship between block-copolymer composition and the state of aggregation for solutions of styrene/ethylene oxide block copolymers as a function of solution concentration and level of doping with phosphoric acid. Specifically, diffusion coefficients, hydrodynamic radii, and critical micelle concentration were evaluated by dynamic light scattering. Radii of gyration were obtained by complementary static light scattering measurements. In all three block copolymers, complete micellization is realized at the 50 mol% H3PO4 doping level. At the 20 mol% H3PO4 doping level, complete micellization is induced with the copolymers containing 11 and 33 mol% of oxyethylene residues. 相似文献
8.
Mª Carmen García Sergio Sánchez Luis A. Trujillo-Cayado José Muñoz Mª Carmen Alfaro 《应用聚合物科学杂志》2019,136(1):46900
Gellan gum is a biopolymer widely used in the food, pharmaceutical, chemical, and agrochemical fields. Its ability to form a strong gel makes it possible to produce fluid gels. These materials present an apparent yield stress, but its value could be influenced by the wall-slip effect when performing the rheological measurements by which it is determined. In this work, the influence of the measuring surface and gap on flow behavior was first determined. The tests revealed the need to use geometries with rough surfaces, although the sample thickness using a parallel plate has no influence. Subsequently, the value of yield stress was obtained by means of creep tests (found to be 4.3 Pa), and, finally, the effect of wall slip on the dynamic viscoelastic behavior was assessed. There was an influence on the extension of the linear viscoelastic region, but not on the viscoelastic functions of the mechanical spectra. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46900. 相似文献
9.
Poly(propylene carbonate) (PPC)/poly(butylenes adipate-co-terephthalate) (PBAT) blends with various composition ratios were prepared via melt mixing using a twin-screw extruder. The effect of melt viscosities of polymers on mechanical behavior, interfacial interaction, thermal properties, rheological responses, and phase morphology was investigated. Results showed that the phase morphology and properties of PPC/PBAT blends were affected by the composition of the blends and the melt viscosities of the two polymers. Results of tensile tests, FTIR, and dynamic rheological measurement of PBAT-rich blends exhibited a better mechanical properties, intermolecular interactions, and compatibility when compared with PPC-rich blends due to the differences of their melt viscosities. Incorporating of PBAT effectively improved the Tg of PPC and the thermal stability of the blends. The Tc of PPC/PBAT blends markedly increased from 37.5 to 66.8 °C with addition of only 10 wt% PPC, indicating an enhanced crystallization ability of PBAT. The improvement of Tc was helpful for blown film extrusion. SEM microphotographs showed that the size of the dispersed phase particles is much smaller and the distribution is more uniform for PBAT-rich blends, compared with that in PPC-rich blends. The processing stability of blown film extrusion was improved by blending PPC with PBAT. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48924. 相似文献
10.
The operating windows of the solution casting of two polymeric liquids were evaluated experimentally. The experimental setup and procedure were the same as used previously for the casting of Newtonian fluids (Journal of Applied Polymer Science 2013, 129, 507–516). Aqueous carboxymethylcellulose/glycerol solutions exhibited pure shear‐thinning behavior at low polymer concentrations but became viscoelastic at high polymer concentrations, whereas polyacrylamide/glycerol solutions showed viscoelastic behavior over a wide range of concentrations. The shear‐thinning behavior, in conjunction with a low level of elasticity, of the casting solution was found to be useful in expanding the stable operating windows. However, an opposite effect on the operating windows was found for highly elastic solutions. The non‐Newtonian effect on the maximum stable casting speed was prominent only when the capillary number exceeded unity. Defects outside of the operating window were mostly similar to those observed in Newtonian solution casting. For highly concentrated solutions, a new rough surface defect was observed. This defect could be attributed to polymer chain entanglement, alignment, or breakup. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41411. 相似文献
11.
Mahboobeh Aminjafari Mehdi Entezam Morteza Sadeghi Mahmood Masoumi Hossein Ali Khonakdar Seyed Hassan Jafari 《应用聚合物科学杂志》2017,134(42)
In this study, the melt linear viscoelastic rheological properties of polyamide 6 (PA6)–acrylonitrile butadiene styrene terpolymer (ABS) immiscible blends were analyzed with the help of Coran and fractional Zener models (FZMs) to assess the microstructure of the blends. For this purpose, dynamic shear flow experiments and scanning electron microscopy investigations were performed. The nonzero value of the elastic modulus of the spring element (Ge) of the FZM for ABS‐rich blends was explained by the formation of a networklike structure because of the agglomeration of the rubber phases of the ABS matrix, whereas for the PA6‐rich blends with a high content of ABS, the interactions and/or interconnectivity of the ABS dispersed phase led to a nonzero value of Ge. The value of the fitting parameter of the Coran model (f) was near to 0.5 for the 50/50 blend; this was fully in agreement with the formed cocontinuous morphology for this blend composition. On the other hand, the f value for the blends with a matrix–droplet‐type morphology was near to zero for the PA6‐rich blends; this indicated the lower continuity of the ABS dispersed phase as a harder phase compared to the PA6 soft matrix, whereas the f value was near to 1 for ABS‐rich blends. This confirmed the formation of an interconnected networklike structure for this series of blends. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45423. 相似文献
12.
Diego Caccavo Rosario Cavallo Michela Abrami Mario Grassi Anna Angela Barba Gaetano Lamberti 《应用聚合物科学杂志》2021,138(29):50702
Hydrogels' viscoelastic behavior is crucial in several applications and an in-depth knowledge and characterization of this property is essential to select the most appropriate gel for the specific use. Oscillatory shear measurements are the most commonly used techniques to perform the viscoelastic characterization of hydrogels, among other materials, and it is performed mainly by using plate-plate shear rheometers. Despite these instruments constitute one of the best options to analyze the mechanical response of materials, they are quite expensive and require well trained operators, which confine their presence exclusively in engineering labs. However, the use of hydrogels brought these materials to be present in countless sectors, and therefore poses the need of reliable characterization with as much simple and common instrumentations. Therefore, aim of this work is to present the possibility to obtain a trustworthy characterization of the viscoelasticity of hydrogel by using a Texture Analyzer set to work with sinusoidal deformations. 相似文献
13.
Hyperbranched poly(ether sulfone) (HPES), a suitable coating additive for improving the rheological properties of linear poly(ether sulfone) (LPES), was easily produced via polymerization of commercially available bisphenol S (A2 monomer, BPS) and synthesized 2,4′,6‐trifluoro‐phenylsulfone (BB′2 monomer, TF). During this reaction, fluoro‐ or phenolic‐terminated HPES (F‐HPES or OH‐HPES) could be facilely obtained by controlling the feed mole ratios of the two monomers. The polymerization mode A2 + BB′2 was confirmed by analyzing the model compounds and the degree of branching (DB) was calculated systematically. In addition, the synthesized polymers' chemical structures were exhibited by FTIR, 1H NMR as well as 19F NMR spectroscopy. Notably, the addition of 1 wt % HPES reduced the melt viscosity and improved the high temperature liquidity of LPES because of its unique spherical shape. Furthermore, the addition of HPES did not have a negative impact on the performance of LPES, which was attributed to the good miscibility between HPES and LPES. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43892. 相似文献
14.
POEGMA‐b‐PAA comb‐like polymer is synthesized through RAFT polymerization, and it is employed as an efficient dispersant for Al2O3 suspensions. The POEGMA‐b‐PAA polymer consists of PAA chains and POEGMA comb‐like chains. The former provide electrostatic attraction between Al2O3 particles and polymer, while the latter extend to solution and maintain the stability of suspension due to strong steric hindrance. The adsorption is proven and the rheology behaviors of Al2O3 suspensions are strongly improved. Different POEGMA‐b‐PAA polymers with different length of side chains have similar but not identical rheological properties. The polymer with the appropriate length of side chain provides the biggest improvement to rheological properties of Al2O3 suspensions, such as apparent viscosity and granularity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43352. 相似文献
15.
Houfang Chi Hui Han Guannan Tian Hengyu Luo Song Hong Junyu Li Haiqing Hu 《应用聚合物科学杂志》2021,138(46):51368
The melt viscosity of triblock copolymer styrene-isoprene-styrene (SIS) filling systems decreased in some sense by adding 0.1 wt% fillers. The types of fillers included both nano- and non-nano fillers. It was insufficient to explain the phenomenon of viscosity reduction only from the view of nanoscale effects of particles. The results of SAXS and TEM enabled us to relate this behavior to the damage of PS microphase in SIS. The PS microphase acted as a strong entanglement point in the SIS system. When it was damaged, the entanglement among molecular chains weakened greatly, resulting in a decrease in viscosity. The dynamic viscoelasticity (complex viscosity, storage modulus, and loss modulus) of the filling systems was also studied. 相似文献
16.
Meiriane Cristina Faria Soares Lima Sthéfany Zaida Silva do Amparo Eder José Siqueira Douglas Rodrigues Miquita Vinicius Caliman Glaura Goulart Silva 《应用聚合物科学杂志》2018,135(25)
Polymer aqueous nanofluids have numerous industrial applications due to their synergic properties as a polymer and nanoparticle in the same fluid. The main goal of this work was to prepare stable aqueous nanofluids with improved viscosity in high temperature and salinity conditions. Aminated carbon nanotube (OCNT‐TEPA) presented a C? N photoemission peak at 285.5 eV in X‐ray photoelectron spectroscopy spectra, which is evidence of a grafting reaction. Fourier transform infrared spectra presented absorption bands attributed to amide and amine bonds. Elemental analyses showed 1.9 and 3.2 mass % N content increases for OCNT‐TEPA and OCNT‐TEPA‐AM, respectively. Samples aged at 70 °C in brine confirmed that the addition of OCNT‐TEPA increased the viscosity of nanofluids to 30% at day 90 compared to acrylamide–acrylic acid copolymer fluids. N anotubes presented only 35% of the aminated functions compared to carbon black (Lima et al., Carbon 2016, 109, 209) , and their effects in the enhancement of viscosity and thermal and colloidal stability were 2× greater. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46382. 相似文献
17.
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
18.
Geometrical dependence of viscosity of polymethylmethacrylate (PMMA) and high density polyethylene (HDPE) are studied by means of a twin‐bore capillary rheometer based on power‐law model. Contrary geometrical dependences of shear viscosity are observed for PMMA between 210 and 255°C, but similar geometrical dependences are revealed for HDPE between 190 and 260°C. The fact that wall slip can not successfully explain the irregular geometrical dependence of PMMA viscosity is found in this work. Then, pressure effect and dependence of fraction of free volume (FFV) on both pressure and temperature are proposed to be responsible for the geometrical dependence of capillary viscosity of polymers. The dependence of shear viscosity on applied pressure is first investigated based on the Barus equation. By introducing a shift factor, shear viscosity curves of PMMA measured under different pressures can be shifted onto a set of parallel plots by correcting the pressure effect and the less shear‐thinning then disappears, especially at high pressure. Meanwhile, the FFV and combining strength among molecular chains are evaluated for both samples based on molecular dynamics simulation, which implies that the irregular geometrical dependence of PMMA viscosity can not be attributed to the wall slip behavior. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39982. 相似文献
19.
Viscoelastic properties and structure of poly(acrylonitrile‐co‐methacrylic acid) polymer solutions for gel spinning at long aging times 
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下载免费PDF全文 Tracy R. Brown Rudra P. Choudhury Caitlin E. Meree Haskell W. Beckham Satish Kumar Meisha L. Shofner 《应用聚合物科学杂志》2014,131(3)
The objective of the research is to obtain a more complete understanding of how aging affects the viscoelastic properties of polymer solutions to be used as starting materials for gel spinning of polymer fibers. Specifically, poly(acrylonitrile‐co‐methacrylic acid) solutions were prepared and characterized using rheological measurements and nuclear magnetic resonance spectroscopy. The results indicate that elastic character increased with increasing polymer concentration and that gelation of these solutions continued up to aging times of several weeks. Additionally, comparing the results from the two characterization methods show that while gelation continues to occur, the viscoelastic properties decrease after a critical time point suggesting that a chemical change occurs in the solutions at long times. However, these changes impact the solution dynamics minimally as the effective network properties were similar at the aging times studied here, but considerations for long‐term storage of polymer solutions for gel spinning are warranted. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39821. 相似文献
20.
《应用聚合物科学杂志》2018,135(23)
Increasing attention has recently been paid to the rheological behavior of microgel colloids and to the physical forces that control their behavior. Here, based on a series of cationic microgels that were synthesized by inverse microemulsion polymerization, the physical forces were explored by viscosity analysis of swollen microgels with different crosslinking densities and cationic contents. The results indicate that within a wide concentration range, the viscosity curves for these cationic microgels perfectly correspond to the Krieger–Dougherty model as modified by Tan et al. In particular, the specific volume in this model decreases at the critical overlapping concentration and reveals the interaction intensity between neighboring microgels. Furthermore, the viscosity index in the Herschel–Bulkley equation indicates that the interaction domain among microgels undergoes a transfer from an electroviscous effect to osmotic deswelling with increasing concentrations. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46297. 相似文献