Effect of molecular weight on strength and deformation characteristics of oriented amorphous polymers

Laius, L. A.; Kuvshinskii, E. V.

doi:10.1007/bf01150948

Cited by 7 publications

(7 citation statements)

References 9 publications

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“…The characterization of prepared membranes was carried out using various analysis methods such as scanning electron microscopy (SEM), mechanical properties, porosity, and contact angle [13]. The pore size distribution of prepared membranes was determined using the Brunauer-Emmett-Teller (BET) method as in our previous work [9,12]. The evaluations of prepared membranes performances have been investigated using the homemade laboratory desalination testing unit Fig.…”

Section: Membrane Characterizationmentioning

confidence: 99%

“…The membrane is prepared by dissolving a suitable polymer such as cellulose acetate, Polyethersulfone (PES) polyamide (PA), Polyvinylalcohol (PVA), polyvinylpyrollidone (PVP) and polyethylene glycol (PEG) in a suitable additive as acetone, N-Methyl pyrrolidone (NMP) and formic acid. [9][10][11][12][13][14][15][16]. Approximately the most problems of membranes are membrane fouling which decrease the lifetime of membrane due to the need more excessive chemical treatment and shut down of the desalination unit.…”

Section: Introductionmentioning

confidence: 99%

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Hydrophilic Coating Layer by Layer on Polyethersulfone Membranes for Desalination

El–Gendi

Mohamed

Shalaby³

2020

Egypt. J. Chem.

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Water Desalination is becoming an issue for saving the required potable and drinking water due to shrinkage of pure water. Thus, this work deals with antifouling membrane preparation using polymeric compounds of Polyethersulfone/ Polyvinylalcohol (PES/PVA) with nanomaterials to produce antifouling membrane for water desalination. The PES membrane has prepared by phase inversion process followed by different coating ways. The coating with PVA provided the highest hydrophilic surface. The characterization of prepared membranes was carried out using various analysis methods such as scanning electron microscopy (SEM), mechanical properties, porosity and contact angle. The pore size distribution of prepared membranes was determined using the Brunauer-Emmett-Teller (BET) method. The result showed that the best membrane performance has a coating with PVA layer, where rejection reached to 99 %, 95% and 88% as a function of concentration 500, 1500, and 3000 ppm respectively, while the permeate flux reached to 48.4 L/m2.h, 32.3 L/m2.h and 21.5 L/m2.h respectively.

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Section: Membrane Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrophilic Coating Layer by Layer on Polyethersulfone Membranes for Desalination

El–Gendi

Mohamed

Shalaby³

2020

Egypt. J. Chem.

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“…With an increased demand for high‐performance and specialized polymeric materials, polypropylene (PP)—which is one of the most versatile polymers for various applications owing to its good cost performance, light weight, and excellent properties— has been made commercially available in varying molecular weight grades from a number of manufacturers. [ 1‐3 ] It is well known that the molecular weight plays an important role in the crystallization behavior [ 4,5 ] and molecular orientation, [ 5,6 ] both of which determine the physical properties, such as density [ 7 ] and viscosity, [ 8 ] and the mechanical properties, [ 8‐11 ] such as strength, stiffness, and toughness, of the final material. It has been shown that the crystallization rate of a blend of low‐ and high‐molecular‐weight components in varying ratios accelerates as compared to that of the individual components under a flow field, resulting in improved processability during extrusion, melt blowing, and injection molding operations.…”

Section: Introductionmentioning

confidence: 99%

Effect of molecular weight on molecular orientation and morphology of polypropylene sheets containing a β‐nucleating agent

Phulkerd

Yamazaki

Iwasaki

et al. 2020

Polymer Engineering & Sci

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In this study, polypropylene (PP) films containing the β nucleating agent, N,N′‐dicyclohexyl‐2,6‐naphthalenedicarboxamide, were prepared using PP with three different molecular weights (low, medium, and high) by extrusion process with T‐shaped die. The structure and morphology of the films were studied after stretching. It was found that a unique molecular orientation, in which both the c‐axis and crystalline lamellae were oriented perpendicular to the flow direction, was formed in all undrawn film samples, irrespective of the molecular weights of the PP. In the PP sheets stretched in the machine direction, the low‐molecular‐weight sample containing the nucleating agent exhibited brittle properties owing to a lack of tie chains in the stretching direction. In contrast, cavitation was prominent in the medium (M‐PP)‐ and high (H‐PP)‐molecular‐weight samples. Notably, M‐PP containing the nucleating agent, with a high degree of molecular orientation, promoted the formation of a large number of voids. In H‐PP containing the nucleating agent, the presence of numerous tie chains inhibited cavitation, resulting in fewer voids. The experimental results demonstrated the influence of the molecular weight on the void structure, which will be useful in the field of microporous membranes.

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“…The mechanic properties of PMMA have long been known to be largely dependent on its molecular weight. For example, the maximum tensile strength for stretched PMMA films with broad molecular weight distributions increased with the increase in molecular weight up to 2.5 × 10 6 Da, after which the strength tended to increase slowly and finally reached an asymptotic limit at higher molecular weights [ 3 , 4 ]. Therefore, it is of great importance to develop a feasible and facile polymerization approach for the synthesis of ultrahigh molecular weight PMMA.…”

Section: Introductionmentioning

confidence: 99%

Facile Synthesis of Ultrahigh Molecular Weight Poly(Methyl Methacrylate) by Organic Halides in the Presence of Palladium Nanoparticles

Yuan

Cui

et al. 2020

Polymers

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A facile and versatile approach for the synthesis of ultrahigh molecular weight poly(methyl methacrylate) (PMMA) at mild conditions was developed. Certain organic halides combined with a catalytical amount of palladium nanoparticles (Pd NPs) were found to be very effective in initiating polymerizations of methyl methacrylate (MMA), methyl acrylate, vinyl acetate and other vinyl monomers. An ultrahigh molecular weight PMMA with a number-average molecular weight of 4.65 × 106 Da and a weight-average molecular weight of 8.08 × 106 Da was synthesized at 70 °C using 2-bromoisobutyric acid ethyl ester (EBiB) as an initiator in the presence of catalytical amount (10.1 ppm) of Pd NPs. A kinetic investigation found that the orders of polymerization with respect to EBiB, Pd NP and MMA were 0.23, 0.50, and 0.58, respectively. Proton nuclear magnetic resonance (1H NMR) combined with matrix-assisted laser desorption ionization time of flight mass spectroscopy (MALDI-TOF) and gel permeation chromatography (GPC) were used to prove that the macromolecular chain had an end-group of EBiB residue. The electron spin resonance (ESR), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) results reveal that the reaction of EBiB with Pd NPs caused a bromo atom (Br) transfer from EBiB to Pd NPs and resulted in the generation of EBiB residue radical to initiate the polymerization of MMA and the formation of PdIIBr2 on the surface of Pd nanoparticles.

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Effect of molecular weight on strength and deformation characteristics of oriented amorphous polymers

Cited by 7 publications

References 9 publications

Hydrophilic Coating Layer by Layer on Polyethersulfone Membranes for Desalination

Hydrophilic Coating Layer by Layer on Polyethersulfone Membranes for Desalination

Effect of molecular weight on molecular orientation and morphology of polypropylene sheets containing a β‐nucleating agent

Facile Synthesis of Ultrahigh Molecular Weight Poly(Methyl Methacrylate) by Organic Halides in the Presence of Palladium Nanoparticles

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