01561nas a2200193   4500008004100000022001400041245005400055210005400109260007100163300001400234490000700248520090200255100002701157700002201184700002601206700002101232700003201253856008201285       2007                        eng d  a0888-588500aGeometrical solution to the sharkskin instability0 aGeometrical solution to the sharkskin instability  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAY  a3048-30560 v463 a<p>We study the effect of die exit divergence on the sharkskin behavior, both experimentally as well as through the use of computational fluid dynamics (CFD) simulations. Sharkskin or surface fracture is known to occur immediately after the die exit, because of the large elongational deformation that a polymer melt experiences as it exits the die. We show that the diverging taper at the die exit postpones or completely removes the occurrence of sharkskin. The corresponding CFD simulations of an equivalent K-BKZ fluid show that the taper at the die exit significantly reduces the severity of the elongational flow, thereby reducing the normal stresses as the polymer melt leaves the die. We believe that, in an extrusion operation, the provision of a diverging taper at the die exit is one of the potential measures by which sharkskin instability can be eliminated on an industrial scale.</p>1 aPol, Harshawardhan, V.1 aJoshi, Yogesh, M.1 aTapadia, Prashant, S.1 aLele, Ashish, K.1 aMashelkar, Raghunath, Anant  uhttps://library.ncl.res.in/content/geometrical-solution-sharkskin-instability01725nas a2200169   4500008004100000022001400041245009500055210006900150260006700219300001400286490000700300520105700307100001801364700002701382700002701409856011901436       2011                        eng d  a0032-388800aInfluence of DMDBS on the morphology and mechanical properties of polypropylene cast films0 aInfluence of DMDBS on the morphology and mechanical properties o  a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcOCT  a2013-20230 v513 a<p>We investigate extrusion film casting (EFC) of polypropylene (PP) and examine the effects of varying the concentration of nucleating agent, dimethyl dibenzylidene sorbitol (DMDBS); melt temperature at the die exit; and the draw ratio. Addition of DMDBS increases the PP crystallization temperature, and consequently the PP lamellar repeat spacing. For the draw ratios explored, we do not observe any substantial orientation of iPP crystals for films of neat iPP. However, addition of DMDBS results in the formation of oriented PP crystals, with greater orientation for higher draw ratios. On cooling from the melt, a network of DMDBS nanofibers forms in the PP. We believe that flow-alignment of this DMDBS network templates the orientation of PP crystals. We observe that the tensile modulus and yield stress increase with PP crystal orientation. However, at high DMDBS concentrations (0.8%), films have poor mechanical strength due to formation of voids and defects. POLYM. ENG. SCI., 51:2013-2023, 2011. (C) 2011 Society of Plastics Engineers</p>1 aSreenivas, K.1 aPol, Harshawardhan, V.1 aKumaraswamy, Guruswamy  uhttps://library.ncl.res.in/content/influence-dmdbs-morphology-and-mechanical-properties-polypropylene-cast-films-002034nas a2200181   4500008004100000022001400041245007900055210006900134260011000203300001200313490000700325520132300332100002701655700002601682700001801708700002101726856010501747       2013                        eng d  a0148-605500aNecking in extrusion film casting: the role of macromolecular architecture0 aNecking in extrusion film casting the role of macromolecular arc  aSTE 1 NO 1, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747-4502 USAbJOURNAL RHEOLOGY AMER INST PHYSICScMAR  a559-5830 v573 a<p>Extrusion film casting (EFC) is used on an industrial scale to produce several thousand tons of polymer films and coatings. While significant research has been carried out on necking of films of viscoelastic melts in EFC, the influence of macromolecular chain architecture on the necking behavior is not yet fully understood. In the present research, we have explored experimentally and theoretically the effects of long chain branching and molecular weight distribution on the extent of necking during EFC. Polyethylenes of essentially linear architecture but having narrow and broad molecular weight distributions, and polyethylenes having long chain branching were used for experimental studies. The EFC process was analyzed using the one-dimensional flow model of Silagy et al. [Polym. Eng. Sci. 36(21), 2614-2625 (1996)] in which multimode molecular constitutive equations namely the ``extended pom-pom'' equation (for long chain branched polymer melts) and the ``Rolie-Poly (Rouse linear entangled polymers)'' equation (for linear polymer melts) were incorporated. We show that the model qualitatively captures the salient features of the experimental data thereby elucidating the role of chain architecture on the extent of necking. (C) 2013 The Society of Rheology. [http://dx.doi.org/10.1122/1.4788911]</p>1 aPol, Harshawardhan, V.1 aThete, Sumeet, Suresh1 aDoshi, Pankaj1 aLele, Ashish, K.  uhttps://library.ncl.res.in/content/necking-extrusion-film-casting-role-macromolecular-architecture-002175nas a2200193   4500008004100000245009800041210006900139260011800208300002700326490000900353520137500362100002701737700001801764700002201782700001801804700001801822700001701840856012401857       2015                        eng d00aInfluence of macromolecular architecture on necking in polymer extrusion film casting process0 aInfluence of macromolecular architecture on necking in polymer e  aCleveland, OHbAmerican Institute of Physics, 2 Huntington Quadrangle, STE 1No1, Melville, NY 11747-4501 USAcJUN  aArticle Number: 0800060 v16643 a<p>Extrusion film casting (EFC) is an important polymer processing technique that is used to produce several thousand tons of polymer films/coatings on an industrial scale. In this research, we are interested in understanding quantitatively how macromolecular chain architecture (for example long chain branching (LCB) or molecular weight distribution (MWD or PDI)) influences the necking and thickness distribution of extrusion cast films. We have used different polymer resins of linear and branched molecular architecture to produce extrusion cast films under controlled experimental conditions. The necking profiles of the films were imaged and the velocity profiles during EFC were monitored using particle tracking velocimetry (PTV) technique. Additionally, the temperature profiles were captured using an IR thermography and thickness profiles were calculated. The experimental results are compared with predictions of one-dimensional flow model of Silagy et al(1) wherein the polymer resin rheology is modeled using molecular constitutive equations such as the Rolie-Poly (RP) and extended Pom Pom (XPP). We demonstrate that the 1-D flow model containing the molecular constitutive equations provides new insights into the role of macromolecular chain architecture on film necking. D-1. Silagy, Y. Demay, and J-F. Agassant, Polym. Eng. Sci., 36, 2614 (1996).</p>1 aPol, Harshawardhan, V.1 aBanik, Sourya1 aAzad, Lal, Busher1 aThete, Sumeet1 aDoshi, Pankaj1 aLele, Ashish  uhttps://library.ncl.res.in/content/influence-macromolecular-architecture-necking-polymer-extrusion-film-casting-process01473nas a2200145   4500008004100000245011400041210006900155260000800224300001300232490000700245520090500252100002701157700002201184856012101206       2016                        eng d00aNecking in extrusion film casting: numerical predictions of the maxwell model and comparison with experiments0 aNecking in extrusion film casting numerical predictions of the m  cSEP  a984-10060 v553 aThe role of viscoelasticity in determining the extent of necking of a web of molten polymer extruded in an isothermal steady state extrusion film casting (EFC) process is considered. Following a brief review of experimental and theoretical efforts on this problem, analytical and numerical solutions to a well-established model for extrusion film casting using the Maxwell constitutive equation is presented. The extent of film necking was found to either increase or decrease with draw ratio (DR) depending on the Deborah number (De). The locus of points on the draw ratio-Deborah number diagram at which the draw ratio dependence of the necking width inverts was calculated and compared with the locus that separates the unattainable regime from the experimentally accessible regime. Predicted trends were found to be in qualitative agreement with experimental data for various polyethylene grades.1 aPol, Harshawardhan, V.1 aThete, Sumeet, S.  uhttps://library.ncl.res.in/content/necking-extrusion-film-casting-numerical-predictions-maxwell-model-and-comparison02308nas a2200193   4500008004100000245007900041210006900120260000800189300001200197490000700209520165900216100002201875700001801897700002001915700002201935700002701957700001901984856011102003       2017                        eng d00aControlling necking in extrusion film casting using polymer nanocomposites0 aControlling necking in extrusion film casting using polymer nano  cFEB  a213-2330 v563 aThe research described was concerned with the effect of layered-silicate-based organically modified nanoclay fillers on controlling the extent of necking in a polymer melt extrusion film casting (EFC) process. We show that a linear polythylene resin (such as a linear low-density polyethylene-LLDPE) filled with a very low percentage of well-dispersed (or intercalated) nanoclay displays an enhanced resistance to the necking phenomenon. In general, melt-compounded nanoclay-filled LLDPE resin formulations displayed a higher final film width (less necking), thus a lower final film thickness (greater draw down for the same draw ratio), and cooled down faster when compared to the base LLDPE resin. Incorporation of nanoclay filler in the mainly linear chain LLDPE resin led to significant modification of the melt rheological properties that, in turn, affected the melt processability of these formulations. Primarily, the intercalated nanoclay-filled LLDPE formulations displayed the presence of strain-hardening in unaxial extensional rheology. Additionally, the presence of well-dispersed nanoclay in the LLDPE resin led to a display of prominent extrudate swell indicating the presence of melt elasticity in such formulations. The presence of melt elasticity, as shown by shear rheology and strain-hardening, observed by uniaxial extensional rheology, contributed to the LLDPE nanoclay formulations displaying an enhanced resistance to necking for these films. It can be concluded that linear chain polymers susceptible to necking in an EFC process can be made more resistant to such necking by using nanoclay fillers at very low levels of loading.1 aRokade, Dhammaraj1 aAzad, Lal, B.1 aPoddar, Suparna1 aMishra, Satyendra1 aPol, Harshawardhan, V.1 aShukla, Rishab  uhttps://library.ncl.res.in/content/controlling-necking-extrusion-film-casting-using-polymer-nanocomposites02315nas a2200157   4500008004100000245012400041210006900165260000800234300001000242490000700252520170300259100002201962700001801984700002702002856012802029       2017                        eng d00aNew insights into the use of multi-mode phenomenological constitutive equations to model extrusion film casting process0 aNew insights into the use of multimode phenomenological constitu  cJAN  a35-710 v333 aThis article is concerned with the effect of the individual viscoelastic relaxation modes of a polymer melt on its behavior in polymer melt extrusion film casting process. We compare the predicted versus experimentally obtained film necking or neck-in profile as a function of draw ratio. The predicted necking profile was obtained using well-established one-dimensional isothermal flow kinematics and consisted of using two different phenomenological constitutive equations, upper convected Maxwell and Phan-Thien-Tanner, with a discrete spectrum of relaxation times. The numerical simulations, containing the two different phenomenological constitutive equations, provided an insight into the effect of the slow and the fast relaxing modes on the stresses, strains, and strain/extensional rates that develop in the molten polymer film as it is stretched from the die exit to the chill-roll. The slow relaxing modes follow trends that are directly proportional to strain (similar to Hookean solids), whereas the fast relaxing modes follow trends that are directly proportional to the stretch rate (in accordance with Newton's law of viscosity). Comparing the numerical predictions with the experiments showed that predictions using the upper convected Maxwell constitutive equation best described the long-chain branched polymers (like low-density polyethylene, which shows extensional strain hardening) in the extrusion film casting process. On the other hand, predictions using the Phan-Thien-Tanner constitutive equation best described the linear polymers (like linear low-density polyethylene, which does not show noticeable extensional strain hardening) in the extrusion film casting process.1 aThete, Sumeet, S.1 aDoshi, Pankaj1 aPol, Harshawardhan, V.  uhttps://library.ncl.res.in/content/new-insights-use-multi-mode-phenomenological-constitutive-equations-model-extrusion-film02195nas a2200301   4500008004100000022001400041245016600055210006900221260001000290300001200300490000800312520113100320653001501451653002401466653003101490653002701521653001901548100002001567700002501587700001601612700002201628700002101650700002701671700002401698700002501722700002101747856012501768       2018                        eng d  a0304-885300aSingle step, phase controlled, large scale synthesis of ferrimagnetic iron oxide polymorph nanoparticles by thermal plasma route and their rheological properties0 aSingle step phase controlled large scale synthesis of ferrimagne  cMAR 1  a232-2420 v4493 a<p>In this paper we report single step large scale synthesis of highly crystalline iron oxide nanoparticles viz. magnetite (Fe3O4) and maghemite (gamma-Fe2O3) via gas phase condensation process, where micron sized iron metal powder was used as a precursor. Selective phases of iron oxide were obtained by variation of gas flow rate of oxygen and hence partial pressure of oxygen inside the plasma reactor. Most of the particles were found to possesses average crystallite size of about 20-30 nm. The DC magnetization curves recorded indicate almost super-paramagnetic nature of the iron oxide magnetic nanoparticles. Further, iron oxide nanoparticles were analyzed using Raman spectroscopy, X-ray photoelectron spectroscopy and Mossbauer spectroscopy. In order to explore the feasibility of these nanoparticles for magnetic damper application, rheological studies have been carried out and compared with commercially available Carbonyl Iron (CI) particles. The nanoparticles obtained by thermal plasma route show improved dispersion which is useful for rheological applications. (C) 2017 Elsevier B.V. All rights reserved.</p>10aIron oxide10amagnetic properties10aNano-crystalline materials10aRheological properties10aThermal plasma1 aRaut, Suyog, A.1 aMutadak, Pallavi, R.1 aKumar, Shiv1 aKanhe, Nilesh, S.1 aHuprikar, Sameer1 aPol, Harshawardhan, V.1 aPhase, Deodatta, M.1 aBhoraskar, Sudha, V.1 aMathe, Vikas, L.  uhttps://library.ncl.res.in/content/single-step-phase-controlled-large-scale-synthesis-ferrimagnetic-iron-oxide-polymorph02339nas a2200205   4500008004100000245011200041210006900153260000800222300002500230490000600255520158100261100001801842700002601860700002401886700002301910700002601933700002701959700002001986856012702006       2020                        eng d00aSynthesis and characterization of nylon 6 polymer nanocomposite using organically modified Indian bentonite0 aSynthesis and characterization of nylon 6 polymer nanocomposite   cJUL  aArticle number: 14120 v23 a<p>In this present research work two different organic compounds are applied for the modification of Indian origin bentonite. One&nbsp;is with n-hexadecyltrimethylammonium bromide (CTAB), intercalated with an&nbsp;interlayer of bentonite via cation exchange mechanism. Whereas, another with 3-Aminopropyl trimethoxysilane (APTES) interlayer functionalization with bentonite –OH group. APTES and CTAB–intercalated bentonites samples were further cross modified with CTAB and APTES to obtain novel co-surfactant locked organo bentonite modeling (CLOM) like matrices. Original and modified bentonite samples were comparatively evaluated by advanced characterization techniques such as, powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis (TGA). Moreover,&nbsp;the&nbsp;applicability of the developed CLOM like materials were investigated in nylon 6 nanocomposite preparation by melt compounding method using a micro twin co-rotated extruder. Additionally, CLOM-nylon-6 polymer nanocomposites were characterized by wide angle X-ray diffraction, TGA, differential scanning calorimetry, atomic force microscopy and tensile strength measurement. The observed thermograph results confirmed no significant difference in the thermal properties of the developed composites. Whereas, the significant variation observed in the tensile strength results particularly for developed composite 5% of N6-OAMSB and N6 AMOSB 5 showed 111.5 and 76.6% respective enhancement in tensile strength results when compared with a bare nylon-6 polymer.</p>
1 aKumaresan, S.1 aRokade, Dhammaraj, S.1 aMarathe, Yogesh, N.1 aIngole, Pravin, G.1 aPawar, Radheshyam, R.1 aPol, Harshawardhan, V.1 aBajaj, Hari, C.  uhttps://library.ncl.res.in/content/synthesis-and-characterization-nylon-6-polymer-nanocomposite-using-organically-modified02263nas a2200217   4500008004100000022001400041245011800055210006900173260000800242300001400250490000700264520147700271100002701748700002401775700002701799700001901826700002201845700002301867700002401890856013101914       2023                        eng d  a1759-995400aPalladium-catalyzed polar solvent empowered synthesis of hyper-branched ethylene oligomers and their applications0 aPalladiumcatalyzed polar solvent empowered synthesis of hyperbra  cJUL  a3239-32510 v143 a<p>
	In this contribution, we report the synthesis of two naphthoxy imine ligands, 2-(((2,6-dibenzhydryl-4-methoxyphenyl)imino)methyl)naphthalen-1-ol (L1) and 2-(((2,6-diisopropylphenyl)imino)methyl)naphthalen-1-ol (L2), with different steric and electronic features. L1 and L2 were treated with [(TMEDA)PdMe2] to obtain the corresponding neutral palladium(ii) complexes Cat.1 and Cat.2 in excellent yields. The identity of Cat.1 and Cat.2 was unambiguously ascertained using a combination of spectroscopic and analytical methods, including single-crystal X-ray diffraction. When exposed to 5 bar ethylene pressure, Cat.1 produced hyperbranched ethylene oligomers. The microstructure analysis of ethylene oligomers confirmed the existence of methyl, ethyl, propyl, and sec-butyl branches, with a molecular weight (M-n) of 500-1400 g mol(-1), a PDI of 1.46-2.10, and 67-106 branches per 1000 carbon atoms. The use of a polar solvent, tetrahydrofuran, led to a remarkable 3-fold increase in oligomerization activity without compromising the branching and molecular weight. The resultant hyperbranched ethylene oligomers were selectively monofunctionalized using industrially practiced hydroformylation, ozonolysis, and epoxidation, almost quantitatively. The hydroxy functionalized ethylene oligomer (F4) (5 wt%) was melt-compounded with LLDPE and Nylon-6 to produce a tough yet flexible blend with a higher strain-to-failure as compared to an uncompatibilized blend.</p>
1 aBirajdar, Rajkumar, S.1 aGonnade, Rajesh, G.1 aPol, Harshawardhan, V.1 aPrabhu, Basava1 aRokade, Dhammaraj1 aNandimath, Sheetal1 aChikkali, Samir, H.  uhttps://library.ncl.res.in/content/palladium-catalyzed-polar-solvent-empowered-synthesis-hyper-branched-ethylene-oligomers-and02648nas a2200277   4500008004100000022001400041245016800055210006900223260000800292300001000300490000700310520163500317653003001952653001901982653002302001653001802024653001202042653003802054100002502092700002602117700002302143700002702166700003102193700002002224856012602244       2024                        eng d  a1042-714700aEffect of covalently functionalized Indian bentonite clay on thermal, mechanical strength and morphology structure of extrusion/injection-molded nylon 6 composites0 aEffect of covalently functionalized Indian bentonite clay on the  cMAY  ae64120 v353 a<p>
	The research and development of functional polymer composites and their production have posed significant challenges, particularly in creating high mechanical strength and thermal stability composites. In this study, we utilized a micro corotation extruder and injection molding to produce covalently functionalized Indian bentonite clay-nylon 6 high-strength nanocomposites. For comparison, two different amines, 3-aminopropyl trimethoxysilane and N-[3-(trimethoxysilyl) propyl] ethylene di-amine, were used to functionalize bentonite clay. Additionally, 3% and 5% less amino clay filler was added in the nanocomposite to manufacture the polymer composite. Analytical techniques such as Powder X-Ray Diffraction, Fourier transform infrared, thermal gravimetric analysis, and Brunauer-Emmett-Teller surface area were used to characterize the molecular orientation of amine functionalization on clay minerals. Wide-angle X-ray diffraction, atomic force microscopy, and transmission electron microscope were used to characterize the nylon 6 intercalated in amino clay nanocomposite and the polymer structure morphology. Thermogravimetric analysis and differential scanning calorimetry were used to investigate the crystalline thermal behavior of clay-nylon 6 composites. From the results, it was observed that the composition containing 5 wt.% amino clay demonstrated a significant improvement in tensile strength when compared with the composition containing 3 wt.% amino clay. The mechanical strength and the thermal behavior showed a significant improvement of similar to 200% for 5% amino clay-nylon 6 nanocomposite.</p>
10aamine-functionalized clay10abentonite clay10amelt intercalation10aNanocomposite10anylon 610athermal and mechanical properties1 aShanmugam, Kumaresan1 aRokade, Dhammaraj, S.1 aIngole, Pravin, G.1 aPol, Harshawardhan, V.1 aArunachalam, Saravanakumar1 aBajaj, Hari, C.  uhttps://library.ncl.res.in/content/effect-covalently-functionalized-indian-bentonite-clay-thermal-mechanical-strength-and