M. H. Wagner

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Organization: Polymertechnik/Polymerphysik , Germany

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Title: (PhD)

Chemicals
References

Synthesis of DV-GO and its effect on the fire safety and thermal stability of bismaleimide

Co-reporter:Zheng Wang, Wei Wu, Manfred H. Wagner, Luchong Zhang, Simon Bard

Polymer Degradation and Stability 2016 Volume 128() pp:209-216

Publication Date(Web):June 2016

DOI:10.1016/j.polymdegradstab.2016.03.016

In this paper, functionalized graphene oxide was used as a flame retardant for 4, 4′-bismaleimidophenyl methane/2, 2′-diallyl bisphenol A (BDM/DBA) resins. The synergistic effect of graphene oxide and silicon-phosphorous containing flame retardant (DOPO-VTES) on the flame retardant property was systematically investigated. BDM/DBA resin containing 3 wt% (DOPO-VTES)-GO (DV-GO) achieved UL94 V-0 rating; the peak heat release (pHRR) value was reduced by 29% in the cone calorimetry test (CCT). TGA data showed that the maximum mass loss rate of decomposition decreased significantly and char residue increased to 34.9 wt% compared with that of the neat BDM/DBA resin. Furthermore, char residue characterization was investigated by SEM-EDX and Raman measurements. These results provided obvious evidence that the existence of DV-GO can catalyze the char formation, of which carbonaceous microstructures and the morphological structures can be observed. All the investigations showed that DV-GO was an effective additive to develop high performance resins with attractive flame retardant properties.

A hierarchical multi-mode MSF model for long-chain branched polymer melts part I: elongational flow

Co-reporter:Esmaeil Narimissa;Víctor H. Rolón-Garrido;Manfred H. Wagner

Rheologica Acta 2015 Volume 54( Issue 9-10) pp:779-791

Publication Date(Web):2015 October

DOI:10.1007/s00397-015-0879-2

A novel hierarchical multi-mode molecular stress function (HMMSF) model for long-chain branched (LCB) polymer melts is proposed, which implements the basic ideas of (i) the pom-pom model, (ii) hierarchal relaxation, (iii) dynamic dilution and (iv) interchain pressure. Here, the capability of this approach is demonstrated in modelling uniaxial extensional viscosity data of numerous broadly distributed long-chain branched polymer melts with only a single non-linear parameter, the dilution modulus.

Scaling relations for elongational flow of polystyrene melts and concentrated solutions of polystyrene in oligomeric styrene

Co-reporter:Manfred H Wagner

Rheologica Acta 2014 Volume 53( Issue 10-11) pp:765-777

Publication Date(Web):2014 November

DOI:10.1007/s00397-014-0791-1

A consistent model of the rheology of polymer melts and concentrated solutions is presented, based on the idea that the pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic (Doi and Edwards. The Theory of Polymer Dynamics, Oxford University Press, 1986). In a tube model with variable tube diameter, chain stretch and tube diameter reduction are related, and at deformation rates larger than the inverse Rouse time τR, the chain is stretched and its confining tube becomes increasingly anisotropic. Tube diameter reduction leads to an interchain pressure in the lateral direction of the tube (Marrucci and Ianniruberto. Macromolecules 37:3934-3942, 2004). Chain stretch is balanced by interchain tube pressure in the lateral direction, which is proportional to the third power of stretch, and by a spring force in the longitudinal direction of the tube, which is linear in stretch. Analyzing elongational viscosity data of Huang et al. (Macromolecules 46:5026-5035, 2013a; ACS Macro Letters 2:741-744, 2013b) shows that dilution of polystyrene by oligomeric styrene does not change the relative interchain tube pressure. Based on this extended interchain pressure concept, scaling relations for linear viscoelasticity and elongational viscosity of polystyrene melts and concentrated solutions of polystyrene in oligomeric styrene are presented based exclusively on the relaxation modulus of a reference polymer melt, the volume fraction of polymer in the solution, and the time-molar-mass shift as well as the time-temperature shift caused by the reduction of the glass transition temperature Tg of the polymer in a solution relative to Tg of the melt.

Rheological behavior of lubricating systems in polypropylene/seaweed composites

Co-reporter:Lixing Luan;Wei Wu;Manfred H. Wagner

Journal of Applied Polymer Science 2011 Volume 121( Issue 4) pp:2143-2148

Publication Date(Web):

DOI:10.1002/app.33940

Abstract

The present article summarizes an experimental study on the effects of two additives on polypropylene/seaweed (PP/SW) biocomposites by dynamic rheological characterization. Storage and loss moduli as a function of frequency were obtained by small-amplitude shear oscillation tests in parallel-plate mode. Maleic anhydride-grafted polypropylene (MAPP) was found to provide good external lubrication, while CNT masterbatch (CESA) promoted fiber–fiber interaction. Han plot and Cole-Cole plot visibly present the difference between the two interaction mechanisms. A synergistic effect was also observed when MAPP and CESA were simultaneously used in biocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Mechanical performance of hybrid rice straw/sea weed polypropylene composites

Co-reporter:M. Masudul Hassan;Marco Mueller;Diana J. Tartakowska ;Manfred H. Wagner

Journal of Applied Polymer Science 2011 Volume 120( Issue 3) pp:1843-1849

Publication Date(Web):

DOI:10.1002/app.33403

Abstract

Rice straw (Rs)/polypropylene (PP) composites were prepared in the different ratio of 5 : 95, 10 : 90, 15 : 85, 20 : 80, 25 : 75, and 30 : 70 (Rs wt % : PP wt %) by an injection molding process. This work investigated the tensile strength (TS), bending strength (BS), and impact strength (IS) of the composites. From the results, it is observed that Rs20 : PP80 mixture composite showed better performance with mechanical properties (TS = 26.2 MPa, BS = 58 N/mm², and IS = 1.7 KJ/mm²) among the composites prepared. Two hybrid composites were also fabricated using 20% Rs, 10% seaweed with 70% PP and 20% Rs, 30% seaweed with 70% PP. In between the two hybrid composites, superior mechanical behavior showed by the hybrid composite in ratio of Rs20 : Sw10 : PP70 with enhanced results such as TS = 28 MPa, BS = 68 N/mm², and IS = 2.5 KJ/mm². Water uptake, simulating weathering, and soil degradation test of different composites were also performed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Seaweed as novel biofiller in polypropylene composites

Co-reporter:Lixing Luan;Wei Wu;Manfred H. Wagner;Marco Mueller

Journal of Applied Polymer Science 2010 Volume 118( Issue 2) pp:997-1005

Publication Date(Web):

DOI:10.1002/app.32462

Abstract

Based on former exploratory research, we used seaweed (SW) fiber as a novel biofiller for the production of polypropylene (PP) biocomposites. Maleic anhydride-grafted polypropylene (MAPP) and a CNT masterbatch (CESA) were applied as compatibilizers. Mechanical properties, crystallization behavior, dynamic mechanical performance as well as interfacial morphology were characterized. SW fiber was successfully incorporated in the PP matrix in terms of mechanical reinforcement. Accelerated crystallization process of PP matrix was observed. DMA results also indicated the favorable adhesion between SW fiber and PP matrix, which could be confirmed by SEM characterization. The effect and efficiency of MAPP and CESA as compatibilizers were evaluated. Moreover, potential flame retardancy of SW fibers for PP matrix was observed, and satisfying results warrant further investigations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The interchain pressure effect in shear rheology

Co-reporter:Manfred H. Wagner;Víctor H. Rolón-Garrido

Rheologica Acta 2010 Volume 49( Issue 5) pp:459-471

Publication Date(Web):2010 May

DOI:10.1007/s00397-009-0427-z

Recently, the tube diameter relaxation time in the evolution equation of the molecular stress function (MSF) model (Wagner et al., J Rheol 49: 1317–1327, 2005) with the interchain pressure effect (Marrucci and Ianniruberto, Macromolecules 37:3934–3942, 2004) included was shown to be equal to three times the Rouse time in the limit of small chain stretch. From this result, an advanced version of the MSF model was proposed, allowing modeling of the transient and steady-state elongational viscosity data of monodisperse polystyrene melts without using any nonlinear parameter, i.e., solely based on the linear viscoelastic characterization of the melts (Wagner and Rolón-Garrido 2009a, b). In this work, the same approach is extended to model experimental data in shear flow. The shear viscosity of two polybutadiene solutions (Ravindranath and Wang, J Rheol 52(3):681–695, 2008), of four styrene-butadiene random copolymer melts (Boukany et al., J Rheol 53(3):617–629, 2009), and of four polyisoprene melts (Auhl et al., J Rheol 52(3):801–835, 2008) as well as the shear viscosity and the first and second normal stress differences of a polystyrene melt (Schweizer et al., J Rheol 48(6):1345–1363, 2004), are analyzed. The capability of the MSF model with the interchain pressure effect included in the evolution equation of the chain stretch to model shear rheology on the basis of linear viscoelastic data alone is confirmed.

The damping function in rheology

Co-reporter:Víctor H. Rolón-Garrido;Manfred H. Wagner

Rheologica Acta 2009 Volume 48( Issue 3) pp:245-284

Publication Date(Web):2009 April

DOI:10.1007/s00397-008-0308-x

The damping function has been a concept introduced in rheology since more than 30 years ago, and although a similar concept was already earlier implemented in studying rubber materials, its implementation in the modeling of polymer melts was an essential step forward in the classification and understanding of nonlinear viscoelasticity phenomena. It is the objective of this contribution to give an overview on the theoretical background and physical interpretation of the concept of the damping function for different types of deformation, as well as a review on the experimental results including the experimental artefacts to be considered. Besides homopolymers, a summary is given on different investigations of other types of systems, where the concept of the damping function has also been applied, for example, rubbers, rubber-like materials, block copolymers, polymer composites, liquid crystals, polymer blends, suspensions, emulsions, micellar systems, and in food rheology.

Study on phase separation of PET/PEN blends by dynamic rheology

Co-reporter:M. H. Wagner;W. Wu;Y. Liu;Q. Qian;Y. Zhang;W. Mielke

Journal of Applied Polymer Science 2008 Volume 110( Issue 1) pp:177-182

Publication Date(Web):

DOI:10.1002/app.28156

Abstract

Blends of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) were processed into biaxially drawn films, and samples taken from the bi-oriented films were then investigated by dynamic rheology experiments in the melt state. Storage modulus G′ and loss modulus G″ were determined in the frequency range of 10⁻²–10² rad/s at temperatures between 260 and 300°C. Although the time–temperature superposition (TTS) principle was found to hold in the high frequency regime, a breakdown of TTS was observed at low frequencies, and the terminal behavior of the storage modulus G′ of the blends departs drastically from the terminal behavior observed for the blend components. This is caused by interfacial surface tension effects. The results indicate that despite the effect of transesterification reactions, the PET/PEN blend systems investigated consist of a microseparate phase of PEN platelets in a matrix of PET. This morphology is produced when the blends are processed into biaxially oriented PET/PEN films, and droplets of PEN are deformed into a lamellar structure consisting of parallel and extended, separate layers. The large interfacial surface area of the bi-oriented PET/PEN blends leads to remarkably strong interfacial tension effects in dynamic rheology measurements. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Exploratory study on seaweed as novel filler in polypropylene composite

Co-reporter:M. Masudul Hassan;Marco Mueller ;Manfred H. Wagners

Journal of Applied Polymer Science 2008 Volume 109( Issue 2) pp:1242-1247

Publication Date(Web):

DOI:10.1002/app.28287

Abstract

Seaweed (SW) is employed as filler to prepare composites on the basis of a polypropylene (PP) matrix in the ratio of 10 : 90, 20 : 80, 30 : 70, 40 : 60, and 50 : 50 (wt % SW : wt % PP) by compounding and injection molding. The tensile, bending and impact properties of the composites were investigated. The 30% SW : 70% PP composite showed the best over-all mechanical performance of the composites prepared. Further improvement of this optimal composite was achieved by incorporating 2% thermoplastic elastomer (TPE) as additive. Interfacial adhesion and bonding between the fibers and PP matrix were investigated by scanning electron microscopy (SEM). Water absorption tests of the different composites were also performed, and addition of TPE was found to lead to a substantial reduction of water uptake. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

The MSF model: relation of nonlinear parameters to molecular structure of long-chain branched polymer melts

Co-reporter:Víctor H. Rolón-Garrido;Manfred H. Wagner

Rheologica Acta 2007 Volume 46( Issue 5) pp:583-593

Publication Date(Web):2007 May

DOI:10.1007/s00397-006-0136-9

The elongational viscosity data of model PS combs (Hepperle J, Einfluss der Molekularen Struktur auf Rheologische Eigenschaften von Polystyrol- und Polycarbonatschmelzen. Doctoral Thesis, University Erlangen-Nürnberg, 2003) are reconsidered by including the interchain pressure term of Marrucci and Ianniruberto [Macromolecules 37:3934–3942, 2004] in the Molecular Stress Function model [Wagner et al., J Rheol 47(3):779–793, 2003, Wagner et al., J Rheol 49:1317–1327, 2005d]. Two nonlinear model parameters are needed to describe elongational flow, β and \( f^{2}_{{{\text{MAX}}}} \). The parameterβ determines the slope of the elongational viscosity after the inception of strain hardening. It is directly related to the molecular structure of the polymer and represents the ratio of the molar mass of the (branched) polymer to the molar mass of the backbone alone. β follows from the hypothesis of Wagner et al. [J Rheol 47(3):779–793, 2003] that side chains are compressed onto the backbone. We consider also the case that side chains are oriented by deformation, but not stretched, and found little difference in the model predictions. The parameter \( f^{2}_{{{\text{MAX}}}} \) represents the maximum strain energy stored in the polymeric system and determines the steady-state value of the viscosity in extensional flows. The relation of this energy parameter to the molecular structure is discussed. Good correlations between the energy parameter and different coil contraction ratios, as determined either experimentally or calculated theoretically by considering the topology of the macromolecule, are found. The smaller the relative size of the polymer coil, the larger is the energy parameter and the more strain energy can be stored in the polymeric system.

The Rheology of Linear and Long-chain Branched Polymer Melts

Co-reporter:Manfred H. Wagner

Macromolecular Symposia 2006 Volume 236(Issue 1) pp:219-227

Publication Date(Web):28 MAR 2006

DOI:10.1002/masy.200690058

By generalising the Doi-Edwards tube model to the Molecular Stress Function theory, the non-linear rheology of polymer melts can be described quantitatively. The strain-hardening of linear polymer melts in extensional flows can be accounted for by a strain energy function, which reflects the increase of strain energy due to tube squeeze. In comparison to linear polymer melts, long-chain branched polymer melts show enhanced strain-hardening. This is due to the fact that while the backbone of the branched macromolecule is stretched by deformation, side chains are compressed. It is demonstrated that the experimentally observed slope of the elongational viscosity after inception of strain-hardening depends on the ratio β of total molar mass to backbone molar mass as predicted by the model. The steady-state (plateau) value of the elongational viscosity depends on the maximum relative stretch, , which can be supported by chain segments and which represents the maximum elastic energy storable in the polymeric system.

The Strain Hardening of Linear and Long-Chain Branched Polymer Melts

Co-reporter:H. Bastian;P. Rubio Dr.-Ing.

Chemie Ingenieur Technik 2001 Volume 73(Issue 11) pp:

Publication Date(Web):27 NOV 2001

DOI:10.1002/1522-2640(200111)73:11<1447::AID-CITE1447>3.0.CO;2-2

An extended interchain tube pressure model for elongational flow of polystyrene melts and concentrated solutions

Co-reporter:Manfred H. Wagner

Journal of Non-Newtonian Fluid Mechanics (August 2015) Volume 222() pp:121-131

Publication Date(Web):1 August 2015

DOI:10.1016/j.jnnfm.2014.09.017

•An extended interchain tube pressure model is presented.•Linear viscoelasticity of melts and solutions is analyzed and scaling laws are derived.•The importance of the reduced glass transition temperature of polymer solutions on the scaling is revealed.•Elongational viscosity data of melts and solutions are analyzed and the model presented is verified.•Nonlinear viscoelastic scaling is presented.An extended interchain tube pressure model for polymer melts and concentrated solutions is presented, based on the idea that the pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic (Doi and Edwards, 1986). In a tube model with variable tube diameter, chain stretch and tube diameter reduction are related, and at deformation rates larger than the inverse Rouse time τR, the chain is stretched and its confining tube becomes increasingly anisotropic. Tube diameter reduction leads to an interchain pressure in the lateral direction of the tube, which is proportional to the 3rd power of stretch (Marrucci and Ianniruberto, 2004). In the extended interchain tube pressure model, it is assumed that chain stretch is balanced by interchain tube pressure in the lateral direction, and by a spring force in the longitudinal direction of the tube, which is linear in stretch. The elongational viscosity data of Huang et al. (2013) are in agreement with the assumption that dilution of polystyrene by oligomeric styrene does not change the relative interchain tube pressure. Quantitative agreement between highly nonlinear viscoelastic experiments in elongation and predictions for polystyrene melts and concentrated solutions of polystyrene in oligomeric styrene is obtained based exclusively on the relaxation modulus of the polymer melt, the volume fraction of polymer in the solution and the time-temperature shift caused by the reduction of the glass transition temperature Tg of the polymer in solution relative to Tg of the melt.Download full-size image

The effect of dynamic tube dilation on chain stretch in nonlinear polymer melt rheology

Co-reporter:Manfred H. Wagner

Journal of Non-Newtonian Fluid Mechanics (1 September 2011) Volume 166(Issue 16) pp:915-924

Publication Date(Web):1 September 2011

DOI:10.1016/j.jnnfm.2011.04.006

The pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic (Doi and Edwards [10]). At deformation rates larger than the inverse Rouse time of the polymer chain, chains are stretched and their confining tubes become increasingly anisotropic. In a tube model with variable tube diameter, this leads to an interchain tube pressure term in the lateral direction of the tube (Marrucci and Ianniruberto [15]), which limits chain stretch. Here we assume that chain stretch is balanced by two restoring tensions with weights of 1/3 in the longitudinal direction of the tube, due to a linear entropic spring force, and 2/3 in the lateral direction, due to a nonlinear interchain tube pressure, both of which are characterized by the Rouse stretch relaxation time τR. This approach is in quantitative agreement with the time-dependent and steady-state elongational viscosity of two monodisperse polystyrene melts with molar masses of 390,000 and 200,000 kg/mol as investigated by Bach et al. [2] and Hassager [12]. In bidisperse polymer blends, the interchain pressure is reduced in accordance with dynamic dilation of the tube. Implementation of the dilation effect into the evolution equation of the stretch leads to a quantitative description of the elongational behavior of bidisperse polystyrene blends consisting of a long and a short chain component as investigated by Nielsen et al. [22]. Due to the effect of chain ends, dynamic tube dilation is also of importance for monodisperse polymer melts with low molar masses having few entanglements, as demonstrated for two polystyrene melts with molar masses of Mw = 102,800 and 51,700 g/mol. If dynamic tube dilation is taken into account, quantitative agreement between highly nonlinear viscoelastic experiments and predictions can be obtained based exclusively on the linear-viscoelastic characterization of polymer melts.HighlightsThe analysis of experimental data in elongational flow of mono and bidsperse polystyrene melts shows that: ► Chain stretch is associated with a reduction of the tube diameter. ► The pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic. ► The increasing interchain tube pressure limits chain stretch. ► Dynamic tube dilation leads to an increase in the tube diameter and reduces the interchain tube pressure. ► Quantitative agreement between experiments and model can be obtained based exclusively on linear viscoelasticity.