Wendi Wang

Institution:
Technical University of Denmark (DTU)

 

Supervisors:
Ole Hassager
Qian Huang

 

Field of expertise:
Extensional Rheology
PhD subject:
Viscoelastic Response of Double Dynamics Polymer Networks under Transient Elongation

My role in DoDyNet project is to characterize “Viscoelastic Response of Double Dynamics Polymer Networks under Transient Elongation”. Especially, to study the nonlinear extensional rheology of different double dynamics networks and to relate the rheological results to mechanical properties towards applications. I am currently working on “rheological and mechanical properties of polystyrene with hydrogen bonding”. Below is an overview of this study.

Recent work [1] shows that polystyrene can become flexible at room temperature by stretching the melt at a rate faster than the inverse Rouse time, followed by rapid quenching below the glass transition temperature (Tg). Long-lasting flexibility and good humidity resistance, combined with other advantages such as light weight and interference immunity, make this flexible polystyrene a good candidate for plastic optical fibers (POFs). However, improvements are required to prevent cracks during filament bending.

In the present work, we investigate if crack prevention can be achieved by introducing hydrogen bonding (carboxylic acid groups) into the backbone. The rheological and mechanical properties of polystyrenes with different acid group contents are studied and compared to the corresponding pure polystyrene sample. Linear viscoelastic (LVE) measurements have experimentally confirmed that all the tested samples have a similar number of entanglements per chain (Z), suggesting that the acid groups do not form (or weakly form) hydrogen bonds at temperatures above Tg. This is further confirmed by non-linear extensional behavior measured by stretching the samples in uniaxial extensional flow. However, different mechanical properties at room temperature have been observed, which may be explained by the Haward and Thackray model.[2] Finally, to further improve mechanical properties of polystyrene based polymers, different types of polystyrene ionomer will be employed for future studies.

[1] Huang et al., ACS Macro Lett. 7, 1126−1130 (2018)
[2] Meijer and Govaert, Prog. Polym. Sci. 30, 915–938 (2005)

Language
  • Chinese: Native language
  • English: Professional proficiency
  • French: Professional proficiency
Software
Software Matlab, Microsoft office, Latex, Origin, Ludovic, Cadmould, REM3D
Extra curricular activities
  • 2011-2014 Responsible of class affairs, Fudan University, Shanghai, China. Manage accounts and in charge of organizing outings
  • 2010-2012 Finance manager at Multifunction Hall, Fudan University, Shanghai, China. Charge of accounting and planning activities

Curriculum Vitae

Experience

CERA, Trèves, Reims & Sophia Antipolis, France

2016 - 2017
Experimental study and simulation of injection molding of polyurethane foam

  • Bibliography study on polyurethane foam and characterization techniques
  • Experiments and simulation study to validate the code foam-REM3D R (pressure, temperature,
    density)
Soft material and Chemistry Laboratory, ESPCI Paris, Paris, France

2016.5 - 7
Synthesis of elastomeric vitrimers using exchangeable transamination reaction;
A manuscript has been prepared

  • Characterization of mechanic properties by: DMA, DSC, tensile test, creep test etc
  • Characterization of chemical properties by: NMR, FTIR-ATR
Department of Analyse, Solvay R&I Paris, France

2015.7 - 12

  • Determination of molecular mass of copolymers PS-b-PMMA with a high mass by NMR DOSY 2D
  • Determination of CMC of amphiphilic copolymers by NMR DOSY 2D and the measurement of
    relaxation time T1
  • Train on two-dimensional NMR sequences (HSQC & HMBC)

 

Henkel R&D Product Development lab of Beauty Care, Shanghai, China

2014.1 - 4

  • Development of Hair Care products: shampooing, conditioner, hair mask etc
  • Analyse of quality of hair care products: pH, viscosity, stability etc
Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, China

2012 -2014

  • Conducting researches on acid degradation behaviours of mesoporous magnetic colloidal nanocrystal
    clusters (MMCNCs), testing the degradability of different types and surface areas of MMCNCs,
    summarizing their degradation patterns
  • Characterization techniques: BET, TEM, FTIR, UV
  • Synthesis of hollow poly methyl methacrylate (PMMA) and apply to drug delivery
    Characterization techniques: TEM, SEM, DLS, UV, FTIR

 

Education

Phd student, Technical University of Denmark, Kongens Lyngby, Denmark

2018 - Present
Subject: Viscoelastic Response of Double Dynamics Polymer Networks under Transient Elongation

 

Advanced Master MaPMod, Mines ParisTech, Sophia Antipolis, France

2016 - 2017
General courses: Continuum Mechanics, Mechanical Testing, Project Management etc
Specialized in Polymers: Polymer Processing, Polymer Physics, Polymer Fluid Rheology etc

 

Engineer student on physical-chemistry, ESPCI ParisTech, Paris, France

2014 - 2016
Cross-disciplinary courses on physics and chemistry
Eiffel Excellence Scholarship Program

B.Sc. of Macromolecular Materials and Engineering, Fudan University, China

2010 - 2014
Polymer Chemistry, Physics and Processing
Excellent Graduated Student of Fudan University; National Scholarship

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