Self-assessment questions 2015.

Please describe the following terms: polymer, monomer, oligomer, repeat unit, degree of
polymerization.

Classify the polymeric materials on the basis of structure. Give examples.

Which are the commodity plastics? Describe their chemical composition, physical,
mechanical etc. properties, respectively.

Which are the engineering plastics? Introduce their general physical, mechanical etc.
properties and give examples.

Introduce the primary chemical bonds. What is their importance at polymers?

Introduce the secondary chemical bonds. What is their importance at polymers? Give
examples.

Introduce the chain-growth polymerization mechanism. Which are the common features
of these?

Introduce the step-growth polymerization methods. Which types do you know? Which are
the general features of these?

Describe the Carothers-equation.

Which are the industrial polymerization methods? Compare them briefly. How the
exothermic heat can be adsorbed during polymerization?

Name the possible industrial reactors of polymerization. Introduce them briefly.

Molecular weight distribution. Determining the molar mass. What is polydispersity?

How does the molecular weight affect the mechanical properties, melt viscosity and
crystalline structure of polymers?

Classify the polymers based on bonding groups.

What is conformation and configuration? Explain it by giving examples.

What is stereoregularity (head-tail connections, tacticity)? What is their effect on the
crystallinity?

What is copolymerization? What types of copolymers do you know?

What does polymer blend and compound mean?

Classify polymers on the basis of their molecule’s shape. What is the difference between
linear and cross-linked polymers?

Draw and explain the specific volume – temperature diagram of semi-crystalline
polymers.

Which crystalline formations occur in a semi-crystalline polymers? Name amorphous and
semi-crystalline polymers.

Explain the fringed micellar model of polymeric materials. What other theories exist to
characterize the structure of semi-crystalline polymers?

How does the degree of crystallinity affect the physical and mechanical properties of
polymers?

Draw the structural graph of polymeric materials.

What is DSC measurement? What is it good for?

What does hydrophilic and hydrophobic mean? Describe the water take up mechanisms of
polymers. Draw the wetting and drying curves as a function of time. List some polymers
which are sensitive to moisture. How does the humidity affect the tensile properties of
polymers?

Classify the mechanical tests of polymeric materials. Introduce the methods briefly and
give examples.

What is the difference between the tensile curve of metallic and polymeric materials?

Explain Hooke’s law. How can we determine the tensile modulus of a polymer?

What do we call stress-relaxation? Give engineering examples.

What do we call creep? Give engineering examples.

Which are the macro-deformation components of viscoelastic polymeric materials? What
is their relation with the micro-structural changes?

Which are the modeling elements of the deformation components? What is their main
characteristics?

How can the stress relaxation of polymers modeled? (Amorphous thermoplastics and
semicrystalline polymers)

How can the creep behavior of polymers modeled? (Amorphous thermoplastics and
semicrystalline polymers)

Explain the following terms: duration stress, duration strength, fatigue strength

What is the difference between the state of matter and the physical state? Which are the
typical physical states that can be present in polymeric materials?

What does micro- and macro-Brownian thermal movement means? What is glass
transition?

Introduce the characteristic transition temperatures (ranges) of polymers and give
structural explanations.

What is DMA test? What is the complex dynamic modulus and how can it be
decomposed?

How can the thermomechanical properties of polymers be determined?

Draw the DM(T)A curve of an amorphous thermoplastic material and explain it.

Draw the DM(T)A curve of a semi-crystalline thermoplastic material and explain it.

Draw the DM(T)A curves of a duromer and an elastomer material and explain it.

What is rheology?

Describe the Newtonean and the Bingham flow models.

Describe the Power law (Ostwald-de Waele model) for polymer materials. How can we
determine the dynamic viscosity from the apparent viscosity?

What is a dilatant material? What do we call pseudoplastic?

Introduce the time-dependent properties of polymer melts.

How does a real polymer flow? Why is it important from the viewpoint of polymer
processing?

Describe the flow of a Newtonean material in a capillary. Where does it have a role in
polymer processing? Speed distribution, stress distribution etc.

Describe the Hagen-Poisseuille equation. What is MFI and MVR and how can we
determine them?

Introduce the thermoforming process. What polymers are processed this way?

Which are the flow instabilities? How can we compensate them?

What does dispersive and distributive mixing mean?

What is static mixing? Which other types of mixers exist?

Which are the typical additives in a polymer compound?

Describe the two roll milling process.

Describe the Banbury-type kneader technology.

What is extrusion process?

Draw an extruder, identify its main parts, draw the pressure diagram.

Which are the sections of an extruder screw? What is their role? How can we increase the
pressure within the extruder? Why is it important? What is the typical L/D ratio of the
screw?

What is the screen pack and breaker plate? What is their role?

Describe the thermal properties of an extruder (work diagram).

Describe the material flow in the homogenization section. Which are the components?

What is the discharge factor of the extruder?

Draw and explain an extruder die capable for tube manufacturing.

Draw and explain a sheet manufacturing extruder die.

Draw and explain a wire-coating die.

Introduce the film-blowing technique.

What is co-extrusion? Draw a simplified die.

Introduce the extrusion blowing technique. How can we adjust the wall thickness?

Describe the injection mould blowing technique. Why can we use pre-stretching?

Which are the main parts on an injection moulding machine?

Describe the injection moulding process by introducing the injection cycle.

Describe the injection moulding process by drawing the pVT diagram.

Which are the multi-cavity injection mould types? Which are their advantages and
disadvantages?

Introduce the calendaring process.

Draw the pressure and speed distributions between calendaring rolls.

How can the calendar roll bending be compensated?

What does composite material mean? Explain the definition in detail.

Which are the typical matrices and fibers of composite material? What is their advantage
and disadvantage?

Why do we use fibers as reinforcement?

Introduce the film-stacking and compression-moulding methods.

Describe the pultrusion technology.

Explain the Kelly-Tyson formula. What does critical fiber length mean?

How can we classify the composite processing technologies? Give examples.

What does rapid tooling mean?

What is 3D printing? Which are the typical rapid prototyping methods?