230523 - Polymer technology

Question 1

Hand laminating advantages

Answer 1

simple procedure
low investment costs
prototype construction

Question 2

disadvantages

Answer 2

low reproducibility
low fiber volume contents

Question 3

reduce bubbles

Answer 3

vacuum foil
laminate is compacted and excess matrix is removed
better mechanical properties

Question 4

prepreg

Answer 4

ribbons and tapes
pre impregnated fiber matrix
store at -20 deg, consolidation temperatures up to 230deg
cold hardening (room temperature, low quality, low mechanical properties)
warm hardening (high temp, high pressure, better quality)

Question 5

autoclave process

Answer 5

hidrostatic pressure holds the pressure all around the 3D shape
adv:
* high fiber volume content (70%)
* high reproducibility
* few defects
dis:
* high investment costs
* high operating costs
* limited component size

Question 6

Processes for thermoset materials

Answer 6

hand lamination
with pressure
with vacuum
(low demand, high cycle times)
* injection and infusion (short cycle times)

Question 7

resin injection and infusion procedure

Answer 7

with vacuum you pull the matrix
adv:
* shorter cycles
* sandwich through the use of foam cores
* high component quality
dis:
* complex preforming (correct positioning of the foil, no folded parts)
* careful positioning of the

Question 8

dynamic mixing of components

Answer 8

a piston pulls out and the same channel is used to mix the components

Question 9

static

Answer 9

separate channels for each component

Question 10

vacuum infusion

Answer 10

vacuum sucks the matrix to the preformed textile, previously covered with a vacuum foil
simple process
large components possible
partial automation

Question 11

vacuum scrimp method

Answer 11

feed line perpendicular to the surface of the part
* Seemann Composites Resin Infusion Moulding Process

Question 12

vacuum assisted process

Answer 12

less resin usage

Answer 13

sustanability of composite materials is not the best at the
a lot of energy is needed
3000 deg celsius to carbonate the material
high CO2 emissions

Question 14

RTM

Answer 14

resin transfer moulding
injection
* gelcoatings possible
* textile, close the press to form the shape (simple parts), injection of resin and fiber, temperature control and demould
release agent can be included already in the resin
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high fiber content (difficult flow) and viscosity of the resin can influence the behavior, high injection speeds can generate air bubbles
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latent chemical reaction (inhibitor, and this produces a reaction after a threshold, temperature, UV light)

Question 15

Structural reaction injection molding

Answer 15

• fast filling due to hydraulic injection
• mixing happens in the tool (rapid injection is needed to avoid hardening of material)

Question 16

Hot pressing process

Answer 16

Feed tool, press it, heating (galing point, first networks inside the polymer), exothermic curing reaction, demoulding
one of the first polymer production processes
b state polymer, precured, a powder

Question 17

impact extrusion

Answer 17

adv:
* short cycle times
* inserts can be inserted
dis:
* brittle material behavior
* wrinkles in corners

Answer 18

large volume: pultrusion, pressing
low volume: hand laminating, wrapping, autoclave