Describe the structure of PMMA
Describe the structure of PHEMA
What are the main applications of PMMA?
Glass replacement
biomedical bone replacement
How is the application procedure for PMMA in bone cements?
The monomers polymerize at the place of application. A temperature of about 120°C develops.
Which assumptions are taken to calculate the molecular weight in lab session 1?
all BPO molecules form 2 radicals
all MMA monomers polymerize
all polymeric chains have the same length before termination
50% are being terminated by combination, 50% terminated by disproportion
The combined chains are twice the length of the disproportioned
Which assumptions were taken to calculate the polimerization energy in LS1?
all MMA reacts
all heat is used to increase the temperature
the heat capacity of the product is that of MMA
How can the glass transition temperature be determined at a given molecular weight?
There is an empirical correlation between the molecular weight and the quotient of the glass temperature and the theoretical glass temperature at infinite molecular weight
Why was the weight of the samples lower after water sorption and drying than the original weight?
The unreacted monomers evaporated during drying
How can the percentage of unreacted monomers be determined?
How can the water content of the polymer be determined?
What were the heat treatment parameters of the Pressure cooker in LS2?
30 min at 120°C
What was the maximum temperature of the heat gun in LS2?
around 200°C
What are the glass transitioning temperatures of PS, PLA, PP?
PS: glas transition: 100°C
PLA: glas transition: 45-65°C, melt temp.: 150-160°C
PP: glass transition: -10°C, melt temp.: 165°C
Which Polymers were treated to which extreme temperatures in LS2 in DSC?
0-300°C: HDPE, PET
0-200°C: PLA, PP, PS
heating, cooling, heating
How is the crystallinity content calculated in DSC?
Hm=melting enthalphy
Hc=crystallization enthalphy
H0= metling enthalphy 100% crystallinity
How is the density after archimedis calculated?
Ma mass in air
Mw mass in water
rho w density of water
Why does a yogurt cup assume a curled flat shape, when subjected to heat treatment?
The production method of thermoforming induces a anisotropy, which reverts, when the needed energy is provided.
Describe the DSC thermogramm of HDPE.
Describe the DSC thermogramm of PP
Describe the DSC thermogramm of PET
Describe the DSC thermogramm of PLA
Describe the DSC thermogramm of PS
Why is PS physically dissolved and PP not?
Because PS has a lot of space between the chains due to benzol groups
PP is semicrystalline
What is measured in the Vicat experiment?
The vicat softening temperature, which describes the pooint at which a needle penetrates 1mm into the material under a load of 10N/50N
What was the heating rate for the Vicat test in LS3?
120°C/h
Is the softening temperture higher in amorphous or crystalline materials? Why?
Higher for semicrystalline materials, because of higher density and lower mobility.
What is the difference between the shore A and D test?
The different geometry of the indenter and a different identation force (a:8N d:44,6N)
In which unit is meltflowindex measured?
g/10min
Describe the machine used for measuring the meltflow index.
capillary diameter after chosen standard
Which temperatures and loads were used in measuring the melt flow index in LS3?
Temp: 190°C, 210°C, 230°C
Load: 2,16 kg, 5 kg, 10 kg
The melt flow of which polymer was tested?
PP
With which equation can the melt flow dependancy on time be determined?
Arrhenius equation
A=factor in g/10min
E=activation energy
How is the swelling ratio calculated?
What is the observation when the load is changed in the Vicat test?
The semicrystalline softening temperature is significantly more influenced compared to amorphous polymers.
What is the major application of shore A tests?
elastomers and foams
What is the major application of shore D tests?
Thermoplastics and thermosets
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