Thesis-1996-Schafer.pdf (9.11 MB)
Polyurethane-based simultaneous interpenetrating polymer networks of controlled microphase morphology and high damping characteristics
thesis
posted on 2014-06-06, 14:53 authored by Franz-Ulrich SchaferA number of simultaneous interpenetrating polymer networks (IPNs) were
investigated with regard to morphology and energy absorbing ability. The materials
were all based on polyurethane (PUR) with the second polymer components being
polystyrene (PS) or poly(ethyl methacrylate) (PEMA). Also, three-component IPNs
were synthesised. This was achieved by incorporating functionalised PS latex particles
into a PUR/poly(butyl methacrylate) (PBMA) IPN. The morphology of the IPNs was
determined with dynamic mechanical thermal analysis (DMTA), transmission (TEM)
and scanning (SEM) electron microscopy and modulated-temperature differential
scanning calorimetry (M-TDSC). The mechanical properties were investigated using
tensile testing and hardness measurements.
The PUR/PS IPNs were found to be grossly phase separated at every composition,
even when crosslinked at very high levels. However, a structural modification of the
materials was conducted by introducing inter-network grafting, compatibilisers and
ionic interactions. All three structure modifications proved successful in achieving a
finer morphology. By conducting a stirred synthesis, a very complicated morphology
with a very high and broad transition was obtained. The PUR/PEMA IPNs were semimiscible
and the 70:30 composition exhibited a very broad, almost rectangular,
transition as evidenced by DMTA data. Phase domains between I - 500 run were
found by TEM. The degree of mixing and, thus, the location and breadth of the
transition could be adjusted by varying the composition and the crosslink densities in
both networks. Also, variation of the chemical nature of the PUR soft and hard
segments proved successful in obtaining a broad transition range.
Materials with a controlled microheterogeneous morphology which exhibited excellent
energy absorbing characteristics were developed. PUR/PEMA IPNs generally
exhibited better damping properties as indicated by the area under the linear loss
modulus (LA) and· loss factor (TA) curves. Some of these materials exhibited values
for the loss factor of >- 0.3 spanning a temperature range of more than 170°C. The
study of IPN s containing latex' particles revealed promising results. Further
concentrating on this approach might yield damping materials with even broader
energy absorbing temperature/frequency ranges.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Materials
Publisher
© Franz-Ulrich SchaferPublication date
1996Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.321247Language
- en