Micromechanical Testing of Polyisobutylene—Polystyrene Block-Type Thermoplastic Elastomers
Bibliographic record
Abstract
Abstract The mechanical properties of a variety of linear triblock copolymers (polysytrene-polyisobutylene-polystyrene, PS-PIB-PS) have been measured. The molecules were synthesized using living carbocationic polymerization of isobutylene, followed by the sequential addition of the second monomer, styrene. The microstructure of the resulting materials was examined as a function of mass fraction of PS using transmission electron microscopy of stained thin films. At small mass fractions, the reinforcing phase (PS) was distributed within the rubbery PIB phase, and the composite could be considered micromechanically using the Bard and Chung model. The comparison of experiment to theory revealed a strong mechanical dependence on Langley-Graessley intermolecular entanglement in the PIB phase. At higher mass fractions the microstructure was seen to consist of interpenetrating networks similar to the double gyroid morphology reported for block copolymers. The experimental approach involved the preparation of solution cast transmission electron microscopy specimens from which the undistorted size, distribution and arrangement of phases could be measured, and the similar preparation of thicker tensile specimens from which the accurate mechanical response could be measured. In this way the correlation between the microstructure and deformation was made accurately. The unique mechanical testing methods and instrumentation to measure tensile properties of thin samples were described.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".