TY  - JOUR
A1  - Behl, Marc
A1  - Balk, Maria
A1  - Mansfeld, Ulrich
A1  - Lendlein, Andreas
T1  - Phase morphology of multiblock copolymers differing in sequence of blocks
JF  - Macromolecular materials and engineering
N2  - The chemical nature, the number length of integrated building blocks, as well as their sequence structure impact the phase morphology of multiblock copolymers (MBC) consisting of two non-miscible block types. It is hypothesized that a strictly alternating sequence should impact phase segregation. A library of well-defined MBC obtained by coupling oligo(epsilon-caprolactone) (OCL) of different molecular weights (2, 4, and 8 kDa) with oligotetrahydrofuran (OTHF, 2.9 kDa) via Steglich esterification results in strictly alternating (MBCalt) or random (MBCran) MBC. The three different series has a weight average molecular weight (M-w) of 65 000, 165 000, and 168 000 g mol(-1) for MBCalt and 80 500, 100 000, and 147 600 g mol(-1) for MBCran. When the chain length of OCL building blocks is increased, the tendency for phase segregation is facilitated, which is attributed to the decrease in chain mobility within the MBC. Furthermore, it is found that the phase segregation disturbs the crystallization by causing heterogeneities in the semi-crystalline alignment, which is attributed to an increase of the disorder of the OCL semi-crystalline alignment.
KW  - electron microscopy
KW  - multiblock copolymers
KW  - phase morphology
KW  - polymer
KW  - libraries
KW  - sequence structures
KW  - wide angle x‐ ray scattering
Y1  - 2021
U6  - https://doi.org/10.1002/mame.202000672
SN  - 1439-2054
VL  - 306
IS  - 3
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Cabeza, Sandra
A1  - Müller, Bernd R.
A1  - Pereyra, Ricio
A1  - Fernandez, Ricardo
A1  - Gonzalez-Doncel, Gaspar
A1  - Bruno, Giovanni
T1  - Evidence of damage evolution during creep of Al-Mg alloy using synchrotron X-ray refraction
JF  - Journal of applied crystallography
N2  - In order to provide further evidence of damage mechanisms predicted by the recent solid-state transformation creep (SSTC) model, direct observation of damage accumulation during creep of Al-3.85Mg was made using synchrotron X-ray refraction. X-ray refraction techniques detect the internal specific surface (i.e. surface per unit volume) on a length scale comparable to the specimen size, but with microscopic sensitivity. A significant rise in the internal specific surface with increasing creep time was observed, providing evidence for the creation of a fine grain substructure, as predicted by the SSTC model. This substructure was also observed by scanning electron microscopy.
KW  - aluminium alloys
KW  - creep
KW  - damage
KW  - synchrotron X-ray refraction
KW  - electron microscopy
KW  - subgrain structure
Y1  - 2018
U6  - https://doi.org/10.1107/S1600576718001449
SN  - 1600-5767
VL  - 51
SP  - 420
EP  - 427
PB  - International Union of Crystallography
CY  - Chester
ER  -