Relation -between Nanostructural Changes and Macroscopic Effects during Reversible Temperature-Memory Effect under Stress-Free Conditions in Semicrystalline Polymer Networks

2015 ◽  
Vol 1718 ◽  
pp. 41-48 ◽  
Author(s):  
U. Nöchel ◽  
K. Kratz ◽  
M. Behl ◽  
A. Lendlein
Keyword(s):  
Memory Effect ◽  
Polymer Networks ◽  
X Ray ◽  
Crosslinked Polymer ◽  
X Ray Scattering ◽  
Temperature Memory Effect ◽  
Separation Temperature ◽  
Temperature Ranges ◽  
Poly Ethylene

ABSTRACTTemperature-memory effects in polymers under stress-free conditions are typically limited to one way effects. Recently, crosslinked polymer networks comprising crystallizable domains, which were capable of a reversible temperature-memory effect (rTME) under stress-free conditions, were introduced. The utilization of crystallizable actuator domains (AD) and shape determining domains (SD) where related to two different temperature ranges of a single broad melting temperature transition in case of rTME. In this study we investigated the nanostructure of crosslinked poly[ethylene-co-(vinyl acetate)] cPEVA capable of rTME in situ during actuation cycles utilizing X-ray scattering techniques and related the changes on the nanoscale to effects on the macroscopic scale. It was observed that 23% of SD obtained at a separation temperature of 75 °C gave the highest reversible strain and when exceeding 80 °C only isotropic crystallization occurred and no rTME was observed. Furthermore, distances between oriented crystalline lamellae correlated to the macroscopic actuation during heating-cooling cycles, exhibiting long-periods from 14 to 17 nm as function of temperature.

In Situ High Temperature X-Ray Diffraction Studies of Modified Poly(Ethylene Terephthalate)

1992 ◽  
Vol 36 ◽  
pp. 379-386
Author(s):  
T. Blanton ◽  
R. Seyler
Keyword(s):  
High Temperature ◽  
Ethylene Terephthalate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Pet Crystallization

The effect of dimethyl-5-sodiosulfoisophthalate, SIP, on poly(ethylene terephthalate), PET, crystallization has been studied using in situ high-temperature x-ray diffraction, HTXRD. At low levels of SIP modification, PET-like crystallinity was observed. At high SIP levels, clustering of polyester ionomers was observed and crystallization was significantly suppressed. The HTXRD data along with differential scanning calorimetry, DSC, and small angle x-ray scattering, SAXS, indicate that the change from bulk crystallization to bulk ionomer formation occurred when 8-12 mol% of the diester linkages contained SIP.

scholarly journals Nanostructural changes in crystallizable controlling units determine the temperature-memory of polymers

2015 ◽  
Vol 3 (16) ◽  
pp. 8284-8293 ◽  
Author(s):  
Ulrich Nöchel ◽  
Chaganti Srinivasa Reddy ◽  
Ke Wang ◽  
Jing Cui ◽  
Ivo Zizak ◽  
...  
Keyword(s):  
Vinyl Acetate ◽  
X Ray ◽  
Memory Mechanism ◽  
X Ray Scattering ◽  
Poly Ethylene ◽  
Ray Scattering

In-situ X-ray scattering experiments of crosslinked poly[ethylene-co-(vinyl acetate)] networks indicate differences in the temperature-memory mechanism for deformation temperatures above or below 50 °C.

scholarly journals Polymer Networks for Enrichment of Calcium Ions

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3506
Author(s):  
Marcus Heinze ◽  
Christoph Horn ◽  
Doris Pospiech ◽  
Regine Boldt ◽  
Oliver Kobsch ◽  
...  
Keyword(s):  
Phosphonic Acid ◽  
Polymer Networks ◽  
Double Diffusion ◽  
Attenuated Total Reflection ◽  
X Ray ◽  
Entropic Elasticity ◽  
X Ray Scattering ◽  
Crosslinker Content ◽  
Phosphonic Acid Groups

In this study, solvogels containing (2-((2-(ethoxycarbonyl)prop-2-en-1-yl)oxy)-ethyl) phosphonic acid (ECPA) and N,N′-diethyl-1,3-bis-(acrylamido)propane (BNEAA) as the crosslinker are synthesized by UV induced crosslinking photopolymerization in various solvents. The polymerization of the ECPA monomer is monitored by the conversion of double bonds with in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The morphology of the networks is characterized by in situ photorheology, solid state NMR spectroscopy, and scanning electron microscopy (SEM) of the dried gels. It is demonstrated that the storage modulus is not only determined by the crosslinker content in the gel, but also by the solvent used for preparation. The networks turn out to be porous structures with G′ being governed by a rigid, phase-separated polymer phase rather than by entropic elasticity. The external and internal pKa values of the poly(ECPA-co-BNEAA) gels were determined by titration with a specially designed method and compared to the calculated values. The polymer-immobilized phosphonic acid groups in the hydrogels induce buffering behavior into the system without using a dissolved buffer. The calcium accumulation in the gels is studied by means of a double diffusion cell filled with calcium ion-containing solutions. The successful accumulation of hydroxyapatite within the gels is shown by a combination of SEM, energy-dispersive X-ray spectroscopy (EDX) and wide-angle X-ray scattering (WAXS).

A Revised O2 Reduction Model in Li-O2 Batteries as Revealed by in Situ Small Angle X-Ray Scattering

2019 ◽  
Author(s):  
Christian Prehal ◽  
Aleksej Samojlov ◽  
Manfred Nachtnebel ◽  
Manfred Kriechbaum ◽  
Heinz Amenitsch ◽  
...  
Keyword(s):  
Small Angle ◽  
Wide Angle ◽  
Reduction Mechanism ◽  
Reduction Model ◽  
X Ray ◽  
X Ray Scattering ◽  
O2 Reduction ◽  
Ray Scattering

<b>Here we use in situ small and wide angle X-ray scattering to elucidate unexpected mechanistic insights of the O2 reduction mechanism in Li-O2 batteries.<br></b>

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