Stress-Induced Crystallization Properties of Natural and Synthetic CIS-Polyisoprene

2004 ◽  
Vol 77 (2) ◽  
pp. 303-316 ◽  
Author(s):  
S. Trabelsi ◽  
P.-A. Albouy ◽  
J. Rault
Keyword(s):  
Draw Ratio ◽  
Room Temperature ◽  
X Ray ◽  
X Ray Scattering ◽  
Synthetic Rubber ◽  
Chain Defects ◽  
Stress Induced Crystallization ◽  
Induced Crystallization ◽  
Melting And Crystallization Temperatures ◽  
Natural And Synthetic

Abstract Stress-induced crystallization and melting of natural and synthetic cis-isoprene are compared by simultaneous Wide Angles X-ray Scattering (WAXS) and mechanical measurements. Natural (NR) and synthetic polyisoprene (SR) rubbers have the same composition and sulfur crosslink density. At fixed elongation and during cyclic deformation, the properties X of the semi crystalline phase are determined as function of draw ratio λ; X being crystallites dimensions and orientation, half-time of crystallization, melting temperature, crystallinity and crystalline zone dimensions around a crack tip. It is shown that all the curves X(λ) of both types of rubber at room temperature can be superposed by a simple translation δλ along the draw ratio axis. This translation factor of the order of 0.5 to 1 does not depend on the property X. These effects are explained by the decrease of the melting and crystallization temperatures due to the presence of chain defects in synthetic rubber.

Stress-induced Bimodal Ordering in POSS/PCL Biodegradable Shape Memory Nanocomposites

2012 ◽  
Vol 1450 ◽  
Author(s):  
Bonifacio Alvarado-Tenorio ◽  
Angel Romo-Uribe ◽  
Patrick T. Mather
Keyword(s):  
Shape Memory ◽  
Network Architecture ◽  
Crosslink Density ◽  
Room Temperature ◽  
Molar Ratio ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Shape Memory Properties ◽  
Induced Crystallization

ABSTRACTSimultaneous wide- and small- angle X-ray scattering (WAXS-SAXS) has revealed a stress-induced bimodal orientation of POSS crystals and PCL chains, both in a constrained POSS/PCL crosslinked network architecture with shape memory properties. POSS/PCL nanocomposites with molecular weight of 2,600 g/mol exhibiting shape memory behavior were synthesized and variation of crosslinker molar ratio was used to obtain POSS/PCL networks with different crosslink density (Alvarado-Tenorio et al., Macromolecules, 44, 5682, 2011). In that study it was shown that there are POSS crystals embedded in an amorphous PCL matrix, and the POSS crystals were ordered in a cubic nanostructure. In this work, it will be shown that elongation at room temperature of all the networks yielded a double-induced orientation (90º and 180º) of the POSS crystals, as indicated by the 101 reflection. Moreover, it was also detected stretched-induced crystallization of the otherwise amorphous PCL chains. Furthermore, SAXS data showed long periods in the meridional and equatorial orientations of 630 Å, 90 Å and 45 Å corresponding to a lamellar nanostructure of PCL chains. The induced bimodal orientation of the POSS-PCL molecular network will be correlated with its shape memory properties.

Single-Crystal X-Ray Scattering Study of Superstructures and Phase Transitions in Graphite-Hno3 and Graphite-Br2 Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
R. Moret ◽  
R. Comes ◽  
G. Furdin ◽  
H. Fuzellier ◽  
F. Rousseaux
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Temperature Phase ◽  
Temperature Structure ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Temperature Liquid ◽  
Low Temperature Phase

ABSTRACTIn α-C5n-HNO3 the condensation of the room-temperature liquid-like diffuse ring associated with the disorder-order transition around 250 K is studied and the low-temperature. superstructure is examined.It is found that β-C8n-HNO3 exhibits an in-plane incommensurate order at room temperature.Two types of graphite-Br2 are found. Low-temperature phase transitions in C8Br are observed at T1 ≍ 277 K and T2 ≍ 297 K. The room-temperature structure of C14Br is reexamined. Special attention is given to diffuse scattering and incommensurability.

A portable extruder forin situwide angle x-ray scattering study on multi-dimensional flow field induced crystallization of polymer

2018 ◽  
Vol 89 (2) ◽  
pp. 025101 ◽  
Author(s):  
Jiarui Chang ◽  
Zhen Wang ◽  
Xiaoliang Tang ◽  
Fucheng Tian ◽  
Ke Ye ◽  
...  
Keyword(s):  
Flow Field ◽  
X Ray ◽  
Dimensional Flow ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Induced Crystallization ◽  
Ray Scattering

Determination of Strain Distributions in Aluminum Thin Films as a Function of Temperature by the use of Synchrotron Grazing Incidence X-Ray Scattering

1991 ◽  
Vol 239 ◽  
Author(s):  
Ramnath Venkatraman ◽  
Paul R. Besser ◽  
Sean Brennan ◽  
John C. Bravman
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Grazing Incidence ◽  
Surface Relaxation ◽  
Line Broadening ◽  
X Ray ◽  
Relaxation Effects ◽  
X Ray Scattering ◽  
Ray Scattering

ABSTRACTWe have measured elastic strain distributions with depth as a function of temperature in Al thin films of various thicknesses on oxidized silicon using synchrotron grazing incidence X-ray scattering (GIXS). Disregarding minor surface relaxation effects that depend on the film thickness, it is shown that there are no gross strain gradients in these films in the range of temperatures (between room temperature and 400°C) considered. We also observe X-ray line broadening effects, suggesting an accumulation of dislocations on cooling the films, and their annealing out as the films are reheated.

Following the structural changes during zinc-induced crystallization of charged membranes using time-resolved solution X-ray scattering

Soft Matter ◽  
2011 ◽  
Vol 7 (4) ◽  
pp. 1512-1523 ◽  
Author(s):  
Moshe Nadler ◽  
Ariel Steiner ◽  
Tom Dvir ◽  
Or Szekely ◽  
Pablo Szekely ◽  
...  
Keyword(s):  
Structural Changes ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Charged Membranes ◽  
Induced Crystallization ◽  
Ray Scattering
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