Influence of the Reference Temperature on the Orientation and Relaxation of Miscible Polystyrene/Poly(vinyl methyl ether) Blends

Pellerin, Christian; Pelletier, Isabelle; Pézolet, Michel; Prud’homme, Robert E.

doi:10.1021/ma021035h

Cited by 18 publications

(22 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Spectra were recorded during a continuous drawing using a homemade stretcher. 73 Each spectrum was obtained from 32 scans with resolution of 8 cm −1 and was acquired in 12.5 s. Some experiments were performed by steps with a fixed increment (λ = 0.5), each spectrum resulting from 16 scans, then acquired in 6.25 s. To avoid a premature rupture of the samples, it was necessary to draw them with the lowest speed of deformation, i.e., 0.03 mm/s.…”

Section: Methodsmentioning

confidence: 99%

Effect of Mechanical Deformation on the Structure of Regenerated Bombyx mori Silk Fibroin Films as Revealed Using Raman and Infrared Spectroscopy

et al. 2015

Self Cite

View full text Add to dashboard Cite

To better understand the effect of mechanical stress during the spinning of silk, the protein orientation and conformation of Bombyx mori regenerated silk fibroin (RSF) films have been studied as a function of deformation in a static mode or in real time by tensile-Raman experiments and polarization modulation infrared linear dichroism (PM-IRLD), respectively. The data show that either for step-by-step or continuous stretching, elongation induces the progressive formation of β-sheets that align along the drawing axis, in particular above a draw ratio of ~2. The formation of β-sheets begins before their alignment during a continuous drawing. Unordered chains were, however, never found to be oriented, which explains the very low level of orientation of the amorphous phase of the natural fiber. Stress-perturbed unordered chains readily convert into β-sheets, the strain-induced transformation following a two-state process. The final level of orientation and β-sheet content are lower than those found in the native fiber, indicating that various parameters have to be optimized in order to implement a spinning process as efficient as the natural one. Finally, during the stress relaxation period in a step-by-step drawing, there is essentially no change of the content and orientation of the β-sheets, suggesting that only unordered structures tend to reorganize.

show abstract

Section: Methodsmentioning

confidence: 99%

Effect of Mechanical Deformation on the Structure of Regenerated Bombyx mori Silk Fibroin Films as Revealed Using Raman and Infrared Spectroscopy

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…[23][24][25] A BYK Gardner pendulum hardness tester was used to determine Persoz pendulum hardness of the annealed networks. The hardness was determined for the Thiol 3 + Ene 3 system which exhibited a glass transition temperature above room temperature.…”

Section: Methodsmentioning

confidence: 99%

Enthalpy Relaxation of Photopolymerized Thiol−Ene Networks: Structural Effects

2008

View full text Add to dashboard Cite

Physical aging behavior of photopolymerized thiol-ene networks was investigated by measuring the extent of enthalpy relaxation in terms of network density and molecular structure. The homogeneous network structure of the thiol-enes, having narrow glass transition temperature ranges, showed characteristic temperature and time dependency relationships for enthalpy relaxation. All thiol-ene films annealed at different temperatures (T a ) for 1 h according to the isochronal method showed maximum enthalpy relaxation peaks at approximately T g -10°C by DSC. The extent of enthalpy relaxation as a function of annealing time (t a ) was obtained by the isothermal aging method. Correlations between the extent of enthalpy relaxation and the heat capacity difference at T g were made and related to thiol-ene chemical group rigidity and network linking density. Pendulum hardness values for a selected thiol-ene film showed a clear change in hardness upon aging, indicating sub-T g mechanical relaxation, consistent with the related enthalpy relaxation process.

show abstract

“…The relationship between drawing and chain orientation in blend systems has attracted much attention for a long time because it is a major factor governing the final mechanical properties of fibers and drawn films. In miscible blends, several works1–5 were particularly focused on the effect of a minor component on the strain‐induced orientation and the relaxation of the major component, which were strongly dependent on their favorable interaction. In contrast, the drawing behavior in immiscible blends is highly dependent on interfacial properties between two components, such as interfacial adhesion and entanglements between dissimilar chains at the interface.…”

Section: Introductionmentioning

confidence: 99%

Uniaxial Drawing of Poly[(R)‐3‐hydroxybutyrate]/Cellulose Acetate Butyrate Blends and Their Orientation Behavior

Park

Tanaka

Doi

et al. 2005

Macromolecular Bioscience

View full text Add to dashboard Cite

Miscible blends of PHB and CAB were prepared by the solvent-casting method with various blend compositions, and their orientation behavior was investigated during uniaxial drawing. X-ray analysis revealed that the orientation of the crystallizable PHB component in the drawn PHB/CAB blends was changed from c-axis-orientation to a-axis-orientation with increasing CAB content. The a-axis-orientation was a result from the a-axis-oriented crystal growth caused by the intramolecular nucleation and the confined crystal growth. For quantitative assessment of the chain orientation, the Hermans orientation functions of the two respective components were obtained from the polarized FT-IR measurements. The orientation function of pure PHB stretched to 5 times of its initial length was approximately 0.8. However the value decreased rapidly with increasing CAB content, and it turned to a negative value from 30 wt.-% CAB content. This indicates that the PHB chains were aligned perpendicular to the drawing direction. On the contrary, the value of the CAB component remained almost unchanged at about 0.1 regardless of the blend composition and the annealing time, indicating that the CAB chains were constantly oriented parallel to the drawing direction without any chain relaxation. In addition, SAXS analysis suggested that the lamellar stacking direction also changed from parallel to perpendicular in the stretching direction with increasing CAB content.

show abstract

Influence of the Reference Temperature on the Orientation and Relaxation of Miscible Polystyrene/Poly(vinyl methyl ether) Blends

Cited by 18 publications

References 56 publications

Effect of Mechanical Deformation on the Structure of Regenerated Bombyx mori Silk Fibroin Films as Revealed Using Raman and Infrared Spectroscopy

Effect of Mechanical Deformation on the Structure of Regenerated Bombyx mori Silk Fibroin Films as Revealed Using Raman and Infrared Spectroscopy

Enthalpy Relaxation of Photopolymerized Thiol−Ene Networks: Structural Effects

Uniaxial Drawing of Poly[(R)‐3‐hydroxybutyrate]/Cellulose Acetate Butyrate Blends and Their Orientation Behavior

Contact Info

Product

Resources

About