Mechanical properties at the gel point of a crystallizing poly(vinyl chloride) solution

Nijenhuis, K. te; Winter, H. Henning

doi:10.1021/ma00191a074

Cited by 277 publications

(191 citation statements)

References 1 publication

Supporting

Mentioning

182

Contrasting

Unclassified

Order By: Relevance

“…According to the Winter-Chambon method the critical ageing time is 0.75 h [8]. This behaviour is in general shown for the development of physical and chemical networks.…”

Section: Examples A) Crystallisationmentioning

confidence: 96%

On the nature of crosslinks in thermoreversible gels

2006

Self Cite

View full text Add to dashboard Cite

SummaryA review is given concerning the nature of crosslinks in thermoreversible gels. In these gels the crosslinks can be formed e.g. by means of crystallisation of parts of polymer molecules, by liquid-liquid phase separation in solution and in bulk, by hydrogen bridging, by complexation of polymer chains, by helix formation, by chemical equilibrium reaction or by interactions between side-chains. One example will be given for each of these eight possibilities of crosslink formation.

show abstract

“…According to the Winter-Chambon method the critical ageing time is 0.75 h [8]. This behaviour is in general shown for the development of physical and chemical networks.…”

Section: Examples A) Crystallisationmentioning

confidence: 96%

On the nature of crosslinks in thermoreversible gels

2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…The definition of the gel point by this power-law is excellent because the gelation variable will lose its dependency of frequency at the gel point. Several works have shown that this method is reliable and valid for determination of the gel point for various polymer gels with different gelation mechanisms [30][31][32][33] . Figure 2(a) shows the application of the Winter-Chambon method to the solution of 2 wt.% alginate within the sol-gel transition region.…”

Section: Sol-gel Transitionmentioning

confidence: 99%

Rheological study on 3D printability of alginate hydrogel and effect of graphene oxide

Liu

Li³

2024

IJB

201

165

View full text Add to dashboard Cite

Rheological study on 3D printability of alginate hydrogel and effect of graphene oxide. © 2016 Huijun Li, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 54 RESEARCH ARTICLERheological study on 3D printability of alginate hydrogel and effect of graphene oxide Abstract: In recent years, hydrogels have been used as important biomaterials for 3D printing of three dimensional tissues or organs. The key issue for printing a successful scaffold is the selection of a material with a good printability. Rheological properties of hydrogels are believed to pay an important role in 3D printability. However the relations between rheological properties of hydrogels and 3D printability have not been extensively studied. In this study, alginate-based hydrogels were prepared as a model material for an extrusion-based printer and graphene oxide was added to modify the rheological properties and 3D printability of the hydrogels. Rheological studies were performed for the hydrogel samples with different formulas. The range of shear rates that the hydrogels suffered during the printing process was deduced. This range of shear rates helped us to select a proper shear rate to investigate the thixotropic properties of the hydrogels. Furthermore, we also defined some measureable parameters to describe and discuss the quality of 3D printing. The present study shows a new approach to analysis of 3D printability of a hydrogel and also provides some suggestion for 3D printing of 3D scaffolds.

show abstract

“…Characteristic time ratio at the gel point versus degree of undercooling for the four iPP samples (points). tc/tA was estimated with the use of experimental gel times tc from Figure 9 and Avrami times tA ) 2.66 × 10 6 e -0.224 ∆T from Kim et al 29 The solid line represents the fit by an empirical parabolic function tc/tA ) -0.809 + 0.127(∆T) -0.0036(∆T) 2 with a maximum at ∆T ) 17.6 K. Figure 15. Relative crystallinity at the gel point Xc/X∞ versus degree of undercooling for the four iPP samples (points).…”

Section: S(t) ) S(tmentioning

confidence: 99%

“…Relative crystallinity at the gel point Xc/X∞ versus degree of undercooling for the four iPP samples (points). Xc/ X∞ was estimated according to eqs 12, and 14 with the use of experimental gel times tc from Figure 9 and Avrami times tA ) 2.66 × 10 6 e -0.224 ∆T from Kim et al 29 The solid line represents the fit by an empirical parabolic function X c ) -0.087 + 0.012(∆T) -3.405 × 10 -4 (∆T) 2 with a maximum at the same undercooling ∆T ) 17.6 K.…”

Section: S(t) ) S(tmentioning

confidence: 99%

Polypropylene Crystallization as a Physical Gelation Process

1998

Self Cite

View full text Add to dashboard Cite

Early stages of crystallization of polymers may be viewed as physical gelation. This is shown with four commercial isotactic polypropylenes, which have been studied by dynamic mechanical experiments at low degrees of undercooling, ∆T ) 10-26 K, below their nominal melting temperature. The physical gel point is manifested by slow power law dynamics, which expresses itself in a shear relaxation modulus G(t) ) St -n at long times, λ0 < t < λpg, where S is the gel stiffness, n is the relaxation exponent, λ0 is the crossover to short time dynamics (entanglements, glass modes), and λpg is the longest relaxation time, which can be considered to be infinite for our experiments due to the long lifetime of the physical bonds. The time to reach the gel point (gel time tc) decreases exponentially with ∆T, and the critical gel becomes stiffer (smaller n, larger S) with increasing ∆T. The absolute critical crystallinity at the gel point, Xc, was found to be only about 2% or less. This value was determined from published DSC data which, however, needed to be extrapolated to tc, as measured by mechanical spectroscopy. This very low crystallinity suggests that only a few junctions are necessary to form a sample spanning network. The network in this case is "loosely" connected, and the critical gel is soft.

show abstract

Mechanical properties at the gel point of a crystallizing poly(vinyl chloride) solution

Cited by 277 publications

References 1 publication

On the nature of crosslinks in thermoreversible gels

On the nature of crosslinks in thermoreversible gels

Rheological study on 3D printability of alginate hydrogel and effect of graphene oxide

Polypropylene Crystallization as a Physical Gelation Process

Contact Info

Product

Resources

About