A Study of Gelatin Molecules, Aggregates and Gels

Boedtker, Helga; Doty, Paul

doi:10.1021/j150521a010

Cited by 252 publications

(98 citation statements)

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“…Doty, Wagner and Signer 14 reported the light-scattering study of the PVCdioxane system, and have shown that the presence of stable aggregates in the solution. The same conclusion has also been reached for gelatin -water 9 and cellulose nitrate-ethanol gels. 10 Newman, et al, also discussed the reasons for the disagreement, and pointed out that the crystallites in the gel are in equilibrium with aggregates, rather than single molecules as assumed by theory.…”

Section: Discussionsupporting

confidence: 79%

The Melting Temperature of Thermally Reversible Gel. I. Poly(vinyl chloride)–Organic Solvent Gels

Takahashi

Nakamura

Kagawa

1972

Polym J

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ABSTRACT:The melting temperatures of gels that were formed from dilute solutions of poly(vinyl chloride) in anisole, dioxane, and ethylene dichloride were measured over a volume fraction range from 0.02 to 0.05. Five fractions of poly(vinyl chloride) with molecular w.iights ranging from 67000 and 200000 having almost identical syndiotacticity a=0.5, were used. The linear relationship was found for each solvent between the reciprocal absolute temperature of melting and the logarithm of v2x, where V2 is the volume fraction of the polymer and x is its degree of polymerization. The X-ray diffraction pattern revealed that the gel was crystalline, thus confirming the supposition that the "cross links" are crystallites. The results were compared with the theory of melting point depression for copolymer-diluent systems. However, the theory did not fit the experimental results and it was concluded that the melting point of gel does not correspond to the thermodynamic singurality. An expression was derived from the condition of gel formation and the free energy of crystallite formation, with the supposition that the "cross links" are crystallites. The expression was compared with the experimental results, and it was found that it fairly well represents the experimentally observed gel melting points as a function of molecular weight, polymer concentration and the thermodynamic nature of the solvent. The syndiotactic sequence length in the crystallite was estimated to be 10-12.KEY WORDS Gel / Melting Temperature of Gel / Poly(vinyl chloride) / Thermally Reversible Gel / Several years ago, we observed that dilue solutions of poly(vinyl chloride) in ethyl acetoacetate are turned into gel on cooling and the gelation is reversible on warming. 1 However, the gelation phenomena is not confined the above polymer-solvent pair. Walter 2 studied the poly(vinyl chloride)-dioctyl-phthalate gel. The systems of poly(vinyl chloride)-anisole, dioxane, 3 and ethylene dichloride which we wish to report herein also exhibit thermally reversible gelation. Very recently, Harrison, Morgan, and Park 3 have reported the melting temperature of poly(vinyl chloride)-dioxan gel. Reversible gelation is by no means a unique property of poly(vinyl chloride), for this behavior has been observed for several polymer-diluent systems. 4 The well-known examples are the systems of gelatin-water and agar-water. mer chain are needed to form a three dimensional network. Taking into account this requirement for gel formation, and by treating the cross-link formation as a chemical equilibrium, Eldridge and Ferry6 derived a useful expression concerning the melting point of gel Tm g and polymer concentration C It is well known 5 from simple geometrical considerations that at least two cross-links per poly-Here C is expressed in g// and ,:JHm is the energy associated with the dissociation of a network in gel. Although many papers on gelation phenomena have appeared in the past two decades, the thermodynamics and kinetics of this sol-gel transition are not completely exp...

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Section: Discussionsupporting

confidence: 79%

The Melting Temperature of Thermally Reversible Gel. I. Poly(vinyl chloride)–Organic Solvent Gels

Takahashi

Nakamura

Kagawa

1972

Polym J

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“…The similarity is not surprising considering that the formation of the gel network junctions has been identified with the formation of microcrystallites in a wide variety of polymers [13,159], including gelatin [158,160]. For example, in gelatin gels, the microcrystallites are believed [13,161,162] to form via partial restoration of the triple helix structure characteristic of collagen that occurs via cooperative hydrogen bonding of gelatin coils.…”

Section: Introductionmentioning

confidence: 85%

Physical Processes

Vyazovkin

2015

Isoconversional Kinetics of Thermally Stimulated Processes

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“…This is necessary because the gelatin molecules aggregate with each other during storage (Boedtker and Doty 1954). Such aggregation affects the coagulating ability of the gelatin when used in a juice.…”

Section: Gelatinmentioning

confidence: 99%

Causes and Prevention of Turbidity in Apple Juice

Buren¹

1989

Processed Apple Products

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A Study of Gelatin Molecules, Aggregates and Gels

Cited by 252 publications

References 0 publications

The Melting Temperature of Thermally Reversible Gel. I. Poly(vinyl chloride)–Organic Solvent Gels

The Melting Temperature of Thermally Reversible Gel. I. Poly(vinyl chloride)–Organic Solvent Gels

Physical Processes

Causes and Prevention of Turbidity in Apple Juice

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