The glass transition temperature of polymeric sulphur

Tobolsky, A. V.; MacKnight, W. J.; Beevers, R. B.; Gupta, V. D.

doi:10.1016/0032-3861(63)90054-5

Cited by 35 publications

(45 citation statements)

References 5 publications

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“…More importantly, at variance with the α-relaxation plateau G ∞ , the plateau value G c turns out to have significant temperature dependence around T λ and, in spite of its small value (G c ≈10 −3 G ∞ ), the large contribution to η is brought about by the large value of τ c . The discovery of this low frequency plateau above T λ also allows to rationalize the abrupt decay of the shear modulus measured by stress relaxation technique [23], in the range −40 < T < −30 o C, in sulphur rapidly quenched from T=250 o C, and substantiates the hypothesis made in Ref. [22].…”

supporting

confidence: 87%

“…In this respect, we believe that the large difference G ∞ −G c that we observe can be related with the decay of the shear modulus reported in Ref. [23] : the value of the plateau in G c (T ) reported here is ≈ 8 · 10 5 Pa, while in the decay observed in Ref. [23] the lowest measured value upon heating is ≈ 6 · 10 4 Pa. We consider such difference as remarkably small, in view of the large variation of the elastic modulus from the solid to the polymeric regime.…”

supporting

confidence: 81%

“…[23] : the value of the plateau in G c (T ) reported here is ≈ 8 · 10 5 Pa, while in the decay observed in Ref. [23] the lowest measured value upon heating is ≈ 6 · 10 4 Pa. We consider such difference as remarkably small, in view of the large variation of the elastic modulus from the solid to the polymeric regime. Moreover, this difference could be ascribed to the finite quenching time which prevents the system from falling instantaneously out of equilibrium.…”

contrasting

confidence: 44%

“…Since τ α < τ α (T m ) ≈ 10 −11 s, τ c >> τ α holds, and being G ∞ ≈ 5 · 10 8 Pa [23] the first term of (2) becomes progressively less important as temperature is raised above T λ . The increase of viscosity with temperature, therefore, is triggered by the appearance of the low frequency relaxation, which largely compensates for the decrease of τ α .…”

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Origin of theλTransition in Liquid Sulfur

et al. 2007

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Developing a novel experimental technique, we applied photon correlation spectroscopy using infrared radiation in liquid Sulphur around T λ , i.e. in the temperature range where an abrupt increase in viscosity by four orders of magnitude is observed upon heating within few degrees. This allowed us -overcoming photo-induced and absorption effects at visible wavelengths -to reveal a chain relaxation process with characteristic time in the ms range. These results do rehabilitate the validity of the Maxwell relation in Sulphur from an apparent failure, allowing rationalizing the mechanical and thermodynamic behavior of this system within a viscoelastic scenario. PACS numbers: 62.60.+v,64.70.Ja,62.10.+s, Common wisdom holds that liquids become less viscous as the temperature is raised. On a microscopic ground, indeed, viscosity can be regarded as arising from continual brushing of molecules which are close to each other. On increasing temperatures the more vigorous thermal motion of the molecules is expected to render such mutual friction progressively less effective. This naive description provides a qualitative interpretation of the decrease in viscosity normally observed in almost all substances as the temperature increases. There exist, however, a few remarkable exceptions exhibiting complex behavior, which can be regarded as extreme examples of how critically viscosity depends upon molecular interactions. Specifically, there are ranges of temperatures in which the viscosity of Sulphur exhibits anomalous temperature dependence. In the liquid state, just above melting (T m =119 o C), eight-membered rings (S8) are the most abundant species, and the viscosity slightly decreases with temperature as normally expected, reaching values as low as 0.01 Pa·s at T = 157 o C. Further increase of temperature causes a dramatic increase of viscosity [1], accompanied by gross changes in optical [2,3,4] and thermodynamic [5,6] properties, which, at T ≈185 o C, reaches a maximum value of 100 Pa·s. Beyond this temperature, a gradual viscosity decrease is observed. Although this phenomenon, known as λ-transition (T λ = 159 o C), has been tackled for more than 150 years, its comprehension is still far from being reached: to rationalize this puzzling temperature dependence of viscosity, indeed, a liquid-liquid transition from a monomeric (i.e. a S8 rings liquid) to a polymeric phase has been invoked [7,8]. The temperature dependence of the mass fraction of S atoms participating in the polymeric component turns out to be a central parameter for extracting information on many thermodynamic aspects of the λ-transition [9,10]. This phenomenon has been classified as a living polymerization [11] transition that essentially involves two steps, the initiation (formation of diradicals through opening of S8 rings) and propagation (concatenation of species to form long polymeric chains). Thermo-chemical models were developed in the past [12,13,14] to relate the transport properties of liquid sulphur to the underlying polymerization phenomenon. T...

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supporting

confidence: 87%

supporting

confidence: 81%

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confidence: 44%

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confidence: 99%

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Origin of theλTransition in Liquid Sulfur

et al. 2007

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“…Rheometric measurements on quick quenched semi polymeric sulphur samples [20] indicate (low temperature trend) a value of G ∞ of about 10 10 Pa, while suggesting (high 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 F o r P e e r R e v i e w O n l y temperature trend) a superior limit for G ∞1 of about 10 6 Pa. Assuming these values, we can consider G ∞1 to be very small when compared to G ∞ .…”

Section: Resultsmentioning

confidence: 99%

A Brillouin light scattering study of the λ transition in liquid sulphur

Scarponi

Fioretto

Crapanzano

et al. 2007

Philosophical Magazine

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Sulfur‐Rich Polymers Coatings

King‐Poole,

Thérien‐Aubin

2024

Adv Funct Materials

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Advancements in the synthesis of sulfur‐rich materials are driving progress across diverse fields owing to the rich and tunable functionalities of those materials. These materials are typically valued for their electrochemical behaviors, high refractive indices, heavy metal affinity, and ability to form dynamic covalent bonding. As a result, their applications span various industries including electronics, catalysis, lithium‐sulfur batteries, water reclamation, and optoelectronics. Moreover, elemental sulfur, a byproduct of the petroleum industry, is produced abundantly, necessitating the exploration of novel valorization routes for polymers made from this feedstock. The unique combination of properties of sulfur‐rich polymers also makes them an ideal platform for the development of high‐performance functional coatings, offering durability and tailored functionalities for protective coatings, thus enhancing materials lifespan and performances in a variety of environmental conditions. The presence of dynamic covalent bonds in many sulfur‐rich polymers enables the creation of self‐healing coatings, while sulfur itself or the comonomers can contribute to antimicrobial, antifouling, and corrosion‐resistant properties. Furthermore, sulfur‐rich polymers have the potential to be used in the design of icephobic and superhydrophobic coatings. This underscores the versatility of sulfur‐rich polymers as a platform for the creation of advanced coatings with superior properties.

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The glass transition temperature of polymeric sulphur

Cited by 35 publications

References 5 publications

Origin of theλTransition in Liquid Sulfur

Origin of theλTransition in Liquid Sulfur

A Brillouin light scattering study of the λ transition in liquid sulphur

Sulfur‐Rich Polymers Coatings

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