Differential scanning calorimetry (DSC) and Raman spectroscopy study of poly(dimethylsiloxane)

Soutzidou, Maria; Panas, Alexandros; Viras, Kyriakos

doi:10.1002/(sici)1099-0488(19981115)36:15<2805::aid-polb14>3.3.co;2-c

Cited by 3 publications

(4 citation statements)

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“…It is similar to thermograms obtained for PDMS in similar conditions. 15,25,70 The DSC scan exhibits the following transitions: glass transition (T g ) at 148 K, cold crystallization (T cc ) at about 184 K with an exothermic peak characterized by ΔH cc = −26.5 J/g, and melting onset at about 209 K with two endothermic peaks at 227 and 235 K and ΔH m = 35.0 J/g. Henceforth, for simplicity, the melting of the crystallites will be denoted as occurring at about T m = 230 K. By taking ΔH m = 4.619 kJ/mol, 71 one finds a weight crystallinity fraction of 0.56.…”

Section: Methodsmentioning

confidence: 99%

Local Reversible Melting in Semicrystalline Poly(dimethylsiloxane): A High-Field Electron Paramagnetic Resonance Study

et al. 2017

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The reorientation of the paramagnetic guest 4-methoxy-TEMPO (spin probe) in the disordered fraction of semicrystalline poly(dimethylsiloxane) (PDMS) is investigated by high-field electron paramagnetic resonance (HF-EPR) at 190 and 285 GHz. The distribution of reorientation times is evidenced by accurate numerical simulations of the HF-EPR line shapes above 200 K. The distribution exhibits a bimodal structure with (i) a broad component corresponding to spin probes with fast and intermediate mobility located in the disordered fraction far from the crystallites and (ii) a narrow component corresponding to spin probes with extremely low mobility trapped close to the crystallites in a glassy environment persisting up to the PDMS melting. The spin probe undergoes an exchange process between the trapped and the more mobile fractions which is accounted for by an equilibrium reversible process with standard Gibbs free energy of reaction per spin probe mole Î\u94Gr0 â\u89\u83 4(Î\u94Hm - TÎ\u94Sm), where Î\u94Sm is the equilibrium melting entropy per monomer mole following the absorption of the heat Î\u94Hm. The process is interpreted as signature of reversible tertiary nucleation, occurring at the intersection of crystalline surfaces, thus suggesting surface roughness of the crystal-amorphous interface. It becomes thermodynamically favored at temperatures higher than T â\u88¼ 209 K where the onset of PDMS melting is located according to differential scanning calorimetry

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Section: Methodsmentioning

confidence: 99%

Local Reversible Melting in Semicrystalline Poly(dimethylsiloxane): A High-Field Electron Paramagnetic Resonance Study

et al. 2017

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“…The same is true for SR/PEG blends. However, in the case of the chemically modified SR/AMPEG films, the results of Table II show that: (a) Δ H m increases (∼ 15 J/g for all SR/AMPEG films) showing higher ease of crystallization at the expense of the amorphous phase39, 40 and (b) Δ H c values are significantly lower than Δ H m , the former ranging from ∼ 9.0 J/g for SR/AMPEG‐2 to negligible for the two higher AMPEG contents, indicating that crystallization occurred during quenching of the samples; this is also verified by the lower values of Δ C p (variation in heat capacity at T g ). These differences in the thermal behavior reflect structural differences attributable mainly to the presence of dangling PDMS chains19, 41 formed due to the occupation of several crosslinking sites by AMPEG.…”

Section: Resultsmentioning

confidence: 97%

“…The thermograph of pure SR film [Figure 2(a,b)] shows the presence of a glass transition ( T g ) at −125.5°C and two peaks: an exothermic one at T c , corresponding to the cold crystallization of PDMS followed by an endothermic one at T m , corresponding to the crystalline melting of PDMS 38, 39. As shown in Table II, the glass transition temperature T g both in blends and in the chemically modified films is lowered by 2°C compared to that of the neat SR films.…”

Section: Resultsmentioning

confidence: 99%

Silicone rubber films modified by ethylenoxy moieties: Characterization and drug delivery properties

Soulas

Papadokostaki

Sanopoulou

2013

J of Applied Polymer Sci

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We present a comparative study between two different types of modification applied on a highly hydrophobic, yet biocompatible polymer, aiming to increase its hydrophilicity. More specifically, silicone rubber (SR) was modified by the introduction of low‐molecular weight poly(ethylene glycol), through either (a) blending or (b) addition‐grafting reaction. The modifications were first evaluated in neat films with respect to their water sorption capacity, stability of ethylenoxy groups' embedment, mechanical and thermal properties. The results from this series of tests showed that blending offered better results in terms of hydrophilicity, both surficial and in the bulk, while the films maintained better mechanical properties. Subsequently, the release kinetics of a relatively hydrophilic drug (theophylline) along with the concurrent water uptake was examined in drug‐loaded, pure and modified SR films. As in the case of the drug‐free films, blending appeared to offer better possibilities in controlling the drug's release rate through increased water sorption. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

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“…4. It can be seen that the T g of PDMS synthetic leather coating is -131.8 °C, and crystallization temperature (T c ) is -73.5 °C, while the T g of the commonly used PU and plasticized PVC synthetic leather were -50 °C or so [24,25]. This is because the molecular structure of organosilicon polymer is helical, the interaction force between chain segments is small, the main chain is soft and easy to rotate, and the rotation steric resistance of the Si-C bond side group is small.…”

Section: Low-temperature Flexibility Of Coatingmentioning

confidence: 99%

Organosilicon leather coating technology based on carbon peak strategy

et al. 2022

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Based on the demand of carbon peak and carbon emission reduction strategy, divinyl-terminated polydimethylsiloxane (ViPDMSVi), poly(methylhydrosiloxane) (PMHS), divinyl-terminated polymethylvinylsiloxane (ViPMVSVi), and fumed silica were used as primary raw materials, polydimethylsiloxane (PDMS) synthetic leather coating was in situ constructed by thermally induced hydrosilylation polymerization on the synthetic leather substrate. The effect of the viscosity of ViPDMSVi, the active hydrogen content of PMHS, the molar ratio of vinyl groups to active hydrogen, the dosage of ViPMVSVi and fumed silica on the performance of PDMS polymer coating, including mechanical properties, cold resistance, flexural resistance, abrasion resistance, hydrophobic and anti-fouling properties were investigated. The results show that ViPDMSVi with high vinyl content and PMHS with low active hydrogen content is more conducive to obtaining organosilicon coating with better mechanical properties, the optimized dosage of ViPMVSVi and fumed silica was 7 wt% and 40 wt%, respectively. In this case, the tensile strength and the broken elongation of the PDMS polymer coating reached 5.96 MPa and 481%, showing reasonable mechanical properties for leather coating. Compared with polyurethane based or polyvinyl chloride based synthetic leather, the silicon based synthetic leather prepared by this method exhibits excellent cold resistance, abrasion resistance, super hydrophobicity, and anti-fouling characteristics. Graphical Abstract

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Differential scanning calorimetry (DSC) and Raman spectroscopy study of poly(dimethylsiloxane)

Cited by 3 publications

References 0 publications

Local Reversible Melting in Semicrystalline Poly(dimethylsiloxane): A High-Field Electron Paramagnetic Resonance Study

Local Reversible Melting in Semicrystalline Poly(dimethylsiloxane): A High-Field Electron Paramagnetic Resonance Study

Silicone rubber films modified by ethylenoxy moieties: Characterization and drug delivery properties

Organosilicon leather coating technology based on carbon peak strategy

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