The re-evaluation of multiple peaks in the DSC melting endotherm of isotactic polypropylene

Passingham, C.; Hendra, P.J.; Cudby, M.E.A.; Zichy, V.; Weller, Mark T.

doi:10.1016/0014-3057(90)90219-t

Cited by 38 publications

(28 citation statements)

References 21 publications

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“…The 1 H and 13 C NMR spectrum obtained with the host polymer matrix were similar to those reported previously for high-molecular-weight polymers [16]. In the 1 H NMR [17].…”

Section: Nuclear Magnetic Resonance Spectroscopy (Nmr)supporting

confidence: 70%

Synthesis and electrochemical characterization of aPEO-based polymer electrolytes

Rodrigues

Silva

Veiga

et al. 2011

J Solid State Electrochem

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In this paper, the preparation and purification of an amorphous polymer network, poly[oxymethylene-oligo (oxyethylene)], designated as aPEO, are described. The flexible CH 2 CH 2 O segments in this host polymer combine appropriate mechanical properties, over a critical temperature range from −20 to 60°C, with labile salt-host interactions. The intensity of these interactions is sufficient to permit solubilisation of the guest salt in the host polymer while permitting adequate mobility of ionic guest species. We also report the preparation and characterisation of a novel polymer electrolyte based on this host polymer with lithium tetrafluoroborate, LiBF 4 , as guest salt. Electrolyte samples are thermally stable up to approximately 250°C and completely amorphous above room temperature. The electrolyte composition determines the glass transition temperature of electrolytes and was found to vary between −50.8 and −62.4°C. The electrolyte composition that supports the maximum room temperature conductivity of this electrolyte system is n =5 (2.10×10 −5 S cm −1 at 25°C). The electrochemical stability domain of the sample with n=5 spans about 5 V measured against a Li/Li + reference. This new electrolyte system represents a promising alternative to LiCF 3 SO 3 and LiClO 4 -doped PEO analogues.

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“…The 1 H and 13 C NMR spectrum obtained with the host polymer matrix were similar to those reported previously for high-molecular-weight polymers [16]. In the 1 H NMR [17].…”

Section: Nuclear Magnetic Resonance Spectroscopy (Nmr)supporting

confidence: 70%

Synthesis and electrochemical characterization of aPEO-based polymer electrolytes

Rodrigues

Silva

Veiga

et al. 2011

J Solid State Electrochem

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“…b) as a function of the filler content. Limited recrystallization occurs only at 7 wt% silica, probably because of α‐ crystals perfection phenomena or because the imperfect β‐crystals recrystallize in the α‐form and/or at the transcrystalline regime . The β–α transition was quantified by computing the recrystallization enthalpy, estimated as the area under the exothermic transformation (Table ).…”

Section: Resultsmentioning

confidence: 99%

Understanding the effect of silica nanoparticles and exfoliated graphite nanoplatelets on the crystallization behavior of isotactic polypropylene

2014

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This study explores how the presence of nanofillers with different structural and chemical characteristics, specifically silica nanoparticles and exfoliated graphite nanoplatelets (GNP), alters the crystallization behavior and polymorphism of a semicrystalline polymer, such as polypropylene (PP). The main focus of this research is to investigate how silica and GNP affect the nucleation and growth of PP crystals during isothermal crystallization. The nonisothermal crystallization behavior, including crystal structures, crystallization temperature, and rate, is also determined. PP composites with nanomaterial content up to 7 wt% were produced by melt mixing and injection molding. Both silica and graphite were found to be effective nucleating agents, significantly increasing the crystallization rate during isothermal crystallization, with greater changes observed in case of GNP composites. The effect of filler type and amount on the PP polymorphism and lamella thickness was studied by X‐ray diffraction and modulated differential scanning calorimetry. Both silica and graphite were found to be effective nucleating agents for the less common β‐phase of PP crystals even at low nanomaterial concentration. α‐−crystal perfection and the recrystallization of the β‐form in the α‐form and/or at the transcrystalline regime were found to be responsible for the recrystallization occurring upon melting in nanocomposites at high silica or medium GNP content. POLYM. ENG. SCI., 55:672–680, 2015. © 2014 Society of Plastics Engineers

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“…There is a large body of published research on the melting behavior of iPP 27–31. Excluding the presence of the trigonal (β) polymorphs,32, 33 the existence of multiple endotherms has been described as being due to various phenomena, such as the existence of recrystallization phenomena during the heating cycle after the isothermal process,34, 35 phase segregation and fractionation during crystallization,36–38 or the existence of lamellar thickening due to the annealing process 39–41. The existence of two monoclinic species associated with different crystalline morphologies, folded chain and extended chain, has also been suggested to explain the melting behavior,42–45 although the formation from the melt at low undercooling of an extended chain morphology is highly improbable 32.…”

Section: Resultsmentioning

confidence: 99%

Analysis of the isothermal crystallization of isotactic polypropylene nucleated with sorbitol derivatives

Marco

Ellis

Gómez

et al. 2003

J of Applied Polymer Sci

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ABSTRACT:The isothermal crystallization kinetics of isotactic polypropylene (iPP) and iPP nucleated with the sorbitol derivatives 1,3:2,4-bis(4-methyldibenzylidene)sorbitol and 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol was studied, along with the subsequent melting behavior, as a function of the nucleating agent concentration. The influence of the agents on the crystallization rate, crystallization temperature, and crystallization range was examined. The isothermal crystallization temperature increased, along with the crystallization rate, with increasing nucleating agent concentration. The maximum effect of the additives occurred at concentrations of 0.3% or greater.

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The re-evaluation of multiple peaks in the DSC melting endotherm of isotactic polypropylene

Cited by 38 publications

References 21 publications

Synthesis and electrochemical characterization of aPEO-based polymer electrolytes

Synthesis and electrochemical characterization of aPEO-based polymer electrolytes

Understanding the effect of silica nanoparticles and exfoliated graphite nanoplatelets on the crystallization behavior of isotactic polypropylene

Analysis of the isothermal crystallization of isotactic polypropylene nucleated with sorbitol derivatives

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