Crystallization and melting behavior of polypropylene and maleated polypropylene blends
149
Citation
20
Reference
10
Related Paper
Citation Trend
Keywords:
Polypropylene
Isothermal process
Small-angle X-ray scattering
Small-angle X-ray scattering
Characterization
Cite
Citations (2)
Small-angle X-ray scattering
Cite
Citations (34)
Abstract The crystallization of a high‐density polyethylene was analyzed with differential scanning calorimetry (DSC) measurements. An intense transcrystallinity was observed at the contact between the polymer and the DSC pans. The modification of the crystallization kinetics induced by this phenomenon was studied as a function of cooling rate and sample thickness. We point out that most of the theoretical predictions of our previous model could be checked. The crystallization temperature was a function of the sample thickness and could be also correlated with the thickness of the transcrystalline zones. The shapes of the DSC traces were complex and correlated with the amount of trancrystallization. The usual interpretations of such DSC curves were not accurate. We conclude that specific experimental procedures must be proposed to understand and correctly use such measurements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 725–733, 2002
High-density polyethylene
Cite
Citations (29)
In this article, the kinetic behavior of a glass/epoxy prepreg, HexPly® 1454, has been investigated using differential scanning calorimetry data. The kinetic parameters of three different kinetic models have been calculated using non-linear curve fitting of isothermal differential scanning calorimetry data. Curve fitting was done based on genetic algorithm to allow to obtain a unique value for each kinetic parameter. The non-isothermal differential scanning calorimetry experiments were predicted using the obtained models. Prediction results demonstrated that only model with the minimum number of kinetic parameters and unique value for each of them can correctly predict non-isothermal experiments at all heating rates.
Isothermal process
Cite
Citations (9)
The degree and the nature of crystallinity determine several key properties of an oriented polymeric system. Thermal analysis, although widely used for crystallinity determination, may have limited precision with oriented polymers, due to the differential nature and overlap of multiple thermal events (cold-crystallisation, chain-relaxation, etc). In this paper we have studied, how MDSC (Modulated Differential Scanning Calorimetry) variables manipulate the thermal behaviour of oriented materials, so that the degree and the nature of crystallisation can be well defined.
Degree (music)
Cite
Citations (2)
Abstract A series of experiments in which small‐angle x‐ray scattering (SAXS) is used to follow microstructural changes in situ is reviewed. The work relates to primary and secondary crystallization, to melting and to physical aging. SAXS curve shapes are used to define whether primary crystallization occurs through the growth of “skeletal” or of “dense” spherulites. The integrated intensity is used to establish whether primary and secondary crystallization occur simultaneously. The ratio of second‐ to first‐order peak intensities, the absolute intensity, and reversible peak shifts are used to study the nature of secondary crystallization in polyethylene, poly(vinylidene fluoride) and a polysiloxane. The last two of these exhibit reversible peak shifts which are not consistent with simple models and it is concluded that thorough replacement of existing structures occurs during this process. SAXS peak shape changes in PE indicate that melting occurs by the random loss of crystals throughout the material. Finally, it is shown that SAXS can be a useful tool for monitoring physical aging in semicrystalline polymers.
Small-angle X-ray scattering
Small-Angle Scattering
Cite
Citations (10)
This chapter presents the basics of differential scanning calorimetry (DSC) analysis and its correlation to polymer morphology for semicrystalline polymeric materials. It concentrates on the applications that are important for the study of polymer thermal properties, nucleation, and crystallization and their relationship with morphology. Standard DSC tests at constant scanning rates can be employed to extract the following data from amorphous or semicrystalline polymers: glass transition temperature, crystallization temperature, melting temperature, latent heat of fusion or enthalpy of fusion, latent heat of crystallization or crystallization enthalpy and crystallinity degree. In order to understand the origin of the transitions detected by DSC, it is useful to understand the differences between first and second-order transitions. The chapter concludes that DSC is one of the most powerful techniques to correlate thermal properties and morphology, although it must always be complemented by other techniques, such as PLOM, SEM, TEM, SAXS, and WAXS.
Cite
Citations (177)
This chapter focuses on methodological developments aiming to interpret small-angle X-ray scattering (SAXS) data for topological structure characterization of large biomolecular assemblies. It also focuses on developments on modeling large protein complexes that can adopt a single conformation or exist in a mixture of multiple conformations. In particular, conformation generation from large-scale computations provides a solid theoretical foundation for SAXS data interpretation. In the midst of broadened SAXS applications, the emerging potential of a SAXS analysis for visualizing the protein topology of biomolecular complexes is apparent, especially when already known structures of individual components are productively used in theoretical and computational studies designed for SAXS data analysis. In fact, it is counter-intuitive that the sample preparation needed for a SAXS measurement could be more stringent when compared to crystallographic requirements given that crystallization itself is a highly efficient purification process.
Small-angle X-ray scattering
Characterization
Small-Angle Scattering
Cite
Citations (1)
Polypropylene
Molding (decorative)
Thermal Stability
Cite
Citations (0)
Polypropylene
Degradation
Induction period
Cite
Citations (27)