New understanding in the influence of melt structure and β-nucleating agents on the polymorphic behavior of isotactic polypropylene

RSC Advances ◽  
2014 ◽  
Vol 4 (56) ◽  
pp. 29514-29526 ◽  
Author(s):  
Jian Kang ◽  
Gengsheng Weng ◽  
Zhengfang Chen ◽  
Jinyao Chen ◽  
Ya Cao ◽  
...  
Keyword(s):  
Isotactic Polypropylene ◽  
Nucleation Mechanism ◽  
Nucleating Agents ◽  
Polymorphic Behavior ◽  
Two Stage ◽  
Melt Structure ◽  
Ordered Structures

Schematic illustration of the two-stage β-nucleation mechanism of β-iPP nucleated with dual-selective β-nucleating agents and the role of ordered structures.

Effects of melt structure on crystallization behavior of isotactic polypropylene nucleated with α/β compounded nucleating agents

2014 ◽  
Vol 132 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Qiyan Zhang ◽  
Zhengfang Chen ◽  
Bing Wang ◽  
Jinyao Chen ◽  
Feng Yang ◽  
...  
Keyword(s):  
Isotactic Polypropylene ◽  
Crystallization Behavior ◽  
Nucleating Agents ◽  
Melt Structure

scholarly journals The role of nucleating agents in high-pressure-induced gamma crystallization in isotactic polypropylene

2014 ◽  
Vol 293 (3) ◽  
pp. 665-675 ◽  
Author(s):  
Przemyslaw Sowinski ◽  
Ewa Piorkowska ◽  
Severine A. E. Boyer ◽  
Jean-Marc Haudin ◽  
Kinga Zapala
Keyword(s):  
High Pressure ◽  
Isotactic Polypropylene ◽  
Nucleating Agents

Investigation on the Roles of β-Nucleating Agents in Crystallization and Polymorphic Behavior of Isotactic Polypropylene

2020 ◽  
Vol 62 (5) ◽  
pp. 470-480
Author(s):  
Yuanjie Li ◽  
Hongyi Liu ◽  
Xinglan Huang ◽  
Xiuduo Song ◽  
Jian Kang ◽  
...  
Keyword(s):  
Isotactic Polypropylene ◽  
Nucleating Agents ◽  
Polymorphic Behavior

Magnetic Properties of xCeO2•(50 − x) PbO•50B2O3 Glasses and Glass Ceramics

2017 ◽  
Vol 13 (1) ◽  
pp. 4486-4494 ◽  
Author(s):  
G.El Damrawi ◽  
F. Gharghar
Keyword(s):  
Magnetic Properties ◽  
Large Scale ◽  
Glass Ceramics ◽  
Magnetic Behavior ◽  
Crystal Formation ◽  
Dual Roles ◽  
Effective Agent ◽  
Ordered Structures ◽  
Essential Change

Cerium oxide in borate glasses of composition xCeO2·(50 − x)PbO·50B2O3 plays an important role in changing both microstructure and magnetic behaviors of the system. The structural role of CeO2 as an effective agent for cluster and crystal formation in borate network is clearly evidenced by XRD technique. Both structure and size of well-formed cerium separated clusters have an effective influence on the structural properties. The cluster aggregations are documented to be found in different range ordered structures, intermediate and long range orders are the most structures in which cerium phases are involved. The nano-sized crystallized cerium species in lead borate phase are evidenced to have magnetic behavior.  The criteria of building new specific borate phase enriched with cerium as ferrimagnetism has been found to keep the magnetization in large scale even at extremely high temperature. Treating the glass thermally or exposing it to an effective dose of ionized radiation is evidenced to have an essential change in magnetic properties. Thermal heat treatment for some of investigated materials is observed to play dual roles in the glass matrix. It can not only enhance alignment processes of the magnetic moment but also increases the capacity of the crystallite species in the magnetic phases. On the other hand, reverse processes are remarked under the effect of irradiation. The magnetization was found to be lowered, since several types of the trap centers which are regarded as defective states can be produced by effect of ionized radiation. 

Impulsivity and Aggression: A Meta-analysis Using the UPPS Model of Impulsivity

2019 ◽  
Author(s):  
Konrad Bresin
Keyword(s):  
Structural Equation Modeling ◽  
Sensation Seeking ◽  
Structural Equation ◽  
Meta Analysis ◽  
The Other ◽  
Equation Modeling ◽  
Negative Urgency ◽  
Two Stage ◽  
Trait Impulsivity

Trait impulsivity has long been proposed to play a role in aggression, but the results across studies have been mixed. One possible explanation for the mixed results is that impulsivity is a multifaceted construct and some, but not all, facets are related to aggression. The goal of the current meta-analysis was to determine the relation between the different facets of impulsivity (i.e., negative urgency, positive urgency, lack of premeditation, lack of perseverance, and sensation seeking) and aggression. The results from 93 papers with 105 unique samples (N = 36, 215) showed significant and small-to-medium correlations between each facet of impulsivity and aggression across several different forms of aggression, with more impulsivity being associated with more aggression. Moreover, negative urgency (r = .24, 95% [.18, .29]), positive urgency (r = .34, 95% [.19, .44]), and lack of premeditation (r = .23, 95% [.20, .26]) had significantly stronger associations with aggression than the other scales (rs < .18). Two-stage meta-analytic structural equation modeling showed that these effects were not due to overlap among facets of impulsivity. These results help advance the field of aggression research by clarifying the role of impulsivity and may be of interest to researchers and practitioners in several disciplines.

scholarly journals Unique Slow Crack Growth Behavior of Isotactic Polypropylene: The Role of Shear Layer-Spherulites Layer Alternated Structure

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2746
Author(s):  
Mingjin Liu ◽  
Jiaxu Luo ◽  
Jin Chen ◽  
Xueqin Gao ◽  
Qiang Fu ◽  
...  
Keyword(s):  
Shear Layer ◽  
Crack Growth ◽  
Isotactic Polypropylene ◽  
Slow Crack Growth ◽  
Crack Growth Behavior ◽  
Polymer Science ◽  
The Past ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

With the development of polymer science, more attention is being paid to the longevity of polymer products. Slow crack growth (SCG), one of the most important factors that reveal the service life of the products, has been investigated widely in the past decades. Here, we manufactured an isotactic polypropylene (iPP) sample with a novel shear layer–spherulites layer alternated structure using multiflow vibration injection molding (MFVIM). However, the effect of the alternated structure on the SCG behavior has never been reported before. Surprisingly, the results showed that the resistivity of polymer to SCG can be enhanced remarkably due to the special alternated structure. Moreover, this sample shows unique slow crack propagation behavior in contrast to the sample with the same thickness of shear layer, presenting multiple microcracks in the spherulites layer, which can explain the reason of the resistivity improvement of polymer to SCG.

Key Role of the Oxidized Citrate-Free Radical in the Nucleation Mechanism of the Metal Nanoparticle Turkevich Synthesis

2019 ◽  
Vol 123 (36) ◽  
pp. 22624-22633 ◽  
Author(s):  
Sarah Al Gharib ◽  
Jean-Louis Marignier ◽  
Abdel Karim El Omar ◽  
Adnan Naja ◽  
Sophie Le Caer ◽  
...  
Keyword(s):  
Free Radical ◽  
Nucleation Mechanism ◽  
Metal Nanoparticle

scholarly journals Nucleating agents based on graphene and graphene oxide for crystallization of the β-form of isotactic polypropylene

2019 ◽  
Vol 55 (4) ◽  
pp. 1436-1450 ◽  
Author(s):  
Jan Broda ◽  
Marcin Baczek ◽  
Janusz Fabia ◽  
Dorota Binias ◽  
Ryszard Fryczkowski
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Isotactic Polypropylene ◽  
Reduced Form ◽  
Pimelic Acid ◽  
Nucleating Agents ◽  
Scanning Calorimetry ◽  
Functionalized Graphene Oxide ◽  
Reduced Graphene ◽  
Carboxylic Groups

Abstract During the investigations, functionalization of graphene oxide synthesized using modified Hummers’ method and its reduced form was performed. Mixtures of graphene oxide and reduced graphene oxide with pimelic acid and calcium hydroxide were prepared for functionalization. During the reaction, the molecules of pimelic acid were attached to the surface of graphene sheets. By forming links between the carboxylic groups of pimelic acid and graphene oxide, the durable connection was achieved. The functionalized graphene oxide and the reduced graphene oxide were used as additives in isotactic polypropylene crystallization. The influence of additives on crystallisation in non-isothermal conditions was examined using polarized optical microscopy and differential scanning calorimetry. The effect of the additives on the polypropylene structure was analysed using wide-angle X-ray scattering. For both functionalized compounds, the nucleating ability towards β-form of polypropylene was detected. Both additives showed the increase in the nucleation rate and promotion of growth of the β-form crystals. Nucleation efficiency similar to other nucleating agents used in the crystallization of the β-form of polypropylene was revealed.

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