scholarly journals Effect of Silver Nanoparticles on the Melting Behavior, Isothermal Crystallization Kinetics and Morphology of Polyoxymethylene

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 594
Author(s):  
Yicheng Zeng ◽  
Yang Liu ◽  
Xun Zhang ◽  
Lumin Wang ◽  
Hongliang Huang ◽  
...  
Keyword(s):  
Crystallization Kinetics ◽  
Ag Nanoparticles ◽  
Isothermal Crystallization ◽  
Crystal Surface ◽  
Polarized Light ◽  
Crystallization Rate ◽  
Melting Behavior ◽  
Half Time ◽  
Isothermal Crystallization Kinetics ◽  
Nucleation Sites

In this work, the effects of silver (Ag) nanoparticles on the melting behavior, isothermal crystallization kinetics, and morphology of polyoxymethylene (POM) were studied. It was found that the melting peak temperature (Tm) and the crystallization temperature (TC) of POM/Ag nanocomposites shifted to higher temperature with the content of Ag nanoparticles increased. In addition, the isothermal crystallization kinetics of POM/Ag nanocomposites were determined by Avrami and Lauritzen-Hoffman models. The results of crystallization half-time (t0.5), reciprocal of crystallization half-time (τ0.5), Avrami exponent (n), and Avrami rate constant (k) showed that low loading of Ag nanoparticles (≤1 wt%) accelerated the crystallization rate of POM. However, when the content of Ag nanoparticles reached 2 wt%, they aggregated together and restrained crystallization of POM. Meanwhile, the results of nucleation parameter (Kg) and surface free energy of folding (δe) revealed that Ag nanoparticles reduced the energy need to create a new crystal surface, leading to faster crystallization. Moreover, the crystallization activation energies (∆E) were determined using the Arrhenius model, which suggested that Ag nanoparticles induced the heterogeneous nucleation by lowing the ∆E. Furthermore, polarized light microscopy results indicated Ag nanoparticles generated a great amount of nucleation sites and led to the formation of smaller spherulites.

scholarly journals Isothermal Crystallization Kinetics of Poly(ethylene oxide)/Poly(ethylene glycol)-g-silica Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 648
Author(s):  
Xiangning Wen ◽  
Yunlan Su ◽  
Shaofan Li ◽  
Weilong Ju ◽  
Dujin Wang
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Poly Ethylene Glycol ◽  
Isothermal Crystallization Kinetics ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Kinetics Of

In this work, the crystallization kinetics of poly(ethylene oxide) (PEO) matrix included with poly(ethylene glycol) (PEG) grafted silica (PEG-g-SiO2) nanoparticles and bare SiO2 were systematically investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM) method. PEG-g-SiO2 can significantly increase the crystallinity and crystallization temperature of PEO matrix under the non-isothermal crystallization process. Pronounced effects of PEG-g-SiO2 on the crystalline morphology and crystallization rate of PEO were further characterized by employing spherulitic morphological observation and isothermal crystallization kinetics analysis. In contrast to the bare SiO2, PEG-g-SiO2 can be well dispersed in PEO matrix at low P/N (P: Molecular weight of matrix chains, N: Molecular weight of grafted chains), which is a key factor to enhance the primary nucleation rate. In particular, we found that the addition of PEG-g-SiO2 slows the spherulitic growth fronts compared to the neat PEO. It is speculated that the interfacial structure of the grafted PEG plays a key role in the formation of nuclei sites, thus ultimately determines the crystallization behavior of PEO PNCs and enhances the overall crystallization rate of the PEO nanocomposites.

Non-Isothermal Crystallization Kinetics of Graphene Oxide-Carbon Nanotubes Hybrids / Polyamide 6 Composites

2019 ◽  
Vol 41 (3) ◽  
pp. 394-394
Author(s):  
Zhi Qiang Wang Zhi Qiang Wang ◽  
Yong Ke Zhao and Xiang Feng Wu Yong Ke Zhao and Xiang Feng Wu
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Cooling Rate ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Polyamide 6 ◽  
Degree Of Crystallinity ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

The hybrids combined by nano-materials with different dimensions usually possess much better enhancement effects than single one. Graphene oxide-carbon nanotubes hybrids / polyamide 6 composites has been fabricated. The non-isothermal crystallization kinetics of the as-prepared samples was discussed. Research results showed that increasing the cooling rate was in favor of increasing the crystallization rate and the degree of crystallinity for the as-prepared samples. Moreover, the crystallization rate was first decreased and then increased with increasing the hybrids loading. Furthermore, the crystallization mechanism was changed with increasing the crystallization temperature and the cooling rate. The nucleation and growth modes of the non-isothermal crystallization could be classified into three different types, according to the Ozawa’s theory. These complicated results could be attributed to the important role of crystallization rate as well as the simultaneous hindering and promoting effects of the as-prepared hybrids. This work has reference values for understanding the crystallization kinetics of the polyamide 6-based composites.

Morphology, Crystalline Structure and Isothermal Crystallization Kinetics of Polybutylene Terephthalate/Montmorillonite Nanocomposites

2005 ◽  
Vol 13 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Defeng Wu ◽  
Chixing Zhou ◽  
Xie Fan ◽  
Dalian Mao ◽  
Zhang Bian
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Polymer Chains ◽  
Isothermal Crystallization Kinetics ◽  
Clay Particles ◽  
Nucleation Sites ◽  
Kinetics Of ◽  
Montmorillonite Nanocomposites

The melt intercalation method was employed to prepare poly(butylene terepathalate)/montmorillonite nanocomposites, and their microstructure was characterized by wide angle X-ray diffraction and transmission electron microscopy. The XRD results showed that the crystalline plane such as (010), (111), (100) was smaller than that of pristine PBT, which indicates that the crystallite size of PBT in the nanocomposites could be diminished by adding clay. Moreover, the isothermal crystallization kinetics of PBT and PBT/MMT nanocomposites was investigated by differential scanning calorimetry (DSC). During isothermal crystallization, the development of crystallinity with time was analysed by the Avrami equation. The results show that very small amounts of clay dramatically increased the rate of crystallization and high clay concentrations reduced the rate of crystallization at the low crystallization temperatures. At low concentrations of clay, the distance between dispersed platelets was large so it was relatively easy for the additional nucleation sites to incorporate surrounding polymer, and the crystal nucleus was formatted easily. However, at high concentrations of clay, the diffusion of polymer chains to the growing crystallites was hindered by large clay particles, despite the formation of additional nucleation sites by the clay layers. At the higher crystallization temperature, the crystallization of the nanocomposites was slower than that of the pure PBT under the experimental conditions, which means that with the increase in chains mobility at the high crystallization temperature, the crystal nuclei are harder to format, and the hindering effect of clay particles on the polymer chains was stronger than the nucleating effect of the layers. In addition, the activation energies of crystallization for PBT and its nanocomposites were calculated by the Arrhenius relationship, and the results showed that the nanocomposites with a low clay content had the lower activation energy values than PBT, while high amounts of clay increased the activation energy of PBT.

scholarly journals Melting behavior and non‐isothermal crystallization kinetics of copolyamide 6/12

2019 ◽  
Vol 2 (4) ◽  
Author(s):  
Chao Lin ◽  
Fei Zou ◽  
María P. Fernández‐Ronco ◽  
Yurong Yan ◽  
Rudolf Hufenus
Keyword(s):  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Melting Behavior ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of
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