Preparation of polymeric foams with bimodal cell size: An application of heterogeneous nucleation effect of nanofillers

2019 ◽  
Vol 147 ◽  
pp. 107-115 ◽  
Author(s):  
Yang Chen ◽  
Chenglong Weng ◽  
Zhen Wang ◽  
Tim Maertens ◽  
Ping Fan ◽  
...  
Keyword(s):  
Cell Size ◽  
Heterogeneous Nucleation ◽  
Polymeric Foams ◽  
Nucleation Effect

scholarly journals Heterogeneous Nucleation Effect of N, N'-Adipic Bis(4-phenylbutyric Acid) Dihydrazide on Crystallization Process of Poly(L-lactic Acid)

2019 ◽  
Vol 25 (4) ◽  
pp. 446-454
Author(s):  
Yan-Hua CAI ◽  
Li-Sha ZHAO
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Heterogeneous Nucleation ◽  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Melting Behavior ◽  
Light Transmittance ◽  
Crystallization Peak ◽  
Nucleation Effect ◽  
Phenylbutyric Acid

Enhancing crystallization ability is a fundamental challenges in Poly(L-lactic acid) (PLLA) industry, therefore, the goal of this work was to synthesis a new organic nucleating agent N, N'-adipic bis(4-phenylbutyric acid) dihydrazide (APAD), and investigate its effect on non-isothermal crystallization, isothermal crystallization, melting behavior, thermal stability, and optical property of PLLA. Non-isothermal melt crystallization results showed that APAD acted as more effective nucleating and accelerating agent for the crystallization of PLLA, as a result, upon cooling at 1 °C/min, PLLA/0.5 %APAD had the highest onset crystallization temperature 136.4 °C and the crystallization peak temperature 132.0 °C, as well as the largest non-isothermal crystallization enthalpy 48.1 J/g. However, with increasing of APAD concentration from 0.5 wt.% to 3 wt.%, the crystallization peak shifted to the lower temperature. In contrast, for the non-isothermal cold crystallization process, the effect of APAD concentration on the crystallization behavior of PLLA was negligible. Additionally, the non-isothermal crystallization process was also depended on the cooling rates and the final melting temperature. In isothermal crystallization section, to compare with the primary PLLA, the crystallization half-time of PLLA/APAD could decrease from 254.3 s to the minimum value 29.4 s, with 0.5 wt.% APAD contents at 125 °C. Melting behavior of PLLA/APAD samples under different conditions further confirmed the heterogeneous nucleation effect of APAD for PLLA, and the appearance of the double melting peaks was attributed to the melting-recrystallization. Finally, the addition of APAD decreased the thermal stability to some extent, although APAD could not change the thermal decomposition profile of PLLA. And a drop of PLLA/APAD samples in light transmittance resulted from the double influence of the enhancement of crystallization and the opaqueness of APAD.

Studies on heterogeneous nucleation effect of dispersing intercalated montmorillonite clay platelets in polyaniline matrix

2010 ◽  
Vol 31 (12) ◽  
pp. 2049-2056 ◽  
Author(s):  
Hsiu-Yu Cheng ◽  
Chang-Jian Weng ◽  
Shir-Joe Liou ◽  
Jui-Ming Yeh ◽  
Sung-Po Liu
Keyword(s):  
Heterogeneous Nucleation ◽  
Montmorillonite Clay ◽  
Nucleation Effect ◽  
Clay Platelets

Heterogeneous nucleation effect of in situ iron-rich nanoparticles on grain refinement of copper alloy

2016 ◽  
Vol 168 ◽  
pp. 188-191 ◽  
Author(s):  
Kaixuan Chen ◽  
Xiaohua Chen ◽  
Ding Ding ◽  
Guodong Shi ◽  
Zidong Wang
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
Copper Alloy ◽  
Nucleation Effect

Heterogeneous nucleation uniformizing cell size distribution in microcellular nanocomposites foams

Polymer ◽  
2006 ◽  
Vol 47 (21) ◽  
pp. 7580-7589 ◽  
Author(s):  
Wentao Zhai ◽  
Jian Yu ◽  
Lichuan Wu ◽  
Weiming Ma ◽  
Jiasong He
Keyword(s):  
Size Distribution ◽  
Cell Size ◽  
Heterogeneous Nucleation ◽  
Cell Size Distribution

Increasing cell density/decreasing cell size to produce microcellular and nanocellular thermoplastic foams: A review

2020 ◽  
pp. 0021955X2095930
Author(s):  
Taher Azdast ◽  
Rezgar Hasanzadeh
Keyword(s):  
Cell Size ◽  
Cell Density ◽  
Low Cost ◽  
Weight Ratio ◽  
High Strength ◽  
Batch Process ◽  
Efficient Solutions ◽  
Sound Insulation ◽  
Polymeric Foams ◽  
Cell Densities

Nowadays, polymeric foams have attracted particular attention in scientific and industrial societies due to their unique properties, such as high strength to weight ratio, excellent thermal and sound insulation, and low cost. Researchers have shown that the extraordinary properties of polymeric foams such as superior thermal insulation, can be achieved by increasing the cell density/decreasing the cell size. In this regard, firstly, the most important foaming processes, i.e. batch, extrusion, and injection molding are studied in the present research. Then, cell nucleation stage as the most crucial phenomenon for achieving high cell density/small cell size is investigated in detail. In the next step, the most important researches in the field of polymeric foams are introduced in which the largest cell densities/smallest cell sizes have been achieved. The investigations show that the most remarkable results (highest cell densities/smallest cell sizes) belong to the batch process. Also, the use of nucleating agents, increasing the solubility of blowing agent into the polymer, and the use of nanoparticles are the most efficient solutions to achieve microcellular and nanocellular structures.

Nonisothermal Crystallization Kinetics of Isotactic Polypropylene Filled with a Novel Nucleating Agent

2013 ◽  
Vol 652-654 ◽  
pp. 501-507
Author(s):  
Nai Xu ◽  
Li Sha Pan ◽  
Su Juan Pang ◽  
Qiang Lin
Keyword(s):  
Crystallization Kinetics ◽  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation ◽  
Nucleating Agent ◽  
Differential Scanning Calorimetric ◽  
Nonisothermal Crystallization ◽  
Crystallization Behaviors ◽  
Nucleation Effect ◽  
Nonisothermal Crystallization Kinetics ◽  
Kinetics Of

The nonisothermal crystallization kinetics of isotactic polypropylene (iPP) filled with a novel nucleating agent (TMC328) was studied by using differential scanning calorimetric. The commonly used Arami, Ozawa, and Mo models were used to model the crystallization kinetics, and it appears that Arami and Mo models can well describe the nonisothermal crystallization behaviors of iPP/TMC328 blends. The results indicate that a small amount of TMC328 can obviously enhance the kinetic crystallizability of iPP due to its heterogeneous nucleation effect.

scholarly journals Time-Varying Compressive Strength Model of Aeolian Sand Concrete considering the Harmful Pore Ratio Variation and Heterogeneous Nucleation Effect

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Yugen Li ◽  
Huimei Zhang ◽  
Xiaoyu Liu ◽  
Guangxiu Liu ◽  
Dawei Hu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Heterogeneous Nucleation ◽  
American Concrete Institute ◽  
Time Varying ◽  
Strength Model ◽  
Aeolian Sand ◽  
Mu Us Desert ◽  
Nucleation Effect ◽  
Influence Mechanism ◽  
Ratio Variation

The aim of this study was to analyze the influence mechanism of aeolian sand on the mechanical property of concrete and establish the time-varying compressive strength model. Test studies on the development of concrete’s compressive strength with aeolian sand from the Mu Us Desert were carried out. Influence mechanism of aeolian sand on the strength of concrete was revealed by using the nuclear magnetic resonance (NMR) to analyze the pore ratio and structures of aeolian sand concrete (ASC) and using the X-ray single crystal diffraction (XRD) to calculate the relative contents of hydration products semiquantitatively. Results show that the strength first increases and then decreases with the increase of aeolian sand content, where 20% was the best replacement ratio. With less than 20% content, it promoted the strength by changing the pore structure of concrete and accelerating the cement hydration speed based on its filling effect and chemical activity; when the content was more than 20%, it led to a decrease of strength because of an increase of harmful pore ratio and a weakening of the interface transition zone (ITZ), where the stress concentration and damage when loading are easier to occur. At last, a time-varying compressive strength model of ASC considering the harmful pore ratio variation and heterogeneous nucleation effect was established based on the discussion, published date, and American Concrete Institute (ACI) model, which agrees well with the experimental results and can easily predict the strength of concrete.

An Investigation on Grain Refinement Mechanism of Master Alloys Al-Ti, Al-TiC and Al-Ti-C Toward Pure Aluminum

2013 ◽  
Vol 652-654 ◽  
pp. 1072-1075 ◽  
Author(s):  
Wan Wu Ding ◽  
Jiang Tao Zhu ◽  
Wen Jun Zhao ◽  
Tian Dong Xia
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
Pure Aluminum ◽  
Grain Refining ◽  
Nucleation Effect ◽  
Commercially Pure ◽  
Master Alloys ◽  
Refinement Mechanism ◽  
Heat Preservation

The grain refining effects of Al-Ti, Al-TiC and Al-Ti-C master alloys on commercially pure aluminum were compared, and the grain refinement mechanism of TiAl3 and TiC among master alloys was discussed. The results show that: the grain refinement of the master alloys Al-TiC and Al-Ti toward pure aluminum mainly stems from the heterogeneous nucleation role of TiC and TiAl3 particles, but with the extension of heat preservation time of fused mass, its role of heterogeneous nucleation will decline due to dissolution of TiAl3 and aggregation and precipitation of TiC. The preferable grain refinement effects of Al-Ti-C master alloys toward pure aluminum are mainly due to the fact that when TiAl3 and TiC particles are acted commonly as heterogeneous nucleation particles, the heterogeneous nucleation effect of TiC particles will be enhanced because of the presence of TiAl3.

Sign in / Sign up

Export Citation Format

Share Document