Study of the relationship between characteristics of aramid fibrids and mechanical property of aramid paper using DSC

e-Polymers ◽  
2014 ◽  
Vol 14 (2) ◽  
pp. 139-144 ◽  
Author(s):  
Huifang Zhao ◽  
Yinbang Zhu ◽  
Lizheng Sha
Keyword(s):  
Molecular Weight ◽  
Thermal Properties ◽  
Mechanical Strength ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
High Strength ◽  
Scanning Calorimetry ◽  
The Relationship ◽  
Different Sources

AbstractFiber classification of aramid fibrids was carried out using a Bauer-McNett fiber classifier, and the molecular weight and thermal properties of different sizes of aramid fibrids were determined with viscometry and differential scanning calorimetry (DSC), respectively. Aramid handsheets were made from different sizes of aramid fibrids and aramid short fibers, and the relationship between mechanical strength of aramid handsheets and thermal properties of aramid fibrids was examined. In addition, aramid papers from four different sources were also investigated to elucidate the relationship between their thermal properties and mechanical strength. It was found that aramid fibrids passing through 30-mesh screens and remaining on 50-mesh screens and aramid fibrids with narrower molecular weight distribution are suitable for the production of high-strength aramid papers. Lower crystallinity and wider molecular weight distribution are important contributors to the lower mechanical strength of domestic aramid paper when compared to that of Nomex paper.

scholarly journals Obtaining of high density carbon materials by coke sintering resulting from heat treatment of tar for applications in sensors manufacture

2020 ◽  
Author(s):  
Maria-Roxana Marinescu ◽  
Elena David ◽  
Liviu-Daniel Ghiculescu
Keyword(s):  
Heat Treatment ◽  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
High Strength ◽  
Volatile Matter ◽  
Heat Treatments ◽  
High Density ◽  
The Self ◽  
Rapid Decomposition

In this research, high-density and high-strength carbonized carbon blocks were manufactured by coke sintering resulted from heat treatments of biomass pyrolysis tar. First, the molecular weight distribution of the tar was controlled through a pressurized heat treatment at 365°C and then this heat-treated tar was treated using a delayed coking system to obtain the self-sintering coke. Finally, carbon blocks were molded from the self-sintering coke and carbonized at 1100°C for 2h. Through rapid decomposition of the high molecular weight compounds in the tar at 360°C, the molecular weight distribution of tar was confirmed to be controllable by this treatment stage. During carbonization was observed a swelling in carbon blocks manufactured that contain more than 15 wt% of volatile matter from 150-500°C. The optimum conditions of the two heat treatments stage were established to be 310°C for 3 h and 500°C for 1.5 h. The highest density and highest strength of the carbonized carbon blocks manufactured were 1.44 g/cm3 and 68.7 MPa, respectively.

Effects of molecular weight distribution on the self-assembly of end-functionalized polystyrenes

2017 ◽  
Vol 8 (29) ◽  
pp. 4290-4298 ◽  
Author(s):  
Bai-Heng Wu ◽  
Qi-Zhi Zhong ◽  
Zhi-Kang Xu ◽  
Ling-Shu Wan
Keyword(s):  
Molecular Weight ◽  
Mechanical Strength ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Self Assembly ◽  
The Self ◽  
Porous Films

The molecular weight distribution of hydroxyl-end-functionalized polystyrenes shows effects on the self-assembly of patterned porous films and the mechanical strength.

Rheological measurement of molecular weight distribution of polymers

e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Maryam Khak ◽  
Ahmad S. A. Ramazani
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Loss Modulus ◽  
Method Comparison ◽  
Polymeric Materials ◽  
Linear Polymers ◽  
Rheological Data ◽  
Log Normal ◽  
The Relationship

Abstract This paper has described a method to obtain the molecular weight distribution (MWD) of polymeric materials from their rheological data. The method has been developed for linear polymers with log normal molecular weight distribution. The rheological data required to obtain the molecular weight distribution are the shear storage modulus,G' (ω) , and shear loss modulus,G" (ω) , extending from the terminal zone to the plateau region. For determining the molecular weight average, the method uses the relationship between stress moduli and relaxation spectrums, with the equation that connects dynamic rheological data with molecular weight distribution, and so it is not necessary to achieve the relaxation spectrums and the molecular weight distribution is obtained directly from dynamic shear experiments and it is one of the main advantageous of the proposed method. Comparison of calculated and experimental data obtained by GPC for five polypropylene samples produced in different conditions show that model can correctly predict molecular weight distribution for these types of polymers.

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