Effect of molecular weight and molecular architecture of PMMA on the phase morphology of pseudo-IPN's of PCU/PMMA

1992 ◽  
Vol 25 (26) ◽  
pp. 7334-7337 ◽  
Author(s):  
P. Zhou ◽  
X. Chen ◽  
H. L. Frisch ◽  
Z. Zhu ◽  
J. Rider ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Phase Morphology ◽  
Molecular Architecture

Role of molecular architecture in interfacial self-adhesion of polyethylene films

2017 ◽  
Vol 33 (3) ◽  
pp. 235-261 ◽  
Author(s):  
Zahra Najarzadeh ◽  
Abdellah Ajji
Keyword(s):  
Molecular Weight ◽  
Adhesion Strength ◽  
Film Surface ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Molecular Architecture ◽  
Melt Temperature ◽  
Long Chain ◽  
Long Chain Branch ◽  
Chain Branch

The influence of molecular architecture on interfacial self-adhesion above polyethylene film melt temperature was examined in this study. The investigated molecular structures include molecular weight (Mw), molecular weight distribution, long chain branch amount and distribution and short chain branch among and along polyethylene chains. The long chain branches concentration was quantified using gel permeation chromatography and short branches concentration using nuclear magnetic resonance techniques. The adhesion strength was measured immediately after melt bonding using a T-Peel test. The results showed that increasing Mw resulted in higher adhesion strength in linear metallocene ethylene α-olefins. Low long chain branch concentrations hinder reptation motion and diffusion, and result in lower adhesion strength. Low density polyethylene with highly branched chains yielded very low self-adhesion. A drastic difference in adhesion strength between metallocene and conventional linear low density polyethylene is attributed to homogeneity versus heterogeneity of composition distribution. The low interfacial self-adhesion in conventional polyethylene was concluded to be due to enrichment of highly branched low molecular weight chains at the film surface. These segregated chains at the interface diffuse before the high molecular weight chains located in the bulk.

scholarly journals Effect of the annealing procedure and the molecular weight on the crystalline phase morphology and thermal properties of polylactide

2019 ◽  
Vol 68 (10) ◽  
pp. 1767-1775 ◽  
Author(s):  
Martí Hortós ◽  
Jon Anakabe ◽  
Alex Arrillaga ◽  
Sebastián Espino ◽  
Jordi J Bou
Keyword(s):  
Molecular Weight ◽  
Thermal Properties ◽  
Crystalline Phase ◽  
Phase Morphology ◽  
Annealing Procedure

A Critique of Asphaltene Fluorescence Decay and Depolarization-Based Claims about Molecular Weight and Molecular Architecture

2008 ◽  
Vol 22 (2) ◽  
pp. 1156-1166 ◽  
Author(s):  
Otto P. Strausz ◽  
I. Safarik ◽  
E. M. Lown ◽  
A. Morales-Izquierdo
Keyword(s):  
Molecular Weight ◽  
Fluorescence Decay ◽  
Molecular Architecture

Laser-Based Mass Spectrometric Assessment of Asphaltene Molecular Weight, Molecular Architecture, and Nanoaggregate Number

2015 ◽  
Vol 29 (5) ◽  
pp. 2833-2842 ◽  
Author(s):  
Andrew E. Pomerantz ◽  
Qinghao Wu ◽  
Oliver C. Mullins ◽  
Richard N. Zare
Keyword(s):  
Molecular Weight ◽  
Mass Spectrometric ◽  
Molecular Architecture

Effect of the molecular architecture of graft copolymers on the phase morphology and tensile properties of PS/EVA blends

2007 ◽  
Vol 107 (2) ◽  
pp. 930-938 ◽  
Author(s):  
Bluma G. Soares ◽  
Ana C. F. Moreira ◽  
Alex S. Sirqueira ◽  
Ronilson V. Barbosa ◽  
Renata A. Simão
Keyword(s):  
Tensile Properties ◽  
Graft Copolymers ◽  
Phase Morphology ◽  
Molecular Architecture

scholarly journals Improved Cell Morphology and Surface Roughness in High-Temperature Foam Injection Molding Using a Long-Chain Branched Polypropylene

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2404
Author(s):  
Steven Mendoza-Cedeno ◽  
Mu Sung Kweon ◽  
Sarah Newby ◽  
Maksim Shivokhin ◽  
George Pehlert ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Surface Roughness ◽  
High Temperature ◽  
Injection Molding ◽  
Cell Morphology ◽  
Molecular Architecture ◽  
Foam Injection Molding ◽  
Branched Polypropylene ◽  
Long Chain ◽  
Long Chain Branched Polypropylene

Long-chain branched polypropylene (LCB PP) has been used extensively to improve cell morphologies in foaming applications. However, most research focuses on low melt flow rate (MFR) resins, whereas foam production methods such as mold-opening foam injection molding (MO-FIM) require high-MFR resins to improve processability. A systematic study was conducted comparing a conventional linear PP, a broad molecular weight distribution (BMWD) linear PP, and a newly developed BMWD LCB PP for use in MO-FIM. The effects of foaming temperature and molecular architecture on cell morphology, surface roughness, and mechanical properties were studied by utilizing two chemical blowing agents (CBAs) with different activation temperatures and varying packing times. At the highest foaming temperatures, BMWD LCB PP foams exhibited 887% higher cell density, 46% smaller cell sizes, and more uniform cell structures than BWMD linear PP. Linear PP was found to have a surface roughness 23% higher on average than other resins. The BMWD LCB PP was found to have increased flexural modulus (44%) at the cost of decreased toughness (−88%) compared to linear PP. The branched architecture and high molecular weight of the BMWD LCB PP contributed to improved foam morphologies and surface quality in high-temperature MO-FIM conditions.

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