Thermal Cis → Trans Isomerization of Covalently Attached Azobenzene Groups in Undrawn and Drawn Polyethylene Films. Characterization and Comparisons of Occupied Sites

2003 ◽  
Vol 36 (11) ◽  
pp. 3833-3840 ◽  
Author(s):  
Caihua Wang ◽  
Richard G. Weiss
Keyword(s):  
Polyethylene Films ◽  
Trans Isomerization ◽  
Azobenzene Groups

Photocontrol of polypeptide membrane functions by cis-trans isomerization in side-chain azobenzene groups

1986 ◽  
Vol 19 (1) ◽  
pp. 51-55 ◽  
Author(s):  
Takatoshi Kinoshita ◽  
Morimasa Sato ◽  
Akira Takizawa ◽  
Yoshiharu Tsujita
Keyword(s):  
Side Chain ◽  
Trans Isomerization ◽  
Azobenzene Groups

The analysis of “Gels” in polymer films

1989 ◽  
Vol 47 ◽  
pp. 362-363
Author(s):  
G. M. Brown ◽  
D. F. Brown ◽  
J. H. Butler
Keyword(s):  
Molecular Weight ◽  
Film Industry ◽  
Local Stress ◽  
Melt Index ◽  
Polyethylene Films ◽  
Crosslinked Polymer ◽  
Polymeric Gels ◽  
Mineral Particles ◽  
Polymeric Species ◽  
Special Concern

The term “gel”, in the jargon of the plastics film industry, may refer to any inclusion that produces a visible artifact in a polymeric film. Although they can occur in any plastic product, gels are a principle concern in films where they detract from the cosmetic appearance of the product and may compromise its mechanical strength by acting as local stress concentrators. Many film gels are small spheres or ellipsoids less than one millimeter in diameter whereas other gels are fusiform-shaped and may reach several centimeters in length. The actual composition of gel inclusions may vary from miscellaneous inorganics (i.e. glass and mineral particles) and processing additives to heavily oxidized, charred or crosslinked polymer. The most commonly observed gels contain polymer differing from the bulk of the sample in its melt viscosity, density or molecular weight.Polymeric gels are a special concern in polyethylene films. Over the years and with the examination of a variety of these samples three predominant polymeric species have been observed: density gels which have different crystallinity than the film; melt-index gels in which the molecular weight is different than the film and crosslinked gels which are comprised of crosslinked polyethylene.

scholarly journals Low-Density Polyethylene Films Carrying ferula asafoetida Extract for Active Food Packaging: Thermal, Mechanical, Optical, Barrier, and Antifungal Properties

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Razieh Niazmand ◽  
Bibi Marzieh Razavizadeh ◽  
Farzaneh Sabbagh
Keyword(s):  
Polymer Matrix ◽  
Food Packaging ◽  
Barrier Properties ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Optical Barrier ◽  
Leaf Extracts ◽  
Polyethylene Films ◽  
Active Food Packaging ◽  
Ferula Asafoetida

The physical, thermal, mechanical, optical, microstructural, and barrier properties of low-density polyethylene films (LDPE) containing ferula asafoetida leaf and gum extracts were investigated. Results showed a reduction in elasticity and tensile strength with increasing extract concentration in the polymer matrix. The melting temperature and enthalpy increased with increasing concentration of extracts. The films containing extracts had lower L∗ and a∗ and higher b∗ indices. The films containing leaf extract had more barrier potential to UV than the gum extracts. The oxygen permeability in films containing 5% of leaf and gum extracts increased by 2.3 and 2.1 times, respectively. The morphology of the active films was similar to bubble swollen islands, which was more pronounced at higher concentrations of gum and leaf extracts. FTIR results confirmed some chemical interactions of ferula extracts with the polymer matrix. At the end of day 14th, the growth rate of Aspergillus niger and Saccharomyces cerevisea in the presence of the PE-Gum-5 reduced more than PE-Leaf-5 (3.7 and 2.4 logarithmic cycles, respectively) compared to the first day. Our findings showed that active LDPE films have desire thermo-mechanical and barrier properties for food packaging.

Cis–trans isomerization and optical laser writing in new heterocycle based azo-polyurethanes

2012 ◽  
Vol 34 (4) ◽  
pp. 724-728 ◽  
Author(s):  
Antonio Ambrosio ◽  
Fabio Borbone ◽  
Antonio Carella ◽  
Roberto Centore ◽  
Sandra Fusco ◽  
...  
Keyword(s):  
Laser Writing ◽  
Trans Isomerization ◽  
Optical Laser

Solvent and viscosity effect on the kinetics of the thermal cis-trans isomerization of 3'-nitro-4-diethylaminoazobenzene

1989 ◽  
Vol 11 (3) ◽  
pp. 179-189 ◽  
Author(s):  
Bruno Marcandalli ◽  
Pier Luigi Beltrame ◽  
Ernestina Dubini-Paglia ◽  
Alberto Seves
Keyword(s):  
Viscosity Effect ◽  
Trans Isomerization ◽  
Kinetics Of

The Crystallization of Modified Cis-Polybutadiene

1960 ◽  
Vol 33 (3) ◽  
pp. 699-702
Author(s):  
G. S. Trick
Keyword(s):  
Melting Point ◽  
Crosslink Density ◽  
Fixed Temperature ◽  
Trans Isomerization

Abstract From a sample of polybutadiene of high cis-1,4 content, the microstructure is modified by cis-trans isomerization or by crosslinking. Measurements of rates of crystallization and melting point are made on the modified samples. An increase in irons content or crosslink density markedly decreases the rate of crystallization at a fixed temperature. It is found, however, that this retardation in rate may usually be accounted for by the depressed melting point of the modified samples.

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