Photosensitive Polyimides

1989 ◽  
Vol 167 ◽  
Author(s):  
Hiroo Hiramoto
Keyword(s):  
Polymer Chains ◽  
Double Bonds ◽  
Acid Base ◽  
Film Properties ◽  
Covalent Bonds ◽  
Two Factors ◽  
Patterned Films ◽  
The Way

AbstractPhotosensitive polyimides are used as insulation and protection layers for microelectronics. They can easily give fine-patterned films with excellent characteristics of polyimides by photolithographic procedure.Photosensitive groups such as double bonds, azides, o-nitrobenzyl and o-naphthoquinonediazides. These photosensitive groups are incorporated to polymer chains through covalent bonds or acid-base ion bonds. Some polyimides have photosensitivity even without intentionally introduced photosensitive groups. Most of photosensitive polyimides are negative working, and a few of them are positive working.Characteristics of photosensitive polyimides are determined by two factors, the way of introducing photosensitive groups and the structures of polyimide backbone chains. Photosensitivity, resolution, purity and easiness of imidization mainly depends on the former factor. The film properties after curing are mainly determined by the latter. The film properties, however, are affected by the former when imide cyclization is imperfect.Photosensitive polyimides are widely used as protection and insulation layers of VLSI, multi-chip modules for computers, telecommunication, linephotosensors, thermal-heads, etc.

scholarly journals Advances in the Multi-Orthogonal Folding of Single Polymer Chains into Single-Chain Nanoparticles

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 293
Author(s):  
Agustín Blazquez-Martín ◽  
Ester Verde-Sesto ◽  
Angel J. Moreno ◽  
Arantxa Arbe ◽  
Juan Colmenero ◽  
...  
Keyword(s):  
Computer Simulations ◽  
Chemical Species ◽  
Synthetic Polymers ◽  
Review Article ◽  
Polymer Chains ◽  
Single Chain ◽  
High Dilution ◽  
Covalent Bonds ◽  
Covalent Interactions ◽  
Individual Polymer

The folding of certain proteins (e.g., enzymes) into perfectly defined 3D conformations via multi-orthogonal interactions is critical to their function. Concerning synthetic polymers chains, the “folding” of individual polymer chains at high dilution via intra-chain interactions leads to so-called single-chain nanoparticles (SCNPs). This review article describes the advances carried out in recent years in the folding of single polymer chains into discrete SCNPs via multi-orthogonal interactions using different reactive chemical species where intra-chain bonding only occurs between groups of the same species. First, we summarize results from computer simulations of multi-orthogonally folded SCNPs. Next, we comprehensively review multi-orthogonally folded SCNPs synthesized via either non-covalent bonds or covalent interactions. Finally, we conclude by summarizing recent research about multi-orthogonally folded SCNPs prepared through both reversible (dynamic) and permanent bonds.

scholarly journals Enzymatic and Chemical Cross-Linking of Bacterial Cellulose/Fish Collagen Composites—A Comparative Study

2021 ◽  
Vol 22 (7) ◽  
pp. 3346
Author(s):  
Agata Sommer ◽  
Paulina Dederko-Kantowicz ◽  
Hanna Staroszczyk ◽  
Sławomir Sommer ◽  
Marek Michalec
Keyword(s):  
Thermal Stability ◽  
Bacterial Cellulose ◽  
Secondary Alcohol ◽  
Water Vapor Permeability ◽  
Polymer Chains ◽  
Cross Linking ◽  
Vapor Permeability ◽  
Covalent Bonds ◽  
Fish Collagen ◽  
Chemical Cross Linking

This article compares the properties of bacterial cellulose/fish collagen composites (BC/Col) after enzymatic and chemical cross-linking. In our methodology, two transglutaminases are used for enzymatic cross-linking—one recommended for the meat and the other proposed for the fish industry—and pre-oxidated BC (oxBC) is used for chemical cross-linking. The structure of the obtained composites is characterized by scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy, and their functional properties by mechanical and water barrier tests. While polymer chains in uncross-linked BC/Col are intertwined by H-bonds, new covalent bonds in enzymatically cross-linked ones are formed—resulting in increased thermal stability and crystallinity of the material. The C2–C3 bonds cleavage in D-glucose units, due to BC oxidation, cause secondary alcohol groups to vanish in favor of the carbonyl groups’ formation, thus reducing the number of H-bonded OHs. Thermal stability and crystallinity of oxBC/Col remain lower than those of BC/Col. The BC/Col formation did not affect tensile strength and water vapor permeability of BC, but enzymatic cross-linking with TGGS improved them significantly.

Effect of Acid–Base Interactions on Conformation of Adsorbed Polymer Chains

2015 ◽  
Vol 5 (1) ◽  
pp. 45-49 ◽  
Author(s):  
He Zhu ◽  
Nishad Dhopatkar ◽  
Ali Dhinojwala
Keyword(s):  
Polymer Chains ◽  
Acid Base ◽  
Adsorbed Polymer

Influence of mineralogy and moisture content on plasticity and induced anisotropic damage of a claystone; application to nuclear waste disposals

2000 ◽  
Vol 171 (6) ◽  
pp. 621-627 ◽  
Author(s):  
Anne-Sophie Chiarelli ◽  
Beatrice Ledesert ◽  
Malek Sibai ◽  
Mohammed Karami ◽  
Nasser Hoteit
Keyword(s):  
Moisture Content ◽  
Nuclear Waste ◽  
Mechanical Behaviour ◽  
Triaxial Compression ◽  
Anisotropic Damage ◽  
Compression Tests ◽  
Two Factors ◽  
Triaxial Compression Tests ◽  
The Way

Abstract The influence of mineralogy and moisture content on mechanical behaviour of a claystone rock is studied by the way of uniaxial and triaxial compression tests and microscopic observations. Some parameters characteristic of phenomena like plasticity and induced anisotropic damage are discussed as a function of these two factors. Rock behaviour becomes more brittle when calcite content grows or when clay or moisture content decreases. At the microlevel, plasticity is induced by slip of clay sheets and induced anisotropic damage appears by growth of oriented microcracks at the interface between grains and matrix.

National Alliances and Global Webs: The Internationalization of Japanese Shipping

1998 ◽  
Author(s):  
William D. Wray
Keyword(s):  
Trade Networks ◽  
Shipping Company ◽  
Two Factors ◽  
Primary Focus ◽  
The Way

This chapter examines the process and factors necessary for the internationalisation of shipping to successfully occur, using Japan as an example. The chapter is divided into two sections:- the first studies the two factors that enable internationalisation - technology and investment - as they apply to Japanese shipping; the second examines the way internationalisation evolves, by presenting and dissecting two narratives - the rise of Japan’s trade networks, and alliances within the global web. The primary focus of study is the Nippon Yusen Kaisha (NYT) shipping company.

A healable waterborne polyurethane synergistically cross-linked by hydrogen bonds and covalent bonds for composite conductors

2020 ◽  
Vol 8 (15) ◽  
pp. 5280-5292 ◽  
Author(s):  
Yan Yang ◽  
Zushan Ye ◽  
Xiaoxuan Liu ◽  
Jiahui Su
Keyword(s):  
Hydrogen Bonds ◽  
Waterborne Polyurethane ◽  
Double Bonds ◽  
Covalent Bonds ◽  
Waterborne Polyurethanes ◽  
Composite Conductors

Healable waterborne polyurethanes synergistically cross-linked by dynamic hydrogen bonds and photo-curable double bonds for composite conductors.

FUNCTIONALIZED SBRs IN SILICA-REINFORCED TIRE TREAD COMPOUNDS: EVIDENCE FOR INTERACTIONS BETWEEN SILICA FILLER AND ZINC OXIDE

2016 ◽  
Vol 89 (4) ◽  
pp. 559-572 ◽  
Author(s):  
S. Maghami ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Carbon Black ◽  
Rolling Resistance ◽  
Major Change ◽  
Polymer Chains ◽  
Silane Coupling Agents ◽  
Covalent Bonds ◽  
Oh Groups ◽  
Polar Functional Groups

ABSTRACT Unlike carbon black, silica is polar and naturally not compatible with nonpolar hydrocarbon elastomers. This lack of interaction or compatibility between the filler and the elastomer typically causes lower properties compared with carbon black–filled compounds. A common approach to deal with this problem is to use silane coupling agents in the system to link the silica and the polymer chains via covalent bonds. An alternative is the introduction of polar functional groups or chemically reactive groups into the elastomer chains, which can improve the compatibility of elastomers with fillers such as silica. In this article, the effect of three functionalized SBRs, one backbone modified with carboxylate moieties, one modified with dithiol groups, and one partially Si-coupled, on the dynamic and mechanical properties of a silica-reinforced tire tread compound will be discussed and compared with a reference compound that contains unmodified s-SBR as the main polymer. The results show the significant potential of two of these modified SBRs to reduce the rolling resistance of tire treads made thereof, while no major change in wet grip occurs. Zinc oxide is known as the best activator for sulfur vulcanization. Zn ions combine with accelerators to form an active complex that catalyzes the vulcanization process. However, in silica-filled compounds, ZnO may interfere with the silanization process because of its alkaline nature, and it may compete with the silanes in reacting with the acidic –OH groups on the surface of silica particles. When functionalized SBRs with higher polarity are used in silica compounds, ZnO may interact with these moieties as well. To investigate the effect of ZnO on the properties of the silica-reinforced tread compound, a series of compounds have been prepared, in which the addition of ZnO in a later stage was compared with conventional mixing. The dynamic and mechanical properties of the final compounds are discussed.

Proton-Conducting Cross-Linked Sulfonated Aromatic Polymers for Fuel Cells Application

2012 ◽  
Vol 1384 ◽  
Author(s):  
B. Maranesi ◽  
L. Pasquini ◽  
M. Khadhraoui ◽  
P. Knauth ◽  
M.L. Di Vona
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Hydrolytic Degradation ◽  
Exchange Capacity ◽  
Polymer Chains ◽  
Cross Linking ◽  
Ionic Exchange ◽  
Acid Base ◽  
Acid Base Titration ◽  
Aromatic Polymers

AbstractThermal stability, hydration and mechanical properties of thermally cross-linked Sulfonated Aromatic Polymers (SAP) with high ionic exchange capacity (IEC) were measured and compared to untreated samples. The formation of cross-linking greatly stabilizes SAP in terms of thermal, mechanical, and hydrolytic degradation: they can resist in water even at a temperature of 145 °C with improved mechanical properties. Acid-base titration and FTIR spectra consistently indicate that SAP microstructure stabilization is related to cross-linking of the polymer chains by SO2 bridges, which is promoted by temperature.

Public Budget Reform and Reform Failure in a Market Model

2001 ◽  
Vol 19 (1) ◽  
pp. 55-69
Author(s):  
Matthew Andrews
Keyword(s):  
Public Choice ◽  
Choice Model ◽  
Current Paper ◽  
Market Model ◽  
Public Budget ◽  
The Public ◽  
Budget Reform ◽  
Two Factors ◽  
Budgeting Process ◽  
The Way

Abstract Budgeting theories have not been able to explain why reforms have a limited influence on the budgeting process [JOYCE, 1993]. The current paper proposes a market-based theory of budget reform, which combines the public choice model with new institutional dunking, in the spirit of authors like Kraan [1996]. The dieory unfolds into specific hypodieses about the way in which reform adoption is dependent on the authority of budgeting bureaucrats to adopt reforms, the level of reform acceptance among these bureaucrats and politicians, and the ability of bureaucrats to adopt the reforms. The first two factors, authority and acceptance, are argued to be more important than ability in influencing the level of budget reform adoption.

Literary vs. Technical Writing: Substitutes vs. Standards for Reality

1988 ◽  
Vol 18 (3) ◽  
pp. 241-262 ◽  
Author(s):  
Alan D. Manning
Keyword(s):  
Technical Writing ◽  
Visual Representation ◽  
Visual Medium ◽  
Line Drawings ◽  
Predominant Type ◽  
Two Factors ◽  
Literary Writing ◽  
The Difference ◽  
The Way

This article proposes a means of characterizing the difference between technical and literary writing, involving a theory of representation in which these distinct writing types are comparable to distinct types of visual representation. Any difference is only intelligible relative to a background of similarlity, but recent discussions of technical writing emphasize its similarity to literature and ignore significant differences. Distinct types of line drawings replicate the literary/technical contrast in a visual medium. This arises from two factors: 1) the way in which the drawing/text is perceived by the viewer/reader, as a substitute or as a standard; and 2) the predominant type of detail in the drawing/text, iterative or contrastive. Literature is most effective if perceived as a substitute for reality, predominated by iterative detail. Technical writing is most effective if perceived as a standard for evaluating reality, predominated by contrastive detail.

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