scholarly journals A Bibliometric Survey on Polyisobutylene Manufacture

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1315
Author(s):  
Jessica B. Alves ◽  
Mateus K. Vasconcelos ◽  
Lys H. R. Mangia ◽  
Maxmiliano Tatagiba ◽  
Juliana Fidalgo ◽  
...  
Keyword(s):  
Cationic Polymerization ◽  
Molar Mass ◽  
Environmentally Friendly ◽  
Developed Countries ◽  
Polymer Materials ◽  
High Polymer ◽  
Technical Aspects ◽  
Mass Distributions ◽  
Highly Reactive Polyisobutylene ◽  
Catalyst Systems

Polyisobutylenes (PIB) constitute a versatile family of polymer materials that have been used mainly as fuel and lubricant additives. Particularly, the current commercial demand for highly reactive polyisobutylene (HR-PIB) products motivates the development of new processes and procedures to produce PIBs with high polymer yields, narrow molar mass distributions and high vinyl contents. For this reason, a bibliometric survey is presented here to map and discuss important technical aspects and technological trends in the field of solution cationic polymerization of isobutylenes. It is shown that investigations in this field are concentrated mainly on developed countries and that industrial initiatives indicate high commercial interest and significant investments in the field. It is also shown that use of catalyst systems based on AlCl3 and ether cocatalysts can be very beneficial for PIB and HR-PIB manufacture. Finally, it is shown that investigations search for cheaper and environmentally friendly catalysts and solvents that can be employed at moderate temperatures, particularly for the production of HR-PIB.

QELSS diffusion data for moderately broad molar mass distribution polymer samples compared with data from classical gradient techniques

1989 ◽  
Vol 54 (7) ◽  
pp. 1821-1829
Author(s):  
Bedřich Porsch ◽  
Simon King ◽  
Lars-Olof Sundelöf
Keyword(s):  
Diffusion Coefficient ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Diffusion Data ◽  
Mass Distributions ◽  
Classical Diffusion ◽  
Polydisperse Polymer

The differences between the QELSS and classical diffusion coefficient of a polydisperse polymer resulting from distinct definitions of experimentally accessible average values are calculated for two assumed specific forms of molar mass distributions. Predicted deviations are compared with the experiment using NBS 706 standard polystyrene. QELSS Dz of this sample relates within 2-4% to the classical diffusion coefficient, if the Schulz-Zimm molar mass distribution is assumed to be valid. In general, differences between the height-area and QELSS diffusion coefficient of about 20% may be found for Mw/Mn ~ 2, and this value may increase above 35%, if strongly tailing molar mass distribution pertains to the sample.

Hypotheses about the Tools Origin of Textile Materials

2015 ◽  
Vol 1090 ◽  
pp. 18-21
Author(s):  
Yuan Tao ◽  
Wei Dong Yu
Keyword(s):  
Soft Materials ◽  
Stone Tools ◽  
Polymer Materials ◽  
Evidence Based ◽  
High Polymer ◽  
Origin Time ◽  
Textile Materials ◽  
Physical Evidence ◽  
Better Than

As high polymer materials, textile materials are easily to be carbonized and then disappear, so it is almost impossible to study the origin of it from physical evidence. Based on the objective historical facts, through analysis and inference, the paper believed that textile materials, as soft materials, are better than stone tools in the aspects of obtaining, making, functions and uses. Two hypotheses about the origin of textile materials are proposed. The first is that textile materials originate from tools, and the origin time of it is not later than stone tools. The second is that signs and clothing application of textile materials both evolve from its usage as tools, so the origin sequence of textile materials is tools, signs, and clothing.

scholarly journals Recent Development of Thermostable High Polymer Materials

Kobunshi ◽  
1967 ◽  
Vol 16 (7) ◽  
pp. 795-799
Author(s):  
Masamoto WATANABE ◽  
Takashi KUZBOTA
Keyword(s):  
Polymer Materials ◽  
High Polymer

scholarly journals Visible Light-Controlled Living Cationic Polymerization of Methoxystyrene

2021 ◽  
Author(s):  
Lei Wang ◽  
Shaodong Zhang ◽  
Yongfeng Zhou ◽  
Yupo Xu ◽  
Quan Zuo ◽  
...  
Keyword(s):  
Visible Light ◽  
Cationic Polymerization ◽  
Molar Mass ◽  
Chain Transfer ◽  
Polymerization Reaction ◽  
Great Success ◽  
Living Cationic Polymerization ◽  
Green Led ◽  
Polymerization System ◽  
Lytic System

Photo-controlled living polymerization has received great attention in recent years. However, despite the great success therein, the report on photo-controlled living cationic polymerization has been greatly limited. We demonstrate here a novel decolorable, metal-free and visible light-controlled living cationic polymerization system by using tris(2,4-dimethoxyphenyl)methylium tetrafluoroborate as the photocatalyst and phosphate as the chain transfer agent (CTA) for polymerization of 4-methoxystyrene. This polymerization reaction under green LED light irradiation shows clear living characteristics including predictable molar mass, narrow molar-mass dispersity (Đ = 1.25), and sequential polymerization capability. In addition, the photocata-lytic system exits excellent “on-off” photo switchability and shows the longest “off period” of 36 h up to now for photo-controlled cationic polymerization. Furthermore, the residual photo-catalyst is easily deactivated and decolored with addition of a base after the polymerization.

scholarly journals Effect of PEEK degradation on commingled fabrics consolidation

2021 ◽  
Author(s):  
Lisa Feuillerat ◽  
Olivier De Almeida ◽  
Jean-Charles Fontanier ◽  
Fabrice Schmidt
Keyword(s):  
Melt Spinning ◽  
Molar Mass ◽  
Degradation Kinetics ◽  
Gel Permeation Chromatography ◽  
Raw Material ◽  
High Porosity ◽  
Absorption Bands ◽  
Mass Distributions ◽  
Key Factor ◽  
Lower Molar

The effects of PEEK degradation on consolidation of commingled semi-finished products have been investigated. Two commingled semi-finished products provided by two different suppliers have been studied and compared to a powdered fabric based on the same PEEK grade. Both were manufactured from aligned AS4 carbon and PEEK yarns but the first product referred as the NCF1 has a lower commingling level than the second one identified as the NCF2. Contrary to what could be expected, under the same processing conditions, consolidation of the NCF1 and the NCF2 systematically results in a high porosity content, above 10%. Fourier Transform Infrared spectrophotometry (FTIR) in ATR mode and Gel Permeation Chromatography (GPC) have shown small molecular structure modifications of PEEK yarns compared to the raw material, such as a shift of molar mass distributions towards lower molar mass and the appearance of C-H absorption bands attributed to non-aromatic alkanes. These modifications have been attributed to sizing of PEEK filament. Calorimetric (DSC) and rheological analyses have demonstrated that the presence of sizing in the semi-finished products have huge consequences on the degradation kinetics. The crystallization temperature decreases and the viscosity increases significantly. This acceleration of the degradation kinetics is the reason of the poor consolidation behavior during composite manufacturing. The conditions of melt spinning extrusion under which the neat PEEK is transformed into filament are therefore a key factor of PEEK degradation.

scholarly journals Meta Analisis Pengembangan Assesment Kelayakan Sistim Pembangkit Tenaga Air

2018 ◽  
Vol 18 (2) ◽  
pp. 123-132
Author(s):  
Suryadimal Suryadimal
Keyword(s):  
Power Plant ◽  
Feasibility Study ◽  
Meta Analysis ◽  
Feasibility Studies ◽  
Developed Countries ◽  
Journal Articles ◽  
Technical Aspects ◽  
Feasibility Assessment ◽  
Cultural Aspects ◽  
Rating Model

Abstract-This study aims to determine the feasibility assessment of hydroelectricity to feasibility studies that have been conducted in various developing and developed countries. In a feasibility study usually consider various important aspects such as technical and non technical aspects that will affect the productivity of a feasibility study.Methododologi research based on the meta-analysis method, in which the analysis is based on a review of a number of research results on similar issues in the case of a feasibility assessment of the power plant system. Approaches are based on journal articles and research reports that are taken based on their compatibility with the theme of research. The technical aspects used are hydraulic and civil aspects, mechanical and electrical aspects, while non technical aspects are economic, social and cultural aspects. So with the development of this feasibility rating model can be a reference for developers, government and investors to decide the feasibility of a power plant investment   Keywords: Assessment Feasibility, Hydropower, Power Plant, Feasibility Study, Meta analysis

Sign in / Sign up

Export Citation Format

Share Document