نتایج جستجو برای: polymer microstructure

تعداد نتایج: 132259  

2017
Ning Li José Darío Perea Thaer Kassar Moses Richter Thomas Heumueller Gebhard J. Matt Yi Hou Nusret S. Güldal Haiwei Chen Shi Chen Stefan Langner Marvin Berlinghof Tobias Unruh Christoph J. Brabec

The performance of organic solar cells is determined by the delicate, meticulously optimized bulk-heterojunction microstructure, which consists of finely mixed and relatively separated donor/acceptor regions. Here we demonstrate an abnormal strong burn-in degradation in highly efficient polymer solar cells caused by spinodal demixing of the donor and acceptor phases, which dramatically reduces ...

2009
M Antunes D Arencón V Realinho J I Velasco

Abstract. The use of polyolefin flexible foams with typical thicknesses between 1 and 3 mm produced by a physical foaming extrusion process is nowadays quite widespread in the packaging sector. Their high flexibility and closed-cell structure allows them to show good energy absorption properties under low loading conditions. Although the compressive response of these materials is well known, th...

Journal: :Soft matter 2014
Yen-Hao Lin Kevin G Yager Bridget Stewart Rafael Verduzco

All-conjugated block copolymers are an emerging class of polymeric materials promising for organic electronic applications, but further progress requires a better understanding of their microstructure including crystallinity and self-assembly through micro-phase segregation. Here, we demonstrate remarkable changes in the thin film structure of a model series of all-conjugated block copolymers w...

2010
Dimitrios Bikiaris

In the last few years, great attention has been paid to the preparation of polypropylene (PP) nanocomposites using carbon nanotubes (CNTs) due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. This is due to the unique combination of structural, mechanical, electrical, and thermal transport properties of CNTs. Howev...

2007
M. Caggioni P. T. Spicer D. L. Blair S. E. Lindberg D. A. Weitz X. R. Wang

Particle tracking microrheology is used to study the effect of a constant applied shear during gelation of aqueous gellan gum with a monovalent salt. Shear modifies the gellan gum hydrogel microstructure and the bulk rheological properties of the system, depending on whether shear is applied during gelation or afterwards. The microstructure determines the linear elastic response of the gel, as ...

2015

Cement-based concrete is the most widely used building and construction material in the world. Although concrete itself is relatively durable when used under the mild environments, its intrinsic weak tensile strength greatly limits its application due to its porous structure. Traditional strategies to overcome this weakness of concrete include utilization of various reinforcing materials, such ...

2012
Hui Yao Zhanping You Liang Li Shu Wei Goh Chee Huei Lee Yoke Khin Yap Xianming Shi

This work aims to improve the rutting and fatigue cracking resistance of asphalt binders using selected nanoor micro-sized materials and to shed light on the microstructure changes induced by such modification to asphalt binders. The four modifiers (Nanomer I.44P, carbon microfiber, non-modified nanoclay and polymer modified nanoclay) were added into the control asphalt binder (PG 58-34). The S...

2013
Mark W. Tibbitt April M. Kloxin Lisa A. Sawicki Kristi S. Anseth

The relationship between polymeric hydrogel microstructure and macroscopic properties is of specific interest to the materials science and polymer science communities for the rational design of materials for targeted applications. Specifically, research has focused on elucidating the role of network formation and connectivity on mechanical integrity and degradation behavior. Here, we compared t...

2008
Darmawati Mohamad Yunos Aldo R. Boccaccini

Designing tissue engineering scaffolds with the required mechanical properties and favourable microstructure to promote cell attachment, growth and new tissue formation is one of the key challenges facing the tissue engineering field. An important class of scaffolds for bone tissue engineering is based on bioceramics and bioactive glasses, including: hydroxyapatite, bioactive glass (e.g. Biogla...

Journal: :polyolefins journal 1999
giovanni ricci giuseppe leone

the stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining ticl4 or ticl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...

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