نتایج جستجو برای: catalytic ethylene polymerization

تعداد نتایج: 135095  

2016
Siew Yin Chan Wee Sim Choo David James Young Xian Jun Loh

Pectin is an anionic, water-soluble polymer predominantly consisting of covalently 1,4-linked α-D-galacturonic acid units. This naturally occurring, renewable and biodegradable polymer is underutilized in polymer science due to its insolubility in organic solvents, which renders conventional polymerization methods impractical. To circumvent this problem, cerium-initiated radical polymerization ...

2001
Madeline Torres-Lugo Nicholas A. Peppas

Novel complexation hydrogel nanospheres of poly(methacrylic acid-grafted-poly(ethylene glycol)) (P(MAA-gEG)) were prepared by dispersion polymerization to be used for protein delivery applications. Polymerization was conducted in solvents such as deionized water, ethanol/water, sodium hydroxide, hydrochloric acid, and acetic acid solutions. When polymerizing in deionized water we produced nanos...

Journal: :Journal of biomedical materials research 2002
Zhiqiang Yang Yuehua Zhang Peter Markland Victor C Yang

A class of new biodegradable hydrogels based on poly(ethylene glycol) methacrylate-graft-poly(glutamic acid) and poly(ethylene glycol) dimethacrylate was synthesized by photoinduced polymerization. Because all the polymeric constituents were highly hydrophilic, crosslinking could be performed in aqueous solutions. This type of crosslinked hydrogel was prepared by modifying a select number of ac...

1999
Robert A. Scott Nicholas A. Peppas

Novel ionizable polymer networks were prepared from oligo(ethylene glycol) (OEG) multiacrylates and acrylic acid (AA), employing bulk radical photopolymerization techniques. The properties of these materials exhibit a complex dependence on the network structure and composition. Dynamic mechanical analysis and penetrant sorption experiments demonstrated that the cross-linked structure of the mat...

Journal: :European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V 2004
Aaron C Foss Nicholas A Peppas

Microparticles or nanospheres of hydrogels of crosslinked poly(methacrylic acid) grafted with poly(ethylene glycol) as well as crosslinked poly(acrylic acid) grafted with poly(ethylene glycol) were prepared for use as oral insulin delivery carriers. The copolymer carriers were synthesized by precipitation/dispersion polymerization that led to gel nanospheres or by bulk polymerization and subseq...

Journal: :Angewandte Chemie 2001
Stefan Mecking

Polyolefins are of vast economic importance, which is reflected by an annual production of more than 70 million tons of polyethylene and polypropylene. While the major portion of these materials is produced with Zieglerand chromium-based catalysts, the older free-radical process that affords low-density polyethylene (LDPE) has maintained its significance.[1] Despite the necessity of working at ...

Journal: :Reaction Kinetics and Catalysis Letters 1979

Journal: :Dalton transactions 2015
Yuguo Ma Emil B Lobkovsky Geoffrey W Coates

New titanium(IV) complexes having two bidentate β-iminoethyl-spiro[4,5]decan-6-onato ligands with various N-aryl substituents have been synthesized. X-ray crystal structure analysis reveals that these titanium complexes all exhibit a C2-symmetric conformation with a distorted octahedral geometry, although the specific orientation of the ligands around the titanium center varies with the identit...

2009
Shuang Deng Songgeng Li Huiquan Li Yi Zhang

The catalytic performance of Fe-Cr/ZrO2 catalysts, prepared by two different methodsscoprecipitation and coprecipitation-impregnation were examined in oxidative dehydrogenation of ethane to ethylene using CO2 as an oxidant. Thermogravimetric analysis and physicochemical characterization such as XPS, XRD, and BET were performed to explore the correlation of catalytic performance with physicochem...

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