While crystallization behavior of isotactic polypropylene homopolymers had been subject to a wide range experimental and modeling studies, this is not the case for propylene-ethylene random copolymers (PPR). This class polymers offers up now significant challenges, both from an as well perspective. The ethylene incorporation in propylene chains, distribution comonomer, has marked effect on kine...

A new product (Application 460B-00) from Agilent Technologies/WassonECE uses a 5973N GC/MSD (gas chromatograph/mass selective detector) for the determination of trace levels of impurities that are moderate-to-low carbon-content such as oxygenates, mercaptans, sulfides, arsine, and phosphine in ethylene and propylene. This work describes the performance of Application 460B-00 with respect to lin...

in this work, new biodegradable abcba type pentablock copolymers with different mole ratio of l-lactide and ppdo-b-peg-b-ppdo triblock copolymer were synthesized and characterized. in the first step, ppdo-b-peg-b-ppdo triblock copolymer was synthesized via a ring-opening polymerization of p-dioxanone (pdo) monomer with poly (ethylene glycol) (peg) using stannous octoate (sn(oct)2) as the cataly...

The temperature-induced structural changes and thermodynamics of ionic microgels based on poly(acrylic acid) (PAA) networks bonded with poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) (Pluronic) copolymers have been studied by small-angle neutron scattering (SANS), ultra-small-angle neutron scattering (USANS), differential scanning calorimetry (DSC), and equili...

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...

The aims of our study were to assess the release of cytotoxic nucleoside analogs 5-fluorouracil and 2-chloro-2'-deoxyadenosine from different lactide-glycolide or lactide-caprolactone biodegradable copolymers and the effects of sterilization on this release. The polymers were sterilized either with ethylene oxide at 37 degrees C, or with gamma radiation (15 kGy, 20 kGy, or 25 kGy). The kinetics...

Tri-block copolymers (poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide), represented as EOxPOyEOx), pluronics (F127 = EO106PO70EO106, P65 = EO20PO30EO20, P85 = EO27PO39EO27, P103 = EO17PO55EO17, and P123 = EO20PO70EO20) and cationic surfactants (cethyltrimethylammonium bromide (CTAB)), two surfactant systems, form complex micelles that self-assemble into mesostructured particles w...

Direct dissolution of glycosylated polybutadiene-poly(ethylene oxide) block copolymers can lead to the spontaneous formation of vesicles or membranes, which on the outside are coated with glucose and on the inside with poly(ethylene oxide).

Ethylene binding to seedling tissue of Vicia faba, Phaseolus vulgaris, Glycine max, and Triticum aestivum was demonstrated by determining transit time required for ethylene to move through a glass tube filled with seedling tissue. Transit time for ethylene was greater than that for methane indicating that these tissues had an affinity for ethylene. However, the following observations suggest th...

Aggregation of thermosensitive polymer-coated gold nanoparticles was performed in aqueous solution in the presence of a triblock copolymer poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic P123, PEO(20)-PPO(68)-PEO(20)). The gold nanoparticles, AuNPs, which are covered by thermosensitive statistical copolymers poly(EO(x)-st-PO(y)), aggregate when the temperat...