Search results for "Polyol"
showing 10 items of 73 documents
Radiation grafting functionalization of poly (vinylidene fluoride) to compatibilize its blends with polyolefin ionomers
1998
Blends of a crystalline vinylidene fluoride copolymer (PVDF) and a polyolefin ionomer were produced by melt mixing and characterized by a variety of techniques to examine the effect of increasing the level of salt formation on morphology. The PVDF component was also grafted with methacrylic acid by irradiating the polymer powder and subsequently treating it with an aqueous monomer solution. The effect of neutralizing the acid in both polymer components to produce the corresponding zinc salt was also investigated. Compatibilization was accomplished by the addition of zinc acetyl acetonate (ZnAcAc) to the mixture. This increased the viscosity of the polyolefin ionomer phase, comparable to tha…
Rapeseed oil-based rigid polyisocyanurate foams modified with nanoparticles of various type
2014
Polyisocyanurate foams have been developed using a polyol system partially derived from rapeseed oil (RO). The effect of nanofillers with iso-dimensional geometry (zinc oxide), nanofibers (carbon nanotubes), and nanoplatelets (organically modified montmorillonite) on stiffness and strength of the foams has been studied. It was demonstrated that the tensile properties of the filled foams are enhanced by roughly the same proportion as the stiffness and strength of monolithic filled polymers.
Hyperbranched aliphatic polyether polyols
2012
Hyperbranched polymers, dendritic macromolecules with branch-on-branch structures, have become an important polymer class since the early 1990s. They combine several advantages of the perfectly branched dendrimers with easy accessibility, typically in a one-step synthesis. Hyperbranched polyethers are a particularly interesting class of chemically stable and often biocompatible materials. Multifunctional hyperbranched polyethers with controllable molar mass and comparably low polydispersities can been prepared using hydroxyl-functional epoxides or oxetanes for polymerization via anionic and cationic polymerization mechanisms. Here, we review the progress in the preparation, characterization…
Halloysite nanotubes as polyolefin fillers
2015
Artykuł stanowi przegląd najnowszej literatury dotyczącej nanokompozytów poliolefinowych napełnianych nanorurkami haloizytowymi (HNT). Omówiono wpływ dodatku HNT na osnowę poliolefinową, ze szczególnym uwzględnieniem morfologii oraz właściwości mechanicznych nanokompozytów poliolefina/HNT. Modyfikowane HNT wykazywały wysoki stopień rozproszenia w osnowie poliolefinowej, dzięki czemu powodowały poprawę właściwości mechanicznych poliolefinowych nanokompozytów napełnianych nanorurkami haloizytowymi. Połączenie korzystnych właściwości poliolefin, ekonomicznych metod ich przetwórstwa oraz unikatowych w³aoeciwooeci HNT pozwoli na szersze rozpowszechnienie nanokompozytów wytworzonych z ich udziałe…
One-pot synthesis of poly(l-lactide) multi-arm star copolymers based on a polyester polyol macroinitiator
2013
Abstract Using a hyperbranched poly(glycolide) ( hb PGA) macroinitiator the synthesis of poly( l -lactide) (PLLA) multi-arm star polyesters has been achieved via a core-first approach. The star-shaped copolymers were prepared in a one-pot two-step process via Sn(Oct) 2 -catalyzed ring-opening polymerization (ROP) conducted in the melt. Complete conversion of the end groups of the hb polyglycolide polyester polyols is ensured by the reactive primary hydroxyl termini. By adjusting the monomer/initiator ratio a series of star copolymers with varying PLLA arm length has been obtained with molecular weights in the range of 1500 to 10,000 g/mol (SEC). The successful coupling of the PLLA arms to t…
Hyperbranched Poly(propylene oxide): A Multifunctional Backbone-Thermoresponsive Polyether Polyol Copolymer
2012
Backbone-thermoresponsive hyperbranched poly(propylene oxide)-based polyether polyols have been synthesized by anionic ring-opening copolymerization of glycidol and propylene oxide. The number of functional hydroxyl end groups and the lower critical solution temperature (LCST) can be readily adjusted by varying the comonomer ratio. Molecular weights in the range of 1200-2000 g/mol were achieved. Hyperbranched polyether polyols with LCST values between 24 and 83 °C can be obtained in a convenient one-step reaction.
Rapid Synthesis and MALDI-ToF Characterization of Poly(ethylene oxide) Multiarm Star Polymers
2009
Multiarm PEO star polymers with a purely aliphatic polyether structure have been synthesized using hyperbranched polyglycerol (PG) with different molecular weights as a multifunctional initiator. Different degrees of deprotonation of the initiator were studied with respect to molecular weight control. The results show that the degree of deprotonation is a crucial parameter for the synthesis of well-defined polymers with controlled molecular weights. Partial deprotonation of the PG hydroxyl groups (5-8%) was proven to represent an optimum for the synthesis of star polymers with molecular masses close to the theoretical values. Molecular weights of the stars ranged between 9 000 and 30000g · …
Novel polyolefin materials via catalysis and reactive processing
1998
Recent advances in transition metal catalyzed olefin polymerization and melt processing stimulate the production of new polymers derived from old monomers Modern polyolefin processes do not require polymer purification and give excellent control of molecular and supermolecular polyolefin architectures. Progress in catalyst design and preparation of tailor-made homo-and copolymers is highlighted for isotactic, syndiotactic, atactic and stereoblock polypropylene (PP), novel 1-olefin copolymers, and ethylene copolymers with polar monomers, e.g., CO and acrylics Today polyethylene short-and long-chain-branching is controlled either by uniform ethylene copolymerization with 1-olefins using singl…
Thermal degradation of highly crosslinked rigid PU-PIR foams based on high functionality tall oil polyol
2019
Abstract This study presents the development and analysis of rigid polyurethane-polyisocyanurate (PU-PIR) foam synthesized from high functionality tall oil (TO) based polyols. Three PU-PIR formulations with varied high functionality TO based polyol content (45, 75 and 95 pbw) and a different tier of isocyanate (NCO) indexes (110, 150, 200, 300 and 400) for each formulation were compared to a formulation developed using conventional raw materials, mainly obtained from petrochemicals. Using the Fourier transform infrared spectral analysis (FTIR), the chemical structure of the foams was evaluated with emphasis on the characteristic PU-PIR signal ratio and isocyanurate signal peaks. The thermal…
Determination of zirconium traces in polymers by ICP-IDMS - a powerful and fast method for routine testing of zirconium residues in polyolefins
1999
Zirconium trace analyses play an important role for polyolefins produced by modern catalytic processes with zirconium metallocenes. A reliable and fast routine testing method by inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) was therefore developed, which allows the determination of zirconium in polymers down to the low ng/g level. With respect to its precision, accuracy, and time-consumption this method is suitable for routine testing of production processes. A spike solution, enriched in the stable isotope 91Zr, was prepared and used for the isotope dilution procedure, which has the advantage of being an internal “one point” calibration method. The polyolefin sam…