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Copolymers Used (copolymer + used)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Essential work of fracture (EWF) analysis for compression molded alternating poly(propylene carbonate)

POLYMER ENGINEERING & SCIENCE, Issue 3 2004
K. L. Fung
In this investigation, the main objective was to study the mechanical properties of alternating poly(propylene carbonate) copolymer (PPC). The PPC used in this study was derived from propylene oxide and carbon dioxide using zinc glutarate as catalyst. The molecular weight of the PPC copolymer used in this study has M,n,33,000. The synthesized PPC was compression molded into sheets of thickness ,1mm. The fracture toughness of the PPC films was determined using the essential work of fracture (EWF) technique, at a laboratory temperature of 20°C, and a loading rate of 1 mm/min. During the EWF measurement, a significant amount of plastic deformation has taken place around the initial ligament region. The measured specific total fracture work (wf) was observed to vary in a linear fashion with the specimen ligament (l), and hence satisfied the basic requirement for EWF analysis. The specific essential fracture work (we) for the PPC film was measured to be 11.0 kJ/m2. The PPC showed a prominent recovery behavior. The severely deformed region surrounding the fracture ligament was observed to recover completely 8 days after fracture testing. Polym. Eng. Sci. 44:580,587, 2004. © 2004 Society of Plastics Engineers. [source]

Synthesis of Poly(3,4-ethylenedioxythiophene) latexes using poly(N -vinylpyrrolidone)-based copolymers as reactive stabilizers

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2010
Muhammad Mumtaz
Abstract The synthesis by oxidative polymerization of well-defined poly(3,4-ethylenedioxythiophene) (PEDOT) nano-objects in the presence of modified and unmodified poly(N -vinylpyrrolidone)-based copolymers used as stabilizers in aqueous media is reported. Ammonium persulfate or a mixture of ammonium persulfate with CuCl2 or CuBr2 was used as oxidants. The effects of several parameters such as the molar mass and the concentration of the stabilizer as well as the nature of the oxidants on the size, morphology, and the conductivity of the PEDOT particles have been investigated. The distribution of the reactive moieties along the copolymer stabilizer backbone was shown to be crucial to get well-defined PEDOT nano-objects. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3841,3855, 2010 [source]

Reactively and physically compatibilized immiscible polymer blends: stability of the copolymer at the interface

MACROMOLECULAR SYMPOSIA, Issue 1 2003
Charef Harrats
Abstract This paper reports on the interfacial behaviour of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been shown in both reactive blending and blend compatibilization by preformed copolymers. Polystyrene (PS)/polyamide6 (PA6), polyphenylene oxide (PPO)/PA6 and polymethylmethacrylate (PMMA)/PA6 blends have been reactively compatibilized by a styrene-maleic anhydride copolymer SMA. The extent of miscibility of SMA with PS, PPO and PMMA is a key criterion for the stability of the graft copolymer at the interface. For the first 10 to 15 minutes of mixing, the in situ formed copolymer is able to decrease the particle size of the dispersed phase and to prevent it from coalescencing. However, upon increasing mixing time, the copolymer leaves the interface which results in phase coalescence. In PS/LDPE blends compatibilized by preformed PS/hydrogenated polybutadiene (hPB) block copolymers, a tapered diblock stabilizes efficiently a co-continuous two-phase morphology, in contrast to a triblock copolymer that was unable to prevent phase coarsening during annealing at 180°C for 150 minutes. [source]

Adhesion control for injection overmolding of polypropylene with elastomeric ethylene copolymers

POLYMER ENGINEERING & SCIENCE, Issue 10 2009
Marco Dondero
Two types of random semicrystalline copolymers (ethylene,octene and ethylene,butene) were overmolded on a core polypropylene. Maximum solid,liquid interface temperature achieved for the overmolding injection process is used as the key parameter for adhesion control. The main bonding process is shown to be a Rouse-type fingering mechanism that develops in short time scales. Normalized peel tests were conducted on overmolded samples to measure the resulting polypropylene copolymers' bonding strength. All the ethylene random copolymers used for this study give good adhesion to polypropylene in overmolding processes, provided the right range of interface temperature is reached. Adhesion strength can be easily controlled for efficient debonding and recycling of used overmolded parts. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]