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Models, together with a comparison with experimental data, are presented for the particle nucleation under monomer-starved conditions. In the first model, simplifications were made to obtain analytical solutions. The Smith and Ewart theory was extended to include particle formation under monomer-starved conditions. It was assumed that the rate of particle growth is controlled by the rate of monomer...
Reactor blends of polyethylene/poly(ethylene-co-1-octene) resins with bimodal molecular weight and bimodal short chain branching distributions were synthesized in a two-step polymerization process. The compositions of these blends range from low molecular weight (LMW) homopolymer to high molecular weight (HMW) copolymer and vice versa HMW homopolymer to LMW copolymer. The shear flow characteristics...
This work investigates the effect of kinetic chain length on the network structure of multi-functional (meth)acrylates. Two chain transfer agents, dodecanethiol and m-toluenethiol, were added to a series of crosslinking free radical polymerizations to decrease the kinetic chain length. Using near-IR spectroscopy and dynamic mechanical analysis, the effect of chain transfer on the polymerization rate...
Nanoindentation measurements are made on thermosetting materials using cantilever deflection vs. piezoelectric scanner position behavior determined by atomic force microscope (AFM). The spring model is used to determine mechanical properties of materials. The generalized Sneddon's equation is utilized to calculate Young's moduli for thermosetting materials at ambient conditions. Our investigations...
The effect of melamine polyphosphate (MpolyP) on the thermal degradation of both polyamide 66 (PA66) and polyamide 6 (PA6) was studied using a combination of solid-state techniques. The mixtures of MpolyP with polyamides were heated for different times at 350 and 450°C. The residues were then analyzed by X-ray diffraction and both solid-state 13 C NMR and 31 P NMR. The chemical structures...
Certain cellulose samples, especially those of higher molecular weight, are initially insoluble in N,N-dimethylacetamide (DMAc, 1)/lithium chloride, which is a very common solvent system for cellulosic materials. According to a common protocol, heating or refluxing these samples in DMAc, or in DMAc containing dissolved LiCl, represents one of several so-called ‘activation’ procedures, which are aimed...
The plasticizing effect on wheat gluten of a series of saturated fatty acids with different carbon chain length (from 6 to 10 carbons) was investigated. Plasticized materials were obtained by mixing in a counter-rotating batch mixer. The wheat gluten plasticization with the saturated fatty acids was shown to be thermodependent. Differential scanning calorimetry enabled the determination of the compatibility...
A computational study of the ethylene–styrene copolymerization with rac-ethylenebis(tetrahydroindenyl)MCl 2 [M=Ti, Zr] systems using DFT methods is presented. The complexation, coordination and insertion energies for ethylene and styrene monomers as well as for the styrene–ethylene copolymerization steps into the catalytic active site models [Et 2 (IndH 4 ) 2 ]MCH ...
A novel, low-cost, rapid, accurate, non-invasive and high throughput method based on the principles of Optical Interferometry (OPTI method) has been developed and applied for the in situ monitoring in one simple run of first (melting) and second (glass transition) order transitions as well as of the thermally induced decomposition of various thin polymeric films spin coated on flat reflective substrates...
New super-tough poly(butylene terephthalate) (PBT) materials were obtained by melt blending PBT with both 20wt% phenoxy (Ph) and 0–30wt% maleic anhydride grafted poly(ethylene–octene) (mPEO) copolymers with different grafting levels. Ph was completely miscible in the PBT matrix. The presence of mPEO did not influence either the nature of the PBT–Ph matrix or the crystallization of PBT. The overall...
To investigate the mechanism of high elongation of natural rubber attained by the ‘racking method’, a strip of smoked-sheet was elongated up to 150 times in length, by stretching rapidly at room temperature and forcing to shrink at 75–80°C repeatedly. On X-ray diffraction, a typical fibre pattern with an amorphous ring appeared already at ×10 (stretch ratio=10). The degree of crystallinity increased...
In this study the influence of the molecular weight of the dispersed phase components on encapsulation effects in the composite droplet phase was examined for high density polyethylene (HDPE)/PS/PMMA ternary blends. Three different blends composed of various PS and PMMA materials dispersed in an HDPE matrix were prepared using an internal mixer. The morphology was studied by light and electron microscopy...
Polypropylene–CaCO 3 composites were prepared on a twin screw extruder with a particle content of 0–32vol%. The influence of particle size (0.07–1.9μm) and surface treatment of the particles (with and without stearic acid) on the toughening properties were studied. The matrix molecular weight of the polypropylene was also varied (MFI 0.3–24dg/min). The experiments included tensile tests, notched...
A series of thermally stable second-order nonlinear optical (NLO) polymeric materials based on bismaleimide chemistry have been developed. Two maleimide containing chromophores with excellent thermal stability were incorporated into the bismaleimide polymer matrices to form interpolymer networks. Moreover, a full interpenetrating polymer network (IPN) was formed through simultaneous addition reaction...
This paper highlights the application of scanning probe microscopy, notably atomic force microscopy in contact mode supported by lateral force microscopy, to the investigation of changes in the morphology of polypropylene (PP) monofilaments during melt-extrusion and subsequent drawing. A gradual deformation at the fibre surface from a spherulitic structure to a shish-kebab type structure is observed...
The curing behaviour of a long-chain dimethacrylate with a series of peroxide initiators was examined by temperature-ramping DSC. The effect of oxygen inhibition on the onset and peak temperatures cure was confirmed and the peak exotherm temperature was correlated with the decomposition rate of the initiator. The gel point temperature, obtained from temperature-ramping rheology studies, was directly...
The influence of water sorption on refractive index of a fluorinated polyimide was demonstrated by measuring water uptake and change in volume due to water sorption. The refractive index of the fluorinated polyimide increased with increasing the water uptake. The change as much as 10 −3 in refractive index was observed at the temperature of 25°C. These results reflected a one order smaller...
We investigate the stability of thin polystyrene (PS) films on chemically identical grafted brushes of various thickness and grafting density. We observe an essential influence of the brush thickness on the stability of the PS films. For brushes with a thickness of 20–35nm no de-wetting of the PS film occurs, while considerably thicker or thinner PS brushes lead to de-wetting of the PS top layer....
Reduced PTFE can be grafted by nitro and bromo-phenyl diazonium tetrafluoroborate salts in a manner similar to that used for carbon, except that no application of a reductive potential during grafting was required. Grafting was evidenced by cyclic voltammetry, X-ray fluorescence or ToF-SIMS. Nitro- and bromo-phenyl moieties were covalently linked to the PTFE material and could be eliminated only by...
The drying kinetics were examined in four cross-linked polymers that form hydrogels: 2,3-Dihydroxypropyl methacrylate (DHPMA) and 2-hydroxyethyl methacrylate (HEMA) and two random copolymers, with one-to-one and three-to-one HEMA-to-DHPMA molar ratios. The hydrogels were saturated with buffered, isotonic saline solution and deionized water; weight loss kinetics were monitored at temperatures from...
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