Monte Carlo simulation of the compatibility of graft copolymer compatibilized two incompatible homopolymer blends: Effect of graft structure

Compatibility of graft copolymer compatibilized two incompatible homopolymer A and B blends was simulated by using Monte Carlo method in a two-dimensional lattice model. The copolymers with various graft structures were introduced in order to study the effect of graft structure on the compatibility. Simulation results showed that incorporation of both A-g-B (A was backbone) and B-g-A (B was backbone) copolymers could much improve the compatibility of the blends. However, A-g-B copolymer was more effective to compatibilize the blend if homopolymer A formed dispersed phase. Furthermore, simulation results indicated that A-g-B copolymers tended to locate at the interface and anchor two immiscible components when the side chain is relatively long. However, most of A-g-B copolymers were likely to be dispersed into the dispersed homopolymer A phase domains if the side chains were relatively short. On the other hand, B-g-A copolymers tended to be dispersed into the matrix formed by homopolymer B. Moreover, it was found that more and more B-g-A copolymers were likely to form thin layers at the phase interface with decreasing the length of side chain.

Relaxation behavior of polymer blends with complex morphologies: Palierne emulsion model for uncompatibilized and compatibilized PP/PA6 blends

This paper deals with the dynamic rheological behavior of polypropylene/polyamide6 (PP/PA6) uncompatibilized blends and those compatibilized with a maleic anhydride grafted PP (PP/PP-g-MAH/PA6). The terminal relaxation times of the blends predicted by the Palierne emulsion model were compared with those obtained from experimental relaxation time spectra. The Palierne model succeeded well in describing PP/PA6 uncompatibilized blends with relatively low dispersed phase contents (10 wt%) and failed doing so for those of which the dispersed contents were high (30 wt%). It also failed for the compatibilized ones, irrespective of the dispersed phase content (10 or 30 wt%) and whether or not interface relaxation was taken into consideration. In the case of the uncompatibilized blend with high dispersed-phase content, interconnections among inclusions of the dispersed phase were responsible for the failure of the Palierne model. As for the compatiblized blends, in addition to particle interconnections, the existence of emulsion-in-emulsion (EE) structures was another factor responsible for the failure of Palieme model.

Effect of chain-length dependence of interaction parameter on spinodals for polydisperse polymer blends

The chain-length dependence of the Flory-Huggins (FH) interaction parameter is introduced into the FH lattice theory for polydisperse polymer-blend systems. The spinodals are calculated for the model polymer blends with different chain lengths and distributions. It is found that all the related variables r(n), r(w), r(z), and chain-length distribution, have effects on the spinodals for polydisperse polymer blends.

Properties of compatibilized nylon 6/ABS polymer blends

Nylon 6/poly(acrylonitrile-butadiene-styrene)(ABS) blends were prepared in the molten state by a twin-screw extruder. Maleic anhydride-grafted polypropylene (MAP) and solid epoxy resin (bisphenol type-A) were used as compatibilizers for these blends. The effects of compatibilizer addition to the blends were studied via tensile, torque, impact properties and morphology tests. The results showed that the additions of epoxy and MA copolymer to nylon 6/ABS blends enhanced the compatibility between nylon 6 and ABS, and this lead to improvement of mechanical properties of their blends and in a size decrease of the ABS domains.

Monte Carlo simulation of miscibility of polymer blends with repulsive interactions: effect of chain structure

The effects of the chain structure and the intramolecular interaction energy of an A/B copolymer on the miscibility of the binary blends of the copolymer and homopolymer C have been studied by means of a Monte Carlo simulation. In the system, the interactions between segments A, B and C are more repulsive than those between themselves. In order to study the effect of the chain structure of the A/B copolymer on the miscibility, the alternating, random and block copolymers were introduced in the simulations, respectively. The simulation results show that the miscibility of the binary blends strongly depends on the intramolecular interaction energy ((ε) over bar (AB)) between segments A and B within the A/B copolymers. The higher the repulsive interaction energy, the more miscible the A/B copolymer and homopolymer C are. For the diblock copolymer/homopolymer blends, they tend to form micro phase domains. However, the phase domains become so small that the blend can be considered as a homogeneous phase for the alternating copolymer/ homopolymer blends. Furthermore, the investigation of the average end-to-end distance ((h) over bar) in different systems indicates that the copolymer chains tend to coil with the decrease Of (ε) over bar (AB) whereas the (h) over bar of the homopolymer chains depends on the chain structure of the copolymers.

Phase behavior of polymer blends

The present report deals with some results on phase behavior, miscibility and phase separation for several polymer blends casting from solutions. These blends are grouped as the amorphous polymer blends, blends containing a crystalline polymer or two crystalline polymers. The blends of PMMA/PVAc were miscible and underwent phase separation at elevated temperature, exhibited LCST behavior. The benzoylated PPO has both UCST and LCST nature. For the systems composed of crystalline polymer poly(ethylene oxide) and amorphous polyurethane, of two crystalline polymers poly(epsilon-caprolactone) and poly[3,3,-bis-(chloromethyl) oxetane], appear a single T-g, indicating these blends are miscible. The interaction parameter B's were determined to be -14 J cm(-3), -15 J cm(-3) respectively. Phase separation of phenolphthalein poly(ether ether sulfone)/PEO blends were discussed in terms of thermal properties, such as their melting and crystallization behavior.

Monte Carlo simulation of phase behavior of polymer blends with special interactions

Full Paper: The phase, behavior of A-B-random copolymer/C-homopolymer, blends with special interaction was studied by a. Monte, Carlo simulation in two dimensions. The interaction between I segment A and segment C was repulsive, whereas it was attractive between segment B and segment C. The simulation results showed that the blend became two large co-continuous phase domains at lower segment-B component compositions, indicating that the blend showed spinodal decomposition. With an increase of the segment-B component, the miscibility between the copolymer,and the polymer was gradually improved up to being miscible. In addition, it was found that segment B tended to move to the surface of the copolymer phase in the case of a lower component of segment B. On the other hand, if was observed that the average, end-to-end distances ((h) over bar) for both copolymer and polymer changed slowly with increasing segment-B component of the copolymer up to 40%, thereafter they increased considerably with increasing segment B component. Moreover, it was found that the (h) over bar of the copolymer was obviously shorter than that of the homopolymer for the segment-B composition, region from 0% to 80%. Finally, a, phase diagram showing I phase and - II phase regions under the condition of constant-temperature is presented.

Reactive reinforcement of the interface of high performance polymer blends by PMR-POI

The effect of PMR-polyimide(POI) as the interfacial agent on the interface characteristics, morphology features and crystallization of poly (ether sulfone) /poly (phenylene sulfide) (PES/PPS) and poly(ether ether ketone)/poly (ether sulfone) (PEEK/PES) partly miscible blends were investigated by means of the scanning electron microscopy, WAXD and XPS surface analysis. It is found that the interfacial adhesion was enhanced remarkably, the size of the dispersed phase particles was reduced significantly and the miscibility was improved by the addition of POI. During melt blending cross-link and/or grafting reaction of POI with PES, PEEK and PPS homopolymers was detected, however the reaction activity of POI with PPS was much higher than that of PES and PEEK. It was also found that POI was an effective nucleation agent of the crystallization of PPS.

Morphologies and physical properties of PA1010/HIPS/HIPS-g-MA ternary blends

The effect of the content of a copolymer consisting of high impact polystyrene grafted with maleic anhydride (HIPS-g-MA) on morphological and mechanical properties of PA1010/HIPS blends has been studied. Blend morphologies were controlled by adding HIPS-g-MA during melt processing, thus the dispersion of the HIPS phase and interfacial adhesion between the domains and matrices in these blends were changed obviously. The weight fractions of HIPS-g-MA in the blends increased from 2.5 to 20, then much finer dispersions of discrete HIPS phase with average domain sizes decreased from 6.1 to 0.1 mu m were obtained. It was found that a compatibilizer, a graft copolymer of HIPS-g-MA and PA1010 was synthesized in situ during the melt mixing of the blends. The mechanical properties of compatibilized blends were obviously better than those of uncompatibilized PA1010/HIPS blends. These behaviors could be attributed to the chemical interactions between the two components of PA1010 and HIPS-g-MA and good dispersion in PA1010/HIPS/HIPS-g-MA blends. Evidence of reactions in the blends was seen in the morphology and mechanical behaviour of the solid. The blend containing 5 wt % HIPS-g-MA component exhibited outstanding toughness. (C) 1999 Kluwer Academic Publishers.

Syndiotactic polystyrene/thermoplastic polyurethane blends using poly(styrene-b-4-vinylpyridine) diblock copolymer as a compatibilizer

The effect of adding diblock copolymer poly(styrene-b-4-vinylpyridine) (P(S-b-4VPy), to immiscible blends of syndiotactic polystyrene (sPS)/thermoplastic polyurethane (TPU) on the morphology, thermal transition, crystalline structure, and rheological and mechanical properties of the blends has been investigated. The diblock copolymer was synthesized by sequential anionic copolymerization and was melt-blended with sPS and TPU. Scanning electron microscopy (SEM) showed that the added block copolymer reduced the domain size of the dispersed phase in the blends. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) revealed that the extent of compatibility between sPS and TPU affected the crystallization of the sPS in the blends. Tensile strength and elongation at break increased, while the dynamic modulus and complex viscosity decreased with the amount of P(S-b-4VPy) in the blend. The compatibilizing effect of the diblock copolymer is the result of its location at the interface between the sPS and the TPU phases and penetration of the blocks into the: corresponding phases, i.e. the polystyrene block enters the noncrystalline regions of the sPS, and the poly(4-vinylpyridine) block interacts with TPU through intermolecular hydrogen bonding. (C) 1999 Elsevier Science Ltd. All rights reserved.

Preparation of the HIPS/MA graft copolymer and its compatibilization in HIPS/PA1010 blends

The graft copolymer of high-impact polystyrene (HIPS) grafted with maleic anhydride (MA) (HIPS-g-MA) was prepared with melt mixing in the presence of a free-radical initiator. The grafting reaction was confirmed by infrared analyses, and the amount of MA grafted on HIPS was evaluated by a titration method. 1-5% of MA can be grafted on HIPS. HIPS-g-MA is miscible with HIPS. Its anhydride group can react with polyamide 1010 (PA1010) during melt mixing of the two components. The compatibility of HIPS-g-MA. in the HIPS/PA1010 blends was evident. Evidence of reactions in the blends was confirmed in the morphology and mechanical behavior of the blends. A significant reduction in domain size was observed because of the compatibilization of HIPS-g-MA in the blends of HIPS and PA1010. The tensile mechanical properties of the prepared blends were investigated, and the fracture surfaces of the blends were examined by means of the scanning electron microscope. The improved adhesion in a 15% HIPS/75% PA1010 blend with 10% HIPS-g-MA copolymer was detected. The morphology of fibrillar ligaments formed by PA1010 connecting HIPS particles was observed. (C) 1999 John Wiley & Sons, Inc.

Interparticle distance-temperature-strain rate equivalence for the brittle-tough transition in polymer blends

From the angle of energy transformation an equation was obtained for the brittle transition in polymer blends. The effects of interparticle distance, temperature and strain rate on the brittle-tough transition in polymer blends were characterized by this equation. The calculations show that, for this transition: (1) increasing temperature and decreasing interparticle distance are equivalent and the shift factor increases with increasing temperature; (2) decreasing strain rate and decreasing interparticle distance have equivalent effects on the transition; (3) the strain rate must be optimum in order to find the brittle-tough transition phenomena for a given temperature region. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

Compatibilization effect of graft copolymer on immiscible polymer blends: 1. LLDPE/SBS/LLDPE-g-PS systems

compatibilizing effect of graft copolymer, linear low density polyethylene-g-polystyrene (LLDPE-g-PS), on immiscible blends of LLDPE with styrene-butadiene-styrene triblock copolymer (SBS) has been investigated by means of C-13 CPMAS n.m.r. and d.s.c. techniques. The results indicate that LLDPE-g-PS is an effective compatibilizer for LLDPE/SBS blends. It was found that LLDPE-g-PS chains connect two immiscible components, LLDPE and SBS, through solubilization of chemically identical segments of LLDPE-g-PS into the amorphous region of LLDPE acid PS block domain of SBS, respectively. It was also found that LLDPE-g-PS chains connect the crystalline region of LLDPE by isomorphism, with serious effects on the supermolecular structure of LLDPE. The effect of LLDPE-g-PS on the supermolecular structure of LLDPE in the LLDPE/SBS blends obviously depends on the composition of the blends, but has little dependence on the PS grafting yields of LLDPE-g-PS. (C) 1998 Elsevier Science Ltd. All rights reserved.

Nonradiative energy transfer study on the interface of compatibilized linear low density polyethylene/poly(methyl methacrylate) blends

Blends of chromophore-labeled LLDPE and chromophore-labeled PMMA compatibilized by block copolymer of hydrogenated polybutadiene and methyl methacrylate (PHB-b-PMMA) were studied by nonradiative energy transfer (NRET) technique. The ratio of fluorescence intensity of the donor at 336 nm and the acceptor at 408 nm (I-D/I-A) decreased with an increase in block copolymer content. At about 8 wt.-% block copolymer content I-D/I-A reached a minimum value, indicating the interdiffusion of LLDPE chains and PMMA chains in the interface is strongest. The influence of temperature on the interdiffusion of polymer chains in the interface was also examined. Samples quenched in liquid nitrogen from 140 degrees C showed lower energy transfer efficiencies than those annealed from 150 degrees C to room temperature.

Crystallization behavior of poly(propylene)/polyamide 1010 blends using poly(propylene)-graft glycidyl methacrylate as compatibilizer

Polyamide 1010/poly(propylene) (PA1010/PP) blends were investigated with and without the addition of poly(propylene)-graft-glycidyl methacrylate (PP-g-GMA). The effect of the compatibilizer on the thermal properties and crystallization behavior was determined by differential scanning calorimetry and wide-angle X-ray diffraction. From the results it is found that the crystallization of PA 1010 is significantly affected by the presence of PP-g-GMA. PP/PA 1010 (75/25) blends containing higher amounts of PP-g-GMA show concurrent crystallization at the crystallization temperature of PP. Isothermal crystallization kinetics also were performed in order to investigate the influence of the compatibilized process on the nucleation and growth mechanism. In the PP/PA 1010 (25/75) blends, concurrent crystallization behavior was not observed, even though the amount of PPg-GMA was high.