Modeling of particle growth and morphology in the gas phase polymerization of butadiene. II. Simulation and discussion

The improved multigrain model was used to simulate the gas phase polymerization of butadiene catalyzed by low‐, medium‐, and high‐activity catalysts, respectively. For the low‐activity catalyst, the mass and heat transfer resistances in the particle were negligible. The morphology of the polymeric particles was uniform. For the medium‐activity catalyst, the overall mass transfer effectiveness was > 90%, the maximal temperature rise was 8K, and the heat transfer resistance in the particle was negligible. Mass transfer resistance does not affect the morphology of product particle significantly. For the high‐activity catalyst, the overall mass transfer effectiveness was within the range of 70–96%, the morphology of the product particle was affected by the mass transfer resistance to some extent. The maximal temperature rise was 21K; the heat transfer resistance in the particle was negligible as well. However, there was some severe mass transfer resistance in the particle, and the maximal temperature rise was ≤ 30K for the large catalyst particle with the same activity. Thus, the polymeric particle morphology was comparatively poor, with the occurrence of particle softening and sticking. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 730–741, 2001     

Modeling of molecular weight distribution of gas‐phase polymerization of butadiene

A mathematical model of the molecular weight distribution (MWD) based on a multilayer model and an improved intrinsic kinetics model was proposed to simulate the MWD of the gas‐phase polymerization of butadiene with a heterogeneous catalyst. Intrinsic kinetics and heat and mass‐transfer resistances based on the multilayer model of a polymeric particle were considered in the modeling of the MWD. The effects of the reaction conditions, catalyst particle size, mass‐transfer resistance, deactivation of active sites, and transfer of the polymer chain on the molecular weight and MWD were simulated. The results show that the effects of the deactivation of active sites and transfer of the polymer chain on the average molecular weight are significant and that the effect of the catalyst particle size on the MWD is not significant. The simulation results of the molecular weight and MWD are compared with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 88–103, 2003     

Particle growth modeling of gas phase polymerization of butadiene

Butadiene polymerization in the gas phase is modeled by a polymeric multilayer model. Intraparticle mass and heat transfer effects are studied. The effects of catalyst size and diffusivity of butadiene on the radial profile of monomer concentration in polymeric particles and on the rate of particle growth are significant. Intraparticle temperature gradients do appear to be negligible under normal reaction conditions. External boundary layer heat effects are studied for various operation conditions. The model predicts that there is no significant temperature rise of the polymeric particles, even in the case of large catalyst particles. The effect of deactivation of active sites on the rate of particle growth is also studied. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 203–212, 1997     

用多粒模型模拟丁二烯气相聚合的颗粒增长

Gas phase polymerization of butadiene by neodymium catalyst was modeled. The effects of mass and heat transfer resistances in the external boundary layer and within particles, sorption of butadiene in polybutadiene,and deactivation of active sites on polymer particle growth and morphology were studied. Simulation results show that the effects of intraparticle mass and heat transfer resistances on the growth rate of polymer particles are insignificant, and that there is no significant effect of mass transfer resistance on the morphology of polymer particles.The simulation results were compared with the experimental results.     

Storage modulus of polybutadiene core in acrylonitrile–butadiene–styrene polymers with different degrees of grafting

The linear viscoelastic behavior of acrylonitrile‐butadiene‐styrene (ABS) polymers in the molten state, with different degrees of grafting, was investigated within the framework of Palierne's emulsion model. The main aim of the present study is to quantitatively analyze the effect of grafting degree on the storage modulus G′ of the polybutadiene (PB) rubber core dispersed in ABS polymers. According to our model calculations, the degree of grafting significantly affects the G′ values of the PB core and, hence, the viscoelastic properties of ABS polymers. Our calculations showed that the Palierne model is very useful to calculate the storage modulus of the rubber particles dispersed in rubber‐modified polymeric materials, at least in the high‐frequency region. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 924–930, 2001     

Particle morphology for polyolefins synthesized with supported metallocene catalysts

A detailed model describing particle growth and morphology in polyolefins synthesized using supported metallocene catalysts is presented. The multigrain model (MGM) is extended to consider metal extraction and the effects of polymer particle compressibility, in addition to monomer sorption and mass and heat transfer considerations. The effects of active metal extraction into the polymer phase and the pores of the particle on the kinetics of polymerization and morphological features of the polymer particle are studied. The effects of greater compressibility of polymer particles on morphological features such as particle porosity are studied. Model predictions for porosity and morphology are shown to reproduce similar trends as have been reported in experimental studies. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2565–2579, 2001     

Application of a one‐dimensional thermal flame spread model on predicting the rate of heat release in the SBI test

A one‐dimensional thermal flame spread model was applied to predict the rate of heat release in the single burning item (SBI) test on the basis of the cone calorimeter data. The input parameters were selected according to the features of the SBI test and using particle board as a model tuning material. The features of the measured and calculated rate of heat release curves were compared for a series of 33 building products. The fire growth rate (FIGRA) indices were calculated to predict the classification in the forthcoming Euroclass system. The model gave correct classification for 90% of the products studied. An essential feature of the model is that only one cone calorimeter test at the exposure level of 50 kW m^?2 is needed. The model, therefore, provides a practical tool for product development and quality control. Copyright © 2001 John Wiley & Sons, Ltd.     

Compatibilization of SBR/NBR blends using chemically modified styrene‐co‐butadiene rubber Part 2. Effect of compatibilizer loading

The present work focuses on the compatibization of styrene‐co‐butadiene rubber (SBR)/acrylonitrile‐co‐butadiene rubber (NBR) blends with dichlorocarbene modified styrene‐co‐butadiene rubber (DCSBR) as a function of concentration of compatibilizer and composition of the blend. FTIR studies, differential scanning calorimetry and dynamic mechanical analysis reveal molecular level miscibility in the blends in the presence of compatibilizer. The formation of interfacial bonding is assessed by analysis of swelling behaviour, cure characteristics, stress–strain data and mechanical properties. These studies show that the compatibilizing action of DCSBR becomes more prominent as the proportion of NBR in the blend increases. The resistance of the vulcanizate towards thermal and oil ageing improved with compatibilization. The change in technological properties is correlated with the crosslink density of the blends assessed from swelling and stress–strain data. © 2001 Society of Chemical Industry     

Toward a better understanding of the emulsion polymerization of butadiene. I. Continuous conductivity measurements

Continuous conductivity measurements were performed during the batch emulsion polymerization of butadiene along with kinetic and particle size measurements. The critical monomer conversion was obtained around 55% and the rate of polymerization was correlated to the surfactant concentration with an exponent of 0.35 which was not in agreement with the exponent offered by Smith and Ewart. In addition, the evolution of some particle‐related quantities such as particle size and number of particles during the three intervals of the emulsion polymerization and their agreements with Smith‐Ewart mechanism were investigated. The behavior of conductivity in the emulsion polymerization of butadiene normally containing a buffering agent was found to be completely different from the unbuffered one. Comparison of the conductivity profiles with the kinetic and particle‐related quantities represented that the conductivity of the reaction mixture is very sensitive to the changes in the particle size so that any small change in the forms of nucleation, growth, and coagulation is clearly observed in the conductivity profiles. Furthermore, the conductimetric data are capable of determining some important points during the polymerization such as the beginning of the reaction that can be important from the industrial process control point of view. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45262.     

Preparation of raspberry‐shaped styrene‐butadiene‐methyl acrylate‐acrylic acid latex particles by emulsion polymerization followed by alkali/heating method

Monodispersed raspberry‐shaped polystyrene‐butadiene‐methyl acrylate‐acrylic acid particles were made by semi‐batch emulsion polymerization followed by alkali and heat treatment. The particle sizes and size distributions were studied by hydrodynamic chromatography and transmission electronic microscopy. The morphology of the particles was observed by SEM, cryo‐SEM, and TEM. Treatment temperature was found to have a significant impact on the particle size and morphology of the treated latexes. Higher temperatures lead to larger particle sizes and more discernible raspberry domains with sizes around 50 nm on the particle surfaces. Higher levels of alkali did not significantly change the particle size but did increase the total titratable acid amount, presumably due to the hydrolysis of methyl acrylate during the treatment. GPC results showed that higher amount of oligomers or polymers are produced in the serum for the heat‐treated latexes. Divinylbenzene crosslinking agent at the levels of 0.05–3% limited the particle expansion and decreased the serum acid. A possible mechanism of raspberry particle formations was proposed, which involves migration of hydrophilic and hydrophobic species during the heat treatment. Lastly, potential applications for raspberry particles in paper coating were explored. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polymerization of olefins through heterogeneous catalysis X: Modeling of particle growth and morphology

The development of a detailed model describing particle growth in olefin copolymerization systems is presented. The Multigrain Model considers in detail monomer sorption, mass transfer, and changing porosity within the growing particle, as well as heat and mass transfer across the external film of the particle. The model predicts catalyst performance, including polymerization rates and particle morphology, in different reactor media without parameter adjustment. Internal void fractions are calculated through an examination of the relative growth rates within the growing particle. The model is used to examine the effects of mass transfer limitations, prepolymerization, and nonuniform metal distribution on the particle growth process. Model predictions of morphology show the same trends as observed experimentally.     

Modeling and experimental studies of emulsion copolymerization systems. II. Styrenics

Using a model previously published, predictions for evolution of conversion and average particle diameter in batch experiments are compared against experimental data for four emulsion copolymerizations of styrene with the following monomers: (1) methyl methacrylate, (2) butyl acrylate, (3) butadiene, and (4) acrylic acid. For each copolymerization system the experiments covered simultaneous variations in five variables: initiator and surfactant concentrations, water to monomer ratio, monomer composition, and temperature. It is shown that after data fitting for unknown or uncertain parameters, the model is capable of explaining quantitatively the experimental observations for conversion evolution and only qualitatively the particle size evolution data. This points out to the possible contribution of particle nucleation mechanisms other than the micellar one, which is the only mechanism included in the model. Some of the adjustable parameter values were found to depend on the copolymer composition. The only case in which the model does not perform well is in the prediction of the effect of initiator concentration on the copolymerization rate for butadiene‐rich formulations. It is also found that the model predictions are very sensitive to the value of the diffusion coefficients of monomeric radicals in the copolymer particle, which are not readily available in the literature. It is concluded that it is important to independently measure these parameters in order to enhance the predictive power of models. It is also concluded that the model can be useful for practical applications. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2380–2397, 2001     

Preparation and properties of phase‐change heat‐storage UV curable polyurethane acrylate coating

Phase‐change heat‐storage UV curable polyurethane acrylate (PUA) coating was prepared by applying microencapsulated phase change materials (microPCMs) to PUA coating. MicroPCMs containing paraffin core with melamine‐formaldehyde shell were synthesized by in situ polymerization. The effect of stirring speed, emulsification time, emulsifier amount, and core/shell mass ratio on particle size, morphology, and phase change properties of the microPCMs was studied by using laser particle size analyzer, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopic analysis, scanning electron microscopy, and differential scanning calorimetry. The results showed that the diameter of the microcapsules decreased with the increase of stirring speed, emulsification time, and emulsifier amount. When the mass ratio of emulsifier to paraffin is 6%, microcapsules fabricated with a core/shell ratio of 75/25 have a compact surface and a mean particle size of 30 μm. The sample made under the above conditions has a higher efficiency of microencapsulation than other samples and was applied to PUA coating. The dispersion of microPCMs in coating and heat‐storage properties of the coating were investigated. The results illustrated that the phase‐change heat‐storage UV curable PUA coating can store energy and insulate heat. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41266.     

Properties and preparation of compatibilized nylon 6 nanocomposites/ABS blends using functionalized metallocene polyolefin elastomer. I. Impact properties

The impact behaviors of nanoclay‐filled nylon 6 (nano‐nylon 6) blended with poly(acrylonitrile–butadiene–styrene) terpolymers (ABS) prepared through a twin screw mixing process were investigated here using metallocene polyethylene grafted maleic anhydride (POE‐g‐MA) as a compatibilizer to enhance the interface interaction. No clear effect of compatibilizer on the dispersion of clay and crystalline structure of nano‐nylon 6 has been observed. In view of morphology and rheological behaviors, the effect of compatibilizer on the mechanical properties could be elucidated. It is found that impact strength increases with the addition of compatibilizer at various ABS compositions. Similar effects are also observed with decreasing test temperature at the nano‐nylon 6/ABS blend composition of 80/20. As for thermal properties, the heat distortion temperature shows a marginal decrease in the nano‐nylon 6/ABS blends. Rheological behavior indicates that increased viscosity is found for the investigated compatibilized systems. Through morphology observations, the etched ABS particle sizes tend to decrease with the addition of compatibilizer for the blends, but are larger with higher contents of ABS concentrations. Those observations account for impact behaviors of the investigated blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1364–1371, 2006     

Influence of filler structure on microhardness of carbon black–polymer composites

The microhardness, H, of carbon black–polycarbonate and carbon black–low‐density polyethylene composites was investigated. Two types of microadditives with different average particle sizes were employed. It has been shown that the morphology of the polymeric matrix conspicuously influences the hardness dependence of the composites with volume concentration of filler, ϕ. The microhardness of the carbon black–polycarbonate composites shows a steplike behavior with respect to carbon black content, while the H value of the carbon black–low‐density polyethylene composite linearly increases with increasing ϕ. The influence of filler structure on the microhardness of the carbon black–polymer composites is also discussed. Results favor the concept that a smaller carbon black particle size (smaller aggregate diameters and interaggregate distances) enhances the microhardness of the composites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 90–95, 2001     

Preparation and application of partially porous poly(styrene‐divinylbenzene) particles for lipase immobilization

Partially porous poly(styrene‐divinylbenzene) (PS‐DVB) particles in the micron size range were prepared by the method of multistep swelling and polymerization involving the use of polymeric porogens. Polystyrene (PS) seeds prepared by dispersion polymerization were expanded in particle size by absorbing styrene and initiator, and then polymerized to form polymeric porogen particles. The newly synthesized PS chains served as the porogens of the PS‐DVB particles, resulting from the copolymerization of styrene and divinylbenzene in the swollen polymeric porogen particles. PS‐DVB particles with a specific surface area of up to 34 m²/g and a pore volume of up to 0.15 cm³/g were obtained. The average pore diameter of PS‐DVB particles was in the range of 15–24 nm. An increasing amount of toluene used in the copolymerization step increased the pore volume and specific surface area. Lipase from Candida rugosa was immobilized on the prepared PS‐DVB by physical adsorption. The optimum temperature for enzymatic activity was increased and the thermal deactivation of enzyme in organic solvent was slowed down by the immobilization. However, compared with soluble enzyme, the immobilized lipase on PS‐DVB retained a less activity after the first stage deactivation, suggesting a possible change in the conformation of enzyme molecule by immobilization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 39–46, 2001     

Blending of styrene‐block‐butadiene‐block‐styrene copolymer with sulfonated vinyl aromatic polymers

Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene‐block‐(ethylene‐co‐1‐butene)‐block‐styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing sulfonated units were prepared by blending styrene‐block‐butadiene‐block‐styrene (SBS), with both sulfonated PS and sulfonated SEBS in a Brabender mixer. Such a procedure was performed as an alternative route to direct sulfonation of SBS which is actually not selective towards benzene rings because of the great reactivity of the double bonds in polybutadiene (PB) blocks to sulfonation agents. Thermal and dynamic‐mechanic analysis, together with morphology characterization of the blends, is consistent with obtaining partially compatible blends characterized by higher T_g of the polystyrene domains and improved thermal stability. © 2001 Society of Chemical Industry     

Study on preparation of protein‐imprinted soft‐wet gel composite microspheres with magnetic susceptibility and their characteristics. I. Preparation and particle morphology

Protein‐imprinted soft‐gel composite microspheres with magnetic susceptibility (MS‐PIGMs) were prepared by inverse suspension polymerization, using Fe₃O₄ particles as magnetically susceptible component, acrylamide (AM) and N,N′‐methylenebisacrylamide (BisAM) as polymeric matrix components, toluene as solvent, and bovine serum albumin (BSA) and lysozyme (Lyz) as templates, respectively. The surface morphology of MS‐PIGMs was observed by environmental scanning electron microscope (ESEM) and scanning electron microscope (SEM). The effects of the kinds and amount of dispersants, stirring rate, the amount and adding methods of initiator, the amount of Fe₃O₄ and monomer concentration on particle morphology of MS‐PIGMs, as well as the effects of crosslinking degree on swelling ratio and particle morphology in wet condition were investigated in detail. ESEM and SEM photographs showed that the resulting MS‐PIGMs were all spheroid form and had large quantity of regularly distributed pores in wet condition, which close in dry condition, and the experimental results indicated that all the affecting factors had obvious effects on particle morphology of MS‐PIGMs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 684–694, 2006     

Shrinkage cracking of styrene butadiene polymeric emulsion‐modified concrete using rapid‐hardening cement

This study was performed to resolve the problem of cracks caused by the rapid hydration heat produced during the early setting stages of rapid‐hardening cement. To address the hydration heat of rapid‐hardening cement, we prepared a modified rapid‐hardening cement using calcium sulfoaluminate clinker combined with a styrene butadiene (SB) polymer. The performance of SB polymeric emulsion‐modified concrete made from modified rapid‐hardening cement was assessed by determining shrinkage (change in length, and plastic and autogenous shrinkage). The modified rapid‐hardening cement in combination with SB polymeric emulsion effectively reduced cracking. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Phase structure and viscoelastic properties of compatibilized blends of PET and HDPE recyclates

Immiscible blends of recycled poly(ethylene terephthalate) (R‐PET), containing some amount of polymeric impurities, and high‐density polyethylene (R‐PE), containing admixture of other polyolefins, in weight compositions of 75 : 25 and 25 : 75 were compatibilized with selected compatibilizers: maleated styrene–ethylene/butylene–styrene block copolymer (SEBS‐g‐MA) and ethylene–glycidyl methacrylate copolymer (EGMA). The efficiency of compatibilization was investigated as a function of the compatibilizer content. The rheological properties, phase structure, thermal, and viscoelastic behavior for compatibilized and binary blends were studied. The results are discussed in terms of phase morphology and interfacial adhesion among components. It was shown that the addition of the compatibilizer to R‐PET‐rich blends and R‐PE‐rich blends increases the melt viscosity of these systems above the level characteristic for the respective binary blends. The dispersion of the minor phase improved with increasing compatibilizer content, and the largest effects were observed for blends compatibilized with EGMA. Calorimetric studies indicated that the presence of a compatibilizer had a slight affect on the crystallization behavior of the blends. The dynamic mechanical analysis provided evidence that the occurrence of interactions of the compatibilizer with blend components occurs through temperature shift and intensity change of a β‐relaxation process of the PET component. An analysis of the loss spectra behavior suggests that the optimal concentration of the compatibilizers in the considered blends is close to 5 wt %. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1423–1436, 2001