Reactor Granule Technology Research Articles

Dielectric Properties of Biaxially Oriented Polypropylene Nanocomposites Prepared Based on Reactor Granule Technology

Dielectric Properties of Biaxially Oriented Polypropylene Nanocomposites Prepared Based on Reactor Granule Technology

Cooperative influences of nanoparticle localization and phase coarsening on thermal conductivity of polypropylene/polyolefin elastomer blends

Polypropylene (PP)/polyolefin elastomer (POE)/aluminum oxide (Al2O3) nanocomposites were prepared based on a reactor granule technology (RGT). The effect of nanoparticle migration and phase morphology evolution on the formation of thermal conductive networks was systematically studied. The utilization of RGT and POE with high viscosity enabled successful migration of in-situ generated Al2O3 nanoparticles at the interface of PP and POE, as combined results of uniform dispersion of Al2O3 and accompanied small phase domain size of PP [1]. The localization of the nanoparticles at the interface also contributed to suppression of the phase coarsening during annealing. The nanoparticle migration to the interface and the retarded phase coarsening synergistically contributed to the enhanced thermal conductivity.

Selective localization of aluminum oxide at interface and its effect on thermal conductivity in polypropylene/polyolefin elastomer blends

A reactor granule technology (RGT) was applied to immiscible polypropylene (PP)/polyolefin elastomer (POE) blends to effectively control the localization of nanoparticles at the interface. The RGT afforded uniform dispersion of in-situ generated aluminum oxide (Al2O3) nanoparticles in PP, and this guaranteed the migration of nanoparticles to the interface of a co-continuous structure when blended with POE. The selective localization of nanoparticles at the interface was confirmed by transmission electron microscope (TEM), scanning electron microscope (SEM), elemental mapping (EDX) and thermal gravimetric analysis (TGA). Such localization was never achieved when preformed Al2O3 nanoparticles were used, and this fact stresses the importance of uniform dispersion in controlling the migration of nanoparticles. The migration was also affected by the viscosity of POE: POE having higher viscosity resulted in a smaller domain size, and thereby more nanoparticles could migrate to the interface without agglomeration. The impacts of the selective localization at the interface and the phase domain size on the thermal conductivity of the resultant nanocomposites were studied and discussed.

Thermal conductivity of polypropylene/aluminum oxide nanocomposites prepared based on reactor granule technology

A reactor granule technology (RGT) is a new method for the in-situ fabrication of polyolefin-based nanocomposites. It involves the impregnation and confinement of inorganic molecular precursors in the porosity of polyolefin reactor granule, and subsequent conversion of the precursors into highly dispersed inorganic nanoparticles during melt processing. In this contribution, the RGT was applied to develop thermally conductive polypropylene (PP)/aluminum oxide (Al2O3) nanocomposites with the aid of two strategies. By melt-blending highly filled reactor granule with unfilled reactor granule, filler-rich and polymer-rich domains were created at around 10 μm scale, in which the filler-rich domains offered a thermally conductive pathway. The other strategy was based on tailoring the interfacial interaction between PP and Al2O3: An aluminum alkoxide precursor and a silane coupling agent were co-impregnated and converted into organically modified Al2O3 nanoparticles. Both of the strategies successfully improved the thermal conductivity of the nanocomposites at a fixed Al2O3 loading. The highest enhancement was achieved based on the interfacial modification using (2-phenylethyl)trimethoxysilane, where the thermal conductivity reached 0.74 W/m K at 20 wt% compared to 0.21 W/m K for pristine PP.

Preparation and characterization of polypropylene/noble metal nanocomposites based on reactor granule technology

The present contribution reports a novel strategy to prepare polypropylene (PP)-based nanocomposites with highly dispersed noble metal nanoparticles (NPs), which includes the impregnation of a metal salt inside the porosity of PP reactor granule and subsequent in-situ generation of the NPs therein. Thus formed nanoparticles were confined and retained in the porosity, thus minimizing the sintering and leaching of the NPs during melt processing. The so-called reactor granule technology was applied to successfully prepare PP-based nanocomposites with Ag and Au NPs, and unique nonlinear optical properties and the antibacterial ability of the PP/Ag nanocomposites were demonstrated.

Reactor granule technology for fabrication of functionally advantageous polypropylene nanocomposites with oxide nanoparticles

Polypropylene (PP)/TiO2 and PP/Al2O3 nanocomposites were fabricated based on a new technology that involves the impregnation of metal alkoxide precursors in the porosity of PP reactor granule and subsequent conversion of the precursors into oxides during melt mixing. The so-called reactor granule technology enabled in-situ generation of highly dispersed oxide nanoparticles over a wide range of the loading extending up to 20 wt% without the use of dispersants. The confinement of metal alkoxide precursors in the porosity of the PP reactor granule and their facile chemical conversion into oxides were found to be crucial for the dispersion of the nanoparticles. The excellent dispersion of Al2O3 nanoparticles led to significant improvements in tensile properties, dielectric constants, and thermal conductivity as compared to conventional nanocomposites using a compatibilizer. It was concluded that the reactor granule technology is a simple and versatile way for the fabrication of polyolefin-based nanocomposites with superior functionalities.

Tailoring the properties of polypropylene in the polymerization reactor using polymeric nucleating agents as prepolymers on the Ziegler–Natta catalyst granule

Nodular polypropylene from reactor granule technology for the production of a stiff and ductile material.

A facile method to prepare polypropylene/poly(butyl acrylate) alloy via water–solid phase suspension grafting polymerization

Abstract Polypropylene/poly(butyl acrylate) alloy is produced by water–solid phase suspension grafting polymerization with a submicrometer microdomain where graft polymerization occurs within micropores of polypropylene particles prepared by reactor granule technology (RGT). The results show that the grafting percentage (GP) of butyl acrylate (BA) increases with the increase of the monomer concentration, which could reach 32.6% while the grafting efficiency (GE) is up to 98%. The addition of the crosslinking agent, triethylene glycol diacrylate (TEGDA), could improve GP up to 36.3%. Transmission electron microscopic (TEM) micrographs demonstrate that PBA microdomains distributed in PP matrix increase in size less than 500 nm. Moreover, TEM images show that the grafting phase exhibits a single-phase behavior with the addition of TEGDA, which implies that the ratio of graft copolymer increased.

New Reactor Granule Technology for Highly Filled Nanocomposites: Effective Flame Retardation of Polypropylene/Magnesium Hydroxide Nanocomposites

A novel additive-free reactor granule technology is reported for the fabrication of polyolefin-based nanocomposites, which involves in situ generation of nanoparticles with unprecedented dispersion even at high filler loadings. Polypropylene reactor powder obtained by catalyzed propylene polymerization is first impregnated with magnesium ethoxide (Mg(OEt)2) solution. After the solvent drying and pre-hydrolysis, the powder is melt mixed to convert partially hydrolyzed Mg(OEt)2 into magnesium hydroxide (Mg(OH)2). Thus, prepared PP/Mg(OH)2 composites exhibit uniform dispersion of the in situ formed Mg(OH)2 nanoparticles even at a high filler loading (e.g., 20 wt%) without the use of dispersants, which is unexpected for the combination of hydrophilic filler and hydrophobic matrices. The obtained nanocomposites significantly improve the flame retardancy at a filler loading much lower than those for conventional composites.

Synthesis of spherical trans-1,4-polyisoprene/trans-1,4-poly(butadiene-co-isoprene) rubber alloys within reactor

Trans-polydiene rubber family as high-performance tire stock possessed excellent dynamic properties, including excellent anti fatigue, low rolling resistance, low heat buildup, good green strength, and low abrasion loss. Here, Reactor Granule Technology (RGT) was introduced into the field of synthetic rubber for the first time to produce trans-1.4-polyisoprene/trans-1,4-poly(butadiene-co-isoprene) rubber alloy, which showed significant improvement in rubber synthetic technologies and great development in abundance of trans-rubber family. A series of trans-polyisoprene alloys with excellent spherical morphology were successfully synthesized by using sequential multistage polymerization. The alloy was fractionated into four fractions by temperature-gradient fractionation, and the fractionation was analyzed by 1H NMR, 13C NMR, DSC and WAXD.

A facile, green, versatile protocol to prepare polypropylene‐g‐poly(methyl methacrylate) copolymer by water‐solid phase suspension grafting polymerization using the surface of reactor granule technology polypropylene granules as reaction loci

AbstractA facile and environment friendly process, called water‐solid phase suspension grafting polymerization, was developed to prepare polypropylene‐g‐poly(methyl methacrylate) (PP‐g‐PMMA) copolymer with a submicrometer microdomain. In this approach, graft polymerization was elaborately regulated to occur within micropores of polypropylene particles prepared by reactor granule technology. FTIR spectra of the samples after extraction demonstrated that PMMA was successfully grafted onto the PP. The results showed grafting percentage (GP) of PMMA increased with the increasing monomer ratios to PP and that could reach 13.6%. Whereas the grafting efficiency decreased as the monomer ratio increased. The addition of second monomer styrene improved GP up to 24.5%. Differential Scanning Calorimetry tests showed that the grafting of PMMA have a slight effect on the melting point and the relative crystallinity of PP. TEM micrographs demonstrated PMMA domains distributed in PP matrix with sizes ranging from about 100 to 300 nm. In addition, Shear viscosity increased with the growing GP indicated by rheological measurement. The preliminary evaluation showed PP‐g‐PMMA was effective in improving the compatibility of PP/acrylonitrile‐styrene‐acrylate blends. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Self‐Similar Growth of Polyolefin Alloy Particles in a Single Granule Multi‐Catalyst Reactor

AbstractIn this news article, a new kind of in‐reactor alloying process (Chinese multi‐catalyst reactor granule technology, CMRGT) is introduced. It provides the possibility to produce series of new polyolefin materials that can be used in automotive and appliances parts by the substitution of some traditional engineering plastics. A characteristic ‘fractal (self‐similar) growth and pore‐filling mechanism’ for the CMRGT‐produced alloy particles is found. It reveals the fundamental scientific principles that govern the chemistry and physics in the formation mechanism of such novel olefinic alloys. This mechanism allows a detailed control of the dispersion and structure of these polyolefin alloys from a nanometer to micrometer size range, and possesses great potential to fulfil the requirements for a new generation of recyclable automotive materials.

Spherizone launched

The progress made in stereo-regular propylene industrial polymerization is briefly summarized. The capability to control the characteristics of heterogeneous Ziegler–Natta catalysts and related slurry and gas phase technologies (Reactor Granule Technology) is described from the early synthesis of polypropylene to current state-of-the-art polymerization processes (Spheripol, Spherizone, and Catalloy technologies). Future developments and challenges for the third millennium are also outlined.

Polypropene product innovation by reactor granule technology

Continuous fine tuning of both chemistry and architecture of heterogeneous, isospecific MgCl2/TiCl4 catalyst systems for propene polymerization has led to a significant improvement in their performances in terms of activity, stereoselectivity, and capability to control both molecular parameters and morphology of the resulting polymers. As a result, a number of improved/innovative propene-based products has recently been developed that clearly outperform the previously available materials. In particular, a family of reactor-grade polymers has been synthesized including homopolymers and heterophasic copolymers offering, respectively, an unprecedented relationship between fluidity and stiffness and between stiffness and impact strenght, and supersoft polypropene alloys that could not have been achieved even via mechanical blending.

THE REACTOR GRANULE TECHNOLOGY: THE ULTIMATE EXPANSION OF POLYPROPYLENE PROPERTIES?

The progresses obtained in both catalyst performances and process technologies have made the continuous expansion of PP properties possible. The discovery of MgCl2-supported catalysts and the development of their controlled spherical morphology produced a real revolution in the catalytic-system performances. A series of definitive improvements in catalyst chemistry and an impressive increase in polymer productivity were allowed by the total control of the “replication” phenomenon of polymer generated by the parent catalyst. The Reactor Granule Technology started up with relevant consequences in terms of development of new polymer properties for new applications and new markets, and of new economic and versatile process technologies with the best environmental impact. Through this technology, it is also possible to use a mixed catalysis combining the heterogeneous Ziegler-Natta catalysts with homogeneous catalysts such as radicalic initiators, metallocenes and single site, and this possibility results in a dramatic development of the material potentials and properties. The recently conceived “Multizone Circulating Reactor Technology” represents the ultimate frontier in the polymeric materials science. It will allow the uniform phase homogenization of dissimilar materials generating novel polymeric alloys with an enormously expanded property/performance envelope.

Combining Ziegler‐Natta and mettalocene catalysis: New heterophasic propylene copolymers from the novel multicatalyst reactor granule technology

A new process that combines the excellent morphology control of Ti-based catalysts with the unique features of polyolefins from mettalocenes has been devised. First, propylene is polymerized with the Ti-based catalysts, having spherical form; then, activated mettalocene catalysts are introduced into the porous PP spheres, through an in situ impregnation and drying process, once the Ti has been deactivated. Then, the olefins polymerization, catalyzed by the mettalocene, is carried out in gas phase. This step, as well as the morphology of the as-polymerized polymer particles, has been investigated in detail. New heterophasic copolymers (PP/EPR) having free-flowing spherical form have been achieved, and the morphology of the copolymer spheres pointed out that the rubber is well dispersed inside the polymer granule. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1831–1837, 1997

Combining Ziegler-Natta and mettalocene catalysis: New heterophasic propylene copolymers from the novel multicatalyst reactor granule technology

A new process that combines the excellent morphology control of Ti-based catalysts with the unique features of polyolefins from mettalocenes has been devised. First, propylene is polymerized with the Ti-based catalysts, having spherical form; then, activated mettalocene catalysts are introduced into the porous PP spheres, through an in situ impregnation and drying process, once the Ti has been deactivated. Then, the olefins polymerization, catalyzed by the mettalocene, is carried out in gas phase. This step, as well as the morphology of the as-polymerized polymer particles, has been investigated in detail. New heterophasic copolymers (PP/EPR) having free-flowing spherical form have been achieved, and the morphology of the copolymer spheres pointed out that the rubber is well dispersed inside the polymer granule. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1831–1837, 1997

Highly flexible heterophasic copolymers through the novel multicatalysts reactor granule technology

New heterophasic copolymers with high rubber content have been synthesized by combining heterogeneous Ti-based catalysts with metallocenes. The molecular, morphological and mechanical features of these materials were evaluated: it was pointed out that the new copolymers, having more than 60Wt.% of rubber, perform as reinforced elastomers whereas traditional ones show a more plastomeric behaviour. This suggests that new polyolefin materials can augment rather than compete with the traditional ones.

New thermoplastic polyolefins elastomers from the novel Multicatalysts Reactor Granule Technology: their relevant physical-mechanical properties after crosslinking

A new process for the sequential copolymerization of olefins has been devised (Multicatalysts Reactor Granule Technology); it allows the synthesis of thermoplastic polyolefin elastomers having polypropylene from Ti-based catalysts and ethylenepropylene rubbers from metallocenes. Such new materials have been cured with peroxides an the relevant mechanical properties measured in comparison with those of heterophasic copolymers synthesized with traditional catalysts. It resulted that the new materials present an improved balance between strength and elasticity, especially at high temperature.

The reactor polymer alloys: The shifting of the frontier of polymer research

AbstractThe discovery (1968) of the high yield Ziegler‐Natta catalysts based on active MgCl2 was the beginning of a scientific and industrial revolution that has brought about the creation of superactive, isospecific, spheriform fourth generation catalytic systems. The rationalization of the polymer/catalyst replication phenomenon and the understanding of the catalyst “architecture” effects on polymer shape and morphology has led to the exploitation of the “Reactor Granule Technology”. This has made the generation of a broad range of homo, copolymers and multiphase alloys (Catalloy) possible by synthesis, most of which having a previously unobtainable spectrum of performance (Refs. 1,2,3). The reactor granule technology concept has also been the basis for the achievement of a family of polyolefin/non polyolefin alloys with engineering properties.More recently, the reactor granule approach has been extended so as to couple the advantages of both heterogeneous and homogeneous metallocene catalysts (mixed catalysis), thus allowing the synthesis of a very new family of “in situ” polyolefin alloys.