最新刊期
卷 34 ， 期 6 ， 2021
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- 摘要：Progress on high-performance polyolefin materials development based on functionalization of Ziegler-Natta catalysts is introduced. Ziegler-Natta catalyst/Advanced Polymerization Coagent (APC) compound strategy greatly expands the property envelop of Ziegler-Natta catalysts. Among the ongoing developments, Ziegler-Natta/ω- alkenylmethyldichlorosilane functional catalyst system has shown its industrial potential in preparation of long-chainbranched/ high-melt-strength polypropylene (PP), while Ziegler-Natta/nonconjugated α,ω-diolefin system provides a revolutionary innovation to heterophasic polymerization of propylene, allowing preparation of PP-based thermoplastic elastomers (TPO, with increasing rubber contents). Other strategies such as Ziegler-Natta/metallocene compound catalysts and nano-supported Ziegler-Natta catalysts further boost Ziegler-Natta catalysts properties for preparation of new high-performance polyolefin materials.关键词：Ziegler-Natta catalyst;Functionalization;High-performance polyolefin materials
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发布时间：2022-08-30 - 摘要：Polyolefins have huge annual production and wide applications. However, one of their biggest limitations is their nonpolar nature. The introduction of small amounts of polar functional groups into non-functionalized polyolefins can greatly improve many properties, broaden their applications and increase their business values. Therefore, functionalized polyolefins are of growing interest scientifically and industrially. This account focuses on the research works from our research group and describes the following topics: the development of new catalyst systems, the selection of polar monomers and the new polymerization techniques. Subsequently, we describe the synthesis of a series of polyolefins with incorporation of some polar groups, as well as the studies of the properties of polar functionalized polyolefins materials.关键词：Catalysts;Polar monomer;Polymerization techniques;Functionalized polyolefins;Materials properties
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发布时间：2022-08-30 -
Research Advances of Multiscale Structure Mediation of Polypropylene: Nucleation Effect and Blending
摘要：As one of the most broadly applied general plastics, polypropylene (PP) has played a significant role in the economy and everyone’s daily life. The performance of PP and its blends are determined largely by the microstructure and morphology, including the crystal type, crystallinity, orientation, phase morphology. We summarized the research advances in our group regarding the structure and property relationship of PP and its blends. The topics cover the PP/ nucleating agents, PP in-reactor alloys, PP/elastomer blends, and PP/rigid particle compounds. There is a clear mismatch between the rapid growth in productivity of PP general grade resins and the shortage of high-end PP resins. It is essential to continue the study of the basic structure and properties relationship of PP materials.关键词：Polypropylene;Crystallization;Blends;Toughening;Property- 16
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发布时间：2022-08-30 - 摘要：As the topological structure of macromolecular chains is very important to the properties of the materials, the relationship between the topological structure of polymer chains and the properties of materials has always been an important topic in the field of polymer materials. Living/controlled polymerization provides a variety of methods for the controlled synthesis of comb-like polymers, through which the topological structure of comb-like polymers can be easily regulated. Currently, there are three main synthesis strategies adopted, namely "Graft onto" strategy, "Graft through "strategy and "Graft from" strategy. Combined with author's research work, this paper summarizes the progress in the polyolefin and polystyrene based comb-like (co)polymers, including the synthesis of comb-like polymers with well-defined structure, and the relationship between chain topological structure and performance of the controllable synthesis of comblike (co)polymers, which focus on the effect of long chain branched structure parameters (branched chain length, density and chemical composition of branch chain) on melt behavior, foaming behavior and crystallization behavior of comb-like (co)polymers.关键词：Comb-like (co)polymer;Living/controlled polymerization;Rheological behavior;Microphase separation
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发布时间：2022-08-30 - 摘要：Electron donors are key components of MgCl2-supported Ziegler-Natta catalyst that enhance stereoselectivity of α-olefin polymerization. This article introduced recent progresses in mechanistic studies on the effects of internal and external electron donors in MgCl2-supported Ziegler-Natta catalyst for propylene polymerization, especially typical research cases and achievements based on spectroscopic analysis, model catalyst studies, molecular modeling and kinetic studies. It shows that remarkable progresses have been made in this research field in the last 1—2 decades, which have formed a solid foundation for completely disclose the mechanism of electron donor effects in polypropylene catalysts in the future, and will greatly promote the research and development of Z-N catalysts for polypropylene.关键词：Ziegler-Natta catalyst;Propylene polymerization;Electron donor;Mechanism
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发布时间：2022-08-30 - 摘要：1-Octene is the main raw material for the production of high-performance polyolefins and high-end lubricants, and its production technology directly affects the development of polyolefin and lubricant industries. Ethylene selective tetramerization to 1-octene offers several advantages, such as high product selectivity, high purity, and good atomic economy. It is the trend of 1-octene production technology and is highly favored by academia and industry. Methylaluminoxane (MAO) is commonly used as cocatalyst in ethylene selective tetramerization catalytic systems, and its dosage directly affects the production cost of ethylene selective tetramerization. Reducing the amount of MAO, or not using MAO, is the goal of ethylene selective tetramerization to 1-octene technology. In this paper, we review the mechanism of MAO cocatalysts in ethylene selective tetramerization catalytic system and the new development of ethylene tetramerization to 1-octene technology in non-MAO system.关键词：Ethylene tetramerization;1-Octene;Chromium catalyst;Methylaluminoxane;Cocatalysts
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发布时间：2022-08-30 - 摘要：Late transition metal catalysts, especially α-diimine nickel and palladium catalysts, have received intensive attention because of their unique catalytic properties including single active center, high activity, and outstanding tolerance toward polar groups that allow for direct copolymerization of ethylene and polar monomers. However, this kind of catalysts often show poor thermal stability and being unsuitable for many industrial synthetic processes that usually operate at high temperatures. Previously, the reported strategy to enhance the stability of α-diimine nickel and palladium catalysts mainly focused on the modifications of the N-aryl substituents. We provided an alternative approach by increasing the steric bulk of the α-diimine ligand backbone for effectively enhancing the thermal stability of catalysts and the controllability of polymerization. These advances in the bulky backbones strategy for α-diimine nickel and palladium catalysts toward olefin polymerization are summarized herein, including ethylene polymerization, α-olefin polymerization, copolymerization of ethylene and polar monomers, polymerization of styrene-based monomers and styrene/CO alternating copolymerization.关键词：Catalyst;Steric effect;Thermal stability;Living polymerization
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发布时间：2022-08-30 - 摘要：A series of o-bulky substituted amine-bis(phenolate) tetradentate Ti(Ⅳ) Complexes: Me2NCH2CH2N(CH2-(2-OC6H2-3-R-5-tBu)2TiCl2 (2a, R = CPhMe2; 3a, R = CMePh2; 4a, R = CPh3), were synthesized and characterized. The catalytic performance of these complexes for ethylene polymerization, ethylene/propylene copolymerization and ethylene/1-hexene was studied and the effects of ligand structure and polymerization conditions on polymerization behavior were investigated. Compared with 1a(R=tBu), these synthesized catalysts showed high catalytic activity and excellent stability in ethylene (co)polymerization. In the presences of MAO, the highest activity of these catalysts toward ethylene polymerization was 1170kg PE/(mol Ti·h). Moreover, the highest Mw of polyethylene obtained by 2a~4a/AliBu3/Ph3CB(C6F5)4 was 113×104g/mol. When activated by MAO, the highest activities of 1a~4a toward ethylene/propylene copolymerization and ethylene/1-hexene copolymerization were 640kg polymer/(mol Ti·h) and 1220kg polymer/(mol Ti·h), respectively; the molecular weight of obtained ethylene-co-propylene and ethylene-co-1-hexene are 3.1×104 ~17.4×104 and 4.9×104 ~15.5×104g/mol, respectively. The highest content of propylene unit in the ethylene-propylene copolymer was 36.9mol%, and the highest content of 1-hexene unit in the ethylene-1-hexene copolymer was 12.5mol%. The content of comonomer in copolymers was dependent on steric hindrance of catalyst ligands, and it was found that the insertion of comonomer decreased with the increase of steric hindrance of catalyst ligands.A series of o-bulky substituted amine-bis(phenolate) tetradentate Ti(Ⅳ) Complexes: Me2NCH2CH2N(CH2-(2-OC6H2-3-R-5-tBu)2TiCl2 (2a, R = CPhMe2; 3a, R = CMePh2; 4a, R = CPh3), were synthesized and characterized. The catalytic performance of these complexes for ethylene polymerization, ethylene/propylene copolymerization and ethylene/1-hexene was studied and the effects of ligand structure and polymerization conditions on polymerization behavior were investigated. Compared with 1a(R=tBu), these synthesized catalysts showed high catalytic activity and excellent stability in ethylene (co)polymerization. In the presences of MAO, the highest activity of these catalysts toward ethylene polymerization was 1170kg PE/(mol Ti·h). Moreover, the highest Mw of polyethylene obtained by 2a~4a/AliBu3/Ph3CB(C6F5)4 was 113×104g/mol. When activated by MAO, the highest activities of 1a~4a toward ethylene/propylene copolymerization and ethylene/1-hexene copolymerization were 640kg polymer/(mol Ti·h) and 1220kg polymer/(mol Ti·h), respectively; the molecular weight of obtained ethylene-co-propylene and ethylene-co-1-hexene are3.1×104 ~17.4×104 and 4.9×104 ~15.5×104g/mol, respectively. The highest content of propylene unit in the ethylene-propylene copolymer was 36.9mol%, and the highest content of 1-hexene unit in the ethylene-1-hexene copolymer was 12.5mol%. The content of comonomer in copolymers was dependent on steric hindrance of catalyst ligands, and it was found that the insertion of comonomer decreased with the increase of steric hindrance of catalyst ligands.关键词：Polyolefin;Ti complexes;Olefine polymerization;Ethylene polymerization
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发布时间：2022-08-30 - 摘要：New iodo-terminated polyolefin based macroinitiators were synthesized for the first time by one-pot method combining polyhomologation of ylides and post functionalization. Then, well-defined polymethylene-b-poly(2,3,4,5,6- pentafluoro styrene) with terminal bi-allyl groups (BA-PM1-b-P(PFSt) (Mn,NMR =10500 and 14600g/mol, Fluorine content=13.5wt% and 20.8wt%)), polymethylene-b-poly(styrene-co-2,3,4,5,6-pentafluoro styrene) with terminal biallyl groups (BA-PM2-b-P(St-co-PFSt)) (Mn,GPC =5200~7130kg/mol, Fluorine content=1.8wt% ~5.4wt%) were achieved efficiently via thermally/light induced degenerative iodine transfer polymerization in the presence of Mn2(CO)10. The chain structures of the obtained copolymers were characterized by 1H-NMR, 19F-NMR, GPC and elemental analysis. In addition, the BA-PM2-b-P(St-co-PFSt)3 porous films with average pore sizes of 5.0~1.5m m were fabricated via a static breath-figure process at 25℃ under 95% relative humidity with different copolymer concentration of 1, 5 and 10mg/ mL, respectively.关键词：Polyhomologation of ylides;Iodo-terminated polyolefin macroinitiator;Thermally/light induced degenerative iodine transfer polymerization;Fluorine-containing block copolymer;Porous films
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发布时间：2022-08-30 - 摘要：The copolymerization of ethylene/6-furyl-1-hexene (FH) was conducted with Ziegler-Natta and metallocene (rac-Et(Ind)2ZrCl2 ) catalysis respectively to synthesize polyethylenes with furyl-pendent group. Cross-linked polyethylenes were then prepared via Diels-Alder reaction by adding 1,6-bismaleimidohexane (BMH) as cross-linking agent into the ethylene/FH copolymer. The copolymers structure was characterized by 1H-NMR and DSC. The cross-linked polyethylene structure and properties were measured by FTIR, creep and tensile tests. The results showed that the crosslinking degree of polyethylene could be adjusted by changing the ratio of maleimide to furan, and thermal reversibility of Diels-Alder reaction endowed cross-linked polyethylenes with reprocessability.关键词：Polyethylene;Diels-Alder reaction;Thermoreversible cross-linking
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发布时间：2022-08-30 - 摘要：Preparation of in-reactor polyolefin alloy by Reactor Granule Technology provides an effective method for the design and modification of new polyolefin materials. In this work, two pilot-scale polypropylene (PP)/polybutene-1(PB-1) in-reactor alloys prepared based on reactor granule technology with the two-stage polymerization technology were fractionated with solvent extraction fractionation and temperature rising elution fractionation. By using differential scanning calorimeter (DSC), high temperature nuclear magnetic carbon spectrum (13C-NMR) and high temperature gel permeation chromatograph (GPC),the structure and composition,especially the composition and distribution, chain sequence structure and distribution of the PP/PB-1 in-reactor alloy and its fractions were further clarified. The relationship between the composition and properties of two alloys was studied. This study is of great significance for the optimization of polymerization process and the development of advanced polyolefin materials.关键词：PP/PB-1 alloy;Temperature rising elution fractionation;Copolymer;Sequence structure;Isotacticity
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发布时间：2022-08-30 - 摘要：Copolymerization of butadiene (BD) and isoprene (IP) catalyzed by PNP-ligand stabilized yttrium bis(alkyl) complex gives a series of cis-1,4-regulated BD-IP copolymers containing 11mol% ~53mol% isoprene units, which are characterized by 1H- and 13C-NMR and GPC. The resulting copolymers are compounded with carbon black and various fillers in a two-step process, and then are vulcanized in a compression molding process. The effects of isoprene content and molecular weight on the tensile strength, tearing strength, abrasion resistance, glass transition temperature and crystalline property of the vulcanized BD-IP copolymers are investigated by means of tensile strength test, Akron-abrasion test and dynamic thermomechanical analysis (DMA).关键词：Poly(BD-co-IP) rubber;Rare earth catalyst;High cis-1, 4-selectivity;Tensile strength
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发布时间：2022-08-30 - 摘要：We designed and synthesized two α-diimine Ni(Ⅱ ) catalysts, with hydroxyethyl-phenoxyl group on acenaphthequinone-backbone and with different electronic-effect substituents on N-aryl, Cat-F and Cat-OCH3. The catalytic activity of the two catalysts in the cocatalyst of diethyl aluminum chloride (DEAC) was studied. We found that temperature and pressure have strong influence on catalyst activity. In addition, differential scanning calorimeter (DSC), carbon nuclear magnetic (13C-NMR), gel permeation chromatography (GPC) and other equipment were used to analyze the effect of polymerization conditions on the melting point, degree of branching, weight average molecular weight and polydispersity index of the obtained polyethylene.关键词：α-Diimine Ni(Ⅱ) catalyst;Ethylene;Branched polyethylene
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发布时间：2022-08-30 - 摘要：In this article, the market predominant metallocene transparent PPs (mTPPs) and Ziegler-Natta PP random copolymers (RCP) are analyzed with several analytical techniques, such as temperature rising elusion fractionation (TREF), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) etc. The analytical results indicate that, from molecular to aggregation state, catalyst structure has a significant influence to the microstructures of the polymer chain; i.e. the products made from single-site metallocene catalyst have narrow molecular distribution, higher stiffness and low haze. With small amount of ethylene comonomer incorporation into the PP chain, the mTPPs exhibit excellent properties such as very narrow molecular weight distribution, high rigidity, and low haze. For different fractions of TREF, the PP microstructural regularity increases with the increasing elusion temperature. The physical properties between the PP products made from different catalysts are compared, it is clear that the TPPs made from metallocene catalyst exhibit better optical properties than the TPPs made from Z-N catalyst.关键词：Transparent PP;Metallocene catalyst;Z-N catalyst;TREF;GPC;DSC;NMR Chain microstructure
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发布时间：2022-08-30 - 摘要：A microchannel reaction system for olefin coordination polymerization was designed and built, using rac- Me2Si(2,5-Me2-4-Ph-ThCp)2ZrCl2 metallocene as the catalyst, methylaluminoxane (MAO) as the cocatalyst, and xylene as the solution, the copolymerizations of ethylene and propylene were performed within a microchannel of 1/8 inch stainless steel tube. The influence of polymerization temperature, residence time, microchannel tube length and feed ratio on its catalytic activity of metallocene, molecular weight and its distribution of ethylene/propylene copolymerization, microstructure and thermal properties are studied. The results show that copolymers of ethylene and propylene are successfully continuous synthesized in the microchannel reactor.关键词：Microchannel reactor;Metallocene catalyst;Ethylene-propylene copolymer
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发布时间：2022-08-30
Special Issue: In Celebration of the 80th Birthday of Professor HU You-liang
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