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Abstract: Melamine (MA) was polymeric modified by condensation reacting with formaldehyde (FA) to form the melamine formaldehyde polycondensate (abbreviation: MF) with high molecule-weight and comparatively high processing thermo-stability. The effect of the reacting molar ratio of MA and FA, and the types and concentrations of the dispersion agents on the structure and properties of MF were discussed, and the finely divided, cross-linked, and thermo-stable MF polycondensates were obtained. The thermal stabilization effect of MF on POM was studied by the isothermal weight loss analysis at 220°C, isothermal weight loss rate analysis at 222°C, thermal gravity analysis (TGA) and balance torque analysis, which showed that MF has almost the equal thermal stabilization on POM to MA. The multiple processing and long-term thermal stability at high temperature measurements indicated that MF showed even higher thermal stabilization on POM than MA. Moreover, the impact strength was improved after five times of extrusion, due to the better dispersion of MF in POM matrix and better nucleation effect of MF on POM. [Copyright &y& Elsevier]

Abstract: The functionalization of polyolefins has long been an industrially important yet scientifically challenging research subject ever since the commercialization of polyethylene (PE) and polypropylene (PP) in the 1950s. However, only until recently has considerable progress been made thanks to the enormous development of transition metal olefin polymerization catalysis (Ziegler-Natta, metallocene and post-metallocene). This review covers recent achievements in the functionalization of polyolefins, with special attention being paid to the chemistries using transition metal-catalyzed process to synthesize structurally well-defined functional polyolefins, including side group-functionalized polyolefins, chain end-functionalized polyolefins and functional polyolefins with graft and block structures. [Copyright &y& Elsevier]

Abstract: An effective route to synthesize the amphiphilic diblock copolymer containing a poly(ε-caprolactone) block and a polyolefin block, such as polyethylene, syndiotactic polystyrene and isotactic polypropylene is discussed in this article. There are two reaction steps including the preparation of polyolefins by the combination of metallocene/methylaluminoxane as catalyst system and various chain transfer agents as well as the subsequent anionic ring-opening polymerization of ε-caprolactone. The molecular structure in terms of composition, molecular weight, molecular weight distribution of the diblock copolymers prepared is controllable by these well-defined reaction mechanisms. The scanning electron microscope (SEM) results showes that the compatibilities of the polyolefins and polycarbonate blends are improved greatly using these amphiphilic diblock copolymers as the polymeric compatilizers. [Copyright &y& Elsevier]

Discusses the synthesis of well-defined functional polyethylene graft copolymer via atom transfer radical polymerization (ATRP) process. Transformation of the pendant styrene groups into ATRP initiator sites; Determination of the quantitative hydrochlorination reaction; Lack of polar functional groups on its polymer chain.

Reversible addition-fragmentation chain transfer radical polymerization of styrene and maleic anhydride was successfully performed in continuous-flow microreactor. Results of the structural characterization showed that the obtained styrene-maleic anhydride (SMA) copolymers possessed controlled molecular weight, low dispersity and alternating structures. Subsequently, effects of the polymerization conditions, including reaction pressure, temperature, feed flowrate and tube length, on the polymerization kinetics and molecular structure of the SMA copolymers were investigated in detail. It was found that the reaction rate was increased as the reaction temperature increased within certain limits, as well as the feed flowrate due to the increased mass and heat transfer efficiency. Besides, first-order kinetics of the polymerization was observed when the reaction times were adjusted by only changing the tube length. Good stability was exhibited when the reaction conducted continuously for 10 h. This approach can reduce the reaction time significantly from several hours to about half an hour. [ABSTRACT FROM AUTHOR]

Reports on the preparation of a series of high molecular weight amphiphilic graft copolymers. Esterification of the copolymers under different conditions; Study of the composition using nuclear magnetic resonance and fourier transform infrared spectroscopy.

A novel macromolecular auxiliary antioxidant with polyethylene (PE) as polymer skeleton and phosphites as side groups is prepared based on commercial ethylene‐vinyl acetate (EVA) copolymers and its potential as polyolefin stabilizers is studied in depth. The synthesis approach of this PE‐grafted antioxidant consists of a typical EVA hydrolysis reaction and a two‐step nucleophilic substitution reaction of PCl3, 2,4‐di‐tert‐butylphenol, and the hydrolysis product. Results of the thermogravimetric analysis show that the macromolecular structures endow the as‐synthesized antioxidant with much better thermal stability than that of the commercial antioxidant 168. In addition, antioxidant behaviors of the PE‐grafted antioxidants in polypropylene (PP) matrix are investigated in detail through characterization of the melt flow index of multiple‐extruded stabilized PP as well as the short‐term oxidation induction time test and the long‐term thermo‐oxidative aging test. Results show that even with extremely low content of the effective antioxidant groups, the as‐synthesized macromolecular antioxidant still has excellent antioxygenic properties. [ABSTRACT FROM AUTHOR]

Novel polyethylene‐based (PE‐based) antioxidants derived from commercially available ethylene‐vinyl acetate copolymer (EVA) with PE as the backbone and hindered phenols as side groups are prepared, and their potential for application as non‐migrating polyolefin stabilizers is investigated. The synthesis route contains the typical hydrolysis of EVA and transesterification reaction between the hydrolysis product and methyl 3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl) propionate. Thermal stabilities of these PE‐based antioxidants (AO‐PE) are studied through thermal analysis under an air atmosphere and shown to be higher than those of antioxidant 1076 and antioxidant 1010 (AO‐1010) due to their macromolecular structures. Antioxidant activities of the AO‐PE are evaluated in polypropylene (PP) by measuring the melt flow index of multiple‐extruded stabilized PP, and the results demonstrate that the antioxidant effectiveness of these antioxidants is strongly related to the molecular weight. [ABSTRACT FROM AUTHOR]

A series of vanadium catalysts with bulky bis(N-heterocyclic carbenes) (bis-NHCs) ligands were synthesized by in-situ reaction. With diethylaluminum chloride (AlEt 2 Cl) as cocatalyst and ethyl trichloroacetate (ETA) as activator, these catalysts exhibit good activity when used to catalyze ethylene (co)polymerization. The structure of the catalyst, especially the bridging carbons number of the bis-NHCs ligands, is related to the performance of the (co)polymer. When the bis-NHCs ligand with t Bu substituted, increased the bridging carbons number of the bis-NHCs ligand is easier to obtain higher molecular weight polymers. But when the bis-NHCs ligand with 2,6-diisopropyl phenyl substituted, the increase of the bridging carbons number is not conducive to obtaining higher molecular weight polymers. Under the same concentration of comonomer, the increase of the bis-NHCs ligand bridged carbon number of the V-complexes is more beneficial to obtain the copolymer with high norbornene (NB) content. [Display omitted] • The first application of bis-NHCs ligands in vanadium (III) catalyzed olefin polymerization. • The bis-NHCs vanadium (III) complex were obtained by in-situ reaction for the first time. • Relationships were found to exist between the bis-NHCs ligand structure of the catalyst and the catalytic performance. [ABSTRACT FROM AUTHOR]

Carbon nanoforms (CNFs, including graphene, carbon nanotube and fullerene) were functionalized via microwave-assisted thiol-ene click chemistry. Different functional CNFs with −COOH, −NH 2 , −NH 3 Cl,-Si(OCH 3 ) 3 , alkyl and furyl groups were obtained and characterized by XPS, EDS, TGA, Raman spectroscopy and MALDI-TOF MS. Microwave was much more efficient to promote reactions than traditional thermal method. XPS confirmed the binding energy of C-S-C (163.3ev) the modified CNFs. Raman spectroscopy showed increasing I D /I G and A D /A G of graphene and CNT after thiol-ene addition reaction. The result of MALDI-TOF MS indicated that the thiol-containing molecules were attached on fullerene. All these results indicated the successful thiol-ene click reactions between CNFs and thiol-containing molecules under microwave. TGA analysis results showed the mass loss of the modified CNFs, which provided that AIBN and 3-merlaptopropionic acid were the most efficient initiator and monomer, respectively. In summary, the microwave-assisted thiol-ene click reaction provided a powerful chemical tool for the preparation of functional CNFs materials. [ABSTRACT FROM AUTHOR]

A new synthetic procedure is described for the preparation of dendritic polyethylene brushes with polysiloxane as the main chain, describing for the first time that it is possible to simply and efficiently prepare highly branched architectures for this type of polymer. Furthermore, as a result of the polymer brush architecture, polyethylene acts as the side chains and Si-O-Si as the backbone. The number average molecular weight (Mn) of the polyethylene brushes, which is determined using a multiple angle laser light scattering detector, increases from 5946 to 27 684 g mol-1 while retaining relatively narrow polydispersities (1.5-2.4). The polymer brushes are characterized by solid 29Si NMR and high-temperature ¹H NMR spectra. In addition, X-ray photoelectron spectroscopy and gel permeation chromatography were used to confirm the structure. [ABSTRACT FROM AUTHOR]

Chain-end-functionalized polyethylenes (Cef-PEs: PESSH (Cef1), PESfurfuryl (Cef2), PESNH2 (Cef4), PESNH2•HCl (Cef5), PESCOONa (Cef6), PESCHA(Cef7), PESSO3Na (Cef8), PESOH (Cef9) and PESCOOH (Cef10)) are synthesized by thiol-ene addition of vinyl-terminated polyethylene (v-PE) with 1,2-ethanedithiol, furfurylmercaptan, cysteamine, cysteamine hydrochloride, sodium thioglycolate, L-cysteine hydrochloride, sodium 2-mercaptoethanesulfonate, mercaptoethanol, and thioglycolic acid, respectively. PEStNCO (Cef3) is obtained by subsequent reaction of Cef9 with anhydrous 4,4′-MDI. Cef-PE1-8 are reported for the first time. The conversions of all the reactions are up to 95%-100%. All the Cef-PEs are characterized by NMR, GPC, DSC, FT-IR, and TGA. In the experiments, it is found that alkaline mercaptans and solvents are adverse to the thiol-ene click reactions. [ABSTRACT FROM AUTHOR]

Fivenew alkoxysilanes with different sizes of hydrocarbon substituentswere first synthesized and employed as external donors for propylenepolymerization with a Ziegler–Natta catalyst. The effects ofthese and industrial alkoxysilanes with different sizes of hydrocarbonsubstituents on the microstructure of polypropylene were studied bySSA and 13C NMR. The results showed that isotactic sequencelength of polypropylene increased with the size of R2substituenton alkoxysilanes in the five donor systems, similar to the regularityof molecular weight, isotacticity, and thermal properties of polypropylene.Although the polypropylene produced by double cycloalkane substituentson alkoxysilanes had lower lamellae thickness L1, its contents were the highest. Moreover, excess large volumeof hydrocarbon substituents on alkoxysilanes might be detrimentalto improving isotactic sequence length of polypropylene. Polypropyleneprepared by MIPDMS had a more uniform distribution of the stereodefects,indicating that MIPDMS might be used for the industrial productionof BOPP. [ABSTRACT FROM AUTHOR]

The new aminosilane compounds including Dimorpholindimethoxysilane (Donor-Pm), Di (1-methylpiperazine) dimethoxysilane (Donor-Pz) and Di (isopropylpiperazine) dimethoxysilane (Donor-Pi) were firstly synthesized and then employed as external donors for propylene polymerization with MgCl-supported Ziegler-Natta catalyst, compared with dipiperidine dimethoxysilane (Donor-Py). The effects of the aminosilane external donors on the catalytic activity, hydrogen response, and molecular weight distribution, crystalline ability, thermal property, isotactic sequence length, isotactic sequence distribution of polypropylene were studied by differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and self-nucleation and annealing (SSA), respectively. It was found that these new aminosilane compounds were conducive to improving the isotacticity of polypropylene and the catalytic activity. The GPC results showed that the molecular weight distribution of polypropylene prepared respectively by Donor-Pz or Donor-Pi with two N atoms on each amino substituent group was broader more than 8.0, especially for Donor-Pi with the large alkyl-substituted group on each nitrogen atom, the molecular weight distribution of polypropylene was about 11.2, which was much broader than that of industrial polypropylene about 4 ~ 5. The DSC results indicated that the degrees of crystallinity of polypropylene prepared by the aminosilane external donors were higher, and the crystallization ability of polypropylene prepared by Donor-Pi was lower but closed to that of polypropylene prepared by Donor-Py. The SSA results indicated Donor-Py and Donor-Pi were conducive to improving the relative contents of the highest isotactic component of polypropylene, and the lamellae thicknesses results showed the sequence length of polypropylene prepared by Donor-Py and Donor-Pi were longer, and the isotactic sequence distribution of polypropylene prepared by Donor-Py and Donor-Pi were broader. The study results showed that the new aminosilane donor Donor-Pi was conducive to improving the stereo-regularity of polypropylene, especially revealing that it was a simple and an effective method to synthesize broad molecular weight distribution of polypropylene by using appropriate aminosilane external donor for propylene polymerization. [ABSTRACT FROM AUTHOR]

Four novel well-defined polyethylene-bound antioxidants (PE-bound antioxidants) with distinct secondary structures are synthesized via transesterification reactions between methyl 3-(3,5-di- tert-butyl-4-hydroxyphenyl)propionate and hydroxyl-terminated polyethylenes. The results of thermal gravimetric analysis under an air atmosphere demonstrate that the thermal stabilities of PE-bound antioxidants are higher than that of commercial antioxidant Irganox1076 and are strongly related to their chemical structures. Particularly, the most thermally stable PE-bound antioxidant is the one bearing both primary and secondary antioxidant moieties. The antioxidant activities of the PE-bound antioxidants are evaluated in polypropylene by their melt flow index. [ABSTRACT FROM AUTHOR]

As the external donor in Ziegler-Natta catalysts have an important influence on the stereo-defects distribution of polypropylene, the effects of the mixed external donors (the mixture of Donor-C (cyclohexylmethyldimethoxysilane) and Donor-N ( n-propyltriethoxysilane) ) on the isotactic sequence length and its distribution of polypropylene prepared by Ziegler-Natta catalyst through propylene bulk polymerization were studied through the Successive self-nucleating and annealing (SSA) and C-NMR techniques. The SSA results showed that the relative contents of the highest isotactic component and the lamellar thickness in the polypropylene chain gradually increased with the increase of the relative component of Donor-C in the C/N mixed external donors, indicating the isotactic sequence length of polypropylene got longer, and the lamellar thickness distribution of polypropylene became broader, revealing the isotactic sequence length distribution of polypropylene got broader. In addition, the C-NMR results showed that the average meso isotactic sequence length ( MSL) of polypropylene gradually increased with the increase of the content of Donor-C in the C/N mixed external donors, which was in good coincident with the results calculated from SSA, showing a good correspondence between the SSA and C-NMR techniques. [ABSTRACT FROM AUTHOR]

Abstract: PP-g-PS copolymers were synthesized with the same polypropylene (PP) backbones and various side chain lengths of PS sequences via reactive comonomer p-allyltoluene (p-AT) by Ziegler–Natta copolymerization and the subsequent living anionic graft-polymerization. 1H NMR characterized that the PP-g-PS copolymer had grafted 3.15 side chains per 1000 carbons in the PP backbones and the length of PS sequences varied in the range of 25.8–309.9 units. PP/PS blends with the PP-g-PS copolymer as compatibilizer (wt. 75/25/5) were prepared and characterized by SEM, WAXD and DMA to investigate the morphologies, crystallinity and glass transition temperatures of the PP/PS blends. All the results pointed out that the average side chain length (GL) of the graft copolymer (GL is from 25.8 to 309.9) made great effects of the PP/PS blends, such as the PS dispersed phase, the crystallinity of the PP component and the two glass transition temperatures of the blends, which showed the same trend with the increase of the GL. Overall, only with a suitable average side chain length, the PP-g-PS copolymer could achieve optimal compatibilizing efficiency of the PP/PS blends. [Copyright &y& Elsevier]

Abstract: The copolymerization of propylene with allyldimethylsilane (ADMS) was carried out with conventional Ziegler–Natta catalyst supported on MgCl2. The effects of the concentration of ADMS in the feed on the polymerization reaction and copolymer properties were investigated. The resulting copolymer PP-co-ADMS was chlorinated to PP–Si–Cl by refluxing the copolymer with SOCl2 in benzene. The chlorinated copolymer was used to initiate ATRP of MMA with CuCl/PMDETA as catalyst to produce graft copolymer PP-g-PMMA, which was characterized with 1H NMR, 13C NMR, GPC and DSC. Polymer blend of iPP/PP-g-PMMA/PMMA was prepared and the results shown that PP-g-PMMA was an effective compatilizer. [Copyright &y& Elsevier]

Abstract: A novel layered calcosilicate (CAS-1) was employed to immobilize an iron-based diimine catalyst 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine iron chloride (I) onto it to form a supported catalyst (CC) for the first time. The crystal structure of CAS-1 was determined by X-ray crystallographic analysis in addition to SEM characterization. The CC-catalyzed ethylene polymerization exhibited good catalytic activities with either co-catalyst methylaluminoxane (MAO) or triethylaluminum (TEA). The resulting polyethylenes possessed not only higher molecular weight, melting temperature (T m), and decomposition onset temperature (T onset) than those obtained with its homogeneous counterpart, but also a unique morphology. [Copyright &y& Elsevier]

Abstract: Methyl methacrylate (MMA) and styrene (St) have been radically polymerized in the presence of chlorotrimethylsilane and CuCl/N,N,N′,N″,N″-pentamethyldiethyltriamine (Me3SiCl/CuCl/PMDETA). An analysis of the resultant polymers by 1H NMR discloses terminal silyl group and chlorine atom in all the obtained polymers. Kinetics studies have been carried out by measuring monomer conversions and polymer molecular weights against polymerization time. The results indicate that, for both MMA and St polymerizations, the monomer conversions exhibit a quasi-linear relationship with polymerization time, and the polymer number-average molecular weight (M n) also increases with monomer conversion. The molecular weights of both PS and PMMA exceed one hundred thousand. Regardless of molecular weight, all the polymers show narrow molecular distributions (M w/M n =1.2–1.5). These polymerization reactions are speculated to follow a mechanism similar to that of atom transfer radical polymerization (ATRP). [Copyright &y& Elsevier]

Abstract: A new reactive comonomer, p-allyltoluene (p-AT), was synthesized and copolymerized with ethylene by catalyst system of Et(Ind)2ZrCl2/MAO. The reactivity ratios of ethylene and p-AT were calculated. The lithiation reaction of PE copolymer was performed efficiently and the results showed that the reactions were occurred on the side chain but not on the backbone of the copolymer. PE-g-PS and PE-g-PDMS were synthesized via graft-from anionic polymerization to modify polyethylene. The results of Molau test showed that PE-g-PS could be potential good compatilizer. [Copyright &y& Elsevier]

Abstract: A novel zirconium complex bearing bis(phenoxyketimine) ligand (1) bis((3,5-di-tert-butyl-C6H2-2-O)PhC N(2,4-di-fluoro-C6H3))ZrCl2 (2) was prepared and successfully immobilized on a mesoporous molecular sieve MCM-41 in chemical method. Results of slurry polymerization of ethylene with MCM-41-supported catalyst (MC) indicated that the morphologies of polyethylene obtained differed greatly in heptane and toluene. Homogeneous catalyst 2 exhibited a very high initial activity in ethylene polymerization at room temperature resulting in great viscosity of the system. When immobilized on MCM-41, MC showed a smooth yet highly active kinetic behavior. With MAO as the cocatalyst, the effects of Al/Zr molar ratio and polymerization temperature on catalytic activity and properties of polyethylene obtained were investigated. The results showed that polyethylene obtained with MC possessed higher molecular weight (M n) and broader molecular weight distribution (M w/M n) than those formed with its homogeneous counterpart. [Copyright &y& Elsevier]

Abstract: An interference-free tandem catalysis based on iron catalyst and TiCl4/MgCl2, activated by MAO, was used to prepare branched polyethylene by polymerization of ethylene. No obvious deactivation due to the side reaction of catalysts and cocatalysts was detected during the reaction process, which commonly existed in tandem catalytic systems based on conventional Ziegler–Natta catalysts. A series of branched polyethylene with different properties have been prepared by adjusting of reaction temperature, Fe/Ti molar ratio and the amount of MAO used. The alteration of oligomers concentration in the reaction system, by changing of reaction conditions, led to the products with different branching degrees, thus the thermal properties and molecular weight. The products obtained in toluene at lower Fe/Ti ratios exhibited better morphology than those obtained at higher Fe/Ti ratios. [Copyright &y& Elsevier]

Examines the design of a novel synthetic route used for preparing propylene-styrene copolymer. Catalysis of a propylene copolymerized with a 4-(3-butenyl) styrene by a propylene active catalyst to form a polymer which has a polypropylene main chain and some styryl side groups.

Isotactic polypropylene (iPP) with narrow molecular mass distribution was freeze-extracted from n-octane solutions with varying concentrations. The recovered samples were characterized by differential scanning calorimetry. It is found that the sample recovered from the very dilute solution exhibits the higher non-isothermal crystallization temperature, faster isothermal crystallization rate, and smaller Avrami index. And there should exist a critical concentration corresponding with the critical overlap concentration proposed by de Gennes in the polymer solutions. In the solution well below the critical concentration, the iPP chains were isolated from each other, resulting in an acceleration of melt crystallization for the recovered samples. It seems that the chain entanglement is a barrier to the melt crystallization of polymer. [Copyright &y& Elsevier]

A series of iron, cobalt and nickel halide complexes, LMX2 (M=Fe, X=Cl; M=Co, X=Cl; M=Ni, X=Br) bearing 2,9-bis(imino)-1,10-phenanthrolinyl ligands [L=2,9-(ArNCH)2C12H6N2] were synthesized. The solid-state structures of 4 and 7 have been determined by single-crystal X-ray diffraction study. Treatment of the complexes LMX2 with methylaluminoxane (MAO) leaded to activate ethylene as oligomerization catalysts. [Copyright &y& Elsevier]

NiII, CoII and FeII complexes of 2-(2-pyridyl)quinoxaline were synthesized and used in the ethylene oligomerization with methyl-aluminoxane (MAO) as cocatalyst. The nickel complex system mainly produced α-olefins with good activity, while the cobalt and iron complexes showed only marginal activity. [Copyright &y& Elsevier]

A new method is proposed in which a chromium-based catalyst system containing chromium(III) tris (2-ethylhexanoate) (Cr(EH)3), 2,5-dimethylpyrrole (2,5-DMP), GeCl4 and triethylaluminum (TEA) coated with solid paraffin is used for oligomerization of ethylene. GC-MS and 1H-NMR analyses show that the coated catalyst system prepared via this approach is air-insensitive so it can be stored under ambient conditions. The selectivity for 1-hexene is up to 97.91 wt.%, and only slightly decreases when the catalyst system is exposed in air for 24 h; in contrast, the selectivity is only 35.6% for its non-coated counterpart. XPS reveals that an attachment of atmospheric oxygen to catalyst makes the chemical state of chromium change from Cr3+ to Cr6+. Such a change, in turn, reduces remarkably its selectivity for 1-hexene. [Copyright &y& Elsevier]

Details the development of a catalytic system with high polymeric activity. Intercalation of the cocatalysts, which included methylaluminoxane (MAO, between layers of montmorillonite (MMT) for ethylene oligomerization; Formation of a dual functional catalytic system by adding metallocene catalyst Me2Si(Ind)2ZrCl2 and MAO; Preparation of the PE/MMT nanocomposite by copolymerization of ethylene with α-olefins produced in situ from ethylene; Conclusion that the PE/MMT nanocomposites are stable and have more tensile strength; Temperature of maximum weight loss (Tonset).

A series of aryl-substituted tetramethylcyclopentadienyl zirconocenes (C5Me4C6H4X-4)Cp′MCl2 [Cp′=C5H5, X=H (5), Me (6), Cl (7) or OMe (8); Cp′=Ind, X=H (9), Me (10) or Cl (11); Cp′=2-Ph-Ind, X=H (12)] and (C5Me4C6H4X-4)2ZrCl2 [X=H (13), Me (14), Cl (15)], with different substituents at the 4-position of phenyl, have been prepared by the reaction of the corresponding ligands (C5Me4HC6H4X-4) [X=H (1), Me (2), Cl (3) or OMe (4)] with n-BuLi, ZrCl4 and Cp′Li or with n-BuLi and ZrCl4. Ethylene polymerization with these complexes in combination with MAO has been studied. The electron donor (Me) at the 4-position of phenyl led to an increase in catalytic activity while the electron-withdrawing group (Cl) and the strong π donor (OMe) led to its decrease. Complexes 5, 6, 9 and 10 exhibited very high activities, but 13–15 showed much lower activities due to the bulky steric effect. The molecular structure of 5 has been determined by X-ray diffraction. The relationship between structures of catalysts and catalytic activities were discussed. [Copyright &y& Elsevier]

Discusses the effects of co-catalysts on the morphology of isotastic polypropene prepared using metallocene catalyst. Preparation of the isotastic polypropene with good morphology and high bulk density; Proposal of the formation mechanism of active centers; Adjustment of the polymerization conditions to solve the problem of morphology.

A series of new cobalt and nickel complexes LMX2 (M=Co, X=Cl; M=Ni, X=Br) bearing 2, 6-bis(imino)phenoxy ligands were synthesized. The solid-state structures of 1 and 4 have been determined by single-crystal X-ray diffraction study. Treatment of the complexes LMX2 with methylaluminoxane (MAO) leads to active catalysts for oligomerization of ethylene with catalytic activities in the range of 1.2×105–2.1×105 g mol−1 h−1 atm−1 for Ni complexes, and ∼103 g mol−1 h−1 atm−1 for Co complexes. The oligomers were olefins from C4 to C16. [Copyright &y& Elsevier]

Examines the polymerization of a linear low-density polyethylene. Observation of high activity in the catalytic system; Determination of the melting point of the polymer; Production of narrow molecular weight distribution.

Investigates the polymerization method in the preparation of long-branched polyethylene (LBPE). Use of late transition metal and metallocene catalysts; Characteristics of LBPE; Determination of narrow molecular weight distribution.

Nitrogen-doped porous carbon with controllable specific surface area or nitrogen content was prepared from chlorinated polypropylene and nitrogen-containing compounds. The product shows high porosity and regular pore structure. [Display omitted] Here we report a facile method to prepare nitrogen-doped porous carbon with controllable specific surface area and nitrogen content through pretreated chlorinated polypropylene with nitrogen-containing compounds(NCCs). The microstructure and porous textures of the obtained carbons are characterized by BET, SEM, TEM, XRD and Raman, respectively. SEM shows that pore structure can be found in carbon matrix. And with the increase of nitrogen content, more amorphous carbon are observed in Raman spectral. The results show that the specific surface areas are effectively increased from 1000 m2/g to 3269 m2/g when the structure of NCCs have a nitrogen-contained hexatomic ring, and nitrogen content are apparently raised from 1.3 at% to 27.73 at% when the NCCs contain guanidyl structure. Besides, XPS shows that when the nitrogen content is relatively low, nitrogen emerge at carbon matrix mainly in form of pyrrolic-N, and with the increase of nitrogen content, the pyridinic-N become the main structure of nitrogen in carbon. [ABSTRACT FROM AUTHOR]

Chlorinated polypropylene(CPP), chlorinated polyethylene(CPE) and chlorinated polyvinyl chloride(CPVC) with high chlorine content were carbonized in inert and air atmosphere. After carbonization condition optimized, porous carbon with a surface area of 1035 m2/g is prepared in mild carbonization condition and without any activation. Chlorinated polypropylene(CPP), chlorinated polyethylene(CPE) and chlorinated polyvinyl chloride(CPVC) with high chlorine content were used to prepare porous carbons under inert gas and air atmosphere, respectively. Due to their flame retardance, carbon materials were both prepared from two atmosphere through thermal dehydrochlorination. The microstructure and porous textures of the obtained carbons were characterized by BET, XPS, SEM, TEM, XRD and Raman, respectively. The results show that the dehydrochlorination of all precursors is more efficient in air than nitrogen, because the oxygen molecular in air atmosphere accelerates the elimination of hydrogen chloride(HCl). Moreover, CPP-derived carbons display apparent higher surface area than that derived from CPE and CPVC. Furthermore, the carbonization condition is optimized and porous carbon with a surface area of 1035 m2/g is prepared in mild carbonization condition and without any activation. [ABSTRACT FROM AUTHOR]

Reports two novel Fe(II) diimine complexes that were synthesized. How they generate active catalytic systems when combined with MAO; Finding they oligomerize ethylene with high catalytic activity and high selectivity for α-olefins; The effects of substituents on the aryl ring, reaction temperatures and molar ratios of Al/Fe on catalytic activity and product distribution.

Polyethylene based polyurethanes (PE-PUs) with 20% ethyl branches were synthesized through hydrogenation reaction of linear and thermoplastic hydroxyl-terminated polybutadiene based polyurethanes (HTPB-PUs), which has not been explored widely. Linear and thermoplastic HTPB-PUs with Mw ranged from 130~280 kg/mol were synthesized by microwave-assisted reaction. More importantly, we systematically researched a series of reaction conditions to ensure the degree of hydrogenation meanwhile slow down the extent of degradation reaction of urethane bond. In addition, structure and thermal performance of PE-PUs have been investigated in the present work by NMR, FT-IR, DSC and TGA. The Mw of PE-PUs ranging from 120~207 kg/mol were carried out with a high temperature GPC. Moreover, the degree of crystalline of PE-PUs with 20% ethyl branches at the range of 10% to 33% were further explored by X-ray diffraction, which in turn certify that the PE-PUs possess certain strength but lower than polyethylene with no branches. [ABSTRACT FROM AUTHOR]