An ESR study of the radiolysis of semi‐crystalline ethylene‐propylene copolymers containing DOP mobilizer

The radiolysis of a poly(ethylene‐co‐propylene), Elpro, marketed by Thai Polypropylene Co. Ltd for the manufacture of medical goods has been investigated at 77 K. Calcium stearate was blended with the Elpro as a processing aid; and dioctyl phthalate, DOP, was added in various amounts as a radiation stabilizer. The ESR spectra of Elpro and Elpro+Ca were very similar and characterized principally by the presence of PP α‐carbon radicals. The spectra of the samples containing DOP were similar to those for Elpro but with an additional narrow singlet arising from DOP radicals. On annealing the irradiated polymers to higher temperatures, the singlet was lost between 250 and 270 K, and at room temperature the principal radicals remaining were allyl radicals. The G‐values for radical formation at 77 K for Elpro and Elpro+Ca at 77 K were 3.0 and 3.2, respectively, but incorporation of DOP resulted in lower G‐values, ranging from 1.6 to 1.4 for 0.5 and 2.5 phr DOP, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 638–643, 2006     

The study of poly(styrene‐co‐p‐(hexafluoro‐2‐hydroxylisopropyl)‐α‐methylstyrene)/poly(ethylene oxide) blends

Different hydroxyl content poly(styrene‐co‐p‐(hexafluoro‐2‐hydroxylisopropyl)‐α‐methylstyene) [PS(OH)‐X] copolymers were synthesized and blends with 2,2,6,6‐tetramrthyl‐piperdine‐1‐oxyl end spin‐labeled PEO [SLPEO] were prepared. The miscibility behavior of all the blends was predicted by comparing the critical miscible polymer–polymer interaction parameter (χ_crit) with the polymer–polymer interaction parameter (χ). The micro heterogeneity, chain motion, and hydrogen bonding interaction of the blends were investigated by the ESR spin label method. Two spectral components with different rates of motion were observed in the ESR composite spectra of all the blends, indicating the existence of microheterogeneity at the molecular level. According to the variations of ESR spectral parameters T_a, T_d, ΔT, T_50G and τ_c, with the increasing hydroxyl content in blends, it was shown that the extent of miscibility was progressively enhanced due to the controllable hydrogen bonding interaction between the hydroxyl in PS(OH) and the ether oxygen in PEO. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2312–2317, 2004     

The effects of acrylate monomers and polystyrene addition on the morphology of DOP‐plasticized styrene–acrylate polymer particles prepared by SPG emulsification and suspension polymerization

Fairly uniform copolymer particles of methyl acrylate (MA), butyl acrylate (BA), or butyl methacrylate (BMA) were synthesized via Shirasu porous glass (SPG) membrane and followed by suspension polymerization. After a single‐step SPG emulsification, the emulsion composed mainly of the monomers. Hydrophobic additives of dioctyl phthalate (DOP), polystyrene molecules, and an oil‐soluble initiator, suspended in an aqueous phase containing poly(vinyl alcohol) (PVA) stabilizer and sodium nitrite inhibitor (NaNO₂), were subsequently subjected to suspension polymerization. Two‐phase copolymers with a soft phase and a hard phase were obtained. The composite particles of poly(St‐co‐MA)/PSt were prepared by varying the St/PSt ratios or the DOP amount. The addition of PSt induced a high viscosity at the dispersion phase. The molecular weight slightly increased with increasing St/PSt concentration. The multiple‐phase separation of the St‐rich phase and PMA domains, observed by transmission electron microscopy, was caused by composition drift because the MA reactivity ratio is greater than that of St. The addition of DOP revealed the greater compatibility between the hard‐St and soft‐MA moieties than that without DOP. The phase morphologies of poly(St‐co‐MA), poly(St‐co‐BMA), and their composites with PSt were revealed under the influence of DOP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1195–1206, 2006     

Molecular weight studies of the γ‐irradiation degradation of poly(methyl methacrylate) doped with poly(p‐sulfanilamide)

The protection of some poly(methyl methacrylate) (PMMA) samples against γ rays was investigated in the absence and presence of poly(p‐sulfanilamide). Pure PMMA (without additives) and PMMA–poly(p‐sulfanilamide) blend samples were irradiated with γ rays for different exposure doses (5, 15, 25, 35, 50, 75, and 100 kGy). The viscosity‐average molecular weights were determined and thin‐layer chromatography measurements were carried out after each irradiation dose. The maximum protection against γ rays was found when 1% poly(p‐sulfanilamide) was used. The radiation chemical yield for main scission (G_s) was calculated and had lower values in the case of 1% poly(p‐sulfanilamide). The energy absorption per scission was maximum for 1% poly(p‐sulfanilamide), and this confirmed the obtained G_s data. From thin‐layer chromatography studies, it was observed that both the retention factor (R_f) values and polydispersity of the PMMA samples increased with an increasing exposure dose. The effect of γ irradiation on PMMA films doped with 1% poly(p‐sulfanilamide) was investigated with UV spectroscopy after the extraction of the additives. A change in the intensity of the absorption bands with an increasing irradiation dose was recorded. It is suggested that PMMA films doped with this type of polymer can be used as dosimeters. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis of star‐shaped poly(ϵ‐caprolactone) by samarium‐based tetrafunctional initiator and its dilute‐solution properties

An in situ–generated tetrafunctional samarium enolate from the reduction of 1,1,1,1‐tetra(2‐bromoisobutyryloxymethyl)methane with divalent samarium complexes [Sm(PPh₂)₂ and SmI₂] in tetrahydrofuran has proven to initiate the ring‐opening polymerization of ?‐caprolactone (CL) giving star‐shaped aliphatic polyesters. The polymerization proceeded with quantitative conversions at room temperature in 2 h and exhibited good controllability of the molecular weight of polymer. The resulting four‐armed poly(?‐caprolactone) (PCL) was fractionated, and the dilute‐solution properties of the fractions were studied in tetrahydrofuran and toluene at 30°C. The Mark–Houwink relations for these solvents were [η] = 2.73 × 10^?2M_w^0.74 and [η] = 1.97 × 10^?2M_w^0.75, respectively. In addition, the unperturbed dimensions of the star‐shaped PCL systems were also evaluated, and a significant solvent effect was observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 175–182, 2006     

Biodegradable polymer made of styrene and N‐benzyl‐4‐vinylpyridinium chloride

A copolymer of styrene with N‐benzyl‐4‐vinylpyridinium chloride (BVP), poly(styrene‐co‐N‐benzyl‐4‐vinylpyridinium chloride) (PST‐co‐BVP), was degradable by activated sludge in soil when the oligo‐styrene portion was sufficiently small. The degradation of the equimolar copolymer followed first‐order kinetics when the polymer sample was 1.0 or 0.5 g/kg and gave a half‐life of 5.6 days. The degradation of PST‐co‐BVP with a reduced BVP content did not follow first‐order kinetics under the aforementioned conditions but appeared to follow the kinetics when the amount of the polymer sample was sufficiently small. Under the ultimate conditions, the half‐life of PST‐co‐BVP that contained 10.6 mol % BVP was estimated to be 12.5 days, and the half‐life of PST‐co‐BVP that contained 5 mol % BVP was expected to be 30–40 days. The incorporation of 5 mol % BVP appeared sufficient for making PST‐co‐BVP substantially biodegradable if we did not expect exceptionally rapid degradation. PST‐co‐BVP was different from conventional polystyrene but possessed biodegradability. Random scission of the main chain much predominated over uniform scission from the end of the polymer chain in the biodegradation of PST‐co‐BVP. The cleavage of the main chain at BVP appeared predominant over that of oligo‐styrene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 554–559. 2006     

Processability and characterization of poly(vinyl chloride)‐b‐poly(n‐butyl acrylate)‐b‐poly(vinyl chloride) prepared by living radical polymerization of vinyl chloride. Comparison with a flexible commercial resin formulation prepared with PVC and dioctyl phthalate

This work reports the synthesis and processing of a new flexible material based on PVC produced by living radical polymerization. The synthesis was carried out in a two‐step process. In the first step the macroinitiator α, ω‐di(iodo)poly(butyl acrylate) [α, ω‐di(iodo)PBA] was synthesized in water by single electron transfer/degenerative chain transfer mediated living radical polymerization (SET‐DTLRP) catalyzed by Na₂S₂O₄. In the second step this macroinitiator was reinitiated by SET‐DTLRP of vinyl chloride (VC), thereby leading to the formation of the block copolymer poly(vinyl chloride)‐b‐poly(butyl acrylate)‐b‐poly(vinyl chloride) [PVC‐b‐PBA‐b‐PVC]. This new material was processed on a laboratory scale. The DMTA traces showed only a single glass transition temperature, thus indicating that no phase segregation was present. The copolymers were studied with regard to their processing, miscibility, and mechanical properties. The first comparison with commercial formulations made with PVC and dioctyl phthalate (DOP) is presented. J. VINYL ADDIT. TECHNOL., 12:156–165, 2006. © 2006 Society of Plastics Engineers     

Physical and electrochemical characterizations of poly(vinylidene fluoride‐co‐hexafluoropropylene)/SiO2‐based polymer electrolytes prepared by the phase‐inversion technique

Highly porous poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF–HFP)‐based polymer membranes filled with fumed silica (SiO₂) were prepared by a phase‐inversion technique, and films were also cast by a conventional casting method for comparison. N‐Methyl‐2‐pyrrolidone as a solvent was used to dissolve the polymer and to make the slurry with SiO₂. Phase inversion occurred just after the impregnation of the applied slurry on a glass plate into flowing water as a nonsolvent, and then a highly porous structure developed by mutual diffusion between the solvent and nonsolvent components. The PVdF–HFP/SiO₂ cast films and phase‐inversion membranes were then characterized by an examination of the morphology, thermal and crystalline properties, absorption ability of an electrolyte solution, ionic conductivity, electrochemical stability, and interfacial resistance with a lithium electrode. LiPF₆ (1M) dissolved in a liquid mixture of ethylene carbonate and dimethyl carbonate (1:1 w/w) was used as the electrolyte solution. Through these characterizations, the phase‐inversion polymer electrolytes were proved to be superior to the cast‐film electrolytes for application to rechargeable lithium batteries. In particular, phase‐inversion PVdF–HFP/SiO₂ (30–40 wt %) electrolytes could be recommended to have optimum properties for the application. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 140–148, 2006     

Preparation and characterization of ceria nanoparticles supported on poly(4‐vinyl pyridine‐co‐divinyl benzene)

Formation of ceria nanoparticles in 2% divinyl benzene (dvb) crosslinked 4‐vinyl pyridine (4vp) polymer [poly(4vp‐co‐dvb)] microspheres was investigated. The polymer was prepared by free radical suspension polymerization method. Poly(4vp‐co‐dvb)/ceria nanocomposites were prepared by reacting CeCl₃·7H₂O and NaOH in the presence of poly(4vp‐co‐dvb) at room temperature in aqueous media. The mole ratio of the metal to polymer was varied from 2.5 to 10% with an increment of 2.5. The polymer and nanocomposities were characterized by various spectrochemical methods. The coordination of nitrogen atoms of the polymer with Ce(IV) of ceria (CeO₂) has been confirmed from X‐ray photoelectron spectroscopy (XPS). The method has yielded ceria nanoparticles in an average size of 15 nm according to transmission electron microscopy. Differential scanning calorimetry, thermogravimetric analysis, X‐ray diffractometry and XPS analysis with respect to mole percentage of ceria in the composite are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3439–3445, 2006     

13C‐NMR, 1H‐NMR,and FT‐Raman study of radiation‐induced modifications in radiation dosimetry polymer gels

¹H‐ and ¹³C‐NMR spectroscopy and FT‐Raman spectroscopy are used to investigate the properties of a polymer gel dosimeter post‐irradiation. The polymer gel (PAG) is composed of acrylamide, N,N′‐methylene‐bisacrylamide, gelatin, and water. The formation of a polyacrylamide network within the gelatin matrix follows a dose dependence nonlinearly correlated to the disappearance of the double bonds from the dissolved monomers within the absorbed dose range of 0–50 Gy. The signal from the gelatin remains constant with irradiation. We show that the NMR spin–spin relaxation times (T₂) of PAGs irradiated to up to 50 Gy measured in a NMR spectrometer and a clinical magnetic resonance imaging scanner can be modeled using the spectroscopic intensity of the growing polymer network. More specifically, we show that the nonlinear T₂ dependence against dose can be understood in terms of the fraction of protons in three different proton pools. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1572–1581, 2001     

Nano‐scaled ordering of hyperbranched and star‐hyperbranched polymers

Hyperbranched polystyrenes (HPS) were prepared by living radical polymerization of 4‐vinylbenzyl N,N‐diethyldithiocarbamate (VBDC) as an inimer under UV irradiation. These HPS exhibited large amounts of photofunctional diethyldithiocarbamate (DC) groups on their outside surfaces. We derived star‐HPS (SHPS) by grafting from such HPS macroinitiator with methyl methacrylate (MMA) or ethyl methacrylate (EMA). The ratios of radius of gyration to hydrodynamic radius R_g/R_h for HPS and SHPS in tetrahydrofuran (THF) were in the range of 0.74–0.90 and 1.05–1.12, respectively. HPS and SHPS behaved in a good solvent as hard and soft spheres, respectively. We demonstrated the structural ordering of both branched polymers in THF through small‐angle X‐ray scattering (SAXS), by varying the polymer concentration. As a result, HPS and SHPS formed face‐centered‐cubic (fcc) and body‐centered‐cubic (bcc) structures, respectively, near the overlap threshold (C*). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3340–3345, 2006     

Peroxide induced cross‐linking by reactive melt processing of two biopolyesters: Poly(3‐hydroxybutyrate) and poly(l‐lactic acid) to improve their melting processability

Poly(3‐hydroxybutyrate) (PHB) and poly(l ‐lactic acid) (PLLA) were individually cross‐linked with dicumyl peroxide (DCP) (0.25–1 wt %) by reactive melt processing. The cross‐linked structures of the polymer gel were investigated by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies. The size of the polymer crystal spherulites, glass transition temperature (T_g), melting transition temperature (T_m), and crystallinity were all decreased as a result of cross‐linking. Cross‐linking density (ν_e) was shown to increase with DCP concentration. Based on parallel plate rheological study (dynamic and steady shear), elastic and viscous modulus (G″ and G′), complex viscosity (η^*) and steady shear viscosity (η) were all shown to increase with cross‐linking. Cross‐linked PHB and PLLA showed broader molar mass distribution and formation of long chain branching (LCB) as estimated by RheoMWD. Improvements in melt strength offer bioplastic processors improved material properties and processing options, such as foaming and thermoforming, for new applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41724.     

Relative strength of H‐bonding groups on biodegradable polymer‐based blends in solution

The intermolecular hydrogen bonding interactions between poly(3‐hydroxybutyrate) and poly(styrene‐co‐vinyl phenol) copolymers with mutual solvent epichlorohydrin were thoroughly investigated by steady‐state fluorescence and viscosity techniques. Fluorescence spectroscopy along with viscosity technique was used to asses the intermolecular hydrogen bonding between poly‐(3‐hydroxybutyrate) and its blends with five copolymer samples of styrene–vinyl phenol, containing different proportions of vinyl phenol but similar average molecular weight and polydispersity index. In the case of very low OH contents (2–4 mol %), as expected, both components of poly(3‐hydroxybutyrate) and poly(styrene‐co‐4‐vinylphenol) chains are well separated and remain so independently of the mixed polymer ratio and overall polymer concentration as well. Conversely, when the OH content reaches 5.8 mol % or more, a significant decrease of the intrinsic fluorescence intensity emitted by the copolymer is detected upon addition of aliquots of poly(3‐hydroxybutyrate). In these cases, an average value for the interassociation equilibrium constant, K_A = 8.7, was obtained using a binding model formalism. A good agreement of these results with those obtained from complementary viscosity measurements, through the interaction parameter, Δb, was found. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 900–910, 2006     

Synthesis of water‐insoluble functional copolymers containing amide,amine, and carboxylic acid groups and their metal‐ion‐uptake properties

The crosslinked poly[N‐(3‐dimethylamino)propylmethacrylamide] [P(NDAPA)] and poly[N‐(3‐dimethylamino)propylmethacrylamide‐co‐acrylic acid] [P(NDAPA‐co‐AA)] were synthesized by radical polymerization. The resins were completely insoluble in water. The metal‐ion‐uptake properties were studied by a batch equilibrium procedure for the following metal ions: silver(I), copper(II), cadmium(II), zinc(II), lead(II), mercury(II), chromium(III), and aluminum(III). The P(NDAPA‐co‐AA) resin showed a lower metal‐ion affinity than P(NDAPA), except for Hg(II), which was retained at 71% at pH 2. At pH 5, the resin showed a higher affinity for Pb(II) (80%) and Cu(II) (60%), but its affinity was very low for Zn(II) and Cr(III). The polymer ligand–metal‐ion equilibrium was achieved during the first 20 min. By changing the pH, we found it possible to remove between 60 and 70% of Cd(II) and Zn(II) ions with (1M, 4M) HClO₄ and (1M, 4M) HNO₃. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5232–5239, 2006     

Towards improving wet‐adhesion in a metal oxide‐polymer coating system

An investigation using a variable radius roll adhesion test (VaRRAT) revealed an irreversible increase in the wet‐adhesion in a metal–oxide–polymer system, under specific experimental conditions. This observation is further confirmed by the T_g measurements and the ATR‐FTIR studies. The increase in wet‐adhesion is attributed to late H₂O‐catalyzed curing of the previously partially cured polymers (epoxy ring opening), as well as the formation of nanocomposite layer within the epoxy primer matrix, because of precipitation of the nanocrystals including zinc ammine complexes formed as a result of dissolution of the zinc/aluminum alloy as well as the metal oxide pigments by the amine crosslinker. High activation energy of ～100 kJ mol^?1 indicated a chemical process to be responsible for the adhesion gain. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3318–3327, 2006     

Acidic hydrolysis of a poly(vinyl acetate) matrix by the catalytic effect of Ag nanoparticles and the micellization of Ag‐metal‐containing polymer

In this study, we conveniently obtained Ag(0)–polymer nanocomposites by reacting AgNO₃ with commercial poly(vinyl acetate) (PVAc) in the absence of a special reducing agent. The formation of Ag(0) metal was detected after formic acid (HCOOH) was added to a PVAc–AgNO₃ complex system, and some of the acetate groups of the PVAc backbone were hydrolyzed to form hydroxyl groups (OH) under the catalytic effect of the reduced Ag(O) metal. Here, the structure of the partially hydrolyzed PVAc backbone was represented as PVOH‐PVAc. X‐ray diffraction spectra showed that the Ag(0) metal generated in this method was in the form of Ag crystals. The structure of the Ag(0)–polymer was analyzed by ¹H‐NMR and ¹³C‐NMR spectroscopy. The micellization of the Ag(0)–polymer was also investigated by the addition of an inducing solvent to the formic acid solution of Ag(0)–polymer. The image showed that the morphology of the Ag micelles in the H₂O‐induced solvent was a Ag corona with a Ag shell, and that in the p‐xylene induced solvent showed a Ag cluster core structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1457–1464, 2006     

Degradation of poly(D,L‐lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(D,L‐lactic acid) copolymer by electron beam radiation

This article investigates the effects of electron beam (EB) radiation on poly(D ,L ‐lactic acid)‐b‐poly (ethylene glycol) copolymer (PLA‐b‐PEG‐b‐PLA). The copolymer films were EB irradiated at doses from 0 to 100 kGy. The degradation of these films was studied by measuring the changes in their molecular weight, mechanical and thermal properties. The dominant effect of EB radiation on PLA‐b‐PEG‐b‐PLA is chain‐scission. With increasing irradiation dose, recombination reactions or partial crosslinking may occur in addition to chain scission. The degree of chain scission G_s and crosslinking G_x of sample are calculated to be 0.213 and 0.043, respectively. A linear relationship is also established between the decreases in molecular weight with increasing irradiation dose. Elongation at break of the irradiated sample decreases significantly, whereas its tensile strength decreases slightly. The glass transition temperature (T_g) is basically invariant as a function of irradiation dose. Thermogravimetric analysis shows that its thermal stability decreases with increasing dose. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Microstructure and glass‐transition temperature of novel star N‐SIBR

In this study, a polymeric N‐functionalized mutilithium (N‐M‐Li) compound was prepared from commercial divinylbenzene (DVB) and lithiohexamethyleneimine (LHMI), and star‐shaped copoly(styrene–butadiene–isoprene) was obtained by anionic polymerization using preformed N‐M‐Li as initiator, tetramethylethlenediamine (TMEDA) as polar modifier, and cyclohexane as solvent. The microstructure and the glass–transition temperature (Tg) of copolymers were characterized by ¹H NMR and differential scanning calorimetry (DSC), respectively. It showed that the non‐1,4‐structure content and the Tg of copolymers increased with the increase of TMEDA dosage or the decrease of polymerization temperature; however, the effects of the initiator concentration and DVB dosage on them were not obvious. We also obtained the relationships between the non‐1,4‐structure content of copolymers and the Tg of copolymers respectively, and between the ln(T/Li) (TMEDA/N‐M‐Li, mole ratio) and the non‐1,4‐structure content of copolymers, as follows: Tg (°C) = 0.6258C_{non 1,4}?55.93 and C_{non 1,4} = 20.79 ln K+59.11, where K is T/Li value. Therefore on the basis of experimental results, we realize polymer design according to our practical requirements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5848–5853, 2006     

Water‐assisted formation of honeycomb films of poly(L‐lactic‐co‐glycolic acid)

The ordered honeycomb structures of poly(L ‐lactic‐co‐glycolic acid) and poly(D ,L ‐lactic‐co‐glycolic acid) fabricated in a humid atmosphere were reported in this paper. It was found that surfactants were important in the formation of honeycomb films of hydrophobic polymer. The affecting factors, such as the environment temperature, the atmosphere humidity, and the concentration of the polymer solution of the honeycomb porous structure, were also tested. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1013–1018, 2006     

Comparative study of propylene polymerization using monosupported and bisupported titanium‐based Ziegler–Natta catalysts

Heterogeneous Ziegler–Natta systems—MgCl₂ (ethoxide type)/TiCl₄/di‐n‐butyl phthalate (DNBP)/triethylaluminum (TEA)/dimethoxymethylcyclohexylsilane (DMMCHS) and SiO₂/MgCl₂ (ethoxide type)/TiCl₄/DNBP/TEA/DMMCHS—were studied for the polymerization of propylene. The slurry polymerization of propylene was carried out with the catalyst systems in n‐heptane. Both systems performed with optimum activity at a particular [Al]/[DMMCHS]/[Ti] molar ratio. The ratio to reach the highest activity was much lower for the bisupported catalyst system. The productivity of the bisupported catalyst was higher than that of the monosupported one. Polypropylene of a high isotacticity index (II; >96%) was obtained with both systems and did not significantly change with an increasing [Al]/[DMMCHS]/[Ti] molar ratio. The addition of hydrogen as a chain‐transfer agent reduced II of the polymers obtained with both systems. The effect of the polymerization temperature (40–75°C) on the viscosity‐average molecular weight (M_v) and II showed a decrease in both cases. The bisupported catalyst system produced a polymer with higher M_v. The effect of temperature on II was similar for both the monosupported and bisupported systems. A monomer pressure of 2.02 × 10⁵ to 0.8 × 10⁶ Pa increased M_v of the obtained polymer. II of the polymer slightly decreased with increasing monomer pressure. The titanium content of the catalyst was 1.70 and 3.55% for the monosupported and bisupported systems, respectively. The surface area of the bisupported catalyst was higher than that of the monosupported catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2220–2226, 2006