Inhibition period of vinyl acetate monomer in suspension,emulsion and bulk polymerization at 730mm Hg and 760 mm Hg

A trend in the inhibition period of vinyl acetate monomer (VAM), using benzoyl peroxide (Bz₂O₂), azobisisobutyronitrile (AIBN) and potassium peroxy disulphate (K₂S₂O₈), during suspension, emulsion and bulk polymerizations, with change in pressure from 730 mm Hg to 760 mm Hg, is reported.     

Emulsion polymerization of butadiene and subsequent grafting of methylmethacrylate. High impact properties of blends from this grafted polymer and polyvinylchloride

The paper illustrates the graft emulsion polymerization of methylmethacrylate onto polybutadiene in two steps. In the first butadiene is polymerized using two radical initiators (AIBN and (NH₄)₂S₂O₈), whose ratio does not influence the relative amount of 1,2-, 1,4-trans and 1,4-cis structures. The second step uses AIBN only: the grafting yield is very high. Grafting mechanism is discussed. The grafted polymer has good mechanical properties and its blends with PVC present very high impact strength. The mechanical properties are discussed. A statistical copolymer of butadiene and methylmethacrylate was prepared and compared with the grafted polymer. The copolymer is also a very good additive for PVC to elevate its impact strength.     

The free radical polymerization of vinyl monomers in the presence of carbon black

The polymerization of vinyl monomers has been carried out in the presence of furnace blacks using initiators such as 2,2′-azobisisobutyronitrile (AIBN) and benzoyl peroxide (Bz₂O₂) in nitrogen or oxygen atmosphere. The results indicate that free radicals form by the decomposition of initiators reacting with carbon blacks to give active sites on their surface which then capture either the free radicals or the growing polymer radicals. Using the monomers with negative e values, such as styrene and vinyl acetate, a marked retardation was observed in Bz₂O₂-initiated polymerization in the presence of furnace blacks, while a moderate inhibition was found in the polymerization initiated by AIBN. The polymerization reaction using Bz₂O₂ was found to be very sensitive to oxygen in the presence of furnace blacks and the involvement of oxygen was found to promote grafting onto the surface of carbon black by the growing polymer radicals, consequently giving polymer-grafted particles while hindering the formation of homopolymers. Furthermore, the reaction of Bz₂O₂ with the surface of furnace blacks in oxygen atmosphere has been studied in carbon tetrachloride at 45°C. The resulting carbon blacks show an increase in the number of surface quinone groups with an increase in reaction time.     

Graft copolymerization of methyl methacrylate and natural rubber

Graft copolymerization of natural rubber and MMA was carried out in the presence of Bz₂O₂ or AIBN as thermal initiator and hydrogen peroxide or benzophenone as photosensitizer. From the overall copolymerization product, the rubber–PMMA graft copolymer fraction was isolated from unreacted rubber and free PMMA fractions and composition characterization of the separated fractions was done by determination of rubber unsaturation. The efficiency of grafting under different conditions has been calculated and compared.     

Swelling-assisted graft copolymerization of 4-vinyl pyridine on poly(ethylene terephthalate) films using a benzoyl peroxide initiator

Graft copolymerization of 4-vinyl pyridine (4-VP) on poly(ethylene terephthalate) (PET) films using a benzoyl peroxide (Bz₂O₂) initiator was investigated under different conditions including polymerization time, temperature, monomer concentration, and initiator concentration. Dimethyl sulfoxide (DMSO) was used as swelling agent to promote the incorporation and the subsequent polymerization of 4-VP to PET films. Maximum percent grafting was obtained when the polymerization was carried for a period of two hours at 65°C. Increasing the monomer concentration from 0.2M to 0.8M and Bz₂O₂ concentration from 1.0×10⁻³M to 2.5×10⁻³M was accompanied by a significant enhancement in percent grafting. Monomer diffusion on PET films and its effect on the grafting yield were studied and intrinsic viscosities of grafted films were also measured. © 1996 John Wiley & Sons, Inc.     

Kinetics of graft copolymerization of acrylamide and 2-hydroxyethylmethacrylate monomer mixture onto poly(ethylene terephthalate) fibers

Poly(ethylene terephthalate) (PET) fibers were grafted with acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of AAm/HEMA onto PET fibers. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 10 mmol/L. The maximum graft yield was obtained (prep.) 273%. The optimum temperature and polymerization time were found to be 85 °C and 120 min, respectively. The rate of grafting was found to be proportional of the 1.39 and 0.37 powers of AAm/HEMA and Bz₂O₂ concentrations, respectively. The grafted PET fibers were characterized by FTIR spectroscopy and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity and diameter were determined. The dyeability of the PET fibers increased with an increase in grafting with acidic and basic dyes.     

Dehydrochlorinated poly(vinyl chloride-g-styrene). I. Effect of synthesis conditions

Dehydrochlorinated poly(vinyl chloride) (DHPVC) was graft copolymerized with styrene monomer using benzoyl peroxide (Bz₂O₂) as free radical initiator, in vacuum. The effect of synthesis conditions such as time, initiator concentration, the ratio of monomer to polymer, and temperature on various grafting parameters was studied. On the whole, a maximum of 47 wt % polystyrene (PSt) in the graft (DHPVC-g-PSt) was obtained. PSt contents of graft copolymers determined by gravimetry, chlorine analysis, and UV spectroscopy have been compared. A “grafting from” mechanism has been proposed for the graft copolymerization.     

Effects of redox initiator on graft copolymerization of methyl methacrylate onto natural rubber

Effects of cumene hydroperoxide (CHPO)/tetraethylene pentamine (TEPA), tert‐butyl hydroperoxide (TBHPO)/TEPA, and potassium persulfate (K₂S₂O₈)/sodium thiosulfate (Na₂S₂O₃) redox initiator on methyl methacrylate (MMA) grafted natural rubber by emulsion polymerization were investigated. The optimum reaction condition for each redox initiator on the grafting of natural rubber was studied. The grafted poly(methyl methacrylate) (PMMA) stays on the surface of rubber particles. CHPO dissolves very well in the oil phase and TBHPO dissolves moderately in the oil phase, and K₂S₂O₈ /Na₂S₂O₃ initiation is water‐soluble. Each can interact with TEPA in the aqueous phase. CHPO was found to give a higher grafting efficiency. To promote a greater grafting efficiency and yield a lower homopolymer content of PMMA, vinyl neo‐decanoate (VneoD) was added. Percentages of grafting of MMA on natural rubber latex initiated by CHPO/TEPA, TBHPO/TEPA, and K₂S₂O₈/K₂S₂O₃ of 84.4, 74.5, and 61.1, respectively, were in good agreement with percentages of PMMA in the aqueous phase as 7.2, 12.0, and 17.9 by CHPO, TBHPO, and K₂S₂O₈. VneoD produces allylic radicals on polyisoprene chains, favoring the grafting reaction with other vinyl monomers. CHPO/TEPA is thus a better redox system for grafting of MMA monomer on natural rubber latex. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2587–2601, 2006     

Morphology and mechanical properties of ABS blends prepared from emulsion‐polymerized PB‐g‐SAN impact modifier with AIBN as initiator

A series of PB‐g‐SAN impact modifiers (polybutadiene particles grafted by styrene and acrylonitrile) are synthesized by seed emulsion copolymerization initiated by oil‐soluble initiator, azobisiobutyronitrile (AIBN). The ABS blends are obtained by mixing SAN resin with PB‐g‐SAN impact modifiers. The mechanical behavior and the phase morphology of ABS blends are investigated. The graft degree (GD) and grafting efficiency (GE) are investigated, and the high GD shows that AIBN has a fine initiating ability in emulsion grafting of PB‐g‐SAN impact modifiers. The morphology of the rubber particles is observed by the transmission electron microscopy (TEM). The TEM photograph shows that the PB‐g‐SAN impact modifier initiated by AIBN is more likely to form subinclusion inside the rubber particles. The dynamic mechanical analysis on ABS blends shows that the subinclusion inside the rubber phase strongly influences the T_g, maximum tan δ, and the storage modulus of the rubber phase. The mechanical test indicates that the ABS blends, which have the small and uniform subinclusions dispersed in the rubber particles, have the maximum impact strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

4-Vinylpyridine and 2-hydroxyethylmethacrylate monomer mixture graft copolymerization onto poly(ethylene terephthalate) fibers using benzoyl peroxide

Summary Poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of 4-VP/HEMA onto PET fibers. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 8×10^-3 mol/L. The maximum graft yield was obtained 280%. The optimum temperature and polymerization time was found to be 85 °C and 100 min. respectively. The rate of grafting was found to be proportional of the 1.5 and 0.3 powers of 4-VP/HEMA and Bz₂O₂ concentrations, respectively. The grafted PET fibers were characterized by thermo gravimetric analysis and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity, intrinsic viscosity and diameter were determined. The dye ability of the PET fibers increased with an increase in grafting with diazo and basic dyes.     

Kinetics of swelling assisted grafting of 4-vinyl pyridine onto poly(ethylene terephthalate) fibers using a benzoyl peroxide initiator

Summary Poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) using benzoyl peroxide (Bz₂O₂) as initiator. Fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of 4-VP onto PET fibers. Variations of graft yield with time, temperature, initiator and monomer concentrations were investigated. Percent grafting was enhanced significantly by increasing Bz₂O₂ concentration up to 2 × 1 0 ^-3 mol/L and then decreased upon further increase in initiator concentration. Increasing the 4-VP concentration up to 0.6 mol/L improves the graft yield significantly. The optimum temperature and polymerization time was found to be 50 °C and 2 h respectively. Further changes in properties of grafted PET fibers such as moisture absorption capacity and intrinsic viscosity were determined. Grafted PET fibers were charactarized by thermogravimetric analysis and scanning electron microscopy (SEM). Molar mass of the grafted chains was also determined.     

Grafting. III. Copolymerization of methyl methacrylate and methacrylic acid

The method of graft copolymerization of methyl methacrylate on halogen-containing polymer has been utilized for grafting of methyl methacrylate–methacrylic acid monomer pair onto poly(vinyl chloride) and chlorinated rubber. Substantial grafting could be obtained by using the method reported earlier. However, the compositions of the grafted chains are found to deviate appreciably from the compositions calculated from r₁ and r₂ values reported in literature. The reactivity ratios for this pair of monomers have been therefore evaluated using azobisisobutyronitrile and n-butane thiol–dimethyl sulfoxide as initiators. The anomalies of the grafted chain compositions have been discussed and an explanation presented on preferential solvation.     

Simulation of the in situ copolymerization of zinc methacrylate and 2-(N-ethylperfluoro-octanesulphonamido)ethyl acrylate in hydrogenated nitrile-butadiene rubber

Radical copolymerizations of zinc dimethacrylate and 2-(N-ethylperfluorooctanesulphonamido)ethyl acrylate initiated with di-t-butyl peroxy di-isopropylbenzene were carried out in various amounts of DMF for 10 h at 140 °C in the presence of hydrogenated nitrile-butadiene rubber (HNBR) as a simulation of copolymerization without solvent. It was revealed that the M_W of the copolymer is about 100 000 and that less than 25 mol% of the comonomer is grafted on HNBR. The molar ratio of monomer involved in copolymerization from crosslinking was 0.23. The material produced by in situ copolymerization can be expected to be changed from a polymer alloy or a blend to a graft polymer depending on the double bond content in the HNBR. © 1999 Society of Chemical Industry     

Thermal aging on ethylene–propylene–diene rubber composites reinforced by samarium oxide,samarium borate and Sb in Sb doped SnO2

Abstract

Ethylene–propylene–diene monomer (EPDM) rubber composites reinforced with 50 phr samarium oxide (Sm₂O₃), samarium borate (SmBO₃) and Sb in antimony doped tin oxide (ATO) are aged at 150°C for different intervals. It is found that neutral Sm₂O₃ and alkaline SmBO₃ can retard the oxidative degradation of EPDM by blocking radical passage. The acidic ATO particles can accelerate the oxidative degradation of EPDM. The trend of tensile strength of EPDM composites is consistent with that of cross-link density of EPDM composites. SmBO₃ and ATO can retard the increase of dielectric loss until 10 days of aging, while Sm₂O₃ can keep the dielectric loss at low level until 14 days of aging. The increased surface charge of filler can make surface and volume resistivity decrease sharply. Antimony doped tin oxide can deteriorate the dielectric strength of EPDM, while SmBO₃ and Sm₂O₃ can keep the dielectric strength of EPDM at a constant level.     

Development of an intermediate layer for multilayer hoses used in turbo lines of motor vehicles

Multilayer hoses for turbo lines can be produced by ethylene acrylic rubber (AEM) as the inner layer and peroxide cured ethylene propylene diene monomer (EPDM) as the outer layer. In such a case, the polar AEM should adhere well to the apolar EPDM to ensure proper functioning. In this work, new blends were developed and optimized to offer potential for using as intermediate bonding layers. Different compositions of dipolymer AEM/EPDM and terpolymer AEM/EPDM blends with and without maleic anhydride grafted EPDM (Ma‐g‐EPDM) as a compatibilizer were successfully prepared. Curing behaviors, as well as mechanical and thermal properties of the blends were investigated in detail. The effects of the compatibilizer addition were also explored by dynamical mechanical analysis, DeMattia and scanning electron microscope. It is found that Ma‐g‐EPDM is more effective in terpolymer AEM containing blends. Additionally, 60/40:AEM/EPDM weight ratio is the most suitable proportion for turbo lines. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46525.     

The study of polystyrene blends: The relationship of phases and structure in blends of polystyrene with ethylene–propylene diene monomer rubber and its grafted copolymer

Pressed films of blends of polystyrene (PS) with ethylene–propylene diene monomer rubber (EPDM) or grafted copolymer of styrene (St) onto EPDM (EPDM-g-St) rubber were examined by small-angle X-ray scattering (SAXS), and scanning electron microscope (SEM). Small-angle X-ray scattering from the relation of phase was analyzed using Porod's Law and led to value of interface layer on blends. The thickness of interface layer (σ_b) had a maximum value at 50/50 (PS–EPDM-g-St) on blends. The radius of gyration of dispersed phase (domain) and correlation distances a_c in blends of PS–EPDM-g-St were calculated using the data of SAXS. The morphology and structure of blends were investigated by SEM. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 805–810, 1998     

Oxidation‐grafting surface modification of waste silicone rubber composite insulator powder: Characterizations and properties of EPDM/modified waste powder composites

In order to broaden the applications of waste silicone rubber composite insulator powder (WSP), modified waste powder (WSP‐KH570) was prepared by a two‐step treatment process involving improved surface oxidation approach by using acidic H₂O₂ solution and subsequently grafting of KH570. Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR‐ATR) analysis revealed the presence of KH570 on the powder surface. The result was confirmed by thermogravimetric analysis (TGA). Blends of ethylene propylene diene monomer (EPDM) with WSP‐KH570 were prepared. The effects of WSP‐KH570 on mechanical properties and thermal properties of the blends were investigated. The WSP‐KH570 showed an observed improvement in tensile strength and elongation at break of EPDM/WSP‐KH570 blends compared with corresponding compositions of EPDM/WSP blends. The TGA cure showed that EPDM filled with WSP‐KH570 had higher thermal stability at 210–380 °C than EPDM/WSP. Dynamic mechanical analysis indicated EPDM and WSP‐KH570 were better miscible with the blend ratio (90/10). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45438.     

Utilization of fly ash acid residue as a reinforcing filler in ethylene propylene diene monomer rubber

Fly ash acid residue (FAAR), a by‐product of circulating fluidized bed fly ash extracted Al₂O₃ by acid leaching method, has been posing problems because of its disposal. The major chemical components of FAAR are amorphous SiO₂ (66.38 wt %) and unburned carbon (20 wt %). Attempts were made for its application as a reinforcing filler for ethylene propylene diene monomer (EPDM) rubber in this article. Surface modification for FAAR by silane coupling agent (Si69) was carried out. The effect of surface modification and unburned carbon existing in FAAR on the performance of FAAR was characterized by Fourier transform infrared and dispersibility test. The results indicated that surface modification could reduce the hydrophilicity of FAAR and unburned carbon also had positive effect on the dispersion of FAAR particles in kerosene. The effect of partial replacement of carbon black by FAAR on the curing behavior, mechanical properties, and morphological characteristics of EPDM rubber was also studied. It was proved that with partial replacement of carbon black by FAAR, the cure time (t₉₀) and maximum torque (M_H) of EPDM composites increased with the content of FAAR. The mechanical properties were significantly improved when 15 wt % of carbon black was replaced by FAAR. SEM micrographs confirmed that surface modification can improve the compatibility between FAAR and rubber matrix. Unburned carbon existing in FAAR was also beneficial to the interface bonding. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Electrical properties of conductive rubber blends subjected to solvent penetration

Abstract

The influence of solvent uptake (%) on the electrical resistivity S of ethylene propylene diene monomer rubber (EPDM)/acrylonitrile butadiene rubber (NBR) blends filled with different concentrations of high abrasion furnace carbon black has been studied. The effects of the EPDM/NBR weight ratio and carbon black content on the room temperature resistivity of the composites were elucidated in detail. The performance of these sensors depends on a number of parameters, including the geometry and concentration of the conductive component dispersed in the polymer. Direct current current–voltage I–V characteristics of the filled rubber blends were studied at room temperature. The current–voltage relationship can be expressed as I?=?AV^B, where A and B are constants that show capability and property of electrical conduction respectively. The I–V curve can be divided into ohmic and non-ohmic regions. A number of important parameters, namely, Schottky and Poole–Frenkel effects, have been determined.     

The effect of moisture presoaking on graft copolymerization of methyl methacrylate in wood under mutual irradiation by electron beam accelerator

Polymerization of MMA was carried out in wood under mutual electron beam irradiation. The changes in molecular weight (M _n, M _m) and the number of polymer branches grafted to holocellulose and lignin were compared with the swelling degree (ΔL_H2O) of base veneers obtained by moisture presoaking before impregnation of the monomer. Increases in molecular weight as well as in the number of both grafted branches were observed with increase in ΔL_H2O up to ca. 4% in the lower range of ΔL_H2O. However, for the number of polymer branches grafted to holocellulose, the increse reached a peak at ΔL_H2O of ca. 4%, in contrast to the continuous increase of both molecular weights M _n and M _w. This is due to the bimolecular recombination-type termination of the propagating radicals mutually between those originating from the holocellulose and the irradiated MMA within the cellular parts or due to their termination onto lignin. The polymer branches grafted to lignin came from the latter termination, and it was found that the lower molecular weight branches grafted to lignin came from those propagating radicals which were produced from irradiated MMA in the void space and terminating onto lignin.