Graft Copolymerization Of Styrene Research Articles

Study of the high-energy alpha particles influence on the styrene accumulation kinetics and functional groups during the synthesis of proton-exchange membranes based on PVDF.

The study investigates the effect of alpha irradiation on the graft copolymerization of styrene with polyvinylidene fluoride (PVDF). Using methods of radiation-chemical modification, a proton exchange membrane (PEM) with a uniform distribution of functional sulfate groups throughout the entire volume was developed. Grafting of styrene was carried out at different temperatures and solution concentrations. Functional sulfo-groups were added to the graft polymer by sulfonation, with the addition of solvents. The degree of grafting (DG), water absorption (W) and exchange capacity (IEC) correlate well with the absorbed dose and alpha particle fluence. Research into this method will allow us to develop an affordable industrial technology for widespread implementation.

Entropic and Energetic Elasticities of Natural Rubber with a Nanomatrix Structure.

The entropic and energetic elasticities of natural rubber with a nanomatrix structure are investigated by measuring the viscoelastic properties of deproteinized natural rubber (DPNR)-graft-polystyrene (PS). A nanomatrix structure is formed by graft copolymerization of styrene onto the surface of natural rubber particles, followed by coagulation. The morphology of the nanomatrix structure is observed with transmission electron microscopy. Natural rubber particles with about 1 μm diameter are well dispersed in a nanomatrix of PS. The horizontal shift factor (aT) and vertical shift factor (bT) are determined by superposition to create a master curve according to the time-temperature superposition principle. The positive slope of DPNR appears in the plot of bT versus temperature, suggesting that entropic elasticity occurs. In contrast, the slopes of DPNR-graft-PS are negative at lower temperatures but positive at higher temperatures. The negative slope, which suggests entropic elasticity, may be attributed to the formation of a nanomatrix structure. Natural rubber with a nanomatrix structure realizes both energetic elasticity and entropic elasticity.

Isotactic polypropylene toughened with poly(acrylonitrile–butadiene–styrene): Compatibilizing role of maleic anhydride grafted polypropylene

The β‐nucleating activity and toughening effect of acrylonitrile–butadiene–styrene (ABS) graft copolymer on isotactic polypropylene (iPP) and the compatibilizing role of maleic anhydride grafted polypropylene (PP‐g‐MAH) on the iPP/ABS blends were investigated. The results show that ABS can induce the formation of β‐crystal in iPP, and its β‐nucleating efficiency depends on its concentration and dispersibility. The relative content of β‐crystal form is up to 36.19% with the addition of 2% ABS. The tensile and impact properties of the iPP were dramatically enhanced by introducing ABS. The incorporation of PP‐g‐MAH into the iPP/ABS blends inhibits the formation of β‐crystal. The crystallization peaks of the blends shift toward higher temperature, due to the heterogeneous nucleation effect of PP‐g‐MAH on iPP. The toughness of iPP/ABS blends improved due to favorable interfacial interaction resulting from the compatibilization of PP‐g‐MAH is significantly better than the β‐crystal toughening effect induced by ABS. POLYM. ENG. SCI., 59:E317–E326, 2019. © 2019 Society of Plastics Engineers

Imidazolium-Based Grafted Anion Exchange Membranes: Interplay between the Morphology and Anion Transport Behavior

In this report, the anion transport behavior of imidazolium-based graft-type anion exchange membranes (AEMs) having imidazolium (Im)/styrene (St) graft-copolymers was studied. We have reported the graft-copolymers coordinately form ion channels where dissociated ions are dispersed and the connectivity of channels increases with the increasing hydration number, λ (the number of water molecules per Im group). Here, we investigated the conductivity, water uptake, and anion diffusivity of AEMs with different grafting degrees (GDs) and different counterions as a function of λ. The plot of the ratio of the anion diffusion coefficient in AEMs to its diffusivity in the dilute solution (D/D0) with λ shows a superimposed master curve. This result strongly evidences that these AEMs have similar morphology relating to the anion transport, regardless of GDs and anion species. The findings in this study provide a guideline for future AEM design to enhance the ion transport efficiency.

Effect of ferrocene on the synthesis of graft copolymers of vinylpolysiloxane and styrene

The effect of ferrocene on the synthesis of graft poly(dimethylsiloxanes) by radical copolymerization of a polysiloxane containing terminal trivinylsiloxy groups with styrene. The backbone in the synthesized graft copolymers is formed by a linear poly(dimethylsiloxane) with a part of its vinyl groups involved in grafting polystyrene chains. The products were studied by gel permeation chromatography, 1Н NMR spectroscopy, and optical microscopy.

Dynamic Mechanical Properties of Vietnam Modified Natural Rubber via Grafting with Styrene

The dynamic mechanical behavior of modified deproteinized natural rubber (DPNR) prepared by graft copolymerization with various styrene contents was investigated at a wide range of temperatures. Graft copolymerization of styrene onto DPNR was performed in latex stage using tert-butyl hydroperoxide (TBHPO) and tetraethylene pentamine (TEPA) as redox initiator. The mechanical properties were measured by tensile test and the viscoelastic properties of the resulting graft copolymers at wide range of temperature and frequency were investigated. It was found that the tensile strength depends on the grafted polystyrene; meanwhile the dynamic mechanical properties of the modification of DPNR meaningfully improved with the increasing of both homopolystyrene and grafted polystyrene compared to DPNR. The dynamic mechanical properties of graft copolymer over a large time scale were studied by constructing the master curves. The value of bT has been used to prove the energetic and entropic elasticity of the graft copolymer.

The study of antimicrobial properties of immobilized fibrous N-chloro sulfonamides

Aim. The determination of antibacterial and antifungal action of nonwoven form of N-chloro sulfonamides immobilized on a polypropylene fiber with a graft copolymer of styrene and divinylbenzene.Materials and methods. The object of the study was a non-woven form of sodium N-chloro sulfonamides immobilized on a polypropylene fiber with a graft copolymer of styrene and divinylbenzene. Determination of antibacterial and antifungal action of the material was carried out by the plate at the meat peptone agar (МPA). As the test cultures of microorganisms we used: E.coli, S.aureus and C.albicans. Microbial load was 1х107 TEM/ml.Results. The growing delay for such test microorganisms as E. coli strains, S.aureus and C.albicans fungi has been observed only for samples of material. Lack of microbial growth delay zones outside the samples occurs due to poor contact with the surface of the MPA. The method of plate has been changed to obtain reliable results of antibacterial and antifungal action of the material. The test material samples were placed in uncured MPA, the further experiment was carried out according to standard procedures of the plates method. Latency test microorganism growth around the sample material lies in the range 6,0 -7,0 mm – for E.coli; 16,0 -25,0 mm – for S.aureus; 4,0 -6,0 mm – for C.albicans. These results are explained by activation with the help of ammonium salts and amino acids, which release the active material of chlorine in case when the material contacts with the liquid nutrient medium. Evidently, this way the material will behave in contact with the skin of human (or animal). In contact with the dry skin covering the material will remain inactive, but in contact with the wound the release of active chlorine will occur within a specified period of time, whereby the material can protect the wound from infection.Conclusions. Antibacterial and antifungal properties of non-woven form of sodium N-chloro sulfonamides immobilized on a polypropylene fiber with a graft copolymer of styrene and divinylbenzene are determined by the degree of contact with ammonium salt solutions and amino acid nutrient medium. While the surface contacts the growth inhibition of test cultures of microorganisms occurs only under the material. Introducing the material into a liquid medium greatly increases its activity. Thus, the material exhibits pronounced antimicrobial properties against the above test strains of microorganisms.

Modification of Vietnam Natural Rubber via Graft Copolymerization with Styrene

Graft copolymerization of styrene onto deproteinized natural rubber (DPNR) using tert-butyl hydroperoxide (TBHPO) and tetraethylene pentamine (TEPA) as redox initiator have been investigated. The effects of initiator and monomer concentration on conversion and grafting efficiency were studied. The dynamic mechanical and thermal properties of the graft copolymer were investigated over the wide range of temperatures. It is shown that a high value of storage modulus for the graft copolymer, which was about 25 times as high as that of DPNR, was achieved. The graft copolymer (DPNR-graft -PS) showed the outstanding tensile strength and stable thermal properties. These enhancements were attributed to the interaction between NR and polystyrene as a result of the graft copolymerization. Morphology observation by transmission electron micrograph (TEM) revealed that the core-shell arrangement of the DPNR-graft -PS with about 30 nm in thickness of polystyrene nano-layer was achieved.

Frozen non-equilibrium structure for anisotropically deformed natural rubber with nanomatrix structure observed by 3D FIB-SEM and electron tomography

Effect of frozen non-equilibrium structure for anisotropically deformed natural rubber with the nanomatrix structure on mechanical properties was investigated with respect to morphology analysis through 3D observation. Natural rubber with the nanomatrix structure was prepared by graft copolymerization of styrene onto natural rubber particles in latex stage followed by coagulation of the resulting latex. The morphology was observed by electron tomography and focused ion beam-scanning electron microscopy (FIB-SEM). The nanomatrix structure in isotropic state was precisely analyzed by electron tomography and synchrotron scattering technique. The nanomatrix structure was found to consist of natural rubber particles and polystyrene nanoparticles. The frequency-independent loss tangent at plateau region was attributed to the discontinuous nanomatrix structure. After annealing at 403 K and 7 MPa, the nanomatrix became continuous, which resulted in the increases in stress at strain of one and storage modulus as well as increase in loss tangent.

Preparation of a Thermoplastic Lignin-Based Biomaterial through Atom Transfer Radical Polymerization

Graft copolymerization of styrene onto kraft lignin (KL) was achieved by atom transfer radical polymerization (ATRP) using a fully substituted lignin-based macroinitiator (KLM). The number average of molecular mass (Mn) of polystyrene copolymer graft side-chains was achieved by varying the ratio of the DMF: water solvent system from 5:0 to 1:4. A Mn of up to ∼206,000 was obtained using a DMF/water ratio of 3:2 (v/v). However, as the Mn increased, the overall ATRP became less controlled. In addition, the thermal properties of the lignin-g-polystyrene copolymers improved significantly with increasing Mn of polystyrene copolymer side-chains.

NANOMATRIX STRUCTURE FORMED BY GRAFT COPOLYMERIZATION OF STYRENE ONTO FRESH NATURAL RUBBER

ABSTRACT Fresh NR was adopted to prepare rubber with a nanomatrix structure. The nanomatrix structure was formed by graft-copolymerization of styrene onto deproteinized fresh NR (fresh DPNR) in the latex stage using tert-butyl hydroperoxide/tetraethylenepentamine as an initiator. Graft-copolymer consisting of fresh DPNR and polystyrene (fresh DPNR-graft-PS) was characterized by 1H-NMR spectroscopy and transmission electron microscopy. Under a suitable condition of the graft-copolymerization, conversion and grafting efficiency of styrene was 98 and 80 mol%, respectively. Morphology of fresh DPNR-graft-PS was observed by transmission electron microscopy. The rubber particles of about 1 μm in diameter were found to be dispersed in polystyrene matrix of 10–30 nm in thickness. Tensile properties of fresh DPNR were dramatically improved by forming the nanomatrix structure, compared with DPNR.

Preparation of polymer electrolyte membrane with nanomatrix channel through sulfonation of natural rubber grafted with polystyrene

The mechanism of proton transport of a polymer electrolyte membrane (PEM) with nanomatrix channel was investigated with respect to the activation energy of proton conductivity. The PEM with nanomatrix channel was prepared by graft-copolymerization of styrene onto deproteinized natural rubber (DPNR) followed by sulfonation with chlorosulfonic acid. The resulting sulfonated graft-copolymer (SDPNR-graft-PS) was characterized by FT-IR spectroscopy, solid-state 13C CP/MAS NMR spectroscopy, elemental analysis, transmission electron microscopy (TEM) and impedance analysis. The PEM was found to form completely continuous nanomatrix channel consisting of natural rubber particle of about 1μm in average diameter as a dispersoid and sulfonated polystyrene of about 60nm in thickness as a matrix. The value of the activation energy of proton conductivity estimated from the slope of Arrhenius plot was 12kJ/mol for SDPNR-graft-PS, suggesting that the proton transport occurred in a manner of Grotthuss mechanism.

Preparation and Characterization of Enzymatically Degraded Starch-g-Poly(styrene-co-butyl acrylate) Latex for Paper Coating

Graft copolymerization of styrene and n-butyl acrylate onto enzymatically degraded starch was carried out via surfactant-free emulsion polymerization. The cassava starch was degraded by α-amylase before copolymerization, which greatly enhanced the starch content in copolymer. A series of latexes with small particle size, narrow size distribution, and high stability were prepared. The effect of starch degradation on graft copolymerization was investigated. High grafting efficiency was obtained. The application test of the latex showed that the surface strength of coated paper was improved, and all the other properties are very close to those of paper coated with conventional styrene-acrylate latex.

Radiation Copolymerization of Styrene/Acrylic Acid Grafted to Silica Surface For separation and purification purposes: I. Characterization and sorption of some organic compounds and Metals.

Highly porous and interconnected styrene/acrylic-based porous materials were prepared by radiation-induced graft copolymerization of styrene/acrylic acid monomers onto surface of silica prepared from rice husk ash. The influence of synthesis conditions; such as irradiation dose, monomer concentrations and different solvents; were studied. It was found that the nature of the solvent had profound influence on the copolymerization reaction and water /ethanol mixture was selected as a suitable solvent for copolymerization processes. Graft copolymers of styrene/ acrylic onto silica surface was verified through Fourier Transform Infrared (FTIR) spectroscopy and Eenergy Dispersive Spectroscopy (EDX) was used to investigate the surface profile of representative copolymers by viewing the distribution of elemental nitrogen. ThermoGravimetric Analysis (TGA) and differential Thermal Analysis (DTA) of the copolymers were investigated. From the characterization of the prepared copolymer it was found that: copolymers of (styrene/acrylic)/silica are considerably different from each other, (styrene/acrylic)/silica based copolymers exhibited relatively more homogenous surface compared to (styrene/acrylic) copolymers. Water uptake percent increases as silica ratio increases to reach 24174 (mol/gm) and this prepared copolymer has a considerable capacity for adsorption of organic compounds and metals.

Synthesis and characterization of chitosan grafted with polystyrene using ammonium persulfate initiator

Graft copolymerization of styrene from chitosan was prepared under various conditions using ammonium persulfate (APS) initiator. The grafting was found to be best at 1:3 chitosan:styrene weight ratio, 0.4g APS and temperature 60°C. The washed products were characterized by spectroscopic and thermal methods. FT-IR analysis indicate the presence of polystyrene peaks, DSC analysis showed the improvement in Tg of the polystyrene. After acid hydrolysis, the copolymer was analyzed using gel permeation chromatography (GPC), and the result revealed the isolated polystyrene having Mw and Mn as 95,249 and 30,755 respectively, with polydispersity index, 2.92.

Toughening Effect of Ethylene Propylene DieneTerpolymer-Graft-Styrene-Acrylonitrile Copolymer (EPDM-g-SAN) on SAN Resin

The reaction product EPDM-g-SAN, synthesized by suspension graft copolymerization of styrene (St) and acrylonitrile (AN) in the presence of ethylene-propylene-diene terpolymer (EPDM), was blended with a commercial styrene-acrylonitrile copolymer (SAN resin) to prepare AES blends with high impact strength. The effects of AN mass percentage in the St-AN comonomer mixture (f AN), EPDM mass percentage in the feed of EPDM and St-AN (f EPDM) and reaction time on monomer conversion ratio (CR), grafting ratio (GR), and AES notched Izod impact strength were characterized. The notched Izod impact strength of AES containing 15 wt% EPDM reached its maximum with f AN of 40 wt% and f EPDM of 45 wt%; this was attributed to the polarity of the SAN copolymer obtained being appropriate with that of the SAN resin matrix. The dependences of GR and the notched Izod impact strength of AES containing 25 wt% EPDM on the reaction time were in rough agreement. The effect of EPDM content on the AES notched Izod impact strength indicated that the brittle-ductile transition of AES occurred for an EPDM content from 12.5 to 15 wt%. TEM and SEM analysis showed that the phase structure of AES exhibited a “salami” like structure, and the toughening mechanism of AES was shear yielding of the SAN resin matrix, which endowed AES with excellent toughness.

The Effect of Process Factors to the Kinetic Studies of Emulsion Copolymerization of Natural Rubber and Styrene

Graft copolymer of styrene on natural rubber was prepared in laboratory by emulsion polymerization using potassium persulfate and sodium laurysulfate as an initiator and an emulsifier, respectively. The concentrations of initiator and emulsifier were varied in the range of 0.7 to 2.0 parts and 5.0 to 11.0 part per 100 parts of organic compositions, respectively. The gross polymers were purified by soxhlet extraction to remove ungrafted polystyrene and ungrafted natural rubber to obtain the graft copolymer (NR-g-PS). Characterization of graft copolymer was confirmed by FTIR spectroscopy. The results of the conversion, the kinetic rate of polymerization and grafting efficiency as a function of initiator and emulsifier concentration were studied. It was found that the conversion and the rate of polymerization increased with initiator and emulsifier concentration. At 1.0 parts of initiator and 5.0 parts of emulsifier were the optimum values. Therefore, the conversion and grafting efficiency can be used to predict the reaction conditions as a guideline for the graft copolymer production in pre-scale up reactor.

Modification of hydrophilic cellulose fibers by monolayer growth of polystyrene chains using ATRP

The chemical modification of biopolymer-based materials by grafting synthetic polymers has received considerable attention in recent years, inasmuch as there are wide varieties of monomers available. Nowadays, the most abundant biomacromolecule, cellulose, has attracted considerable attention due to its biodegradable, biocompatible, and renewable characteristics. In this study, the surface of hydrophilic cellulose microfibers was successfully modified by polymerization of hydrophobic polystyrene using atom transfer radical polymerization (ATRP) technique in dispersion medium. In this medium, only the outer surface of the macroinitiator is available for the polymerization, so the grown polymer chains are formed as monolayer on the surface of the macroinitiator. This type of modification not only increases the mechanical properties of the cellulose backbone, but also turns the hydrophilic characteristics of cellulose into hydrophobic state. For this purpose, in the first part of this research, chloroacetylated cellulose was synthesized as macroinitiator. In the second part, the acyl content of the macroinitiator and the degree of substitution, which show the efficiency of the esterification reaction, have been determined by basic hydrolysis of the macroinitiator with KOH and back-titration of the excess alkali with HCl. Finally, the chloroacetylated cellulose was modified by graft copolymerization of styrene using ATRP method. The polystyrene chain growth is confirmed by the atomic force microscopy images.

Phase morphology and dynamic mechanical behavior for MIS toughened polyvinyl chloride

Graft copolymers of isoprene (Is), styrene (St), and methyl methacrylate (MMA) monomers (MIS) with typical core–shell structure were synthesized by seed emulsion polymerization and used as a toughening agent for preparation of polyvinyl chloride (PVC)/MIS blends. The St and MMA monomers were separately grafted on the cross-linked poly-isoprene rubber core. The toughness, sub-micro-morphology, and dynamic mechanical behavior of the blends were characterized by impact machine, scanning electron microscopy (SEM), and dynamic mechanical analyzer. The results showed that the impact strength of the blends was optimized when the content of MIS in PVC/MIS blends was kept at a constant value of 8 wt %, while the content of Is in MIS was 70 wt %. SEM morphologies of impact fractured surface showed that the PVC/MIS blends were typical ductile fracture because of the toughness effect of rubber particles, which correlated well with the mechanical properties. Under the same rubber content condition, the curves of the dynamic mechanical behavior of MIS toughened PVC blends appeared a more obvious rubber peak, indicating that the rubber content of MIS was higher than that of methyl methacrylate–butadiene–styrene (MBS), which explained the better toughening effect of MIS compared with MBS. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Phase Transfer Catalyzed Polymerization of Styrene and Graft Copolymerization of Styrene onto Gelatin

The use of tetrabutylammonium bromide (TBAB), as phase transfer catalyst during polymerization of styrene in the presence of water-soluble radical initiator, potassium persulfate (KPS), and graft copolymerization of styrene onto gelatin, a water soluble polymer, using a water-insoluble radical initiator, benzoyl peroxide (BPO), has been explored in a water-benzene biphasic system. The percentage conversion (Pc) of styrene to polystyrene and percent grafting (Pg) of styrene onto gelatin was studied as a function of various reaction parameters. Under optimum reaction conditions, maximum Pc (76%) was obtained at [KPS] = 12.9 × 10−4 moles/L, [Sty] = 4.3 ×10−3 moles/L, and maximum Pg (87%) was obtained at [BPO] = 4.6× 10−4 moles/L, [Sty] = 13.88 × 10−3 moles/L using [PTC] = 2.89 × 10−4 moles/Lin 10 mL each of water and benzene in 120 min at 60 °C. The graft copolymer, Gel-g-poly(Sty), was characterized by IR, Thermogravimetric Analysis, Scanning Electron Microscopy and swelling behaviour in different solvents. Metal uptake and degradation studies of the grafted sample were also carried out. The grafted sample showed maximum uptake for Cu2+ (88%), Ni2+ (80%) and Fe2+ (50%). Degradation studies of Gel-g-poly(Sty) were carried out by soil burial test and UV radiations. Photo-degradation showed better degradation (5.26% wt. loss) in 32 h of exposure to UV radiations as compared to soil burial degradation (8.46% wt. loss) in 30 days. Gelatin-styrene graft copolymers can thus be used as bio- and photo-degradable materials for environmental management.