Factorial experimental design for graft copolymerization of styrene and methyl methacrylate onto styrene–butadiene rubber

The graft copolymerization of styrene (ST) and methyl methacrylate (MMA) onto styrene–butadiene rubber (SBR) latex prepared by seeded emulsion polymerization has been studied under various reaction conditions using cumene hydroperoxide redox initiator. The mechanism of graft copolymerization has been investigated. The synthesized graft copolymers were purified and then characterized by proton nuclear magnetic resonance (¹H NMR) analysis. A 2 2 fractional factorial experimental design was applied to study the effects of the process variables such as the amount of initiator and emulsifier, the presence or absence of chain‐transfer agent, ST to MMA ratio, monomer to rubber ratio, and reaction temperature on the grafting efficiency. The analysis of the results from the design showed the sequence of the main effect on the observed response of the grafting of ST and MMA onto SBR and that the amount of chain‐transfer agent had a significant effect. Transmission electron microscopy was used to study the morphology of the graft copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2867–2874, 2006     

Factorial experimental design for grafting of vinyl monomers onto natural rubber latex

Graft copolymerization of styrene (St) and methyl methacrylate (MMA) in the presence of natural rubber latex using cumene hydroperoxide/tetraethylenepentamine redox initiator system was prepared at various process variables. The synthesized graft copolymers were purified and then characterized by Fourier transformed infrared spectroscopy analysis. A full 2⁴ factorial experimental design was applied to study the effect of various process variables on grafting efficiency. The following four independent variables considered to be mainly affecting the grafting efficiency were reaction temperature, rubber‐to‐monomer ratio, St‐to‐MMA ratio, and initiator amount used in the secondary polymerization. It was shown in this study that the reaction temperature significantly influenced the grafting efficiency, increasing as the temperature was increased. The amount of grafting increased with increasing rubber‐to‐monomer ratio and St‐to‐MMA ratio, whereas the amount of grafting decreased with increasing amount of initiator. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 455–463, 2004     

Natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) blends

The grafting of the methyl methacrylate (MMA) monomer onto natural rubber using potassium persulfate as an initiator was carried out by emulsion polymerization. The rubber macroradicals reacted with MMA to form graft copolymers. The morphology of grafted natural rubber (GNR) was determined by transmission electron microscopy and it was confirmed that the graft copolymerization was a surface‐controlled process. The effects of the initiator concentration, reaction temperature, monomer concentration, and reaction time on the monomer conversion and grafting efficiency were investigated. The grafting efficiency of the GNR was determined by a solvent‐extraction technique. The natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) (NR‐g‐MMA/PMMA) blends were prepared by a melt‐mixing system. The mechanical properties and the fracture behavior of GNR/PMMA blends were evaluated as a function of the graft copolymer composition and the blend ratio. The tensile strength, tear strength, and hardness increased with an increase in PMMA content. The tensile fracture surface examined by scanning electron microscopy disclosed that the graft copolymer acted as an interfacial agent and gave a good adhesion between the two phases of the compatibilized blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 428–439, 2001     

Synthesis of graft copolymers from natural rubber using cumene hydroperoxide redox initiator

The graft copolymerization of 50/50 (w/w) styrene/methyl methacrylate mixtures onto natural rubber seed latex were carried out by using cumene hydroperoxide/sodium formaldehyde sulfoxylate dihydrate/EDTA‐chelated Fe²⁺ as a redox initiator. The effects of the process factors such as the amount of initiator, emulsifier, and chain‐transfer agent; monomer‐to‐rubber ratio; and temperature on the grafting efficiency (GE) and grafting level (GL) are reported. The mechanism of graft copolymerization was investigated. The synthesized graft copolymers were purified and then characterized by proton nuclear magnetic resonance (¹H‐NMR) analysis. Transmission electron microscopy (TEM) was used to study the morphology of the graft copolymers. It appears that the formation of graft copolymers occurs on the surface of the latex particles through a chain‐transfer process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2993–3001, 2002; DOI 10.1002/app.2328     

Ultraviolet-initiated photografting of glycidyl methacrylate onto styrene–butadiene rubber

Photografting reaction onto styrene–butadiene rubber (SBR) as a function of monomer concentration, grafting method, irradiation time, and the carbon black content has been studied using ultraviolet (UV). Glycidyl methacrylate and benzophenone are used as monomer and initiator, respectively. The occurrence of graft reaction onto SBR surface is identified by infrared attenuated total reflection (IR-ATR) analysis. The degree of monomer graft increases with monomer concentration and tends to level off at high monomer concentration (>8.3M/L). Graft ratio also increases with UV irradiation time. Carbon black content is found as one of important factors that determine the monomer graft efficiency. The amount of monomer graft onto SBR decreases with increasing carbon black content and it is attributed to the reduction of irradiation absorbance due to the presence of carbon black. The occurrence of reaction between glycidyl methacrylate grafted SBR and nylon-6 via melt phase reaction is also identified using IR-ATR analysis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1733–1739, 1999     

Morphology of latex particles formed by poly(methyl methacrylate)-seeded emulsion polymerization of styrene

Poly(methyl methacrylate)–polystyrene composite particle latexes were prepared by poly(methyl methacrylate)-seeded emulsion polymerization of styrene employing batch, swelling-batch, and semibatch methods. The changes in particle morphology taking place during the polymerization reaction were followed by electron microscopy. Anchoring effect exerted by ionic terminal groups introduced by ionic initiator was found to be the main factor in controlling the particle morphology. The polymer particles obtained by oil-soluble hydrophobic initiators such as azobisisobutyronitrile and 4,4′-azobis-(4-cyanovaleric acid) gave the inverted core-shell morphology. Water-soluble hydrophilic initiator, K₂S₂O₈, also gave the inverted core-shell morphology. However, in this case the occurrence of the halfmoonlike, the sandwichlike, and the core-shell morphologies were also observed depending upon the polymerization conditions. The distribution of terminal ? SO groups on the surface area of polystyrene particles could be controlled by initiator concentration and polymerization temperature. Viscosity of polymerization loci dictated the movement of polymer molecules, thus causing the unevenness of particle shape and phase separation at high viscosity state. Viscosity was controlled by the styrene/poly(methyl methacrylate) ratio, the addition of a chain transfer agent or a solvent which is common to polystyrene and poly(methyl methacrylate).     

Graft copolymerization onto rubber. VII. Graft copolymerization of methyl methacrylate onto rubber using potassium peroxydisulfate catalyzed by silver ion

The graft copolymerization of methyl methacrylate onto natural rubber (NR) was carried out varying the concentration of monomer, initiator, thiourea, and silver nitrate over a wide range. The grafting reaction was temperature-dependent. From the Arrhenius plot, the overall energy of activation was computed. A suitable reaction scheme and rate expression for the rate of polymerization was suggested.     

微波法接枝改性天然胶乳的制备与表征

采用微波辐射的方法对天然浓缩胶乳进行接枝改性,单体选用甲基丙烯酸甲酯,考察了微波温度、时间、引发剂和单体用量对接枝率、接枝效率的影响,用傅里叶变换红外光谱仪、核磁共振波谱仪来表征接枝产物。结果表明,微波法接枝改性天然胶乳的方法是可行的;适宜的反应条件为:采用过硫酸钾和亚硫酸钠作为引发剂,其用量为0.4%(占橡胶质量的百分数),微波温度为80℃,反应时间为1～2h,单体与胶乳质量比为1∶1。     

Morphological studies in thermally initiated emulsion (co)polymerization without conventional initiators

Poly(methyl methacrylate‐co‐styrene) composite latices were prepared by thermally initiated seed emulsion (co)polymerization of styrene (ST), methyl methacrylate (MMA), or ST and MMA employing a PST or PMMA seed in the absence of conventional initiators. The changes of particle morphology, observed by transmission electron microscopy (TEM), were investigated by varying seed particle component, the weight ratio of monomer to seed polymer, monomer composition, and employing preswelling of the seed particles. The size distribution of polymer particles obtained from thermally initiated emulsion (co)polymerization was improved by employing the seed process. Hemisphere‐like, sandwich‐like, core‐shell, and inverted core‐shell particle morphologies were observed depending upon the polymerization conditions. The preswelling of seed particles did not affect the morphology of final particles. The particle morphologies, obtained from the thermal process, were compared with those obtained from conventional seed emulsion polymerization. The incorporation of an initiator fragment SO to polymer chain ends seemed to allow the PST chains to gain some hydrophilicity. From the observation of particle morphology, the hydrophilicity of involved polymers were in the following order: PMMA with ionic (? SO) chain ends > PMMA with no ionic ends > PST with ionic ends > 60% MMA P(MMA‐co‐ST) with no polar ends > 40% MMA P(MMA‐co‐ST) with no polar ends > PST with no polar ends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1737–1748, 2002; DOI 10.1002/app.10581     

CR／MMA接枝胶粘剂的研究

本文研究了反应温度、引发剂用量、单体用量及体系浓度对ＣＲ／ＭＭＡ接枝聚合反应的影响，运用正交设计总结出了最佳反应条件。     

Modification of Polychloroprene Rubber Latex by Grafting Polymerization and Its Application as a Waterborne Contact Adhesive

Grafting of methyl methacrylate (MMA) onto polychloroprene rubber latex (CRL) was carried out by emulsion polymerization using a redox initiator. The effects of the principal factors such as emulsifier, initiator and their concentrations and monomer/polymer ratio on monomer conversion, and grafting efficiency were studied. Infrared (FTIR) spectra, proton nuclear magnetic resonance (HNMR), and differential scanning calorimetry (DSC) analysis of the graft copolymer showed the occurrence of grafting. The surface-diffusion controlled process model was proposed to describe the grafting mechanism. The graft copolymer was blended with tackifier and filler for waterborne contact adhesive applications. The 180 degree peel strength of the above adhesive for canvas to other decoration materials was investigated.     

Surface functionalization of Si3N4 nanoparticles by graft polymerization of glycidyl methacrylate and styrene

To improve dispersibility and interfacial interaction of nano‐Si₃N₄ particles in epoxy‐based composites, graft of glycidyl methacrylate (GMA) and styrene (St)/GMA onto the nanoparticles' surface was carried out in terms of emulsion polymerization method. The grafting polymers proved to be chemically attached to the nanoparticles via the double bonds introduced during the coupling agent pretreatment. The factors affecting the graft parameters, such as monomer concentration, initiator consumption, reaction time, etc., were investigated. It was shown that higher concentrations of monomer and initiator are favorable for the graft polymerization. When St/GMA was employed as the grafting monomer, the nanoparticles were found to play the role of polymerization loci. The grafted nanoparticles exhibit greatly improved dispersibility in cured epoxy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 992–999, 2006     

Effect of grafting methacrylate monomers onto jute constituents with a potassium persulfate initiator catalyzed by Fe(II)

The graft copolymerization of methyl methacrylate and ethyl methacrylate monomers onto jute fiber was carried out in an aqueous medium with potassium persulfate as an initiator under the catalytic influence of ferrous sulfate in the presence of air. The effects of parameter variables, such as the monomer, initiator, and catalyst concentrations, the reaction time, and the temperature, on grafting and the effect of grafting the monomers onto jute constituents were studied. The degree of grafting depended on the kinds of monomers and the parameter variables. The maximum graft yield percentages with methyl methacrylate and ethyl methacrylate under optimized conditions were 18.9 and 38.8%, respectively, and the grafting onto jute fiber was largely affected by one of its main constituents, such as hemicellulose. The graft copolymers were characterized, and their improved properties were also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2369–2375, 2007     

A study on grafting of methyl methacrylate onto jute fiber (S2O-thiourea redox system)

A study of the graft copolymerization of methyl methacrylate onto jute fiber, using K₂S₂O₈-thiourea (TU) redox-initiating system has been made. The effects of concentration of monomer, S₂O, TU on graft yield have been studied. Besides the effects of time, temperature, acid, and amount of jute fiber, some inorganic salts and organic solvents on graft yield have been investigated. The most remarkable features of the investigation include proposition of a mechanism for the grafting process and characterization of grafted fiber by infrared (IR) and thermogravimetric studies. Grafting has improved the light fastness of jute fibers dyed with basic dyes. More than 200% graft yield could be achieved in the present investigation.     

Graft copolymerization studies. III. Methyl methacrylate onto polypropylene and polyethylene terephthalate

The tert‐butoxy radical‐facilitated grafting of methyl methacrylate (MMA) onto commercial polypropylene (PP) pellets and fiber was investigated in heterogeneous conditions similar to practical systems. Free‐radical grafting of several other monomers onto PP fiber was also investigated. Also, preliminary data from the grafting of MMA onto poly(ethylene terephthalate) pellets is presented. The PP‐graft‐PMMA residues were detected by solid‐state ¹³C‐NMR and photoacoustic IR spectroscopy. There was a good correlation between the degree of grafting (DG) determined from these spectroscopic techniques and the results from gravimetric methods. A maximum grafting efficiency of over 50% was found, whereas DG (20%) remained constant at various PP pellet, initiator, and monomer concentrations. However, at relatively low PP fiber concentrations, the DG was 27%; the increase was most likely due to the greater surface area of the fiber. There was also a reduction in DG (14%) at relatively low initiator concentrations. The reaction conditions were altered to favor grafting by the addition of more polymer substrate. When the ratio of tert‐butoxy radicals to PP was decreased, more of the substrate remained unmodified, and empirical calculations showed the formation of grafts with up to 40 monomer units. At high initiator concentrations, calculations showed that the graft residues were 1–2 units long. Therefore, variation of the polymer, initiator, and monomer concentrations was shown to have a significant effect on grafting. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 898–915, 2002     

Graft copolymerization of methyl acrylate onto poly(vinyl alcohol) initiated by potassium diperiodatonickelate(IV)

The graft copolymerization of methyl acrylate onto poly(vinyl alcohol) (PVA) with a potassium diperiodatonickelate(IV) [Ni(IV)]–PVA redox system as an initiator was investigated in an alkaline medium. The grafting parameters were determined as functions of the temperature and the concentrations of the monomer and initiator. The structures of the graft copolymers were confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The Ni(IV)–PVA system was found to be an efficient redox initiator for this graft copolymerization. A single‐electron‐transfer mechanism was proposed for the formation of radicals and the initiation. Other acrylate monomers, such as methyl methacrylate, ethyl acrylate, n‐butyl acrylate, and n‐butyl methacrylate, were used as reductants for graft copolymerization. These reactions definitely occurred to some degree. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 529–534, 2003     

Graft copolymerization of acrylate monomers onto sulfonated jute–cotton blended fabric

Graft copolymerization of acrylate monomers, e.g., methyl methacrylate and ethyl methacrylate, onto bleached sulfonated jute–cotton‐blended fabric was carried out in an aqueous medium, using potassium persulfate as an initiator under the catalytic influence of ferrous sulfate in a nitrogen atmosphere. The parameter variables, e.g., concentrations of monomer, potassium persulfate, ferrous sulfate, reaction time, and reaction temperature, directly influenced the percent graft yield. The percent graft yield increased to a certain value in each variable, and the percent graft yield of methyl methacrylate and ethyl methacrylate was about 15.9 and 17.1%, respectively. Polymer grafting was characterized by thermogravimetric analysis, infrared spectroscopy, and X‐ray diffractometry. Grafting improved the thermal stability, protected from photo‐oxidative degradation, decreased the dyeability, and had positive impact on fastness characteristics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4393–4398, 2006     

Surface modification of coir fibers. II. Cu(II)‐ IO initiated graft copolymerization of acrylonitrile onto chemically modified coir fibers

A study of the graft copolymerization of acrylonitrile (AN) onto chemically modified coir fibers was carried out using a CuSO₄ and NaIO₄ combination as the initiator in an aqueous medium in a temperature range of 50–70°C. The graft yield was influenced by the reaction time, temperature, concentration of CuSO₄, concentration of NaIO₄, and monomer concentration. Grafting was also carried out in the presence of inorganic salts and organic solvents. A combination of copper(II) and sodium periodate (Cu²⁺‐IO) in an aqueous medium with an IO concentration of 0.005 mol L^?1 and a Cu²⁺ concentration of 0.004 mol L^?1 produced optimum grafting. The chemically modified and AN grafted fibers were characterized by FTIR and scanning electron microscopy (SEM). The SEM studies revealed that grafting not only takes place on the surface of the fibers but also penetrates the fiber matrix. The tensile properties like the maximum stress at break and extension at break of untreated, chemically modified, and AN grafted coir fibers were evaluated and compared. The extent of absorption of water of untreated, chemically modified, and grafted coir fibers was determined. It was found that grafting of AN imparts hydrophobicity onto coir fibers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 75–82, 2002; DOI 10.1002/app.10221     

Synthesis of cassava starch‐g‐poly(methyl methacrylate) copolymers with benzoyl peroxide as an initiator

Graft copolymers of cassava starch and methyl methacrylate (MMA) were synthesized by free‐radical polymerization with benzoyl peroxide (BPO) as an initiator in an aqueous medium at 80°C. The formation of graft copolymers was confirmed by analysis of the obtained products with Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of the amount of cassava starch, the amount of MMA monomer, the amount of BPO, and the reaction time on the grafting characteristics were studied. The optimum condition for grafting were obtained when 5 g of cassava starch, 5 g of MMA, 0.1 g of BPO, and a reaction time of 3 h were used. These condition provided a graft copolymer with 25.00% add‐on, 81.40% monomer conversion, 54.30% homopoly(methyl methacrylate) formed, 45.70% grafting efficiency, 37.20% grafting ratio, and 95.54% yield. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4083–4089, 2006     

超声-微波共辐射法合成纤维素-MMA接枝共聚物

引言纤维素作为一种天然的可再生高分子材料,存在于丰富的绿色植物中,是自然界取之不尽用之不竭的清洁资源。因此,在煤、石油、天然气的储量日益减少的今天,纤维素可作为一种可持续发展的绿色资源来研究和开发。而且天然植物纤维资源丰富、价格低廉,并且具有较好的生物可降解性,在