Synthesis and characterization of butyl acrylate graft sodium salt of partially carboxymethylated starch

Graft copolymers were synthesized by graft copolymerization of butyl acrylate (BA) onto sodium salt of partially carboxymethylated starch (Na‐PCMS). Ceric ammonium nitrate (CAN), a redox initiator, was used for initiation of graft copolymerization reaction. All the experiments were run with Na‐PCMS having degree of substitution, DS = 0.35. The grafting reaction was characterized by parameters such as % total conversion (%Ct), % grafting (%G), % grafting efficiency (%GE), and % add‐on. Graft copolymers were characterized by infrared spectral analysis and scanning electron microscopy. Variables affecting graft copolymerization reaction such as nitric acid concentration, reaction time, reaction temperature, and ceric ion concentration were investigated. The results revealed that 0.3M CAN as initiator, 0.3M HNO₃, with reaction time 4–4.5 h at 25–30°C were found as suitable parameters for maximum yield of graft copolymerization reaction. © 2006 Wiley Periodicals, Inc. JAppl Polym Sci 102: 3334–3340, 2006     

Chemically Induced Graft Copolymerization of Methacrylic Acid onto Low Density Polyethylene Films Using Sodium Bisulfite

Abstract

A simple and inexpensive technique for preparation of membranes by chemically induced graft copolymerization of methacrylic acid (MAA) onto low-density polyethylene (PE) films using sodium bisulfite (SBS) initiator was developed. Several parameters affecting the grafting rate and yield, such as the concentration of aqueous monomer solutions (4–20%) and initiator (0.025–0.2 M/L), reaction temperature (50–70°C), and within reaction times ranging from 1 to 6 h were studied. The results show that grafted films with 20% up to 500% graft were obtained under the synthesis conditions mentioned. Some selective properties of the grafted films (membranes), such as swelling behavior and mechanical properties were investigated. Also, the films were characterized by infrared (IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Such prepared graft copolymers may be of great interest in some practical uses such as dialysis and ultrafiltration membranes and also for wastewater treatment from heavy and toxic metals.     

Effects of polyethylene‐grafted maleic anhydride (PE‐g‐MA) on thermal properties,morphology, and tensile properties of low‐density polyethylene (LDPE) and corn starch blends

The effects of polyethylene‐grafted maleic anhydride (PE‐g‐MA) on the thermal properties, morphology, and tensile properties of blends of low‐density polyethylene (LDPE) and corn starch were studied with a differential scanning calorimeter (DSC), scanning electron microscope (SEM), and Instron Universal Testing Machine, respectively. Corn starch–LDPE blends with different starch content and with or without the addition of PE‐g‐MA were prepared with a lab‐scale twin‐screw extruder. The crystallization temperature of LDPE–corn starch–PE‐g‐MA blends was similar to that of pure LDPE but higher than that of LDPE–corn starch blends. The interfacial properties between corn starch and LDPE were improved after PE‐g‐MA addition, as evidenced by the structure morphology revealed by SEM. The tensile strength and elongation at break of corn starch–LDPE–PE‐g‐MA blends were greater than those of LDPE–corn starch blends, and their differences became more pronounced at higher starch contents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2904–2911, 2003     

Synthesis and characterization of starch‐poly(methyl methacrylate) graft copolymers

The graft copolymerization was carried out by methyl methacrylate with starch in which azobisisobutyronitrile was used as an initiator. The grafting reactions were carried out within a 65–95°C temperature range, and the effect of the monomer, initiator concentrations, and the amount of starch on the graft yield were also investigated. The maximum graft yield was obtained at a azobisisobutyronitrile concentration of 2.0 × 10^?3 mol/L. The overall rate activation energy of the reaction was found to be 89.42 kJ/mol. The grafted starches were characterized with infrared spectroscopy, scanning electron microscopy, and thermogravimetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 53–57, 2002     

Chemically induced graft copolymerization of vinyl monomers onto cotton fibers

We investigated the chemically induced graft copolymerizations of acrylic acid (AA), acrylamide, crotonic acid, and itaconic acid (IA) onto cotton fibers. Benzoyl peroxide was used as an initiator. The effects of grafting temperature, grafting time, and monomer and initiator concentrations on the grafting yields were studied, and optimum grafting conditions were determined for the sample material. The maximum grafting yield value obtained was 23.8% for AA. Swelling tests, Fourier transform infrared spectroscopy, and scanning electron microscopy analyses of grafted and ungrafted fibers were also performed to characterize fiber properties. IA‐grafted fibers were measured as the most swollen fibers, with a swelling value of 510%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2343–2347, 2006     

Preparation and properties of polyethylene–clay nanocomposites by an in situ graft method

The polyethylene–clay nanocomposites were prepared by the in situ graft copolymerization of styrene containing twin‐benzyldimethyldioctadecylammonium bromine modified montmorillonite (TBDO‐MMT) in polyethylene with dicumyl peroxide (DCP) as an initiator in molten state. XRD and TEM analysis indicated that intercalated polyethylene/MMT nanocomposites are obtained. The mechanics performance, crystal behavior, thermal properties, and the effect of MMT contents on PE/MMT nanocomposite were also studied. As comparison, polyethylene/montmorillonite composites prepared by a simply melt compounding without styrene were studied as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4921–4927, 2006     

Graft polymerization of acrylonitrile onto starch‐coated polyethylene film surfaces

Starch‐coated polyethylene (PE) films were prepared by immersing PE in a hot, jet cooked solution of starch. They were allowed to react with acrylonitrile (AN) in the presence of ceric ammonium nitrate initiator, and the graft polymerization that occurred produced starch‐g‐polyacrylonitrile (PAN) coatings that contained about 25 wt % grafted PAN. The starch‐g‐PAN coatings tightly adhered to the PE film surfaces. When grafted starch coatings were wetted with water and the surfaces vigorously rubbed, less than 20% of the coating was removed. The fact that PAN‐grafted coatings were not removed with boiling water provided further evidence for their strong adherence. When starch was removed from the coating by acid hydrolysis, the residual grafted PAN still remained adsorbed on the PE surface. Because the grafted coating was completely removed by treatment with refluxing 0.7N sodium hydroxide, there is apparently no chemical bonding between starch‐g‐PAN and PE. The dimensional changes associated with the evaporation of water from these PAN‐grafted coatings caused the films to curl during drying. Because the final shape of these coated films depends upon the presence or absence of water in the surrounding environment, these films may be considered to be a type of stimulus‐responsive polymer. Attempts to graft polymerize methyl methacrylate and methyl acrylate onto starch‐coated PE surfaces, under conditions similar to those used with AN, were unsuccessful. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3323–3328, 2003     

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     

Grafting of vinyl acetate onto low density polyethylene—starch biodegradable films for printing and packaging applications

Starch‐based biodegradable low‐density polyethylene (LDPE) films were used for graft copolymerization of vinyl acetate with ceric ammonium nitrate (CAN) in aqueous acidic medium as redox initiator with nitric acid. The extent of grafting was examined by Fourier‐transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR) spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The objective behind the grafting of vinyl acetate onto the LDPE–starch biodegradable films is to make these suitable for printing and packaging applications without affecting the biodegradability of the original films. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of graft copolymers of ethyl acrylate/acrylamide mixtures onto starch

Graft copolymerization of ethyl acrylate/acrylamide onto corn starch using potassium permanganate–citric acid initiation system was investigated. Major factors affecting the polymerization reaction were thoroughly investigated in terms of initiator concentration, monomer concentration, polymerization time, polymerization temperature, and starch/liquor, and the obtained results implied that the polymer yield which were expressed by total monomer conversion, grafting ratio, and grafting efficiency were determined by these factors. The optimum reaction conditions were as follows: starch, 30 g; potassium permanganate (based on weight of starch), 0.1%; citric acid (based on weight of starch), 0.5%; ethyl acrylate, 20%; acrylamide, 0.4 g; time, 3 h; temperature, 40°C; starch/liquor, 1:3. We concluded that the initiator of potassium permanganate–citric acid system could be used as a cheap initiator in manufacturing the starch graft copolymer. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Graft polymerization of acrylic acid onto starch using potassium permanganate acid (redox system)

Graft polymerization of acrylic acid (AA) onto rice starch using postassium permanganate/acid redox system as initiator was investigated. When starch was reacted with KMnO₄ solution, MnO₂ was deposited onto starch. The dependence of MnO₂ amount deposited was directly related to KMnO₄ concentration. Subjecting the MnO₂-containing starch to a solution consisting of monomer (AA) and acid (citric, tartaric, oxalic and hydrochloric acid) formed poly(AA)–starch graft copolymers. The graft yield, expressed as meq COOH/100 g starch, was measured by the amount of MnO₂ deposited, AA concentration, material-to-liquor ratio, kind and concentration of acid, as well as temperature and duration. Finally, the newly prepared poly(AA)–starch graft copolymers were applied to cotton textiles to determine their suitability as sizing agents. The highest graft yield was obtained with citric acid and the least with hydrochloric acid, with tartaric and oxalic acid in between. The graft yield increased by increasing the concentration of acid to a certain concentration beyond which grafting leveled off. A similar trend was observed when the magnitude of grafting was related to the amount of MnO₂ deposited. The graft yield increased by increasing the polymerization temperature from 30° to 50°C. Increasing the temperature to 60°C is accompanied by decreased grafting. On the other hand, fabric samples sized with poly(AA)–starch graft copolymers acquire higher tensile strength, elongation at break, and abrasion resistance than that sized with native rice starch, i.e., poly(AA)–starch graft copolymers serve as good sizing agents for cotton textiles. A tentative mechanism for grafting rice starch with AA using the KMnO₄/acid redox system was elucidated. © 1995 John Wiley & Sons, Inc.     

Synthesis,characterization, and evaluation of novel Hibiscus sabdariffa‐g‐poly(EA) copolymer

In this article, the morphologic transformation of Hibiscus sabdariffa, a natural fiber through graft copolymerization with ethyl acrylate using ceric ammonium nitrate–nitric acid initiator system, has been reported. Different reaction parameters such as temperature, time, initiator concentration, monomer concentration, and pH were optimized to get maximum graft yield (117.3%). The graft copolymer thus formed was characterized by Fourier transform infrared, scanning electron micrographs, X‐ray diffraction, thermogravimetric analysis, and differential thermogravimetric analysis techniques. The graft copolymer was found to be moisture, chemical, and thermal resistant. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and Characterization of Starch-g-Polymethacrylamide Copolymers

In this article, methacrylamide was successfully grafted onto starch using benzoyl peroxide as a radical initiator in aqueous medium. The extent of grafting was found to be affected by the initiator, monomer, starch concentration, and temperature. The optimum initiator concentration is 2.0×10⁻³ mol/L. The graft yield was observed to increase with the monomer concentration and temperature. No optimum values for the monomer concentration and temperature were found. The overall activation energy for graft copolymerization was obtained. The grafted starches were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). TGA thermograms showed that the thermal stability of starch increased as a result of grafting. SEM micrographs showed that the granular structure of starch was not maintained after graft copolymerization. The water uptake and moisture retainment values of starch graft copolymers were investigated.     

Kinetics and mechanism of free radical grafting of methyl acrylate onto sago starch

The graft copolymerization was carried out by methyl acrylate with sago starch in which ceric ammonium nitrate was used as an initiator. It has been found that the rates of graft polymerization and grafting efficiency were dependent upon the concentration of ceric ammonium nitrate (CAN), methyl acrylate (MA), sago starch (AGU, anhydro glucose unit), mineral acid (H₂SO₄), and as well as reaction temperature and period. A rate equation of polymerization was established from the proposed reaction mechanism, and the rate of polymerization (R_p) was the first‐order dependence of the MA monomer concentration and square root of the CAN concentration. A new kinetic model of the grafting reaction has been proposed, and a normal kinetics of methyl acrylate polymerization was observed. An equation of a predicted model relating the graft fraction of poly(methyl acrylate) with the sago starch has been derived, and validity of the predicted model was verified by the experimental results. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 784–791, 2000     

Immobilization of a cyclodextrin glucanotransferase (CGTase) onto polyethylene film with a carboxylic acid group and production of cyclodextrins from corn starch using CGTase‐immobilized PE film

Carboxylic acid groups were introduced onto polyethylene (PE) film by radiation‐induced graft copolymerization. Subsequently, the clodextrin glucanotransferase (CGTase) was immobilized on the PE film with a carboxylic acid group. The activity of the immobilized CGTase on PE film was in the range of 0.40–1.04 U/cm² per min. The production of cyclodextrins (CDs) from corn starch was examined using the CGTase‐immobilized PE film. The production ratios of CDs using CGTase‐immobilized PE film was in the following order: α–CD > β–CD > γ–CD. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2451–2457, 2002     

Waste‐reducing preparation of PE‐g‐MAH and PE‐g‐DBM via solid phase grafting reaction and their application as compatibilizers

Kinetics for grafting two reactive monomers (dibutyl maleate (DBM) and maleic anhydride (MAH)) on polyethylene (PE) was investigated for the modified PE (PE‐g‐MAH and PE‐g‐DBM) using solid phase grafting process. This process avoided solvent waste produced in solution process and high operation temperature in melt process. In the presence of the radical initiator, coupling reactions, between the PE and product, and macromolecular radicals, routinely form gels and/or increase molecular weight, resulting in a worse rheological behavior for the grafting products. By adding small amount of interface agents, using combined initiators and optimizing reactor design, graft copolymers with controlled grafting degrees and good rheological properties were prepared. The grafting degrees of copolymers were determined by chemical analysis. FTIR, DSC, and pure water contact angle characterized the chemical structure, the thermal property, and the hydrophilic property of the grafting copolymers, respectively. The peel strength of the graft copolymer as powder coating on the stainless steel surface was measured as high as 12–24 kgf/cm. Mechanical strength and toughness of PE/kaolin clay, PVC/CPE, and PVC/CPE/CaCO₃ alloys with small amount of the graft copolymer (～5 wt %) added were improved significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3781–3790, 2006     

Modification of carbohydrate polymers via grafting of methacrylonitrile onto pregelled starch using potassium monopersulfate/Fe2+ redox pair

The graft copolymerization of reactive pregelled starch (PGS) with methacrylonitrile (MAN) was performed and the reaction conditions were optimized using potassium monopersulfate (PMPS) in the presence of ferrous ion redox pair as initiator. Emphasis was directed towards increasing the graft formation and decreasing homopolymerization. The grafting parameters were studied with respect to graft yield and graft reaction efficiency percent. In addition, the newly prepared polymethacrylonitrile (polyMAN)‐pregelled starch graft copolymers were applied to cotton textiles to see their suitability as a new sizing agent. Based on the results obtained, appropriate conditions for grafting MAN onto pregelled starch was established and the graft yield was higher under the following conditions: using 0.004 mol l^?1 potassium monopersulfate as initiator, 0.005 mol l^?1 ferrous ion concentration, 0.003 mol l^?1, sulfuric acid, 50 % MAN concentration (based on weight of substrate), material to liquor ratio 1:2.5, reaction time 60 min, and polymerization temperature 40 °C. Finally, fabric samples sized with polyMAN‐pregelled starch graft copolymers acquired higher tensile strength and abrasion resistance than that sized with original pregelled starch, while elongation at break was unaltered. Copyright © 2004 Society of Chemical Industry     

Ce(IV)-N-acetylglycine initiated graft copolymerization of acrylonitrile onto chemically modified pineapple leaf fibers

Graft copolymerization of acrylonitrile (AN) onto chemically modified pineapple leaf fiber (PALF) was studied using Ce(IV) and N-acetylglycine (NAG) combination as initiator in the temperature range 40–60°C. The effects of concentration of monomer, Ce(IV), and NAG on graft yield have been studied. Besides the effects of time, temperature, acid, amount of PALF, some inorganic salts and organic solvents on graft yield have been investigated. FTIR and scanning electron microscopy of PALF and grafted PALF have been studied. Grafting has improved the thermal stability of PALF. © 1996 John Wiley & Sons, Inc.     

A modified model and algorithm for flow‐enhanced crystallization—Application to fiber spinning

The graft copolymerization of acrylamide (AAm) monomer onto polyethylene‐coated polypropylene (PE‐co‐PP) nonwoven fabric was carried out by the mutual irradiation method. The general peculiarities of the grafting have been studied by gravimetric, scanning electron microscope (SEM), mechanical properties, and Fourier transform infrared (FTIR) methods. The influence of absorbed dose, dose rate, as well as the monomer concentration on the degree of grafting has been determined. Metal ions uptake of Cu²⁺, Co²⁺, Ni²⁺ by the grafted fabrics was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3240–3245, 2006     

Effects of glycerol and PE‐g‐MA on morphology,thermal and tensile properties of LDPE and rice starch blends

The effects of glycerol and polyethylene‐grafted maleic anhydride (PE‐g‐MA) on the morphology, thermal properties, and tensile properties of low‐density polyethylene (LDPE) and rice starch blends were studied by scanning electron microscopy (SEM), differential scanning calorimetry, and the Instron Universal Testing Machine, respectively. Blends of LDPE/rice starch, LDPE/rice starch/glycerol, and LDPE/rice starch/glycerol/PE‐g‐MA with different starch contents were prepared by using a laboratory scale twin‐screw extruder. The distribution of rice starch in LDPE matrix became homogenous after the addition of glycerol. The interfacial adhesion between rice starch and LDPE was improved by the addition of PE‐g‐MA as demonstrated by SEM. The crystallization temperatures of LDPE/rice starch/glycerol blends and LDPE/rice starch/glycerol/PE‐g‐MA blends were similar to that of pure LDPE but higher than that of LDPE/rice starch blends. Both the tensile strength and the elongation at break followed the order of rice starch/LDPE/glycerol/PE‐g‐MA blends > rice starch/LDPE/glycerol > LDPE/rice starch blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 344–350, 2004