Studies on the kinetics and mechanism of the copolymerization of acrylonitrile with styrene in the presence of zinc chloride

Radical copolymerization of acrylonitrile (AN) with styrene (Sty), using x,x′-azobisisobutyronitrile as initiator, was carried out in the presence of zinc chloride (ZnCl₂) dilatometrically at 65/pm 0.1 C for 120min. The rate of polymerization was a direct function of the concentrations of ZnCl₂, AN and Sty, and polymerization temperature. The viscosity-average molecular weight of the copolymer increased with ZnCl₂ concentration. The energy of activation in the presence and absence of the complex was evaluated as 82.5 kJ mol^?1 and 115.5 kJ mol^?1, respectively. The copolymerization of AN with Sty proceeded via the radical-complex mechanism.     

Grafting of acrylic monomers onto cotton fabric using an activated cellulose thiocarbonate–azobisisobutyronitrile redox system

The feasibility of a cellulose thiocarbonate–azobisisobutyronitrile (AIBN) initiation system to induce graft copolymerization of methyl methacrylate (MMA) and other acrylic monomers onto cotton fabric was investigated. Other acrylic monomers were acrylic acid, acrylonitrile, and methyl acrylate. The initiation system under investigation was highly activated in the presence of a metal‐ion reductant or a metal‐ion oxidant in the polymerization medium. A number of variables in the grafting reaction were studied, including AIBN concentration, pH of the polymerization medium, nature of substrate, monomer concentration, duration and temperature of polymerization, and composition of the solvent/water polymerization medium. The solvents used were methanol, isopropanol, 1,4‐dioxane, cyclohexane, benzene, dimethyl formamide, and dimethyl sulfoxide. There were optimal concentrations of AIBN (5 mmol/L), MMA (8%), Fe²⁺ (0.1 mmol/L), Mn²⁺ (8 mmol/L), and Fe³⁺ (2 mmol/L). A polymerization medium of pH 2 and temperature of 70°C constituted the optimal conditions for grafting. The methanol/water mixture constituted the most favorable reaction medium for grafting MMA onto cotton fabric by using the Fe²⁺–cellulose thiocarbonate–AIBN redox system. MMA was superior to other monomers for grafting. The unmodified cotton cellulose showed very little tendency to be grafted with MMA compared with the chemically modified cellulosic substrate. A tentative mechanism for the grafting reaction was proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1261–1274, 2004     

Peroxydiphosphate–metal ion–cellulose thiocarbonate redox system‐induced graft copolymerization of vinyl monomers onto cotton fabric

The grafting of methacrylic acid (MAA) and other vinyl monomers onto cotton cellulose in fabric form was investigated in an aqueous medium with a potassium peroxydiphosphate–metal ion–cellulose thiocarbonate redox initiation system. The graft copolymerization reaction was influenced by peroxydiphosphate (PP) concentration, the pH of the reaction medium, monomer concentration, the duration and temperature of polymerization, the nature of vinyl monomers, and the nature and concentration of metallic ions (activators). On the basis of a detailed investigation of these factors, the optimal conditions for the grafting of MAA onto cotton fabric with the said redox system were as follows: [Fe²⁺] = 0.1 mmol/L, [PP] = 2 mmol/L, [MAA] = 4%, pH‐2, grafting time = 2 h, grafting temperature = 70°C, and material/liquor ratio = 1 : 50. Under these optimal conditions, the graft yields of different monomers were in the following sequence: MAA ? acrylonitrile > acrylic acid > methyl acrylate > methyl methacrylate. The unmodified cellulosic fabric (the control) had no ability to be grafted with MAA with the PP–Fe²⁺ redox system. The percentage of grafting onto the thiocarbonated cellulosic fabric was more greatly enhanced in the presence of iron salts than in their absence. This held true when the lowest concentrations of these salts were used separately. A suitable mechanism for the grafting processes is suggested, in accordance with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1879–1889, 2003     

Latexes of starch-based graft polymers containing polymerized acrylonitrile

The scope of graft reactions to produce starch-based latexes was extended by graft polymerization of acrylonitrile (AN) onto gelatinized cationic starch possessing quaternary amine functionality and by graft terpolymerization of AN and t-butylaminoethyl methacrylate (TBAEM) onto gelatinized starch by cerium (IV) initiation at 25°C. Grafting onto starches containing highly basic quaternary amines gave polyacrylonitrile [poly(AN)] grafts having about one fourth the number-average molecular weight (M?_n) (178,000–232,000) of those produced by grafting AN onto starches containing the less basic tertiary amine groups. Sonification at 20 KHz of graft polymerization reaction mixtures having up to 8% solids reduced viscosities from 400–3000 cP to 10–40 cP. Diameters of dried particles measured about 300–1500 Å. Shaker-type agitation during grafting onto starch having quaternary amine groups produced poly(AN) chains with lower M?_n values than those produced during blade stirrer-type agitation. M?_n values of grafted poly(AN) decreased with increasing reaction time, degree of substitution of amine in the starch, gelation time of cationic starch at 95°C, and cerium (IV) concentration. AN was copolymerized with TBAEM at molar ratios of 14–85:1 in grafting onto gelatinized starch to yield copolymer side-chain grafts analyzing 8–52:1 of polymerized AN to TBAEM moieties.     

Competitive removal of heavy metal ions by cellulose graft copolymers

The effect of composition of graft chains of four types cellulose graft copolymers on the competitive removal of Pb²⁺, Cu²⁺, and Cd²⁺ ions from aqueous solution was investigated. The copolymers used were (1) cellulose‐g‐polyacrylic acid (cellulose‐g‐pAA) with grafting percentages of 7, 18, and 30%; (2) cellulose‐g‐p(AA–NMBA) prepared by grafting of AA onto cellulose in the presence of crosslinking agent of N,N′‐methylene bisacrylamide (NMBA); (3) cellulose‐g‐p(AA–AASO₃H) prepared by grafting of a monomer mixture of acrylic acid (AA) and 2‐acrylamido‐2‐methyl propane sulphonic acid (AASO₃H) containing 10% (in mole) AASO₃H; and (4) cellulose‐g‐pAASO₃H obtained by grafting of AASO₃H onto cellulose. The concentrations of ions which were kept constant at 4 mmol/L in an aqueous solution of pH 4.5 were equal. Metal ion removal capacities and removal percentages of the copolymers was determined. Metal ion removal capacity of cellulose‐g‐pAA did not change with the increase in grafting percentages of the copolymer and determined to be 0.27 mmol metal ion/g_copolymer. Although the metal removal rate of cellulose‐g‐p(AA–NMBA) copolymer was lower than that of cellulose‐g‐pAA, removal capacities of both copolymers were the same which was equal to 0.24 mmol metal ion/g_copolymer. Cellulose did not remove any ion under the same conditions. In addition, cellulose‐g‐pAASO₃H removed practically no ion from the aqueous solution (0.02 mmol metal ion/g_copolymer). The presence of AASO₃H in the graft chains of cellulose‐g‐p(AA–AASO₃H) created a synergistic effect with respect to metal removal and led to a slight increase in metal ion adsorption capability in comparison to that of cellulose‐g‐pAA. All types of cellulose copolymers were found to be selective for the removal of Pb²⁺ over Cu²⁺ and Cd²⁺. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2034–2039, 2003     

Homogeneous graft copolymerization of acrylonitrile onto high α‐cellulose in a dimethyl acetamide and lithium chloride solvent system

Homogeneous graft copolymerization of acrylonitrile (AN) monomer onto high α‐cellulose was investigated in a lithium chloride/N,N‐dimethyl acetamide (DMAc/LiCl) solvent system. Benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were used as radical initiators. By varying temperature, time, and monomer concentrations in grafting reactions, the optimum conditions for both initiator systems were fixed. The graft yield for the AN–BPO system was higher than that for the AN–AIBN system. The optimum conditions of reactions were at temperatures of 70 and 60°C with initiator concentrations of 0.4% (0.36 mmol) and 2% (1.24 mmol) for the AN–AIBN and AN–BPO systems, respectively, at a monomer concentration of 5% (14.1 mmol) solution. The number of grafts per cellulose chain was in the range from 2.2 to 1.1 for AN–BPO and 0.5 to 2.1 for the AN–AIBN system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 630–637, 2003     

Synthesis and characterization of N‐vinyl pyrrolidone and cellulosics based functional graft copolymers for use as metal ions and iodine sorbents

To develop cost effective and eco friendly polymeric materials for enrichment and separation technologies, 1‐vinyl‐2‐pyrrolidone (N‐VP) was graft copolymerized onto cellulose, extracted from pine needles. Optimum conditions have been evaluated for the grafting of N‐VP onto cellulose and at these conditions it was also grafted onto cellulose phosphate, hydroxypropyl cellulose, cyanoethyl cellulose, and deoxyhydrazino cellulose. At the optimum grafting conditions for N‐VP, it was also cografted with maleic anhydride. Kinetics of radiochemical graft copolymerization has been studied and evaluation of the polymerization and grafting parameters as percent grafting, percent grafting efficiency, rate of polymerization, homopolymerization, and graft copolymerization have been evaluated. Graft copolymers have been characterized by elemental analysis, FTIR, and swelling studies. An attempt has been made to study sorption of some metal ions such as Fe²⁺ and Cu²⁺ and iodine on select graft copolymers to investigate selectivity in metal ion sorption and iodine sorption as a function of structural aspects of the functionalized graft copolymers to find their end uses in separation and enrichment technologies. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 373–382, 2005     

Studies on the radical copolymerization of methylacrylate with styrene using ZnCl2 as an accelerator

The kinetic investigation of the radical copolymerization of methylacrylate (MA) with styrene (Sty) using zinc chloride (ZnCl₂) as an accelerator was carried out at 60 ± 0.1 °C for 120 min. The rate of polymerization was proportional to the concentrations of ZnCl₂ and monomers. The energies of activation in the presence and absence of the complex are 34 and 89 kJ mol^?1, respectively.     

Preparation of soapless latexes by sonification of starch-based poly(isoprene–co–acrylonitrile) graft reaction mixtures

Graft copolymerization of isoprene (IP) and acrylonitrile (AN) onto gelatinized starch (S) and cationic starch having quaternary amine functionality through cerium(IV) initiation gave grafted side chains of poly(IP–co–AN). Grafts of various compositions are obtained by controlling the amounts and ratios of monomers added to starch. IP alone does not homograft onto gelatinized starch at 25° or 50°C by cerium(IV) initiation and requires the presence of an “initiator–monomer” such as AN to obtain copolymer side chains. Although cografting of IP and AN onto starch depends on AN to initiate radical chains, the ratio employed of the two monomers is critical for graft polymerization to occur. For example, at a molar ratio of IP to AN of 1 or greater, little polymer was produced; at molar ratios in the range of 0.4 to 0.67, considerable amounts of polymer were produced; and at a molar ratio of 0.13 or less, polymerization of AN was greatly retarded. Concentration of HNO₃ in the cerium(IV) reagent and reaction temperature also influence the grafting reaction. Lower HNO₃ concentrations favor grafting at 50°C, while higher acid concentrations favor grafting at 25°C. Starch graft reaction mixtures were sonified at 20 kHz to form latexes that air dry to clear pliable films. Poly(IP–co–AN) obtained by acid hydrolysis of the starch portion of the grafts failed to dissolve in either dimethylformamide or benzene, thus indicating presence of crosslinks. S–g–poly(IP–co–AN), having about one third starch and grafted side chains averaging about 2 parts polymerized IP per part of polymerized AN, was masticated on steel rolls at 100°C to a tough pliable film which was subsequently vulcanized to a rubber.     

Graft copolymerization of styrene and acrylonitrile onto EPDM

Acrylonitrile–EPDM–styrene (AES) graft copolymers were synthesized by solution graft polymerization of styrene (St) and acrylonitrile (AN) onto EPDM in an n‐hexane/benzene solvent with benzoyl peroxide (BPO) as an initiator. The structure changes were studied by an FTIR spectrophotometer. The grafting parameters were calculated gravimetrically. The influence of the polymerization conditions, such as the reaction time, concentration of the initiator, EPDM content, and weight ratio of St/AN, on the structure of the products was investigated. It was found that a proper initiator concentration and EPDM content will give a high grafting ratio of the AES resin. The thermal property of the copolymer was studied using programmed thermogravimetric analysis (TGA). The results showed that the copolymer has a better heat‐resistant property than that of ABS, especially for the initial decomposition temperature (T_in) and the maximum weight loss rate temperature (T_max). Also, the mechanism of the graft reaction was discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 428–432, 2002     

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     

Surface modification of nylon‐6 fibers for medical applications

Hydroxyethylmethacrylate (HEMA) is considered to be one of the important vinyl monomers. The ability of polyhydroxyethyl‐methacylate (PHEMA) graft sites to consecutive chemical modification makes the use of nylon‐6 fibers grafted with PHEMA a feasible bed for immobilization of a wide range of biologically active reagents, specially enzymes, drugs, cells, and immunadsorbents. Stemming from the above discussions, in this article, the graft copolymerization of HEMA onto modified nylon‐6 fibers containing Polydiallyldimethylammonium chloride (PDADMAC) in the presence of Cu²⁺–K₂S₂O₈ as a redox initiating system was carried out, with very high rate and almost without homopolymer formation. The factors affecting the grafting reaction (monomer, K₂S₂O₈ and cupric ion concentrations, the amount of PDADMAC as well as the reaction temperature) were studied. Kinetic investigation revealed that the rate of grafting (R_p) of HEMA onto modified nylon‐6 fibers is proportional to [HEMA]¹, [CuSO₄.5H₂O] ^0.7, [PDADMAC]^0.4, and [K₂S₂O₈]^1.4. The overall activation energy was calculated (71 KJ/mol). The fine structure, surface topography, thermal and electrical properties of parent and grafted nylon‐6 fibers were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3788–3796, 2007     

Polymers from renewable resources: Kinetics studies of the radiochemical graft copolymerization of styrene onto cellulose extracted from pine needles and the effect of some additives on the grafting parameters in an aqueous medium

In an attempt to develop an alternative to petro‐based polymers, we graft‐copolymerized cellulose isolated from the needles of Pinus roxburghii with styrene in a limited aqueous medium in air by simultaneous irradiation using gamma rays as the initiator. The optimum conditions for obtaining maximum grafting were determined as a function of monomer concentration, total dose of irradiation, and amount of water. Maximum percentage of grafting (P_g; 79.9) was obtained at a total dose of 1.152 × 10⁴ Gy with 1.325 × 10^?4 mol of styrene. The effect of methanol, LiNO₃, Cu(NO₃)₂, Mohr's salt, H₂SO₄, HNO₃, and AcOH on P_g was studied. All the additives were found to decrease graft yield, contrary to some reported studies. Total percentage conversion and rates of polymerization, grafting, and homopolymerization were evaluated. Evidence of grafting was provided by the characterization of cellulose and its graft copolymers by Fourier transform infrared spectroscopy, thermogravimetry, and observation of the swelling behavior in some solvents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1490–1500, 2002     

Synthesis and characterization of polyacrylonitrile pregelled starch graft copolymers using ferrous sulfate‐hydrogen peroxide redox initiation system as surface sizing agent

A graft copolymer was synthesized by graft copolymerization of starch with styrene (St) and butyl acrylate (BA), using ferrous sulfate‐hydrogen peroxide redox initiation system. The starch was pregelled in the presence of acrylonitrile (AN) in aqueous alkali at high temperature before graft polymerization. Major factors affecting the polymerization reaction were investigated. It was found that a graft copolymer with higher percentage conversion (PC), graft efficiency (GE) and graft percentage (GP) was obtained by controlling the initiator concentration, concentration, and ratio of monomers and polymerization temperature. The optimum conditions were as follows: H₂O₂ concentration, 12%; monomer concentration, 120%; St/BA ratio, 1 : 1; polymerization temperature, 65°C. Fourier transform infrared spectroscopy and NMR analyses were used to gain information on the structure of the products. It was demonstrated that St, BA, and AN had been successfully grafted onto starch and ? CN had been saponified into ? CONH₂ and ? COO^? to a certain degree when pregelling. Scanning electron microscope micrographs showed the coarse structure and broad network. The graft polymerization took place on the surface of starch granule and led to amorphization of the starch structure. Graft polymer had better thermal stability and was endowed with pseudo‐plasticity. It was observed that the starch graft copolymer offers good properties such as water resistance as surface‐sizing agent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Ammonia adsorption behavior of polypropylene nonwoven fabric grafted with acrylic acid

An attempt was made to synthesize an adsorbent by the photoinduced grafting of acrylic acid (AA) onto polypropylene nonwoven fabrics using benzophenone (BP) as a photosensitizer in a CH₃OH/H₂O medium. As the BP concentration was increased, the graft yield was increased up to a specific value and then decreased, and the effect of AA concentration showed the same tendency. It was also found that the graft yield increased with the reaction time and temperature. The amounts of ammonia adsorbed onto polypropylene nonwoven fabrics grafted with AA (PP‐g‐AA) were dependent on the graft yield, adsorption time, and ammonia gas pressure. The adsorption capacity of PP‐g‐AA was 5.86 mmol/g at the graft yield of 116.6%, which was much higher than that of active carbon or silica gel. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 295–301, 2002; DOI 10.1002/app.10328     

Aminating modification of viscose fibers and their CO2 adsorption properties

An adsorbent for CO₂ capture was prepared by the grafting of acrylonitrile (AN) onto viscose fibers (VFs); this was followed by amination with triethylene tetramine (TETA). The effects of the reaction conditions, such as the concentrations of the monomer, initiator, and nitric acid, on the grafting degree and grafting efficiency were studied. The adsorption performance of the adsorbent for CO₂ was evaluated by fixed‐bed adsorption. The highest dynamic adsorption capacity of the adsorbent for CO₂ was 4.35 mmol/g when the amine content of the adsorbent VF–AN–TETA reached 13.21 mmol/g. Compared with the polypropylene (PP)‐fiber‐based adsorbent (PP–AN–TETA), VF–AN–TETA with hydroxyl groups on the fibers facilitated the diffusion of CO₂ and water and led to a higher CO₂ adsorption capacity than that of PP–AN–TETA. The VF–AN–TETA adsorbent also showed good regeneration performance: its CO₂ adsorption capacity could still retain almost the same capacity as the fresh adsorbent after 10 adsorption–desorption cycles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42840.     

Mechanism of the copolymerization of styrene with methyl,ethyl, and n-butyl acrylates in the presence of zinc chloride

The complexes of methyl acrylate (MA), ethyl acrylate (EA) and n-butyl acrylate (BA) with zinc chloride (ZnCl₂) were prepared at 300 K and found to be polar in nature. The viscosity and density of the complexes increased while the tendency to form a binary complex decreased with increase in size of the alkyl substituents of the acrylate monomers. The copolymerization of MA and BA with styrene (Sty) followed a cross-propagation mechanism, whereas the copolymerization of EA with Sty followed a radical-complex mechanism in the presence of their complexes with ZnCl₂.     

Copolymerization of n‐butylacrylate with styrene by a novel photoinitiator, 1‐(bromoacetyl)pyrene

A comparative study on photoinitiated solution copolymerization of n‐butylacrylate (BA) with styrene (Sty) using pyrene (Py), 1‐acetylpyrene (AP), and 1‐(bromoacetyl)pyrene (BP) as initiators showed that the introduction of a chromophoric moiety, bromoacetyl (? COCH₂Br), significantly increased the photoinitiating ability of pyrene. The kinetics and mechanism of copolymerization of BA with Sty using BP as photoinitiator have been studied in detail. The system follows nonideal kinetics (R_p ∝ [BP]^0.34 [BA]^1.07 [Sty]^0.97). The nonideality was attributed to both primary radical termination and degradative initiator transfer. The monomer reactivity ratios of Sty and BA have been estimated by the Finemann–Ross and Kelen–Tudos methods, by analyzing copolymer compositions determined by ¹H NMR spectra. The values of r₁ (Sty) and r₂ (BA) were found to be 0.78 and 0.25, respectively, which suggested the high concentration of alternating sequences in the random copolymers obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3233–3239, 2006     

Acrylonitrile graft copolymerization of casein proteins for enhanced solubility and thermal properties

Casein proteins are soluble in 5% aq. ethanolamine, triehtylamine, and triethanolamine, but insoluble in organic solvents. Graft copolymerization of casein (40 g/L) with acrylonitrile (AN) was carried out in 5% w/v aq. triethanolamine at 60°C using potassium persulfate K₂S₂O₈ as an initiator. Percent grafting and grafting efficiency increased with increasing initiator concentrations (up to 1.7 × 10⁻² mole L⁻¹) and reaction times, but decreasing [M]/[I] ratios. Fourier transform IR spectra confirmed the formation of the acrylonitrile‐grafted‐casein (AN‐g‐casein) copolymers. Under the reaction conditions studied, the grafted PAN side chains were characterized by gel permeation chromatography to have M_n between 1.58 and 5.88 × 10⁴ dalton and polydispersities between 2.6 and 4.5. The AN‐g‐casein copolymers behaved more like a PAN homopolymer in terms of their thermal properties and solubilities. The decomposition temperatures of AN‐g‐casein copolymers were between 255 and 273°C, closer to the T_d of the PAN homopolymer (275°C) and significantly higher than that of casein (180°C). The AN‐g‐casein copolymers are soluble in 50% aq. NaSCN and ZnCl₂, but are insoluble in 32:28:40 wt % CaCl₂/CH₃CH₂OH/H₂O like PAN and dimethylformamide‐like casein. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2543–2551, 2000     

Graft polymerization of acrylonitrile onto paper and characterization of the grafted product

The chemical graft copolymerization reaction of acrylonitrile (AN) onto paper sheet was performed. The effect of initiator concentration, monomer concentration, and temperature on the reaction rate was studied. The reaction rate equation of the graft copolymerization reaction is found to be R_P = K₂ [initiator]^0.54[monomer]^1.13. The apparent activation energy (E_a) of the copolymerization reaction is found to be 35.99 KJ/mol. The infrared characteristic absorption bands for cellulosic paper structure and the paper gr‐AN are studied. Tensile break load, porosity, and burst strength were measured for the grafted and pure paper sheet. It was found that the mechanical properties are improved by grafting. The chemical resistance of the graft product against strong acid (HCl), strong alkali (NaOH), polar and nonpolar solvents was investigated. It was found that the resistance to these chemicals is enhanced by grafting. From the TGA and DTA data, it is clear that the grafted paper sheet is more thermally stable than pure paper sheet. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011