Reinforcement of polypropylene using sisal fibers grafted with poly(methyl methacrylate)

Sisal fiber (SF) surface modification was carried out by grafting with methyl methacrylate (MMA) using cerium and ammonium nitrate as initiator. The effects of reaction time, monomer, and initiator concentration on the grafting parameters were systematically investigated. The results showed that MMA was successfully grafted onto the sisal fiber surface. The PMMA‐grafted sisal fibers were melt blended with polypropylene (PP) and then injection molded. The PP/SF composites were characterized by means of thermal analysis, mechanical testing, wide‐angle X‐ray diffraction, and SEM examination. PMMA grafted onto the surface of SF enhanced the intermolecular interaction between the reinforcing SF and PP matrix, improved the dispersion of SF in the PP matrix, and promoted the formation of β‐crystalline PP. These enhanced the thermal stability and mechanical properties of PP/SF composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1055–1064, 2003     

Synthesis and characterization of amphiphilic graft copolymer poly(ethylene oxide)-graft-poly(methyl acrylate)

A novel well-defined amphiphilic graft copolymer of poly(ethylene oxide) as main chain and poly(methyl acrylate) as graft chains is successfully prepared by combination of anionic copolymerization with atom transfer radical polymerization (ATRP). The glycidol is protected by ethyl vinyl ether first, then obtained 2,3-epoxypropyl-1-ethoxyethyl ether (EPEE) is copolymerized with EO by initiation of mixture of diphenylmethyl potassium and triethylene glycol to give the well-defined poly(EO-co-EPEE), the latter is deprotected in the acidic conditions, then the recovered copolymer [(poly(EO-co-Gly)] with multi-pending hydroxyls is esterified with 2-bromoisobutyryl bromide to produce the ATRP macroinitiator with multi-pending activated bromides [poly(EO-co-Gly)_(ATRP)] to initiate the polymerization of methyl acrylate (MA). The object products and intermediates are characterized by NMR, MALDI-TOF-MS, FT-IR, and SEC in detail. In solution polymerization, the molecular weight distribution of the graft copolymers is rather narrow (M_w/M_n < 1.2), and the linear dependence of Ln [M₀]/[M] on time demonstrates that the MA polymerization is well controlled.     

Tensile properties of a poly(vinyl chloride) composite filled with poly(methyl methacrylate) grafted to oil palm empty fruit bunches

The influence of oil palm empty fruit bunch (OPEFB) fiber and oil palm empty fruit bunches grafted with poly(methyl methacrylate) (OPEFB‐g‐PMMA) on the tensile properties of poly(vinyl chloride) (PVC) was investigated. The OPEFB‐g‐PMMA fiber was first prepared with the optimum conditions for the grafting reaction, which were determined in our previous study. To produce composites, the PVC resin, OPEFB‐g‐PMMA fiber or ungrafted OPEFB fiber, and other additives were first dry‐blended with a laboratory blender before being milled into sheets on a two‐roll mill. Test specimens were then hot‐pressed, and then the tensile properties were determined. A comparison with the composite filled with the ungrafted OPEFB fiber showed that the tensile strength and elongation at break increased, whereas Young's modulus decreased, with the incorporation of 20 phr OPEFB‐g‐PMMA fiber into the PVC matrix. The trend of the tensile properties obtained in this study was supported by functional group analysis, glass‐transition temperature measurements, and surface morphological analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polypropylene fibers grafted with poly(acrylic acid)

An effective method for the grafting of poly(acrylic acid) on polypropylene fibers has been developed, using diphenyl and a dispersing agent (NNO) in the grafting bath as additives to facilitate the grafting process. The method makes it possible to obtain high grafting degrees of poly(acrylic acid) on polypropylene fibers with a minimal quantity of homopolymer as a side product. The effect of grafting degree on the moisture absorption and swelling of the modified fibers has been examined and described with mathematical equations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2295–2299, 2002     

含规整 PMMA支链的 PBA合成及其力学性能

研究了聚甲基丙烯酸甲酯大单体与丙烯酸丁酯在苯中的共聚，该大单体由甲基丙烯酸甲酯在巯基乙酸链转移剂存在下聚合，用甲基烯酸缩不甘油酯封端，研究了共聚速率、大单体相对分子质量、大单体与小单体投料比、引发剂用量、单体浓度及共聚温度对接枝效率及共聚物相对分子质量的影响。用分级沉淀法精制共聚物。用凝胶渗透色谱法、红外光谱法及差示扫描量热法对共聚物进行表征，用蒸汽压式渗透压力计及膜渗透压测定了结构参数，结果表明，平均接枝数随转化率增加而降低，在一定的组成范围内，共聚物呈热塑性弹性体行为。     

Surface modification of polythiophene and poly(3‐methyl thiophene) films by graft copolymerization

Polythiophene (PTH) and poly(3‐methyl thiophene) (PMT) films were electrochemically polymerized in an electrolyte solution of boron fluoride–ethyl ether. Ozone‐pretreated PTH and PMT films were subjected to UV‐light‐induced graft copolymerization with different monomers, including poly(ethylene glycol) monomethacrylate, acrylic acid, and glycidyl methacrylate. Surface grafting with the hydrophilic polymers gave rise to more hydrophilic PTH and PMT films. The structure and chemical composition of each copolymer surface were studied by X‐ray photoelectron spectroscopy. The surface grafting with the hydrophilic polymers resulted in a more hydrophilic PTH film. The dependence of the density of surface grafting and the conductivities of the grafted PTH and PMT films on the ozone pretreatment was also studied. A large amount of the grafted groups at the surface of the PTH and PMT films remained free for further surface modification and functionalization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Modification of starch–poly(methyl acrylate) graft copolymers by steam jet cooking

Starch-g-poly(methyl acrylate) containing 12.3, 31.9, 51.7, and 58.3% PMA, by weight, were prepared by ceric ammonium nitrate-initiated polymerization of methyl acrylate onto granular cornstarch. The granular structures of these graft copolymers were not disrupted by steam jet cooking at 140°C. At most, only 13% of the polymer was dissolved, and this soluble fraction was comprised largely of starch. The probability of crosslinking within these graft copolymer granules was considered. Physical properties of extruded ribbons depended upon whether or not granular graft copolymers were jet cooked prior to extrusion. Although tensile strengths were not greatly affected by steam jet cooking, cooked samples showed significant increases in both percent elongation and tear resistance. The effects of jet cooking upon the properties of extruded ribbons can be explained by gelatinization of starch within the grafted starch granules. Although jet-cooked granules still remain intact, gelatinization of the starch moiety causes these granules to be less rigid, more deformable, and more easily plasticized by small amounts of water. Loss of starch crystallinity after steam jet cooking was proved by both differential scanning calorimetry and X-ray diffraction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1021–1029, 1997     

Dyeing properties of Bombyx mori silks grafted with methyl methacrylate and methacrylamide

To improve their dyeing and colorfastness properties, degummed Bombyx mori silks were chemically modified by a grafting technique with either methyl methacrylate (MMA) monomer or methacrylamide (MAA) monomer. Both commercial synthetic dyes, that is, acid and basic dyes, and natural dyes extracted from turmeric, without and with potassium aluminum sulfate mordant, were used in this study. Percentage dye uptake increased with the presence of poly(methyl methacrylate) or polymethacrylamide in the silk fibroin structure regardless of the types of the dyestuffs. Furthermore, compared to the degummed silk, the colorfastness to washing of the MMA‐grafted and MAA‐grafted silks dyed with acid, basic, and curcumin dyestuffs were greatly improved. Colorfastness to both acid and basic perspirations with acid and basic dyestuffs was slightly improved, whereas perspiration fastness remained unchanged for curcumin dyeing without and with the presence of the mordant. Also, the low‐light resistances of the degummed and grafted silks dyed by curcumin dyestuff were notably improved by the MMA and MAA grafting technique. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:1169–1175, 2006     

丙烯酸酯接枝硅油消泡剂的制备与性能

分别以丙烯酸甲酯接枝硅油(MA-g-PHMS)、丙烯酸乙酯接枝硅油(EA-g-PHMS)和丙烯酸丁酯接枝硅油(BA-g-PHMS)为原料,制得了3种有机硅乳液消泡剂;并用正交试验优化了工艺条件,优化后的条件分别为:MA-g-PHMS硅膏质量分数为24%,乳化剂质量分数为4%,于70℃反应5 h;EA-g-PHMS硅膏质量分数为24%,乳化剂质量分数为3%,于70℃反应4 h;BA-g-PHMS硅膏质量分数为24%,乳化剂质量分数为3%,于75℃反应6 h。3种消泡剂都具有高效的消泡性能,其中EA-g-PHMS消泡剂性能极佳,其消泡时间为10.1 s,抑泡时间为21.6 min。     

Effects of compatibilizing agents in poly(n-butyl acrylate)/poly(methyl methacrylate) composite latexes

Graft copolymers with poly(n-butyl acrylate) (PBA) backbones and poly(methyl methacrylate) (PMMA) macromonomer side chains are used as compatibilizing agents for PBA/PMMA composite latexes. The composite latexes are prepared by seeded emulsion polymerization of methyl methacrylate (MMA) in the presence of PBA particles. Graft copolymers were already incorporated into the PBA particles prior to using these particles as seed via miniemulsion (co)polymerization of n-butyl acrylate (BA) in the presence of the macromonomers. Comparison between size averages of composite and seed particles indicates no secondary nucleation of MMA during seeded emulsion polymerization. Transmission electron microscopy (TEM) observations of composite particles show the dependence of particle morphologies with the amount of macromonomer (i.e., mole ratio of macromonomer to BA and molecular weight of macromonomer) in seed latex. The more uniform coverage with the higher amount of macromonomer suggests that graft copolymers decrease the interfacial tension between core and shell layers in the composite particles. Dynamic mechanical analysis of composite latex films indicates the existence of an interphase region between PBA and PMMA. The dynamic mechanical properties of these films are related to the morphology of the composite particles, the arrangement of phases in the films, and the volume of the interphase polymer. © 1997 John Wiley & Sons, Inc.     

Toughening of polylactide with natural rubber grafted with poly(butyl acrylate)

Natural rubber grafted with poly(butyl acrylate) (NR‐g‐PBA) in an attempt to toughen polylactide (PLA) was prepared by grafting butyl acrylate onto natural rubber (NR) through emulsion polymerization. The purified NR‐g‐PBA was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. NR‐g‐PBA/PLA blend and NR/PLA blend were prepared with a Haake internal melt mixer. The morphology and mechanical properties of the blends were investigated as a function of rubber content. Observations by scanning electron microscopy showed that the spherical‐particle‐dispersed phase appearing in the NR/PLA blend was not found in the NR‐g‐PBA/PLA blend, which showed that NR grafted with PBA is compatible with PLA, and accounted for the efficient toughening effect on PLA. The elongation at break and the impact strength were significantly improved with an increase in NR‐g‐PBA content. The thermal stability of PLA decreased when blended with NR but was retained with NR‐g‐PBA. Copyright © 2011 Society of Chemical Industry     

Effects of graft polymer compatibilizers in blends of cellulose triacetate and poly(lactic acid)

Blends of cellulose triacetate (CTA) and poly(l ‐lactic acid) (PLLA) were prepared using graft polymer compatibilizers. The graft polymers were synthesized using a grafting‐from approach via ring‐opening polymerization of l ‐ and d ,l ‐lactide initiated from free hydroxyl groups along the CTA backbone. The blends incorporating either 1, 2.5 or 5% of each of the two graft polymer compatibilizers by weight in a 20:80 mixture of CTA:PLLA were solution‐cast to yield films. Characterization of graft polymers included the use of ¹H NMR spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis. Mechanical properties of the compatibilized films were evaluated using tensile testing, and thermomechanical properties were analyzed using dynamic mechanical analysis (DMA). The compatibilized films exhibited greater tensile stress at yield than the uncompatibilized films for both types of compatibilizers, but no statistically significant changes were observed in modulus or strain at break, although modulus trended higher in compatibilized films. Stereochemical differences in tensile performance were statistically insignificant, though some differences in thermal behavior were observed. DMA and DSC revealed that crystallization of PLLA was altered by the addition of compatibilizer and CTA. © 2019 Society of Chemical Industry     

Synthesis and characterization of poly(butyl acrylate)/silica and poly(butyl acrylate)/silica/poly(methyl methacrylate) composite particles

Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006     

Enhancement of PVC/ENR blend properties by poly(methyl acrylate) grafted oil palm empty fruit bunch fiber

Effect of oil palm empty fruit bunch (OPEFB) fiber and poly(methyl acrylate) grafted OPEFB on several mechanical properties of poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends were studied. The composites were prepared by mixing the fiber and the PVC/ENR blends using HAKEE Rheomixer at the rotor speed of 50 rpm, mixing temperature 150°C, and mixing period of 20 min. The fiber loadings were varied from 0 to 30% and the effect of fiber content in the composites on their ultimate tensile strength (UTS), Young's modulus, elongation at break, flexural modulus, hardness, and impact strength were determined. An increasing trend was observed in the Young's modulus, flexural modulus, and hardness with the addition of grafted and ungrafted fiber to the PVC/ENR blends. However the impact strength, UTS, and elongation at break of the composites were found to decrease with the increase in fiber loading. An increase in elongation at break and UTS and decrease in the flexural and Young's modulus was observed with the addition of PMA‐g‐OPEFB fiber compared to ungrafted fiber. This observation indicates that grafting of PMA onto OPEFB impart some flexibility to the blend. The morphology of cryogenically fractured and tensile fracture surfaces of the composites, examined by a scanning electron microscope shows that the adhesion between the fiber and the matrix is improved upon grafting of the OPEFB fiber. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Kinetics of graft copolymerization of poly(hexanedioic acid ethylene glycol) and methyl acrylate initiated by potassium diperiodatocuprate(III)

A redox system, potassium diperiodatocuprate(III) [DPC]/poly(hexanedioic acid ethylene glycol) (PEA) system, was employed to initiate graft copolymers of methyl acrylate (MA) and PEA in alkaline medium. The results indicate that the equation of the polymerization rate (R_p) is as follows: R_p = k [MA]^1.62[Cu(III)]^0.69, and that the overall activation energy of graft polymerization is 42.5 kJ/mol. The total conversion at different conditions (concentration of reactants, temperature, concentration of the DPC, and reaction time) was also investigated. The infrared spectra proved that the graft copolymers were synthesized successfully. Some basic properties of the graft copolymer were studied by instrumental analyses, including thermogravimetry and scanning electron microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2376–2381, 2007     

Toughening of poly(lactide) using polyethylene glycol methyl ether acrylate: Reactive versus physical blending

To design high‐performance poly(lactide)‐based materials (PLA‐based) with improved toughness, two approaches based on the reactive extrusion (REx) process are investigated and compared in the present study. The first approach relies upon a two‐step procedure using a REx‐polymerized poly(ethylene glycol) methyl ether acrylate, i.e., poly(AcrylPEG), as a highly‐branched and compatible impact modifier for PLA. The free‐radical polymerization proves to be very efficient with a peroxide initiator concentration of 1 wt%. The as‐produced poly(AcrylPEG) is then melt‐blended with PLA by extrusion. The resulting materials exhibit largely increase impact resistance (ca. 35 kJ/m²) in presence of 20 wt% poly(AcrylPEG) in comparison with neat PLA (2.7 kJ/m²), while moderate ductility (tensile elongation at break <40%) and limited plasticization effect are observed. The second “one‐step” approach consists in in situ grafting of AcrylPEG onto PLA backbone via a one‐stage REx. The resulting materials exhibit substantially improved impact resistance (ca. 102 kJ/m²) for AcrylPEG loading of 20 wt%, high ductility (tensile elongation at break of ca. 150%) and efficient plasticization. A detailed characterization of the morphology of the materials has been performed using PF‐QNM‐AFM to better elucidate the structure‐property relationships. POLYM. ENG. SCI., 55:1408–1419, 2015. © 2015 Society of Plastics Engineers     

Investigation of poly(methyl acrylate) grafted chitosan as a polymeric drug carrier

The graft copolymerization of methyl acrylate (MA) onto chitosan in aqueous medium was investigated using potassium persulfate (KPS) as initiator. The grafting conditions were optimized by studying the effects of the polymerization variables (the initiator concentration, the ratio of monomer to chitosan, and reaction temperature) on the percentage of grafting (PG). PG was found to depend on these variables, and the highest grafting percentage (256 %) could be obtained at chitosan = 1 g, KPS = 4.5 × 10^?3 M, methyl acrylate monomer = 6 g, T = 60 °C and t = 180 min. The graft copolymer was characterized by Fourier transform infrared spectra analysis, thermogravimetry (differential thermogravimetry, differential scanning calorimetric), X-ray powder diffraction as well as CP-MAS ¹³C NMR spectroscopy. These analyses are highly confirmed the formation of poly(methyl acrylate) grafted chitosan (PMAGC). Furthermore, the gelation of the grafted polymers (PG 68, 122, 218 and 256 %) in distilled water has been studied, and the results revealed that the percentage of swelling number increase with increasing PG of the polymers. Controlled release of niacin (vitamin B₃) from the hydrogel of the grafted polymers (PG 68, 122 and 256 %) in aqueous medium has been studied using ultraviolet absorption to follow quantities released at different times (for each experiment: PMAGC 100 mg, niacin 2.46 mg, distilled water 100 ml). The study was repeated again with same conditions except the using of 4.92 mg of niacin instead of 2.46 mg (PG of the grafted polymer is 256 %). The diffusion coefficient (D, cm²/h) of niacin from the hydrogel of the grafted polymer (PG 256 %) was calculated depending on Higuchi model (diffusion coefficient of the first load is 0.00194 cm²/h while 0.00255 cm²/h of the second load).     

Effects of poly(methyl methacrylate-co-n-butyl acrylate) on the properties and processing behavior of poly(vinyl chloride)

Random copolymers of methyl methacrylate/n-butyl acrylate with a BA content of 0–50% and M?_v = 0.16–4.04 × 10⁶ were synthesized and evaluated as a processing aid (PA) for poly(vinyl chloride) (PVC). Their effects on the processability and properties of PVC were investigated with respect to the composition, molecular weight, and the amount of the copolymer added. It was found that the fusion rate of PVC could be improved (i) by increasing the amount of the copolymer used, (ii) by increasing the butyl acrylate content in the copolymer, and (iii) by lowering the molecular weight of the copolymer. The effect of molecular weight, composition, and amount of copolymer on the ultimate mechanical properties of PVC was investigated. The presence of copolymer did not affect the impact strength. However, the tensile strength and elongation at break were improved, particularly at high temperature (125°C). It was also found that the “plate out” phenomenon of PVC could be significantly reduced in the presence of the processing aid.     

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     

Hydrogels based on gelatin poly(hydroxyethyl methacrylate) and poly(butyl acrylate) graft copolymer impregnated with fibrin

Gelatin was graft copolymerized with poly(hydroxyethyl methacrylate and butyl acrylate) and subsequently crosslinked with glutaraldehyde. Fibrin of bovine origin was incorporated onto this graft copolymer and characterized for the percentage of grafting. The infrared spectroscopy, mechanical strength, and water absorption capacity of the composite were also studied. This biomaterial can be used as a hemostat in many phases of surgery and as a wound dressing material. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:555–560, 1997