Studies on Graft Copolymerization of Acrylic Acid onto Ramie Fibers with Chromic Acid Initiation System

The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).

Study on Structure and Performance of Starch and Styrene Graft Copolymer

[Objective] The paper was to study the structure and performance of starch and styrene graft copolymer. [Method] The microscopic structure of corn starch and styrene graft copolymer was analyzed by using infrared spectrum and scanning electron microscope, and the property of starch and styrene graft copoly- mer was confirmed through grinding experiment, tensile strength, water absorption rate, hot water resistance properties and enzymatic properties analysis. [Result] The starch and styrene graft copolymer had the properties of thermoplastic and microbial degradation. IConclusion] The starch and styrene graft copolymer is expected to be developed as a biodegradable material.

STUDIES ON GRAFT COPOLYMERIZATION OF DL-LACTIDE ON CORN STARCH AND BIODEGRADABILITY OF THE COPOLYMERS

The starch/D,L-lactide graft copolymers were synthesized by reacting D,L-lactide with corn starch in N,N-dimethylacetamide (DMAM) in the presence of triethylamine (NEt3) and anhydrous lithium chloride. The effect of reaction time and the molar ratio of D,L-lactide to glucose structural unit of starch on monomer conversion(C%), graft (G%) and graft efficiency (GE%) were studied. The C%, G% and GE% could approach 37.3%,179.7% and 68.0%, respectively when the molar ratio of D,L-lactide to glucose structural unit of starch is 10:1 and the graft copolymerization was carried out at 80-85℃ for 4 hours under nitrogen atmosphere. The Fourier transforms infra-red (FTIR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) spectroscopy were used in order to characterize the graft copolymers. FTIR spectra show that absorption band at 1740 cm-1 confirmed the formation of ester bond, indicating the starch /D,L-lactide graft copolymers were produced, the DSC characteristic results show the melting temperature of the graft copolymer were elevated slightly as the molar ratio of D,L-lactide to glucose structural units of starch increased and the X-ray diffraction spectra show the synthesized graft copolymers were amorphous. The degradability of graft copolymer was tested with the aid of acid, alkali and microbe such as bacillus subtilis and staphylococcus aureus. The results of water resistance show the graft copolymer produced can be used as a component of impermeable coating for cardboard.

GRAFT COPOLYMERIZATION OF VINYL MONOMERS ONTO STARCH INITIATED BY TRANSITION METAL-THIOUREA REDOX SYSTEMS

In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiated by Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in the presence of sulfuric acid of different concentrations. It was shown that the grafting capability of Mn(VII)-TU is the highest in these initiating systems. Using Mn (VII-TU as initiator, the effects of various acids (HClO4, H2SO4, HNO3, HCl) on the graft copolymerization of acrylonitrile onto starch were discussed, and the capabilities of graft copolymerization of methyl methacrylate (MMA), acrylamide (AM), acrylic acid (AA) onto starch were investigated. The experimental results show that the order of the influences of different acids is HClO4 > H2SO4 > HNO3 > HCl, and the order of grafting capabilities of different monomers grafted onto starch is MMA > AN > AM > AA. The structure and morphology of graft, copolymers were studied with infrared spectroscopy and scanning electron microscopy. The size, shape and roughness of surface of the grafted starch granules are changed after grafting.

SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC GRAFT COPOLYMER CONTAINING MICROPHASE SEPARATED AND LONG POLY(ETHYLENE OXIDE) SIDE CHAIN STRUCTURES

Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called 'selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed 'comb- model' was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.

THE ADHESIVE CAPACITY OF STARCH GRAFT COPOLYMERS TO POLYESTER/COTTON FIBER

The advantages of using starch graft copolymers as warp sizes in textile were briefly discussed, and the factors of affecting adhesive capacity to the fiber were analysed. By using eerie ammonium nitrate as an initiator under nitrogen atomosphere, a number of vinyl and/or acrylic monomers such as acrylic acid, acrylamide, methyl acrylate, ethyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, butyl methacrylate, vinyl acetate and the combinations among them were graft copolymerized respectively onto granular corn starch in aqueous dispersion. The adhesive capacity of these starch graft copolymers to polyester/cotton fibers was evaluated by a slightly sized rovings according to V. K. Aggarwal’s method which measures the breaking strength and elongation of the rovings impregnated with the size paste. The influences of the monomers and their combinations, the grafting technological processes and the pretreatment methods before graft copolymerization upon adhesive capacity have been

MODIFICATION OF SILK FIBER via EMULSION GRAFT COPOLYMERIZATION WITH FLUOROACRYLATE

2,2,3,3,4,4,5,5-Octafluoropentyl acrylate was grafted onto silk fiber in a two-step heterogeneous system through the vinyl bonds of acryloyloxyethyl isocyanate modified on the silk.The grafted copolylner was analyzed by FTIR and WAXD,and the results revealed that the fluoroacrylate was successfully grafted onto silk fiber and the crystalline structure of silk fibroin withβ-sheet structure was not changed after graft copolymerization.The FT-IR corrected method was used to simulate the grafting yield onto sil...

SYNTHESIS OF GRAFT COPOLYMERS WITH POLYISOBUTYLENE BRANCH CHAINS

The copolymerization of 4-vinylbenzyl chloride （VBC） and vinyl acetate （VAC） was carried out in toluene at 75℃ via radical polymerization using 2,2＇-azo-bis-（isobutyronitrile） （AIBN） as an initiator. The random copolymers of poly（4-vinylbenzyl chloride-co-vinyl acetate） （P（VBC-co-VAC）） with number average molecular weight （Mn） from 2000 to 6900, relatively narrow molecular weight distribution （MWD, Mw/Mn ca. 2.0） and with different copolymer composition of 4-vinylbenzyl chloride （VBC） from 17 mol% to 62 mol% could be obtained. The P（VBC-co-VAC） copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene （IB）. The cationic polymerizations of IB were further conducted by using P（VBC-co-VAC） copolymers as macroinitiators in conjunction with TICl4 at -40℃ in CH2Cl2. The effects of VBC/TiCl4 （molar ratio） on monomer conversion, Mn and MWD of the resultant copolymers were investigated under 3 sets of conditions. It is found that P（VBC-co-VAC）-g-PIB copolymers with relatively narrow MWD （Mw/Mn ca. 2.0） and with terminal tert-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl4 （molar ratio） was set in the range from 0.10 to 1.12. The unimodal GPC curve of the P（VBC-co-VAC）-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector. The TEM image of the P（VBC-co-VAC）-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P（VBC-co-VAC）-rich domains of 20-100 um in size tethered by PIB branch segments.

Graft Copolymerization of Ethyl Acrylate onto Hydroxypropyl Methylcellulose Using Potassium Persulfate as Initiator

With potassium persulfate (KPS) as initiator, graft copolymerization of ethyl acrylate (EA) onto water-soluble hydroxypropyl methylcellulose (HPMC) was investigated in aqueous medium. Effects of monomer concentration, initiator concentration, matrix concentration, and reaction temperature on the percentage of grafting (G) and grafting efficiency (G_E) were studied. The results show that G and G_E values both increase with the the increase of EA concentration and KPS concentration; when raising HPMC concentration from 0.12 mmol/L to 0.47 mmol/L, G decreases, while G_E increases;and when raising reaction temperature from 50 ℃ to 65 ℃,G increases, but G_E decreases. In addition, the graft copolymers were characterized by Fourier transform infrared (FTIR) spectra and transmission electron microscopy (TEM) methods.

The Optimization of Synthesizing Graft Copolymer of Starch with Vinyl Monomers

The graft copolymerization of acrylamide （ AM ） / acrylic acid （ AA ） onto starch （ St- g-pAA and St-g-p（AA-co-AM） ） was carried out using an orthngonal test method. The combined effects of different reaction conditions on the water absorbency of the graft copolymers were optimized through mathematical statistical methods of range and square variance analysis. The maximum water absorbency was obtained when the ratio of dried starch to distilled water was 1 ： 8 （ w/w ）, the ratio of starch to monomer 1 ： 6 （ w/w ）, the initiator concentration 4.40 × 10^-3 mol/L, the crosslinker concentration 10.86 × 10^-2 mol/L, and the basicity to AA 0. 70（ mol/mol ）. Both the graft copolymers have an excellent water absorption capacity in distilled water aact in 0. 9wt% NaCl solution. It was also found that in distilled water the water absorbency of St-g-pAA was higher than that of St-g-p（ AA-co-AM） , while in 0.9wt% NaCl solution, the situation was just the reverse. The correlation between the water absorbeacy anct the nature of the solution anct the properties of the copolymers, which is related to the properties of the monomers, was discussed. The grafting of AA ancl AM onto starch was confirmed by the IR spectra of St-g-pAA and St-g-p（ AA-co-AM）.

Research on the Graft Copolymerization of EH-lignin with acrylamide

Lignin isolated from enzymatic hydrolyzed corn-stalks (EH-lignin) is a renewable natural polymer noted for its versatility and applicability in a vari-ety of uses. Graft copolymerization of EH-lignin with acrylamide (AM) and the application of this copolymer as a flocculant in dye wastewater treatment were studied in this article. The influ-ences of some factors on yield of copolymer and the grafting ratio were investigated and the structure of EH-lignin/AM graft copolymer was characterized by FT-IR. According to the yield and the grafting ratio, the optimum conditions for graft copolymerization were as follows: initiator K2S2O8-Na2S2O3 with a quantity 3 wt% of EH-lignin, mass ratio of AM to EH-lignin was 2~3, reaction time 4h and temperature at 50℃. It was found that the absorption capacity of graft copolymer to two azo-dyes was enhanced with the increase of grafting ratio. Furthermore, the residue concen-tration of EH-lignin/AM graft copolymer remained in the supernatant after flocculation was much lower than that of pure EH-lignin.

SYNTHESIS AND CHARACTERIZATION OF GRAFT COPOLYMERS BASED ON POLY(p-PHENYLENE TEREPHTHALAMIDE) BACKBONE AND WELL-DEFINED POLYSTYRENE SIDE CHAINS

A novel dualfunctional monomer, 2-（2＇,2＇,6＇,6＇-tetramethyl-piperidinyl-1＇-oxy）methylbenzene-1,4-dioyl chloride hydrochloride, with two acid chloride groups for step-growth polymerization and a nitroxide group for the mediation of living radical polymerization was synthesized. It was first copolymerized with terephthaloyl chloride and p- phenylenediamine at a feed molar ratio of 1：3：4 in N-methyl-2-pyrrolidone containing 10 wt% calcium chloride at -10℃ to yield a poly（p-phenylene terephthalamide） based macroinitiator, which initiated radical polymerization of styrene at 125℃ to obtain a series of poly（p-phenylene terephthalamide）-g-polystyrenes. A combinatory analysis of proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elementary analysis, thermogravimetry and gel permeation chromatography indicated that the macroinitiator induced the radical polymerization of styrene to proceed in a well- controlled way. The molecular weight of side-chains increased with an increase of monomer conversion, and the molecular weight distribution index remained lower than 1.5. The graft copolymers showed a remarkably improved solubility in N- methyl-2-pyrrolidone and much depressed crystallinity in bulk.

Graft copolymerization of cellulose and 2-hydroxyethyl methacrylate in an ionic liquid

Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride （AmimCl） with 2-hydroxyethyl methacrylate. The synthesized AmimCl and cellulose graft copolymers were characterized by FTIR, ^1 H-NMR and XRD spectroscopy. The results show that AmimCl dissolved cellulose directly by destroying intermolecular and intramolecular hydrogen bonds in cellulose and the crystalline form of cellulose was transformed from cellulose Ⅰ to cellulose Ⅱ after regeneration from AmimCl. The best synthetic condition of the cellulose-graft-P （2-hydroxyethyl methacrylate） was that cellulose 0.5 g, 2-hydroxyethyl methacrylate 3.00 g and initiator ammonium persulfate 0.05 g reacted for 180 min at 60℃; the rate of grafting reached 77.3%.

Photo-Grafting Copolymerization of PP Nonwoven Fabric and Its Application for Acidic Dye Adsorption and Filtration

The monomer methacrylamido propyl trimethy ammonium chloride( MAPTAC) was copolymerized onto the fiber surface of polypropylene( PP) nonwoven fabric under ultroviole radiation. The weak acid red GN dye adsorption and adsorptive filtration performance of the resulted PP fabrics were investigated.The results showed that the grafting copolymerization preferred to happen in the inner layer of the fabrics. The water flux of the grafted fabrics decreases with the increase of grafting yield. The collapse of the grafted polymer chains causes the flux increase in acidic condition,or vice versa at alkaline version. The coiling of the polyelectrolyte chains upon the dye adsorption seems to violate the routine assumption of the rigid substrate, and this gets the adsorption energy constant negative. The static adsorption process follows the Lagergren's pseudo-second order kinetic equation. The removals of circa( ca.) 100% of the total permeation volume3 500 mL simulated dye wastewater was reached during permeation.The dye adsorbed fabrics were regenerated by the mixed media of the cationic surfactant / ethanol /water. The grafted fabric assumes stable fabric integrity and stability during permeation,and presents excellent dye adsorption capacity,easy desorption, and repeatable utilization.

Determining the degree of grafting for poly(vinylidene fluoride) graft-copolymers using fluorine elemental analysis

Acrylic acid (AAc) and styrene (St) were grafted onto poly(vinylidene fluoride) (PVDF) powder or membrane samples by pre-irradiation graft copolymerization.The grafted chains were proved by FT-IR spectroscopy analysis.The degree of grafting (DG) of the grafted PVDF was determined by fluorine elemental analysis (FEA) method,and was compared with the DGs determined by weighing method,acid-base back titration method and quantitative FT-IR method.The results show that the FEA method is accurate,convenient and universal,especially for the grafted polymer powders.

Graft Copolymerization of N,N-Dimethylacrylamide to Cellulose in Homogeneous Media Using Atom Transfer Radical Polymerization for Hemocompatibility

In homogeneous media, N,N-Dimethylacrylamide (DMA) was grafted copolymerization to cellulose by a metal-catalyzed atom transfer radical polymerization (ATRP) process. First, cellulose was dissolved in DMAc/LiCl system, and it reacted with 2-bromoisobutyloyl bromide (BiBBr) to produce macroinitiator (cell-BiB). Then DMA was polymerized to the cellulose backbone in a homogeneous DMSO solution in presence of the cell-BiB. Characterization with FT-IR, NMR, and GPC measurements showed that there obtained a graft copolymer with cellulose backbone and PDMA side chains (cell-PDMA) in well-defined structure. The proteins adsorption studies showed that the cellulose membranes modified by the as-prepared cell-PDMA copolymer owns good protein adsorption resistancet.

THE EFFECTS OF MAGNETIC FIELD ON GRAFT COPOLYMERIZATION OF METHYL METHACRYLATE ONTO POLYVINYL ALCOHOL IN THE PRESENCE OF BENZOPHENONE DURING UV IRRADIATION

The effects of magnetic field on the graft ratio and stereoregularity of grafts of PVA-g-MMA in the presence ofbenzophenone during UV irradiation are discussed. By means of IR, it was found that the graft ratio was increased with the increment of magnetic field strength. Furthermore, application of relative weak magnetic field of 0.4 Tesla had been shown to substantially enhance the stereo-regularity of graft copolymer. The maximum stereo-regularity appeared when the graft ratio approached to 85% with the magnetic field of 1.2 Tesla (T). The resistance to moisture and heat resistance of the grafted copolymer in the presence of magnetic field were also improved.

GRAFTING OF ACRYLAMIDE ONTO SURFACE OF COPOLYMERS CONTAINING P-TOLYLCARBAMOYL PENDANT GROUP INITIATED WITH CERIC SALT

Two copolymers containing p-tolylcarbamoyl pendant group poly (MAMT-co-VAc) and poly(MAMT-co-MA) were synthesized f and the graft copolymerization of AAM onto these two func-tional copolymers films initiated with ceric salt were carried out in aqueous solution for variousperiods at 30℃. The formation of graft copolymer was verified by water absorption, ESCA andSEM photographs. Based on the results of the study of the initiation mechanism of model com-pounds and ceric salt systems, the reaction mechanism of the graft copolymerization initiated withceric salt was proposed.

Graft Copolymerization of Modified Oxidized Starch and Its ER Effect

To enhance the polarization of starch, the oxidized starch-BA-MAA-Gd copolymer was synthesized by radical graft copolymerization. The structure of the graft copolymer was determined by IR, scanning electron microscopy, state thermal analysis and X-ray diffraction. The electrorheological properties of the graft copolymer were also investigated. The results show that shear stress increases with the increase of the graft copolymer loadings and the electric field intensity.

RADICAL GRAFTING REACTIONS ONTO STARCH AND OTHER WATER-SOLUBLE COPOLYMERS IN ISOLATED GEL DROPLETS

A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-soluble graft copolymers having starch or dextran as the backbone chain with grafted side chains of polyacrylamide (—AM—), poly (acrylic acid ) (—AA—), poly (acrylamide-co-acrylic acid) (—AM—NH_4AA—) or poly ( acrylamide-co-2-acryiamido-2-methyl-l-propanesulphinic acid) (—AM—AMPS—) have been synthesized in gel droplets using aceric sulphate redox initiator, and their properties compared. The reaction conditions were optimized taking into account reaction kinetic data and the observed properties of the products produced under different reaction conditions. The effects of the ratios of [backbone]/[graft monomer], [ AM]/[ AA]/[AMPS] , [Ce^(4+)]/[ S_2O_8=] and pH value on the reaction rate , conversion, grafting degree, grafted chain length and the product molecular weight have been investigated.