Modification of polyester fibers by grafting with poly(acrylic acid)

The grafting of acrylic acid on PET using benzoyl peroxide has been investigated. The influence of the main parameters of grafting, the effect of additives on the degree of grafting, and the amount of homopolymer formed during the process have been determined. Futhermore, the values of apparent activation energy have been calculated. Also, the influence of the degree of grafting on the moisture sorption and swelling of modified fibers have been determined. By an additional treatment of the grafted fibers with antibiotics it is possible to provide the fibers with antibacterial properties. Liberation of antibiotics from fibers into solutions has been examined and mathematically described. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:967–977, 1997     

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     

Effect of an allyl pretreatment of starch on the grafting efficiency and properties of allyl starch‐g‐poly(acrylic acid)

Starch was pretreated with allyl etherification to enhance the grafting efficiency of the copolymerization of granular starch with acrylic acid and to improve the properties of starch‐g‐poly(acrylic acid) used as a warp sizing agent. The graft copolymerization was carried out in an aqueous dispersion with ferrous ammonium sulfate and hydrogen peroxide as initiators. Through the introduction of allyl groups into starch before the copolymerization, the grafting efficiency could evidently be enhanced, and properties such as fiber adhesion and film behaviors of the copolymer were improved. The pretreatment was capable of enhancing the grafting efficiency by about 10–20% when the degree of substitution of allyl starch ranged from 0.011 to 0.037. The adhesion and film behaviors also depended on the modification extent of the starch pretreatment and on the grafting ratio of the copolymer. The adhesion reached a maximum at a degree of substitution of 0.025, and the film behaviors were best when the degree of substitution ranged from 0.011 to 0.025. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polyamide fibers (PA6) with antibacterial properties

The graft polymerization of acrylic acid (AA) on PA6 yarn was examined. Prior to the grafting process, the fibers were activated with a benzene solution of benzoyl peroxide. The effects of the main process parameters and auxiliary additives on the degree of grafting, quantity of the homopolymer formed during grafting, effectiveness of grafting, extent of conversion, and grafting ratio were determined. The resultant fibers, containing carboxylic groups in their structure, were additionatly modified with penicillin, neomycin, or gentamycin to obtain antibacterial fibers in relation to Gram-positive and Gram negative microorganisms (Staphylococcus aureus, Escherichia coli, and Pseudomonas aerruginosa). This was confirmed in vitro by measuring the stunted growth zones of the above-mentioned bacteria. The modified fibers show different activities in relation to the microorganisms, being dependent on the type and quantity of the added biocide. The kinetics of antibiotic release into water was examined and described by means of a mathematical equation. The release of antibiotics into solution proceeds for quite a long time after which there is still enough antibiotic on the fibers to provide them with antibacterial properties. © 1996 John Wiley & Sons, Inc.     

Novel fishnet fibers with anti‐adhesion of seaweeds obtained by UV‐irradiation technique

A novel Nylon‐6 fishnet fiber with the antiadhesion of seaweeds was prepared by UV radiation‐initiated grafting of acrylic acid (AA) onto Nylon‐6 fibers, and its structure was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The influences of grafting conditions, such as irradiation dose, temperature, concentration of monomer, inorganic acid, and inhibitor etc., on grafting rate were studied, and the antiadhesion of seaweeds was evaluated with Dunaliella. The results showed that the grafting amount of Nylon‐g‐AA was increased with the increase of irradiation time. With the increase of concentration of AA, temperature, reaction time, inorganic acid, and inhibitor, the grafting amount increased firstly and then decreased, respectively. Nylon‐6 fibers modified by Poly(acrylic acid) (PAA) had a strong effect on the adhesion of Dunaliella, and the antiadhesion was improved with the increase of the grafting amount. Results from the mechanical analysis revealed that the tensile strength of the UV‐irradiation fibers decreased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1252–1256, 2007     

Synthesis and long-term stability of acrylic acid and N,N-methylene-bis-acrylamide radiation grafted polypropylene fibers

New carboxyl ion-exchange fibers prepared by acrylic acid (AA) and N, N-methylene-bis-acrylamide (MBAA) monomer grafting to polypropylene (PP) fibers based on the method of γ-rays pre-irradiation in air followed by a Mohr's salt redox initiation of grafting reaction were studied. Grafting degree, homopolymer quantity, monomer conversion and grafting efficiency were determined. FTIR spectroscopy was used to establish the nature of the grafted fibers. The thermal stability of the materials was investigated based on DSC analysis in N₂/O₂ mixture. The long-term stability during 6–8 years of storage was examined by the measurement of the tensile strength and the elongation at break of the fibers, and the chemical oxygen demand in water extracts as well as in the oxygen uptake experiments. The influence of some factors on the useful life of the grafted fibers was studied: a MBAA cross-linking, exposure to day light, the Fe (III) residue presence, a grafting reaction temperature. It was found that small amounts of the adsorbed Fe (III) ions increase the deterioration rate of the grafted fibers, while small amounts of MBAA delay this negative process.     

Grafting of poly(acrylic acid) onto cellulosic microfibers and continuous cellulose filaments and characterization

Results from the grafting of poly(acrylic acid) (PAA) onto cellulosic microfibers and continuous cellulose filaments are presented. The grafting of PAA onto cellulosic fibers offers the possibility of developing enhanced ion exchange and fluid absorbency on the fibers. The grafting of PAA was carried out with a two‐step procedure. First, vinyl‐terminated ethoxy silane was deposited on the surface of the fiber. This was followed by a grafting polymerization reaction in aqueous media of acrylic acid with different concentrations of potassium persulfate (KPS), which acted as the initiator. The percentage of grafting increased with increasing KPS concentration and reached a maximum value at a concentration of about 0.4 wt % with respect to the weight of the fiber. The grafted copolymer was characterized by Fourier transform infrared spectroscopy. Strong evidence that the grafting reaction was successful was given by the presence of a band, with a maximum at 1732 cm^?1, that was characteristic of carbonyl group absorption and was not initially present in the cellulosic fibers. The water absorption of the cellulosic microfibers grafted with PAA was three times greater than the water absorption of the nongrafted microfibers. The mechanical properties of continuous cellulose filaments did not change drastically with PAA grafting. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 386–393, 2002     

Efforts to decrease crosslinking extent of polyethylene in a reactive extrusion grafting process

Grafting of acrylic acid and glycidyl methacrylate onto low density polyethylene (LDPE) was performed by using a corotating twin‐screw extruder. The effects of residence time and concentration of initiator and monomers on degree of grafting and gel content of grafting LDPE were studied systematically. Paraffin, styrene, p‐benzoquinone, triphenyl phosphite, tetrachloromethane, and oleic acid were added to try to decrease the extent of crosslinking of LDPE. 4‐hydroxyl‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy (4‐hydroxyl‐TEMPO) and dipentamethylenethiuram tetrasulfide were also tried to inhibit crosslinking reaction of LDPE during its extruding grafting process. It was found that p‐benzoquinone, triphenyl phosphite and tetrachloromethane were good inhibitors for crosslinking of LDPE. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 535–543, 2001     

Study on the Graft Reaction of Poly(propylene) Fiber with Acrylic Acid

Summary: In this paper, the graft of poly(propylene) fiber with acrylic acid is investigated. The effects of grafting temperature, monomer concentration, and grafting time on the grafting degree of acrylic acid onto poly(propylene) fiber are discussed. In contrast to the conventional method of determining the grafting degree gravimetrically, the acid‐base titration method used in this paper was more efficient, even at low grafting degree. High‐performance liquid chromatography (HPLC) was used to estimate the averaged length of the grafted poly(acrylic acid) chains on each grafted site of poly(propylene) backbone. And also a mechanism for the grafting polymerization is proposed.

Possible microstructures of two PP‐g‐AA samples at the same grafting degree.     

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     

Lipases improve the grafting of poly(ethylene terephthalate) fabrics with acrylic acid

In this study, poly(ethylene terephthalate) (PET) fabrics were modified with two types of commercial lipases, namely, Lipex and Lipolase, and grafted with acrylic acid (AA) to improve their absorption properties. The effects of the enzyme concentration, reaction temperature, time, and pH on the grafting of AA onto PET were investigated. The pretreatment of PET with lipases increased the amount of AA that was introduced to the PET fibers, whereas AA grafting onto the untreated PET fabrics led to lower graft yields. Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the AA‐grafted pretreated polyester fabrics. A new band appearing at 1546 cm^?1 in the Fourier transform infrared spectrum implied that AA was introduced onto the PET fabrics. The surfaces of the fabric fibers presented in scanning electron microscopy micrographs clearly indicated the formation of a layer of grafted poly (acrylic acid). The results show that the density of surface grafting was improved by the lipase pretreatment. The increase in grafting was higher for Lipex than for Lipolase. The highest graft yield was obtained with 1% Lipex and Lipolase for 30 min at pH values of 7 and 5, respectively. There were no significant changes in the tenacity or weight reduction of the fabrics. The moisture content of the samples increased linearly with increasing graft yield. This was higher for the pretreated fabrics grafted with Lipex. A higher color strength was obtained for grafted PET samples that were pretreated with Lipex when they were dyed in alkaline aqueous solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Radiation induced grafting of mixed monomers onto polyester and polypropylene fibers

Grafting of the mixture of acrylamide and acrylic acid onto polyester and polypropylene fibers and mixture of acrylic acid and methacrylic acid onto polypropylene by the radiation method are reported. It is observed that when pure acrylamide was used for grafting, the grafting extent was small, whereas when the mixture was used, the amount of acrylamide content in the copolymer was found to be more than the feed ratios. The results are explained on the basis of chain transfer mechanism. With methacrylic acid and acrylic acid mixtures, the rate of grafting decreased with the increase in the concentration of acrylic acid in the feed ratio, and this has been explained on the basis of the formation of either a 3-dimensional network structure or a highly branched structure involving backbone polymer molecules with acrylic acid, which prevents the diffusion of the monomer from the solution phase to the swollen phase.     

H2O2-induced graft polymerization of acrylic acid/styrene mixtures on poly(ethylene terephthalate) fibers

Graft polymerization of acrylic acid/styrene mixtures on poly(ethylene terephthalate) fibers using H₂O₂ as initiator was investigated under different conditions including acrylic acid/styrene ratio, monomer mixtures concentration, initiator concentration, polymerization temperature, pH of polymerization medium, addition of metallic salts, and use of solvent/water mixture instead of aqueous medium. It was found that the rate and extent of grafting for acrylic acid/styrene mixtures were much higher than those of single monomers, indicating a synergestic effect. Maximum percent grafting occurred when acrylic acid/styrene mixture at a ratio of 30:70 was used. Increasing the monomer mixture concentration from 2% to 40% was accompanied by a significant enhancement in percent grafting. The latter increased also significantly as the H₂O₂ concentration increased from 10 to 150 meq/L; a further increase in H₂O₂ concentration decreased grafting. No grafting took place at 65°C even after 4 h. Raising the polymerization temperature to 75°C expedited grafting; the magnitude of the latter increased by increasing the temperature up to 95°C. Addition of copper sulphate and ferrous ammonium sulphate to the polymerization system offset grafting, the opposite holds true for lithium chloride provided that its concentration does not exceed 15 mmole/L. Methyl alchol/water mixture (20:80) constituted the optimal medium for polymerization. Grafting of acrylic acid/styrene mixtures to poly(ethylene terephtalate) fibers resulted in considerable improvement in moisture regain of the latter.     

Preparation of poly(vinyl alcohol) grafted with acrylic acid/styrene binary monomers for selective permeation of heavy metals

A study was made to modify water‐soluble poly(vinyl alcohol) (PVA) by grafting acrylic acid and styrene (AAc/Sty) comonomers using gamma rays as an initiator. The factors that affect the preparation process and grafting yield were studied and more economical grafts under the most favorable reaction conditions were obtained. It was found that the high degree of grafting in such systems was obtained in the presence of an ethanol–water mixture in which water plays a significant role in enhancing the graft copolymerization. The critical amount of water to afford the maximum grafting yield was evaluated. The effect of the comonomer composition on the grafting yield was also investigated and it was observed that using a mixture of AAc/Sty monomers influences the extent of grafting of each monomer onto the PVA substrate and the phenomenon of synergism occurs during such a reaction. Also, the degree of grafting increases as the content of the solvent decreases in the reaction medium. However, the grafting yield increased as the total dose increased. The graft copolymer was characterized by IR and UV spectroscopic methods. The permeation of heavy metals such as Ni and Co through the grafted membranes was investigated and the efficiency of the separation process was also determined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 806–815, 1999     

Plasma‐induced graft polymerization of acrylic acid onto poly(ethylene terephthalate) films

The graft polymerization of acrylic acid was carried out onto poly(ethylene terephthalate) films that had been pretreated with argon plasma and subsequently exposed to oxygen to create peroxides. The influence of synthesis conditions, such as plasma treatment time, plasma power, monomer concentration, temperature, and the presence of Mohr's salt, on the degree of grafting was investigated. The observed initial increase in grafting with monomer concentration accelerated at about 20% monomer. The grafting reached a maximum at 40% monomer and subsequently decreased with further increases in monomer concentration. The reaction temperature had a pronounced effect on the degree of grafting. The initial rate of grafting increased with increasing temperature, but the degree of grafting showed a maximum at 50°C. The activation energy of the grafting obtained from an Arrhenius plot was 29.1 kJ/mol. The addition of Mohr's salt to the reaction medium not only led to a homopolymer‐free grafting reaction but also diminished the degree of grafting. The degree of grafting increased with increasing plasma power and plasma treatment time. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2993–3001, 2001     

机械活化甘蔗渣与丙烯[BF]酸(钠)的接枝共聚反应

采用搅拌球磨对甘蔗渣进行机械活化,以不同活化时间的甘蔗渣为原料,过硫酸铵和亚硫酸钠为引发剂,在水溶液中与部分中和的丙烯酸进行接枝共聚反应。以接枝率和接枝效率为评价指标,考察了活化时间、丙烯酸与甘蔗渣的用量比、反应时间和反应温度等因素对接枝反应的影响。并采用SEM、FT-IR对甘蔗渣和产物进行表征。结果表明：机械活化明显强化了甘蔗渣与丙烯酸的接枝共聚反应,接枝率和接枝效率随着活化时间的延长而增大,主要是由于机械活化破坏了甘蔗渣中木质素对纤维素的包裹作用,降低纤维素的结晶度,提高了其反应活性。以活化1.5 h的甘蔗渣为原料进行接枝共聚反应,在反应时间为3 h、丙烯酸（体积,ml）与甘蔗渣（质量,g）的用量比为6、反应温度为60℃的条件下,制得接枝率和接枝效率分别为165.29%和82.70%的接枝共聚产物。     

Grafting of poly (methyl acrylate) onto sulfite pulp fibers and its effect on water absorbance

To prepare super water absorbent hydrogels of wood cellulose fibers, poly (methyl acrylate) (PMA) was copolymerized onto softwood sulfite pulp fibers using free radical initiator followed by alkaline hydrolysis. Ceric ammonium nitrate (CAN) was used as the free radical initiator. Effects of various parameters such as fiber concentration, monomer/pulp (M/pulp) ratio, CAN concentration, and reaction time on the grafting yield and on other grafting parameters were investigated. The graft conversion was the same from low to medium fiber concentration. The amount of initiator required was found to be independent of fiber concentration to achieve maximum grafting yield. Different fiber fractions (classified based on their length) have no effect on the grafting yield. The evidence of graft copolymerization was determined by using ATR‐IR spectroscopy. The X‐ray diffraction (XRD) analysis shows that grafting takes place both in amorphous and crystalline regions of cellulose fibers and the decrease in crystallinity of the grafted fibers with an increase in grafting yield was confirmed. The surface morphology of the PMA‐g‐cellulose was characterized by scanning electron microscopy (SEM). The water retention value of the hydrolyzed grafted pulp was determined based on a centrifugation technique. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Grafting of methyl methacrylate (MMA) onto Antheraea assama silk fiber

Graft copolymerization of methyl methacrylate (MMA) onto nonmulberry silk fiber Antheraea assama was investigated in aqueous medium using the KMnO₄–oxalic acid redox system. Grafting (%) was determined as a function of the reaction time, temperature, and monomer and initiator concentrations. The rate of grafting increased progressively with increase of the reaction time up to 4 h and then decreased. The extent of grafting was maximum at 55°C. The extent was also dependent upon monomer and initiator concentrations up to 75.5 × 10^?2 and 6 × 10^?3 M, respectively. The grafted products were evaluated by infrared spectroscopy and their thermal decompositions were studied by TG and DTG techniques in static air at 20°C min^?1 and 30°C min^?1 in the range 30–800°C. The kinetic parameters for ungrafted and grafted fibers were evaluated using the Coats and Redfern method. The grafted products were found to be thermally more stable than were those of the ungrafted fibers. The surface characteristics of the ungrafted and grafted fibers were evaluated by scanning electron microscopy. The water‐retention values (WRVs) of the grafted fibers were in decreasing order with increase in the grafting (%). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2633–2641, 2001     

Supercritical carbon dioxide-assisted preparation of polypropylene grafted acrylic acid with high grafted content and small gel percent

This work was aimed at preparing polypropylene grafted acrylic acid (PP-g-AA) with high grafted content and small gel percent by using a supercritical carbon dioxide (scCO₂)-assisted solid-state free radical grafting process. The effects of various factors on both the grafted acrylic acid content and gel percent in PP-g-AA were investigated. Those factors included the reaction time, reaction temperature, CO₂ pressure, monomer and initiator concentrations. Results showed that self-polymerization of acrylic acid resulted in crosslinking of PP chains and production of gel in PP-g-AA. There exists an optimal reaction time to produce PP-g-AA with high grafted content and small gel percent at a certain temperature. Both the initial AA/PP mass ratio and CO₂ pressure constituted very sensitive process parameters that could control the gel percent and grafted content in PP-g-AA to a significant extent and with ease. The crystallization temperature, melting temperature and crystallinity increased with the increasing of the grafted content of PP-g-AA. Moreover, the PP-g-AA removal of gel has a higher thermal stability than the blank PP.     

壳聚糖-硅藻土-聚丙烯酸高吸水性树脂

以丙烯酸,硅藻土为原料,过硫酸铵为引发剂,N,N’-亚甲基双丙烯酰胺为交联剂,通过接枝壳聚糖制备了壳聚糖-硅藻土-聚丙烯酸高吸水性树脂,并对高吸水性树脂的结构进行了红外光谱的表征,系统研究了引发剂、交联剂、硅藻土的用量,丙烯酸与壳聚糖的质量比,丙烯酸的中和度,反应温度以及反应时间对高吸水性树脂吸水率的影响。实验结果表明,丙烯酸与壳聚糖的质量比为12∶1,硅藻土的含量为1%,引发剂和交联剂的用量分别为2.5%和0.16%,中和度为70%,反应温度为60℃,反应时间为5.5h时,合成的壳聚糖-硅藻土-聚丙烯酸高吸水性树脂吸水(盐)率最高,分别为145g/g和30g/g。