Thermal properties of nylon 6 fibres grafted with acrylic monomers

Thermal Properties of methyl methacrylate (MMA), ethyl methacrylate (EMA) and n-butyl methacrylate (n-BMA) grafted onto nylon 6 fibre with various graft levels were investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and the results compared with that of parent nylon 6 fibre. It was found that the initial decomposition temperatures (IDT) of the grafted samples were lower than that of the parent nylon 6 fibre. On the other hand with all the three monomers, there was an increase in overall thermal stability followed by subsequent decrease with increase in the graft level. Among the grafted samples both the IDT and IPDT (initial procedural decomposition temperature) followed the order MMA-g nylon > EMA-g nylon < n-BMA-g nylon Differential thermal analysis shows a depression in glass transition temperature (T_g) as well as in melting temperature (T_m). In the case of the MMA and EMA grafted samples, the depression is small over a wide range of graft level. In the case of the n-BMA grafted samples, the depression is higher. A wide melting range was obtained in the grafted samples. Flammability studies also showed that with an increase in the graft level as well as an increase in the alkyl chain the ease of flammability increased as expressed by limiting oxygen index (LOI) values. The possible reasons for the phenomena occurred have been discussed.     

Characterization of nylon 6 fibers grafted by acrylic monomers

Samples of nylon 6 fibers grafted with the acrylic monomers methyl methacrylate (MMA), ethyl methacrylate (EMA), and n-butyl methacrylate (n-BMA) with various graft levels were investigated by infrared, X-ray and scanning electron microscopic studies and the changes due to grafting with respect to the parent nylon 6 fibers were studied. The IR spectra of grafted nylon 6 samples show that there is a little change in the peak heights by grafting of nylon 6 with various monomers. The characteristic peaks of parent nylon are, more or less, maintained in the case of grafted samples. A peak at 1730 cm^?1 of the ester group was noted which confirms that the polymer has been grafted with the monomer. X-ray diffraction data on the grafted samples show some remarkable variations with the degree of grafting, depending upon the nature of the graft monomer. The percentage of crystallinity varies with the degree of grafting. In the initial stages of grafting it shows a decrease in the case of PMMA graft and an increase in the case of PEMA and Pn-BMA graft. At higher degrees of grafting (above 50% graft add-on) the percentage of crystallinity decreases in all the three cases. Orientation index has been found to increase in the initial stages of grafting in the case of EMA and n-BMA grafted nylon 6 and it decreases later on, whereas in the case of MMA graft it decreases continuously even at low graft level. The studies of surface characteristics for the parent and grafted samples show that spectacular changes on the surface of the various samples have taken place. With the increase in the graft level the diameter of the fiber increases and also the voids and cracks appear on the surface.     

Chemical grafting of 2‐ethyl methacrylate phosphoric acid onto nylon 6 fabric

Graft copolymerization of 2‐ethyl methacrylate phosphoric acid (EMPA) onto nylon 6 fabric is carried out using the K₂S₂O₈/CuSO₄ system as reaction initiators. The most important factors affecting the graft yield are monomer concentration, reaction time and temperature. It was found that the graft yield increased with increasing EMPA concentration, grafting time, and temperature. The grafted nylon 6 fabric shows an increase in moisture regain to reach a maximum of 8.01% with increasing the graft yield to 35.6%. Also, the dyeability with the basic dye was significantly increased due to grafting with EMPA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1357–1361, 2000     

Chemical initiated-grafted nylon 4 membranes

To improve the performance of nylon 4 membranes, this study attempts to utilize chemical initiation which induces different hydrophilicities vinyl monomers grafted onto nylon 4 membranes. Sodium styrene sulfonate, chloromethyl styrene, styrene, and glycidyl methacrylate were used as grafting monomers. The factors that affect the degree of grafting considered were chemical initiators, pH values, kinds and concentrations of monomers, reaction time, and temperatures. The mechanical strength and the transport properties of these chemical-initiated grafted nylon 4 membranes were also investigated. Both the water flux and the salt rejection of sodium styrene sulfonated-grafted membrane were increased significantly, compared to our previous paper,¹ and the casein rejections of all of the four grafted nylon 4 membranes studied exceeded 90%. The quaternized nylon 4-g-poly(chloromethyl styrene) membranes were prepared and possessed high water uptake behavior and high transfer number (0.99) for electrodialysis. The sulfonating process was also applied to improve the hydrophilicity of nylon 4-g-poly(glycidyl methacrylate) membrane so that the water flux and the salt rejection were both increased.     

Some physicochemical properties of methyl methacrylate-grafted nylon 6. II.

Graft copolymerization of methyl methacrylate on nylon 6 was investigated using KMnO₄ as initiator at 60°C. The optimum conditions of the grafting process using various amounts of methyl methacrylate have been utilized. Physical and chemical properties of the grafted nylon such as moisture regain, density, and infrared spectra are studied. Furthermore, the dyeing behavior of the grafted nylon toward acid and direct dyes is also investigated. The rate of graft copolymerization (R_p) of methyl methacrylate with this system was evaluated and expressed by the following equation depending upon the potassium permanganate concentration used: The degree of polymerization of isolated poly(methyl methacrylate) from the grafted nylon was found to be a first-order dependence.     

Thermal behavior of graft copolymers of cotton cellulose and acrylate monomers

Cotton cellulose yarn was grafted with methyl acrylate, ethyl acrylate, n-butyl acrylate, and methyl methacrylate at various percentages of grafting. The effects of concentration of the initiator, concentration of the acid, and of temperature on grafting was studied and the mechanism discussed. The effect of reactivity of the monomer on the percentage graft-on is pointed out. Thermal behavior of natural and grafted cotton yarn was studied using dynamic thermogravimetry in air at a heating rate of 6°C/min up to a temperature of 500°C. The thermal stabilities of the samples grafted with various acrylate monomers to various percentages of grafting were computed from their primary thermograms by calculating the values of IDT, IPDT, and E^*. The results show that the thermal stability increases with increase in graft-on per cent, and the thermal stabilities of natural cotton and cotton grafted with different monomers are in the order ethyl > methyl > natural cellulose > methyl methacrylate > n-butyl acrylate.     

Free‐radical grafting of 4‐vinyl pyridine onto nylon 6 fiber

The chemistry of free‐radical graft copolymerization initiated with peroxomonosulfate (PMS)–thioglycolic acid (TGA) redox system has been investigated by using 4‐vinyl pyridine (4VP) as a model for nylon 6 fiber in aqueous solution under nitrogen atmosphere. Effects of concentration of 4VP, PMS, TGA, nylon 6, time, and temperature on R_h and graft parameters were studied. The FTIR spectrum of nylon 6‐g‐4VP was reported. Water retention capacity (WRC) of the grafted fiber was tested. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3108–3113, 2002     

Pervaporation of ethanol—water mixture by Co60 γ-ray irradiation-modified nylon 4 membrane

The ethanol—water separation by pervaporation with γ-ray irradiation-modified nylon 4 membrane was investigated. The membrane was prepared by homografting γ-ray irradiation of vinyl acetate (VAc) monomer onto nylon 4, poly(vinyl acetate) (PVAc)-homo-g-nylon 4 followed by hydrolysis treatment, poly(vinyl alcohol) (PVA)-homo-g-nylon 4. The homografting method shows significant improvement in the degree of grafting of (VAc) onto nylon 4 over the heterografting method. For example, the degree of grafting of the VAc with 30 vol % and total dose of 2 Mrad for the heterografted method and for the homografted method are 14.1 and 42.2%, respectively. The effects of irradiation with or without oxygen in solution, irradiation time, VAc content, degree of grafting, crystallinity, feed concentration, and operating temperature on performances of the PVA-homo-g-nylon 4 membrane were carried out. Comparison of the separation factor of sorption in membrane (α_sorp) and that of pervaporation (α_perv) was made. A separation factor of 7.3 and a 0.691 kg/m² h permeation rate can be obtained by the PVA-homo-g-nylon 4 membrane with a degree of grafting of 42.2% for 90 wt % ethanol feed concentration. Compared with the unmodified nylon 4 membrane, which has the separation factor of 4 and permeation rate of 0.350 kg/m² h, the PVA-homo-g-nylon 4 membrane shows improved a separation factor and permeation rate. © 1993 John Wiley & Sons, Inc.     

Photo-initiated vapor-phase grafting of acrylic monomers onto fibrous substrates in the presence of biacetyl

A novel vapor-phase process has been developed for grafting relatively volatile acrylic monomers onto various polymeric substrates, using photo-initiation by near ultraviolet irradiation in the presence of biacetyl vapors. With it, very even graft polymerizations on the substrates, with minimum amounts of homopolymerization, were found. Furthermore, there were essentially no changes in the tensile or aesthetic properties of the treated surfaces. The degree of photografting is dependent upon the chemical composition and porosity of the substrate, the volatility and reactivity of the monomers, prewetting of the substrate with a suitable wetting agent, and the conditions of irradiation used. The effects of various reaction parameters on the photo-induced grafting of methyl acrylate, methyl methacrylate, and acrylonitrile on wool keratin are studied in detail. Increasing biacetyl and monomer flow rates and flow times, irradiation times, and moisture content of the wool all caused progressive increases in the amount of polymer grafted to the wool, up to limiting values dependent on the reaction parameters involved and monomer used. In all instances, the amount of homopolymer found on the fiber was limited and remained essentially constant over the range of conditions studied. A series of acrylic monomers of different volatilities and reactivities including methyl acrylate, methyl methacrylate, butyl acrylate, acrylic acid, acrylamide, acrylonitrile, N,N-dimethylaminoethyl methacrylate, and 2,2,2-trifluoroethyl methacrylate was successfully grafted onto several hydrophilic and hydrophobic textile fibers (wool, cotton, rayon, nylon, acrylics, polyester, and polypropylene) and other polymeric surfaces such as filter paper, cellophane, and acetate film by this process. The wetting agents used included water, methyl and n-propyl alcohol, N,N-dimethylformamide, dimethylsulfoxide, benzene, and chlorinated hydrocarbon solvents.     

Physical properties of natural and modified cotton cellulose grafted with acrylate monomers

Natural, cyanoethylated, and formaldehyde-crosslinked cotton cellulose has been grafted with methyl, ethyl, and n-butyl acrylate and methyl methacrylate monomers. Various physical properties such as density, moisture regain, birefringence, and mechanical properties were studied. The results indicate that the density and moisture regain of the grafted fibers are less than those of natural cotton. The birefringence of grafted fibers is also less than that of natural cotton. The variation in birefringence with percent graft-on depends on the monomer. Parameters such as orientation factor, helix angle, and refractive power of fibers were calculated from the birefringence data and the results discussed. It was observed that due to grafting of both natural and crosslinked cotton, there is a decrease in tensile strength, increase in elongation at break, and decrease in the initial modulus. Attempts are made to understand these changes in the properties of cotton in terms of the changes occurring in the fine structure of the fiber.     

Influence of interfacial adhesion on toughening of polyethylene–octene elastomer/nylon 6 blends

Super-tough nylon 6 was prepared by using polyethylene–octene elastomer (POE) grafted with maleic anhydride as a toughener. The influences of maleating and a compatibilizer on interfacial adhesion and mechanical properties of nylon 6/POE blends were investigated in terms of mechanical testing, Molau tests, SEM observations, IR analyses, and rheological behavior. The results show that the unmodified POE has hardly any contribution to toughness of nylon 6, whereas the maleic anhydride-grafted POE (POE-g-MA) significantly improves the compatibility of POE with nylon 6 and sharply reduces its size in the nylon 6 matrix due to the in situ formation of a graft copolymer between POE-g-MA and nylon 6 during melt processing. With the POE-g-MA, a transition from brittle to ductile occurs. Besides, the use of a compatibilizer in nylon 6/POE-g-MA system shifts the brittle–ductile transition curve to a lower POE-g-MA content, which is attributed, in part, to the chain-extending effect of CE-96 on the nylon 6 matrix leading to further reduction of the sizes of POE-g-MA in the matrix, in part, to the coupling reaction of CE-96 between POE-g-MA and nylon 6. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1711–1718, 1998     

Physical,chemical, and dyeing properties of Bombyx mori silks grafted by 2‐hydroxyethyl methacrylate and methyl methacrylate

To obtain silk weight gain and to improve silk properties, Bombyx mori silks were grafted with either 2‐hydroxyethyl methacrylate (HEMA) or methyl methacrylate (MMA). The moisture regain of the HEMA‐grafted and MMA‐grafted silks depended on the hydrophilicity of the used monomers. The acid and alkaline resistances of the HEMA‐grafted and MMA‐grafted silks were clearly improved. Both commercial synthetic dyes, that is, acid and reactive dyes, and a natural dye extracted from turmeric, with potassium aluminum sulfate as a mordant, were used in this study. The results suggested that the dye uptake increased in the presence of poly(2‐hydroxyethyl methacrylate) or poly(methyl methacrylate) in the silk fibroin structures when acid and curcumin dyes were used. The washfastness level of the HEMA‐grafted silk dyed by acid and reactive dyes was similar to that of the degummed silk. However, the colorfastness to washing of the MMA‐grafted silk dyed by an acid dye was improved when the polymer add‐on concentration was 65%. In addition, the washfastness for both grafted silks was improved when they were dyed with natural curcumin dyestuff. The acid and alkaline perspiration fastness properties remained unchanged for the HEMA‐grafted and MMA‐grafted silks when acid, reactive, and curcumin dyes were applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Surface modification of nylon membrane by glycidyl methacrylate graft copolymerization for antibody immobilization

Surface of nylon membrane was modified by the graft copolymerization of glycidyl methacrylate (GMA) using persulfate and thiosulfate as redox initiator system. Effect of various reaction parameters such as initiator concentration, monomer concentration, polymerization time, and temperature on degree of grafting was also studied. Maximum grafting of 100% was achieved by using equimolar concentration (0.008M) of redox initiator and 0.5M of GMA monomer at 70°C in 60 min. Grafted nylon membranes with various graft levels of GMA were characterized by various techniques such as fourier transform infrared spectroscopy, thermo gravimetric analysis, and scanning electron microscopy. The GMA grafted nylon (NyM‐g‐GMA) membranes with different graft levels were evaluated as a support for immobilization of rabbit anti goat antibody (RAG IgG). Antibody (Ab) immobilized NyM‐g‐GMA membranes were evaluated using ELISA and Bradford protein estimation method. Nylon membrane with 60% graft level showed optimum immobilization of Ab at RAG IgG conc. of 0.625 μg/mL with low nonspecific binding. Maximum immobilization efficiency (I.E.%) of 56% was observed for membrane with 60% graft level at 50 μg/mL of RAG IgG in PBS (pH 7.4). Ab immobilized NyM‐g‐GMA discs were found to be stable up to 6 weeks at 4°C and 2 days at 37°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Photoinduced grafting of vinyl benzyl trimethyl ammonium chloride on polyester nonwoven fabric with surfactant coating and its anion‐exchange properties

Vinyl benzyl trimethyl ammonium chloride (VBTAC) could be efficiently and stably grafted onto polyester fiber coated with a surfactant polyester (PET) by a photoirradiation‐induced graft polymerization with benzophenone as the photoinitiator without any cografting monomer required. The degree of VBTAC grafting could be controlled simply by the irradiation time and concentration of VBTAC in the monomer solution. The anion‐exchange capacity (AEC) of the PET‐g‐VBTAC fabrics increased with increasing degree of grafting up to 80 ± 5% and then leveled off. The maximum AEC of PET‐g‐VBTAC was 2.2 mequiv/g; this was similar to that of a commercial anion‐exchange resin (2.16 ± 0.04 mequiv/g) and much higher than those of nylon‐g‐VBTAC–2‐hydroxyethyl methacrylate fabrics (≤1.0 mequiv/g) prepared with a conventional cografting system. The grafted fabric was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy studies, and the sorption selectivity for anions and regeneration efficiency were estimated. The results suggest that the grafting system, in which VBTAC alone was grafted onto PET fiber coated with surfactant, was more practical and effective for the preparation of the VBTAC‐containing anion exchanger, and the resulting PET‐g‐VBTAC fabrics could be used as an effective anion exchanger. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41674.     

Modification of polyvinyl chloride-vinyl acetate latex by seed emulsion polymerization of acrylic monomers

Fundamental studies were carried out to modify the thermal properties of polyvinyl chloride (PVC)-based latices. General features of composite PVC-vinyl acetate (VAc) copolymer latices synthesized from the seed emulsion polymerization of acrylic monomers are reported, in particular, the observation of particle morphology and the measurements of minimum film formation temperature (MFT) and DSC spectra. Acrylic monomers used as modifiers were methyl methacrylate (MMA), n-butyl methacrylate (BMA), methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (nBA), and MMA-nBA 75:25,50:50 and 25:75 wt%. Styrene whose polymer is incompatible with PVC-VAc was used as a counterpart of compatible PMMA. Compatibility between seed and modifier polymer and the mode of operation, either batch (flooded and pre-swollen) or semi-batch (starved and no swelling), induced morphology differences, and consequently variations of thermal properties.     

PMMA composites of single‐walled carbon nanotubes‐graft‐PMMA

To facilitate the dispersion of single‐walled carbon nanotubes (SWCNT) into poly(methyl methacrylate) (PMMA), SWCNT were functionalized with a RAFT chain transfer agent, and PMMA was grafted from the SWCNT by reversible addition–fragmentation transfer (RAFT) polymerization to give SWCNT‐g‐PMMA containing 6 wt % PMMA. SWCNT‐g‐PMMA in the form of small bundles was dispersed into PMMA matrices. The SWCNT‐g‐PMMA filler increased the glass transition temperature (T_g) of the composite when the matrix molecular weight M_n was less than the graft molecular weight, but not when the matrix M_n was equal to or greater than the graft M_n. The threshold of electrical conductivity of the composites as a function of weight percent SWCNT increased from 0.2% when matrix M_n was less than graft M_n to about 1% when matrix M_n was greater than graft M_n. Dynamic mechanical analyses of the composites having graft M_n less than or equal to matrix M_n showed broader rubbery plateaus with increased SWCNT content but no significant differences between samples with different grafted PMMAs. The results indicate that lower M_n matrix wets the SWCNT‐g‐PMMA whereas higher M_n matrix does not wet the SWCNT‐g‐PMMA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39884.     

Grafting. III. Copolymerization of methyl methacrylate and methacrylic acid

The method of graft copolymerization of methyl methacrylate on halogen-containing polymer has been utilized for grafting of methyl methacrylate–methacrylic acid monomer pair onto poly(vinyl chloride) and chlorinated rubber. Substantial grafting could be obtained by using the method reported earlier. However, the compositions of the grafted chains are found to deviate appreciably from the compositions calculated from r₁ and r₂ values reported in literature. The reactivity ratios for this pair of monomers have been therefore evaluated using azobisisobutyronitrile and n-butane thiol–dimethyl sulfoxide as initiators. The anomalies of the grafted chain compositions have been discussed and an explanation presented on preferential solvation.     

Peroxomonosulphate initiated graft copolymerization of o‐toluidine onto nylon 6 and wool fibers—A kinetic approach

Chemical polymerization of o‐toluidine (OT) in the presence of nylon 6 and wool fibers initiated by peroxomonosulphate (PMS) in an aqueous acidic medium was carried out under nitrogen atmosphere. During the polymerization process, graft copolymers were formed along with homopolymers of OT. A procedure is given for the separation of poly(o‐toluidine) (POT) grafted fiber from the homopolymer. Rate of homopolymerization (R_h), rate of grafting (R_g), percentage grafting, and percentage grafting efficiency were determined. Rate constants were evaluated from the experimental results. The chemical grafting of POT onto nylon 6 and wool fibers was confirmed through Fourier transform infrared (FTIR) spectroscopy and electrical conductivity measurements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2317–2326, 2002     

Grafting onto wool. XVI. Graft copolymerization of vinyl monomers by use of TBHP–FAS as redox initiator

Methyl acrylate (MA), methyl methacrylate (MMA), and n-butyl vinyl ether (n-BVE) have been graft-copolymerized onto Himachali wool in an aqueous medium by using tertiary butyl hydroperoxide ferrous ammonium sulfate (TBHP-FAS) redox system at 40°C, 50°C, 60°C, and 70°C for various reaction periods. Percentage of grafting and percent efficiency have been determined as functions of concentration of monomers, molar ratios of [TBHP]/[FAS], time and temperture. Molar ratios of [TBHP]/[FAS] were found to influence grafting of different monomers studied. Chemical evidence indicates that a covalent bond formation occurs between grafted polymeric chain and backbone polymer. The rate of grafting (R_p) and induction period (I_p) of different monomers towards graft copolymerization were determined as function of total initial monomer concentrations. R_p and I_p of n-BVE are independent of total initial monomer concentrations while R_p and I_p of both MA and MMA were found to depend on the total initial monomer concentrations. MA, MMA, and n-BVE were found to differ in reactivity towards grafting onto wool in the presence of (TBHP-FAS) redox system; the following reactivity order was observed: MMA > MA > n-BVE.     

Manganese(IV)-initiated graft polymerization of vinyl monomers on polyamide fibers

The feasibility of potassium permanganate to induce graft polymerization of vinyl monomers onto nylon 6 was investigated. The graft yield is greatly enhanced by increasing the monomer concentration, reaction time, and temperature. The addition of metallic ions as promoters to the grafting medium accelerates the graft polymerization. A mechanism for grafting was proposed. The activation energy of initiation E_i for methyl methacrylate was calculated and found to be 5 kcal/mole. The overall rate of graft polymerization R_p depends on the monomer concentration.