Preirradiated Polypropylene Research Articles

A Novel Method for the Preparation of Poly (Acrylamide-co-Acrylonitrile) Upper Critical Solution Temperature Thermosensitive Hydrogel by the Partial Dehydration of Acrylamide Grafted Polypropylene Sheets.

In an attempt to find a potential application of cell culture harvesting, a novel method for the preparation of an upper critical solution temperature (UCST) thermosensitive hydrogel was studied. An electron accelerator was used as the electron beam (EB) radiation source, and acrylamide (AAm) was first grafted onto the pre-irradiated polypropylene (PP) sheet. Then, the grafting layer of poly (acrylamide-co-acrylonitrile) (P (AAm-co-AN)) was obtained by the partial dehydration of the acylamino group into the cyano group in the solution mixture of sulfoxide chloride (SOCl2) and dimethyl formamide (DMF). The effects of the absorbed dose, AAm concentration, reaction time, and temperature on the degree of grafting were studied, respectively. The effect of the SOCl2 concentration on the conversion degree of the cyano group from the acylamino group was studied, followed by the temperature of the UCST. The UCST properties of the grafted samples with P (AAm-co-AN) were studied by quartz crystal microbalance (QCM) and atomic force microscope (AFM), respectively. The cytotoxicities of the hydrogels against cells were verified by CCK-8 studies.

Effect of two different RAFT reactions on grafting MMA from pre-irradiated PP film

The graft polymerization of methyl methacrylate (MMA) from pre-irradiated polypropylene (PP) films mediated by two different addition-fragmentation chain transfer (RAFT) polymerization mechanisms—surface-initiated RAFT polymerization and interface-mediated RAFT polymerization was studied. In the first mechanism, electron beam irradiation technique was applied to produce the initial radical active sites and peroxides on PP films. 4-cyanopentanoic acid dithiobenzoate (CPADB) was added in the solution to mediate the graft polymerization. In the second mechanism, a new technique utilizing the decomposition and recombination of peroxides produced by electron beam and di(thiobenzoyl) disulfide (DBDS) to anchor CTA on PP films was applied. GPC, ATR-FTIR, XPS, SEM and water contact angle were used to characterize graft layer. Surface-initiated RAFT polymerization was found to be fast and facile with high degree of grafting (Dg) and large number-average molecular weight. But the samples after reaction were swelling and out of shape. Interface-mediated RAFT polymerization led to rather low Dg and low molecular weight. But the samples kept their pristine shapes and had better surface properties.

Application of full-factorial design in the synthesis of polypropylene-g-poly(glycidyl methacrylate) functional material for metal ion adsorption

The graft polymerization of glycidyl methacrylate onto electron beam pre-irradiated polypropylene (PP) nonwoven fabric was optimized using a 43 full factorial design analysis. The analysis yielded a polynomial equation that relates the linear, quadratic and interaction effects of the independent parameters to degree of grafting (Dg). The linear terms (i.e. absorbed dose, reaction time and monomer concentration), quadratic terms of time and concentration, and interaction term between absorbed dose and time were determined as significant independent parameters based from analysis of variance (ANOVA). The optimum grafting time and absorbed dose to achieve 150% Dg at 5% monomer concentration were 3.5h and 39.8kGy, respectively. The pristine PP, polypropylene-g-poly(glycidyl methacrylate) (PP-g-PGMA) and functionalized grafted materials were characterized using ATR-FTIR spectroscopy, thermogravimetric analysis and scanning electron microscopy. The affinities of the synthesized adsorbents towards the target metal ions at pH 4 were established to be in the following order: Cr(VI) >> Pb(II) ~ Cd(II) for the amine functionalized PP-g-PGMA; and Pb(II) > Cd(II) > Cr(VI) for the carboxylic acid functionalized PP-g-PGMA.

Preparation of a surface molecularly imprinted fiber for bisphenol a recognition

Surface molecularly imprinted polypropylene-based fibers for specifically recognizing bisphenol A (BPA-MIF) have been prepared through non-covalent surface molecular imprinting and self-assembly post-polymerization techniques. Acrylic acid (AA) was grafted onto pre-irradiated polypropylene (PP) fiber, and then polyethyleneimine (PEI) was assembled onto the AA grafted fiber surface to introduce amine groups for binding BPA templates from its aqueous solution. The imprinted binding sites were stabilized by cross-linking with glutaraldehyde in the presence of BPA templates. The Scatchard analysis indicated that two classes of amine binding sites were formed in the imprinted fiber BPA-MIF. The maximum adsorption capacity and association constant were 85.9 μmol/g and 56.1 μmol/L, respectively. The selectivity of BPA-MIF fibers for BPA against its analogues was obviously increased by adopting the surface molecular imprinting technique. In this work, a new path was given for the preparation of molecular imprinting materials in water system for other toxics with low solubility in aqueous solution.

A Novel Sorbent Prepared by Two-Step Grafting of Acrylic Acid and Methyl Methacrylate Monomer onto a Polypropylene Matrix

In order to improve the hydrophilicity of polypropylene (PP) nonwovens, grafting of acrylic acid (AA) and methyl methacrylate (MMA) onto PP matrix through ultraviolet (UV) radiation was achieved in an isopropanol/water acidic aqueous solution. AA and MMA were grafted onto a pre irradiated PP matrix by a two-step grafting reaction for preparation of a novel composite sorbent PP-g-(AA+MMA). The grafting conditions were optimized and the effects of grafting parameters were investigated. The present study suggested that the grafting degree played a dominant role in the sorption implication of PP-g-(AA+MMA). Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectra (XPS) were used to characterize the chemical changes of the PP matrix surface. The morphological behaviors have been estimated using specific surface area, porosity and scanning electron microscopy (SEM). Static contact angle (CA) measurements showed that the hydrophilicity of PP nonwoven was enhanced after graft polymerization. The thermal stability of PP-g-(AA+MMA) was evaluated by different thermo analysis (DTG) and differential scanning calorimetry (DSC). The improvement of reusability are shown as the increased of tensile modulus as a function of physical properties.

Synthesis and characterization of dextrin-grafted polypropylene

We carried out the graft copolymerization of the water-soluble natural polymer dextrin onto preirradiated polypropylene (PP) in an aqueous medium using benzoyl peroxide (BPO) as the radical initiator. PP was irradiated by γ rays from a Co60 source at a constant dose rate of 3.40 kGy/h to introduce hydroperoxide linkages, which served as the sites for grafting. The graft copolymerization was studied as a function of different reaction parameters, and the maximum percentage grafting (Pg; 55%) of dextrin onto PP was obtained at optimum conditions of [BPO] = 5.165 × 10−2 mol/L, temperature = 60°C in 120 min with 15 mL of water. Different grafting parameters, such as the percentage apparent grafting, percentage grafting, and percentage true grafting have been evaluated. The graft copolymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Swelling studies were carried out in pure, binary, ternary, and quaternary solvent systems composed of water, ethanol (EtOH), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF) at different ratios. The maximum swelling percentage PP-g-dextrin (both composite and true graft) was observed in pure DMSO and DMF followed by EtOH and water. Water-retention studies of PP and PP-g-dextrin (both composite and true graft) were investigated at different time periods, temperatures, and pH values. The maximum percentage water retention of PP-g-dextrin (composite, 124%) was observed at 8 h and 50°C in a neutral medium (pH 7). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Starch‐grafted polypropylene: Synthesis and characterization

AbstractGraft copolymerization of starch has been carried out onto preirradiated polypropylene (PP) in an aqueous medium using benzoyl peroxide (BPO) as the radical initiator. The maximum percentage of grafting (115%) of starch onto PP was obtained at optimum conditions of BPO concentration, 1.239 × 10−3 moles; temperature, 65°C; in 120 min. using 30 mL of water. Swelling studies were carried out in pure, binary, ternary and quaternary solvent systems comprising of water, ethanol (EtOH), dimethylsulphoxide (DMSO), and N,N‐dimethylformamide (DMF) in different ratios. Maximum swelling is observed in DMSO and DMF, followed by EtOH and least in water for true graft. Water retention studies of pristine PP and PP‐g‐Starch (both composite and true graft) were investigated at different time periods, temperature and pH. The composite contains grafted PP, unreacted starch and unreacted PP whereas true graft is the product from which both unreacted polymers have been removed. Maximum % water retention of PP‐g‐Starch (composite) (110%) was observed in 8 h at 50°C in neutral medium (pH = 7). The graft copolymers were characterized by FTIR, DTG, DTA, TGA, and SEM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation of PP-g-PEG by using partial pre-irradiated polypropylene as initiator and its properties

Polypropylene (PP) grafted with poly(ethylene glycol) acrylate (PEG acrylate) was prepared through melting reaction with partial pre-irradiated PP (rPP) as initiator and its properties were investigated. Along with the increase of the PEG acrylate content, the grafting degree of functionalized PP increased, while the degradation of PP was accordingly alleviated. The PEG grafts on the PP backbones may act as nucleating agent of the crystallization of PP. The crystallization temperature of PP-g-PEG gradually increased from 111.8° of PP to 118.9°, and the size of spherulites gradually decreased with increasing the amount of PEG acrylate grafts. Comparing to that of pure PP, the contact angles of functionalized PP film decreased from 112.2° to 88.2° and the surface energies increased from 15.85 to 30.34 mJ/m2 when the PEG grafting degree was 5.62%. And the number of blood platelet adhesion was also obviously decreased onto the functionalized PP film compared to that of pure PP.

Acrylation of pre-irradiated polypropylene and its application for removal of organic pollutants

Reactive extrusion of pre-irradiated polypropylene (PP) at different doses of gamma radiation was studied in the presence of different concentrations of acrylic acid monomer (AAc). Preliminary investigations study the feasibility or removal of organic pollutants. The optical properties and surface morphology of the grafted polypropylene were observed by FT–IR, UV/vis and scanning electron microscopy (SEM). The affinity of this membrane to the basic dye was found to be increased with increase in the dose of gamma irradiation and the ratio of acrylic acid monomer (AAc).

Radiation-induced grafting of N-isopropylacrylamide and acrylic acid onto polypropylene films by two step method

Binary graft copolymerization of pH sensitive acrylic acid (AAc) and thermosensitive N-isopropylacrylamide (NIPAAm) monomers onto pre-irradiated polypropylene films (PP) was carried out by two individual steps using a Co 60 gamma radiation source. The influence of preparation conditions, such as pre-irradiation dose and reaction time on grafting yield was studied. The swelling behavior and FTIR-ATR study for PP films grafted films were investigated.

Grafting copolymerization of dimethylaminoethyl methacrylate and acrylic acid onto preirradiated polypropylene film by two-step reactions

An intelligent hydrogel with both pH and temperature sensitivity was obtained by grafting acrylic acid and dimethylaminoethylmethacrylate onto preirradiated polypropylene (PP) film by two-step reactions. The effect of first and second reactions on the degree of grafting was studied. The grafted sample films were checked by Fourier transform infrared spectrophotometry in the attenuated total reflectance mode. The morphology of the PP samples was observed by scanning electron microscope in different conditions before and after grafting, respectively.

Grafting acrylic acid onto polypropylene by reactive extrusion with pre-irradiated PP as initiator

In this paper, the modification of polypropylene (PP) with acrylic acid (AA) by reactive extrusion using pre-irradiated PP (rPP) as initiator was investigated. It was found the relatively high graft degree (Gd) and slight degradation of modified PP was obtained when 20 wt% rPP was used. This result can be explained in terms of effective concentration of free radicals. Compared with the neat PP, the modified PP showed the high-notched impact strength and improved adhesion of PP to polar substrate. This technique is of potential industrial interest for PP modification.

Grafting copolymerization of N, N-dimethyacrylaminoethylmethacrylate (DMAEMA) onto preirradiated polypropylene films

Grafting copolymerization of dimethylaminoethylmethacrylate (DMAEMA) onto preirradiated polypropylene (PP) films was studied. PP samples were irradiated by electron beam in air. The effects of co-solvent system of ethanol/water (EtOH/H 2O), absorbed dose, monomer concentration, reaction time, and reaction temperature on the degree of grafting were determined. The grafted sample films were investigated by Fourier transform infrared (FTIR) spectroscopy in the attenuated total reflectance mode (ATR).

An interesting grafting reactivity of EB preirradiated polypropylene film

An interesting grafting reactivity of electron beam preirradiated polypropylene (PP) film was found by grafting of acrylic acid (AAc) and acrylamide (AAm) repeatedly or intermittently. The preirradiated PP film could be grafted several times intermittently and the free radicals or peroxides on the samples could be determined after several times grafting reaction. The effects of storage time, reaction time and repeated reaction times on the degree of grafting were investigated. The trapped radicals, peroxy-radicals and peroxides on the preirradiated and reacted PP films were determined by using electron spin resonance (ESR) and 1,1-diphenyl-2-picryl hydrazyl (DPPH), respectively. An interpenetrating polymer networks (IPN) with both temperature and pH sensitive properties was obtained by two times grafting of AAm and AAc onto preirradiated PP film.

Thermo-responsive interpenetrating polymer networks composed of AAc/AAm/NMA by radiation grafting

Interpenetrating polymer network (IPN) hydrogels were prepared by grafting of acrylamide (AAm), N-methylol acrylamide (NMA) and acrylic acid (AAc) onto preirradiated polypropylene (PP) membrane. To obtain PP-g-AAc/AAm/NMA IPN hydrogels, at first, AAc were grafted onto preirradiated PP and then AAm were grafted onto the PP-g-AAc membranes. Finally NMA were grafted onto PP-g-AAc/AAm membranes. In the different stages of grafting under different reaction conditions, trapped radicals in the membrane samples were probed by electron spin resonance (ESR). The temperature response behaviors of the IPN hydrogels were studied. Reversible behavior and controlled release of drug tests made reflecting the switching to “on” state at higher temperatures and to “off” state at lower temperatures were achieved. By increasing the grafted content of NMA, higher transition temperature of the hydrogel could be attained.

Preparation of interpenetrating polymer networks by two times grafting of monomers onto preirradiated polypropylene film

An interpenetrating polymer network (IPN) hydrogel was made by the grafting of acrylamide (AAm) and acrylic acid (AAc) onto preirradiated polypropylene (PP) film. AAm and AAc were grafted onto preirradiated PP film by two times grafting reaction. Thermo-sensitive behaviors were determined. The effect of first and second reactions on the degree of grafting was studied. Trapped radicals on samples with different storage conditions and reaction conditions were determined by electron spin resonance (ESR).

Study of modified polypropylene nonwoven cloth. I. graft copolymerization of 4-vinylpyridine onto polypropylene nonwoven cloth by preirradiation method

Polypropylene (PP) nonwoven cloth was grafted with 4-vinylpyridine (4-VP) by a preirradiation method. The effects of preirradiation conditions on the mechanical properties of preirradiated PP nonwoven cloth and the percentage of grafting (Pg) of 4-VP onto the preirradiated PP nonwoven cloth were systematically investigated. The results indicated that the mechanical properties of preirradiated PP nonwoven cloth decreased with increasing irradiation dose and that the Pg was greatly affected by the concentration of monomer, irradiation dose, grafting reaction temperature, and the addition of inhibitor and inorganic acid in the grafting reaction system. The grafted nonwoven cloth samples were characterized using IR spectroscopy and SEM. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1861–1868, 2000

Grafting polymerization of styrene onto preirradiated polypropylene fabric

Grafting copolymerization of styrene onto polypropylene fabric has been studied by using a gamma ray preirradiation technique. The polypropylene fabric samples were irradiated in an environment of air and nitrogen gas. The effects of the absorbed dose, styrene concentration in methanol, reaction temperature and reaction time on the degree of grafting were determined. The effects of a polyfunctional monomer and sulphuric acid on the grafting yield were also examined. The samples irradiated in nitrogen gas gave a much higher degree of grafting than those in air. The addition of sulfuric acid and polyfunctional monomer in the grafting solution enhanced greatly the grafting yield.

Grafting polymerization of acrylic acid onto preirradiated polypropylene fabric

Acrylic acid (AAc) was grafted onto polypropylene (PP) fabric by a preirradiation method using a Co-60 gamma ray. The effect of absorbed dose, AAc concentration, reaction temperature, reaction time, storage time, as well as the effect of ferrous ion and sulfuric acid on the degree of grafting were determined. It has been shown that the synergistic effect of sulfuric acid with the ferrous sulfate can not only increase the grafting yield, but also decrease the apparent activation energy for the grafting. It leads to the possibility of getting a particular grafting yield at a lower absorbed dose. In this experiment, It has also been shown that the grafting activity of preirradiated PP fabric in AAc aqueous solution could be well kept at room temperature for a long period.

The Distribution of Irradiation-Grafted Acrylic Acid in the Cross-Section of Polypropylene Fibers

Abstract The relative efficiency of grafting of acrylic acid (AA) in the surface layer and in the bulk of preirradiated polypropylene fibers was studied by combining the ATR and transmission IR techniques. At graft percentage from 41 to 98, the surface layer contains 2–3 times higher concentration of the grafted chemical groups than the fiber bulk. At 140% of AA, the surface of the host polymer becomes screened by the grafted material.