Grafting Of Acrylic Monomers Research Articles

Grafting of various acrylic monomers on to natural rubber: Effects of glutaraldehyde curing on mechanical and thermo-mechanical properties

Natural rubber (NR) grafted with different acrylic-monomers, namely butyl acrylate (BA), methyl methacrylate (MMA), n-butyl methacrylate (BMA) and cyclohexyl methacrylate (CHMA), were prepared via redox polymerization. This aims to enhance the mechanical and thermal properties of pristine NR by using a novel curing system of glutaraldehye (GA). Grafting of acrylic-monomers onto NR molecular chains was clarified using ATR-FTIR and 1H-NMR. It was found that the grafted-NR vulcanizates effectively improved the mechanical properties. Here, NR-g-PBMA showed enhancement in moduli, tensile strength and elongation at break of approximately 100, 280, and 40 %, respectively, when compared to the one without modification. It was also observed that, all the grafted-NR vulcanizates exhibited an improved crosslinking. This was elucidated through the engine oil swelling and the TSSR (i.e. Temperature Scanning Stress Relaxation) measurements. The latter test was also first proposed for characterizing the grafted-NR in terms of mechanical and thermo-mechanical interpretations. The thermogram clearly exhibited that the thermal properties of NR were significantly improved after graft copolymerization owing to the presence of functional groups on the molecular chain which enhanced the intermolecular attraction of the grafted-NR molecules. It can be summarized that two possibilities of interaction were observed: (I) the chemical interaction of GA-Rubber through the CC bonds and through the active ester groups of grafted-NR molecules, and (II) the physical polar-polar interaction through the presence of carbonyl groups of grafted-NR molecules. Thus, the present work is found to be beneficial to the future applications of NR which requires high specific modulus and thermal stability at low strain in case of flexible actuators and sensors. Furthermore, the newly curing technique can be easily used to fabricate article at low temperature with greater ease of processing.

Free-Radical Graft Polymerization onto Starch as a Tool to Tune Properties in Relation to Potential Applications. A Review

Grafting of acrylic monomers onto the renewable feedstock starch via free radical polymerizations has been investigated for many years. Many potential applications have been studied, such as superabsorbents, flocculants, thickening agents and so forth. It is expected that size and spacing of the grafts have a large influence on the performance of such polymers. Yet, information upon the structure-property relationships is only scarcely found in literature. Moreover, there is no clear overview of how reaction variables can be used to influence the grafted structure. In this review, an assessment has been made of the relation between the architecture of the grafts and potential applications. Then, from a selection of relevant literature data it is demonstrated that reaction variables such as the relative concentrations of initiator and monomer, have a large impact on the average size and spacing of the grafts. The emergence of controlled radical polymerizations, like Atom Transfer Radical Polymerization (ATRP) and Reversible Addition-Fragmentation chain Transfer (RAFT), is discussed, both the current status and future prospects. These methods are promising in the future of starch grafting, especially for systems where homopolymer formation may be a problem. Nevertheless, higher costs and other related issues make these advanced methods more suitable in high added-value products.

Chemical structure of fibers of ultra-high-molecular-weight polyethylene upon ion-beam treatment and post-irradiation grafting of acrylic monomers

Surface modification of fibers fabricated from ultra-high-molecular-weight polyethylene by pulsed ion-beam treatment was studied. The structure and morphology of the surface layer were examined by the IR MFTIR method and X-ray diffraction analysis. A post-irradiation grafting of a number of acrylic monomers to the fiber surface was performed.

Starch graft copolymers as superabsorbents obtained via reactive extrusion processing

Starch graft copolymers as superabsorbents obtained via reactive extrusion processing Starch graft copolymers have been obtained via grafting of acrylic monomers i.e. acrylamide (AAm) and acrylic acid (AA) during the reactive extrusion processes. 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH) was used as a radical initiator and N'N-methylenebisacrylamide (MBA), mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (trade name PETIA) and alkoxylated pentaerithritol acrylate (trade name Ebecryl 40) were applied as acrylic crosslinkers. The obtained materials were characterized by FTIR and their water sorption properties investigated using swelling (vol. %) and sorption (wt. %) tests. Sorption of water into these graft copolymer samples reached values of ca. 6-13 g of water per g of dry materials. It was also found that water sorption values were dependent on ratio of AAm and AA as well as on a type of the applied crosslinking agent.

Effectiveness of Graft Synthetic Polymers in Preventing Biodeterioration of Cellulose‐Based Materials

AbstractSynthetic polymers have been occasionally applied to the consolidation and protection of paper and cellulose‐based textiles especially when traditional conservation methods were not sufficient to improve the mechanical resistance of the degraded artefacts. In this paper, the potential of the innovative technique of grafting polymerisation with synthetic polymers was investigated to prevent biodeterioration. Cotton, linen and Whatman paper were consolidated by a) coating Paraloid B72®, b) coating ethyl acrylate/methyl methacrylate (EA/MMA) preformed copolymer, and c) grafting onto cellulose chains EA and MMA monomers in the ratio 75/25. All the samples were artificially biodeteriorated to obtain biodegraded model samples of both consolidated and non‐consolidated substrates, according to the ASTM G21‐96(2002) “Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi”. The consolidating effect was examined evaluating the mechanical behaviour of the grafted and coated samples, before and after the artificial biodeterioration. In addition, SEM observations were applied to monitor both the grafting level and the biodeterioration of the samples. With the grafting of acrylic monomers, the mechanical strength of cellulose‐based textiles and paper was greatly improved, as well as the resistance to biological agents. Therefore, with regards to biodeterioration, the graft copolymer EA/MMA (75/25 wt) was proved to be a suitable method to help prevent possible deterioration of paper and textiles.

Paper Conservation Part II: Consolidation by Grafting of Acrylic Monomers

In the present work a consolidation method for cellulose or paper is proposed, based on the insertion of an acrylic monomer on the cellulose macromolecule, exploiting its active sites deriving from oxidation. The acrylic monomers used are: methylmetacrylate, ethylacrylate and methylacrylate in the form of vapour and the copolymerisation reaction photo-induced by UV. Some parameters of the reaction have been studied and in particular the ratio of monomer conversion to the polymerisation time. Furthermore, this research focuses on the importance of the pre irradiation of the samples. The work has been carried out on pure cellulose, artificially oxidised with the purpose of applying the method to naturally aged paper documents.

The electron-beam (EB) irradiation and grafting of acrylic monomers onto EPDM copolymer

Radiation techniques (electron-beam, γ-ray, ete.) are usually used f or improving the compatibility between polymer and ingredients in composite materials. Electron-beam pre-irradiation has been used for the first time to enhance the flame retardance of EVA copolymer. Efforts are being made to decline the flammability for EPDM copolymer by EB technique and remarkable reduction has been attained through a series of treatments: pre-irradiation, grafting and saponification.

An approach to the flame retardancy of EVA copolymer by plasma grafting of acrylic monomers

An attempt has been made in this study to render polymers flame-retardant by a grafting method induced by plasma. Based on ethylene-vinyl acetate (EVA) copolymer with different vinyl acetate contents (%), it was found that the grafting yield was influenced by the plasma treatment conditions and the grafting reaction conditions when EVA copolymer was grafted with acrylic monomers. The flame retardance of the grafted sample was characterized. It was found that the time to ignition of the grafted sample was extended. The limiting oxygen index and char residue were increased. This indicates that the side-group of -COO-Na+ in the grafted layer not only can be charred in the thermal degradation stage, but also can promote charring of the substrate polymer.

On the electron-beam (EB) irradiation and grafting of acrylic monomers onto EVA copolymers

On the electron-beam (EB) irradiation and grafting of acrylic monomers onto EVA copolymers

Approaches to the Flame Retardancy of Polymers. I.: Electron-Beam Pre-Irradiation and Grafting of Acrylic Monomers onto EVA Copolymers

An attempt has been made in the paper to impart flame retar dancy to polymers with grafting induced by the electron-beam (EB) pre- irradiation technique. Based on EVA copolymers with different VA contents (%), the authors have tried to use EB pre-irradiation under atmosphere fol lowed by grafting with/without subsequent saponification expediting the char ring of polymers upon heating. Characterization of the flammability of the irra diated EVA copolymers grafted with acrylic monomers (MAA, AA, and AAm) indicates that this approach turns out to be promising and worth pursuing in research and/or in applications.

Porous bead aliphatic‐aromatic methacrylate copolymers V. Grafting of acrylic monomers onto MMA‐DMN copolymers

AbstractPorous methyl methacrylate‐di(methacryloyloxymethyl)‐naphthalene (DMN) copolymers were subjected to superficial grafting processes with engagement of double bonds present in the polymer structure. Grafting monomers were acrylic and methacrylic acids, acrylonitrile, acrylamide, and glycidyl methacrylate. Grafted copolymers were investigated by elemental analysis, infra‐red measurements, adsorptiondesorption isotherms of nitrogen and scanning electron microscopy. Irrespective of low grafting efficiency, the changes due to grafting with respect to the parent copolymers were easy to observe.

Grafting of acrylate monomers onto chlorinated rubber

AbstractGrafting of chlorinated rubber with ethylacrylate and butyl methacrylate in xylene solution has been studied using benzoyl peroxide as the initiator. It is observed that the grafting reaction follows conventional kinetic behavior under the present experimental conditions. The energies of activation obtained for both monomers were 10.8 and 10.95 K.cals, respectively. The grafting efficiency and percent grafting were calculated. Additional proof for grafting onto chlorinated rubber was also obtained by characterization of the graft copolymer by gel permeation chromatography.

Redox-Initiated Grafting of Acrylic Monomers onto Poly(vinyl Alcohol)

Abstract Loss of capacity of magnetic micro ion-exchange resins has been suggested to be caused by cleavage of unstable linkages formed during the graft polymerization reaction. The nature of the grafting process was investigated by using a series of model compounds having the same structural features as the glutaraldehyde-crosslinked poly(vinyl alcohol) core matrix. These compounds were then subjected to hydrogen peroxide oxidation, followed by the addition of monomer in the presence of iron(II). The identity and extent of peroxidation of the intermediate compounds was determined. In each of the peroxidation reactions the tertiary acetal hydrogen was oxidized to a hydroperoxy derivative. Some of these derivatives were able to dimerize to form peroxy compounds. The reactions occurred rapidly at room temperature when an acetal compound was shaken with hydrogen peroxide. Good yields could be obtained by precipitation of the sodium salts of the hydroperoxides. The hydroperoxy derivatives were shown to initia...

Grafting of acrylate monomers in cotton fabrics

AbstractThe graft copolymerization of acrylate monomers, methyl, ethyl, n‐propyl, and n‐ or isobutyl, in cotton fabrics was carried out in the aqueous emulsion system by the ceric ion method. The rate of grafting decreases with increasing length of the ester group. The maximum improvement of dry crease recovery, thus raising its value, increases with increasing graft‐on shifts towards the higher extents of grafting, and with decreasing second‐order transition temperature of graft polymer. The improvement of wet crease recovery, equilibrated in the presence of a wetting agent, is always greater than that in the dry crease recovery even when the hydrophobic propyl or butyl acrylate‐grafted cotton levels off with increasing graft‐on. The improvement of crease recovery was explained by the stabilization of the opened fiber structures by grafting with acrylates, especially those having bulky ester groups, the entangled crosslinking between the graft polymers or the graft polymers and cellulose chains, and the consequently developed elastomeric or swelling, elastomeric behaviors due to the segmental movements in the amorphous regions of graft copolymer. Furthermore, from the measurements of water imbibition and repellency, moisture regains, tensile properties, stiffness, flex abrasion, and thermosetting properties, it has been concluded that the improvements of physical properties are remarkable in the propyl or butyl acrylate‐grafted cotton.