Graft Copolymerization Of Styrene Research Articles

Preparation of Chitin/Polystyrene Hybrid Materials by Efficient Graft Copolymerization Based on Mercaptochitin

Graft copolymerization of styrene onto mercaptochitin has been examined. Chitin was first tosylated to give tosylchitin, which was subsequently transformed into mercaptochitin. Athough the graft copolymerization was carried out in suspension, it proceeded efficiently to give chitin derivatives having polystyrene branches, a novel type of hybrid materials composed of a natural polysaccharide and a synthetic polymer. Under appropriate conditions, the grafting percentage reached 970%, indicating the high efficiency of the mercaptochitin as an initiator for the polymerization of styrene. The resulting graft copolymers exhibited glass transition phenomena at 115 °C and showed high swelling in organic solvents as a result of the introduction of polystyrene branches. Hydrolytic degradation of the chitin main chain allowed the isolation of the side chains, and the polystyrene isolated from the graft copolymer with a grafting percentage of 940% had Mn, Mw, and Mw/Mn values of 9.74 × 104, 2.55 × 105, and 2.62. Thes...

Graft Copolymers of Lignin with 1-Ethenylbenzene. 2. Properties

The graft copolymerization of lignin and 1-ethenylbenzene was coinitiated by lignin, calcium chloride, and hydrogen peroxide in dimethyl sulfoxide solution. Conversion of 1-ethenylbenzene and yield of polymerized product of 90% or more were obtained. The copolymerization reaction changes the hydrodynamic radius of the product. Grafting has changed the surface properties of the original lignin from hydrophilic to hydrophobic. The copolymerization product is a thermoplastic material. White rot Basidiomycete were able to biodegrade styrene (1-ethenylbenzene) graft copolymers of lignin containing different proportions of lignin and poly(1-phenylethylene). The polymer samples were incubated with white rot Pleurotus ostreatus, Phanerochaete chrysosporium, and Trametes versicolor and brown rot Gleophyllum trabeum. White rot fungi degraded the plastic samples at a rate which increased with increasing lignin content in the copolymer sample. Both poly(1-phenylethylene) and lignin components of the copolymer were readily degraded. Poly(1-phenylethylene) pellets were not degradable in these tests. Observation by scanning electron microscopy of incubated copolymers showed a deterioration of the plastic surface. Brown rot fungus did not affect any of these plastics. The FTIR of the graft copolymers shows a series of characteristic absorbance peaks from multisubstituted aromatic rings and a strong poly(1-phenylethylene) (polystyrene) absorbance peak from monosubstituted aromatic rings. Subtraction of copolymer spectra taken after 50 days of incubation with the four tested fungi from spectra taken before incubation shows the loss of functional groups from the copolymer. The graft copolymer with long poly(1-phenylethylene) side chains is a macromolecular surface active material because in each graft molecule, a long hydrocarbon side chain has been grown off of a natural (oxyphenyl)propyl backbone. Surface activity of the graft copolymers is indicated by their capacity to form stable emulsions between incompatible fluid phases and to adhesively bond to wood surfaces. Dynamic contact angle measurement using the Wilhelmy plate technique shows that the graft copolymers change the contact angle of water on wood from 50 to 110°. The copolymerization product and its fractions have a coupling effect in the connection of wood to poly(1-phenylethylene). Lap shear strengths increase 56%, from 1826 to 2840 kPa, when the wood is coated with a graft copolymer containing 51.7% lignin.

Synthesis and identification of graft copolymers of wood pulp and styrene

Based on the graft copolymerization reactions of lignin and vinyl monomers, a series of graft copolymers of wood pulp and styrene (1-phenylethene) has been synthesized. The wood pulps used in this research are unbleached products produced by chemical, thermal, and mechanical pulping. All of them contain a high content of lignin (25–29 wt%). The grafting reaction is a free radical polymerization coinitiated by calcium chloride, hydrogen peroxide, and wood pulp in dimethylsulfoxide at 30°C. The effect of reaction temperature, reaction time, and the amount of the reactants on the conversion of monomer, yield of product, weight increase of pulp, and grafting efficiency of monomer has been studied. The grafted wood pulp was separated from homopolystyrene formed during the reaction by extraction of the reaction product with benzene in a Soxhlet apparatus for at least 48 h. The results show that after the reaction, the weight of all wood pulps was significantly increased and the weight increase of very high yield sodium bisulfite pulp (VHYS) was 333%. This proves that a part of the polymerized styrene was chemically bound to the wood pulp. The Fourier transform infrared (FTIR) spectra of the extracted products show absorbance peaks characteristic of both wood and polystyrene and, thus, provide strong proof of grafting. Grafting has completely changed the surface properties of the starting wood pulp from hydrophilic to hydrophobic, and under ordinary thermal compression conditions, thermoplastic composite objects of good uniformity can be made directly from reaction products which contain up to 52 wt% wood pulp.

Microdeformation in thin films of 3FDA/PMDA polyimide and polyimide nanofoams

AbstractTransmission electron microscopy has been used to investigate the microdeformation behavior of thermally imidized thermoplastic pyromellitic dianhydride/1,1‐bis(4‐amino‐phenyl)‐1‐phenyl‐2,2,2 trifluoroethylene (3FDA/PMDA) polyimide films with a Tg of ∼ 440°C, prepared by solution casting of a polyamic ester precursor. Failure of the films at room temperature was by unstable cracking at about 5% strain, accompanied by homogeneous shear deformation at the crack tips. As the temperature was raised to above 100°C, zones of mixed shear and crazing were observed, and a stick‐slip mode of cracking. Above about 300°C shear was once again the dominant deformation mechanism and the films became fully ductile. In films containing porosity on a scale of a few nanometers, prepared by thermal degradation/imidization of a 3FDA/PMDA/poly α‐methyl styrene graft copolymer, film failure at room temperature was also by unstable cracking, but a zone of multiple craze‐like features was observed at crack tips, rather than a single shear deformation zone. The increase in extent of this zone of craze‐like features as the temperature was raised was again associated with an increase in crack stability. ©1995 John Wiley & Sons, Inc.

Plasma induced grafting of styrene onto nascent polyethylene powder

In this paper, the graft copolymers of styrene to nascent linear polyethylene reactor powders were prepared through plasma graft polymerization. The grafting reaction was initiated by the alkyl radicals formed on the surface of nascent polyethylene with plasma treatment as indicated by electron spin resonance spectra. In graft copolymerization by alkyl radicals, the grafting yield increased with either the plasma power or the plasma treatment time. Compared with ordinary polyethylene powders, nascent polyethylene reactor powders were found to be more easily plasma-grafted. This has been attributed to the greater sensitivity to irradiation in producing reactive centres under the same conditions. High density polyethylene showed almost the same grafting yield as linear low density polyethylene at 50 °C. The surface morphology of nascent polyethylene observed by scanning electron microscope before and after the grafting showed that the silk-like fibrils were not destroyed by plasma treatment.

A process for coupling wood to thermoplastic using graft copolymers

AbstractA chemical modification method has been developed to convert lignin into lignin–styrene graft copolymers. The graft products are macromolecular surface active agents because, within each molecule, a hydrocarbon sidechain has been grown off of a natural oxyphenylpropyl backbone. Surface activity of the graft copolymers was indicated by their capacity to form stable emulsions between incompatible fluid phases and to adhesively bond to wood surfaces. Dynamic contact angle measurement using the Wilhelmy plate technique showed that the graft copolymers changed the contact angle of water on wood from 50° to 110°. Coating birch wood (Betula papyrifera) with lignin–styrene graft copolymerization product increases the water contact angle and the binding strength of polystyrene on the wood. Lap shear strengths increased 56%, from 1826 to 2840 kPa, when the wood was coated with a graft copolymer containing 51.7% lignin. Binding was tested by coating the birch with a solution of graft copolymer, drying the wood, injection molding polystyrene onto the surface of the wood, and pulling the polystyrene off the wood surface in a lap shear brace. These properties of the copolymers were used to design a process for forming wood‐thermoplastic composites. © 1995 John Wiley & Sons, Inc.

Synthesis of PBA/PMSAN core-shell graft copolymer and its application as a processing aid for PVC

The core—shell graft copolymer of α-methyl styrene with acrylonitrile on poly(butyl acrylate) was synthesized. The graft polymerization was investigated as a function of reaction temperature, initiator concentration used in the secondary polymerization, monomer to polymer ratio and emulsifier concentration. The compatibility of this core—shell graft copolymer with poly(vinyl chloride) (PVC) was determined by the solubility parameter method and scanning electron microscopy. The mechanical and rheological behaviour of the blend show that this core—shell graft copolymer can be used as a processing aid for PVC.

Copolymerization of poly(propylene oxide) methacrylate macromonomer with styrene

Graft copolymers of styrene and poly(propylene oxide) were prepared by reaction between styrene and a poly(propylene oxide) methacrylate macromonomer. The graft copolymers were characterized by i.r., GPC and 1H-NMR and mechanical properties were examined. The effect of zinc chloride on the copolymerization was evaluated. The results showed a decrease in the incorporation of macromonomer in the graft copolymer when zinc chloride was added to the system. This effect has been attributed to interaction among chains of poly(propylene oxide) and the zinc chloride.

Grafting mechanism in SBR–St–MMA core–shell emulsion copolymerization

AbstractThe graft copolymerization of styrene and methyl methacrylate on SBR latex particles in the core–shell emulsion process was conducted in a 600 mL glass stirred vessel with the BPOFe2+ redox initiator. The effects of the principal factors such as the polymerization temperature, monomer‐to‐polymer ratio, the frequency of monomer addition and conversion on the grafting degree, and the grafting efficiency were studied. The surface‐controlled process model was proposed to describe the grafting mechanism. © 1994 John Wiley & Sons, Inc.

Photoinduced Graft Copolymerization of Styrene onto Secondary Cellulose Acetate Containing Vanadium(V) Chelate

Abstract Photoactive polymer has been prepared by the reaction of VOQ2OH (Q: 8-quinolyloxo ligand) with secondary cellulose acetate in dry benzene solution. The photoactive polymer produced, red-violet in color, was characterized by IR and UV-visible spectroscopy. Irradiation of this type of polymer in styrene monomer, both in bulk and in benzene solutions, produces a graft and cross-linked copolymer. This indicates that a radical is produced on the backbone of the secondary cellulose acetate molecule by the so-called intraphotoredox reaction. UV-visible spectral changes during irradiation in styrene solution suggest that the photoreaction is relatively uncomplicated with production of vanadium(IV) species. The grafted polymer was characterized by IR spectroscopy, and the percent grafting and grafting efficiency were determined and monitored as a function of the photoactive cellulose acetate concentration.

Initiator Dependence of Cellolose Graft Copolymerization Conducted by Chain Transter Mechanism.

In the graft copolymerization of styrene onto cellulose using benzoyl peroxide (BPO) as initiator graft copolymer was not formed and at the same time the phenomenon suggesting the consumption of BPO with cellulose was observed. Model reactions revealed that the degradation of BPO was accelerated with cellulose and that cellulose was readily oxidized with BPO. These results may imply that BPO/cellulose redox system lacks the ability to intiate graft copolymerization. On the other hand, α, α'-azobisisobutyronitrile was confirmed to bring about the graft copolymerization induced by the transfer reaction of propagating radicals. In this case, the initiator was not consumed with cellulose.

Improving graft level during photoinduced graft‐copolymerization of styrene onto cotton cellulose

AbstractStyrene was graft‐copolymerized onto cotton cellulose using photoinitiators uranyl nitrate (UN), ceric ammonium nitrate (CAN), and benzoin ethyl ether (BEE) under ultraviolet radiation. UN gave somewhat higher graft add‐on. Preswelling of the substrate or using divinyl benzene in the grafting bath gave an increased level of graft, the later technique being more efficient. The moisture regain and tenacity decreased, whereas thermal stability increased in proportion to the graft add‐on. © 1993 John Wiley & Sons, Inc.

Fungal biodegradation of lignopolystyrene graft copolymers.

White rot basidiomycetes were able to biodegrade styrene (1-phenylethene) graft copolymers of lignin containing different proportions of lignin and polystyrene [poly(1-phenylethylene)]. The biodegradation tests were run on lignin-styrene copolymerization products which contained 10.3, 32.2, and 50.4% (wt/wt) lignin. The polymer samples were incubated with the white rot fungi Pleurotus ostreatus, Phanerochaete chrysosporium, and Trametes versicolor and the brown rot fungus Gloeophyllum trabeum. White rot fungi degraded the plastic samples at a rate which increased with increasing lignin content in the copolymer sample. Both polystyrene and lignin components of the copolymer were readily degraded. Polystyrene pellets were not degradable in these tests. Degradation was verified for both incubated and control samples by weight loss, quantitative UV spectrophotometric analysis of both lignin and styrene residues, scanning electron microscopy of the plastic surface, and the presence of enzymes active in degradation during incubation. Brown rot fungus did not affect any of the plastics. White rot fungi produced and secreted oxidative enzymes associated with lignin degradation in liquid media during incubation with lignin-polystyrene copolymer.

Ultraviolet‐radiation‐induced graft copolymerization of styrene and acrylonitrile onto cotton cellulose

AbstractPhotoinitiated graft copolymerization of the vinyl monomers, styrene and acrylonitrile, onto cotton cellulose was studied using uranyl nitrate and ceric ammonium nitrate as photoinitiators. Uranyl nitrate photoinitiation showed a higher level of grafting for styrene, whereas in the case of acrylonitrile ceric ammonium nitrate was found to be the better photoinitiator. Optimized conditions of grafting, when employed to cotton swollen with sodium hydroxide and zinc chloride, enhanced the graft levels for both monomers. Grafted samples were subjected to thermal analysis, as well as estimation of moisture regain and tenacity. Thermal stability increased, whereas, the moisture regain and tenacity decreased, with the increase in graft add‐on in the case of both monomers. Acrylonitrile‐grafted cotton showed dyeability with cationic dye that improved with the level of graft add‐on. Possible explanations have been given.

Graft copolymerization of styrene and acrylonitrile on to polybutadiene in the presence of n-butyl acrylate

The preparation of graft copolymers of styrene, acrylonitrile and n-butyl acrylate on to a polybutadiene rubber by emulsion polymerization and up to high degrees of conversion are described and investigated theoretically. The resulting graft copolymers have a higher styrene content and a lower acrylonitrile content than predicted by theory, whereas the n-butyl acrylate has the expected content. Impact and notched impact resistances, bending and tensile strengths, ball-puncture resistance, Vicat softening temperature and glass transition temperatures of the graft copolymers have been measured and are discussed.

Bifunctional monomers in photoinduced vinyl grafting on cotton cellulose: use of divinyl benzene in grafting of styrene

The effect of a bifunctional monomer, divinyl benzene (DVB) on the graft copolymerization of styrene onto cotton cellulose was studied using uranyl nitrate (UN) and benzoin ethyl ether (BEE) as photoinitiators. UN gave higher graft add-on as compared to BEE. Incorporation of DVB in the grafting bath containing styrene led to a great enhancement of graft add-on which was higher than that obtained by using cotton preswollen with sodium hydroxide as substrate. With increase in the graft add-on, the moisture regain and tenacity decreased, whereas thermal stability of cotton improved.

Graft 1-phenylethylene copolymers of lignin. 1. Synthesis and proof of copolymerization

A method of grafting lignin was developed which allows styrene graft copolymers of lignine to be quantitatively made. The reaction was carried out in solution using a redox reaction involving hydrogen peroxide and chloride ions. Grafting changes the solubility and surface properties of lignin, converting it to a thermoplastic.

Preparation of block and graft copolymers by peroxycarbamates

AbstractBlock copolymers of cyclohexanone‐formaldehyde resin (CF‐resin) and polystyrene and graft copolymers of styrene on ethyl cellulose, respectively, were prepared via peroxycarbamates. NCO/OH ratio was the important parameter during preparation of polymeric peroxycarbamates from prepolymeric isocyanate‐terminated peroxycarbamates and CF‐resin. Cross‐linked copolymers were produced if NCO/OH ratio was above 2:9. Ethyl cellulose with low hydroxy value was used as hydroxy compound for the preparation of peroxycarbamate. About one of every two anhydroglucose units of ethyl cellulose was grafted with polystyrene.

Graft copolymerization of styrene onto ethylene‐vinyl p‐nitrobenzoate copolymer by chain transfer reaction

AbstractThe effect of steric hindrance on the attack of growing polymer radicals to the reaction sites on a trunk polymer was examined in the graft copolymerization of styrene onto a trunk polymer with pendant aromatic nitro groups by chain transfer reaction of growing polymer radicals to the pendant nitro groups. The nitro groups on ethylene‐vinyl p‐nitro benzoate copolymer (EVNB) are more effectively utilized in the graft copolymerization than those on the vinyl p‐nitro benzoate homopolymer (PVNB) previously used as a trunk polymer, because the nitro groups are distributed less frequently on the trunk polymer in the former than in the latter. This was also confirmed by the higher chain transfer constant of growing polystyrene radicals to EVNB compared to that of PVNB.

Fine structure of styrene grafted cellulose.

Graft copolymerization of styrene onto γ-ray irradiated cellulose was carried out with various trunk polymers; untreated cotton cellulose, mercerized cellulose, and carbamoylethylated and carboxyethylated celluloses. Then the fine structures of styrene grafted celluloses were studied by measuring moisture regain, water imbibition and degree of crystallinity under dry and wet conditions. Although hydrophilicity of untreated cellulose, carbamoylethylated and carboxyethylated cellulose in 3% sodium hydroxide solution and mercerized cellulose was not lost by grafting reaction, highly hydrophilic nature was lost by styrene grafting onto carbamoylethylated and carboxyethylated cellulose in 20% sodium hydroxide. Consequently it was confirmed that polystyrene grafts were introduced to amorphous regions in the first stage of grafting reaction, then to semicrystalline regions and finally to crystalline regions with disarranging the crystal structure. Such phenomena are the same in all samples, but the extent of grafting beyond which disarrangement of crystalline regions occurs depends on the samples. In other words, the amounts of amorphous and semicrystalline regions in the samples determine the behavior of grafting.