CONFORMATIONAL CHARACTERISTICS OF POLY(ACRYLIC ACID) AND POLY(METHACRYLIC ACID)

A full-relaxation optimization of molecule and the Dreiding force field are employed to obtain the geometry parameters and the conformational energy surfaces of meso or racemic dyad of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA). Three different carbonyl-bond orientations of side-groups resulted in the differences in depth of potential wells in their energetic contours for a meso or a racemic dyad. These discrepancies are interpreted as a result of various fine structures corresponding to grid search conformations as well as thereby different interactions. The analysis on the most stable conformations of PMAA confirmed that the ester groups are nearly perpendicular to the plane defined by the two adjacent skeletal bonds but may possibly change their relative orientations to meet the requirement of lower energy during the conformational state transition. For each polymer, two global energy maps of a meso and a racemic dyad were finally constructed from the superposition of energy data for the three kinds of side-group orientations by the Boltzmann factors. From an ensemble average, the proposed scheme with three rotational isomeric states (RIS) allowed us to access the experimentally unperturbed dimensions of PAA chain via the configurational statistical mechanics. Although the calculation was based on the short-range, local interactions, it was interested to note that the experimental characteristic ratios just fell within the range calculated for atactic chains.

Poly-Acrylic Acid Derivatives as Diesel Flow Improver for Paraffin-Based Daqing Diesel

Since the diesel products from paraffin-based Daqing crude oil showed low sensitivity to certain commercial diesel pour point depressant （PPDs） that resulted from the high content of paraffin, certain poly-acrylic acid derivatives （PADE） with-COOR, -COOH,-CONHR, and -COO-NH3^＋R groups by molecular design on the mechanics of diesel; PPDs were synthesized and evaluated as cold flow improver for Daqing 0^# diesel in this paper. The pure PADE was superior to the commercial PPDs and displayed a substantial ability of wax crystals dispersion. There was a synergistic effect among the PADE and T1804 and secondary amine. The synergism clearly improved the low temperature performance of Daqing diesel products and could reduce the cold filter plugging point of 0^# diesel by 6-7 ℃.

Redox active polymer metal chelates for use in flexible symmetrical supercapacitors:Cobalt-containing poly(acrylic acid)polymer electrolytes

The novel polymer metal chelate electrolytes(polychelates)were prepared by incorporation of cobalt sulfate(Co)into poly(acrylic acid)(PAA)host matrix.Quasi-solid state supercapacitor devices were fabricated using polychelates,PAA-Co X(X:3,5,7,and 10)where X represents the doping fraction(w/w)of Co in PAA.All polymer metal electrolytes were showed excellent bending-stretching properties,thermal stability and electrochemical durability with an optimum ionic conductivity of 3.15×10^(-4) S cm^(-1).Hierarchically porous activated carbon and nano-sized conductive carbon were used to form carbon composite symmetrical device electrodes.The electric double-layer capacitor(EDLC)and redox reactions of Co-incorporated polychelates at the interfaces of porous activated carbon provided an optimum specific capacitance of 341.33 F g^(-1) with a device of PAA-Co7,which is at least 15 times enhancement compared to the device of pristine PAA.The PAA-Co7 device also provided energy density of 21.25 Wh kg^(-1) at a power density of 117.69 W kg^(-1).A prolonged cyclic stability of the device exhibited superior capacitive performance after 10,000 charge-discharge cycles and the maintained 90%of its initial performance.In addition,the supercapacitor with a dimension of 1.5 cm×3 cm containing PAA-Co7 successfully operated the red-blue-green(RGB)LED light.

Selective oxidation of propane to acrylic acid over mixed metal oxide catalysts

The effects of metal atomic ratio, water content, oxygen content, and calcination temperature on the catalytic performances of MoVTeNbO mixed oxide catalyst system for the selective oxidation of propane to acrylic acid have been investigated and discussed. Among the catalysts studied, it was found that the MoVTeNbO catalyst calcined at a temperature of 600 ℃ showed the best performance in terms of propane conversion and selectivity for acrylic acid under an atmosphere of nitrogen. An effective MoVTeNbO oxide catalyst for propane selective oxidation to acrylic acid was obtained with a combination of a preferred metal atomic ratio （Mo1V0.31Te0.23Nb0.12）. The optimum reaction condition for the selective oxidation of propane was the molar ratio of C3H8 ：O2 ： H2O ： N2 = 4.4： 12.8 ： 15.3 ： 36.9. Under such conditions, the conversion of propane and the maximum yield of acrylic acid reached about 50% and 21%, respectively.

NATURAL PRODUCTIVITY OF ACRYLIC ACID AND DIMETHYL SULPHIDE DURING A SUMMER BLOOM OF PHAEOCYSTIS POUCHETII IN ANTARCTIC COASTAL WATER

Water samples were collected over P. ponchetii bloom period beginning in November 1988, in 15m water column, from 10km offshore of Davis Station, Vestfold Hill, Antarctica. The concentrations of acrylic acid and dimethyl sulphide (DMS), which are toxic compounds in the water samples, were determined by HPLC and GC. The result shows that the concentration of acrylic acid varies in 0. 001 - 0. 510μmol ?L-1 and the concentration of DMS in 0. 003-0. 588 μmol ?L-1 during P. pouchetii bloom. Both the increased since late December 1988 and reached the highest concentration in early January 1989, then they decreased rapidly and returned to lower level from middle January to February in agreement with variation in cell number of the unicell alga P. pouchetii. The correlation coefficients between acrylic acid and P. pouchetii and between DMS and P. pouchetii are all 0. 998. It is undoubted that P. pouchetii produced acrylic acid and DMS. The highest productivity of acrylic acid and DMS were 9. 76X 10-8 umol cell-1 and 13. 09 ×10-8 μmol ?cell-1, respectively, during P. pouchelii bloom. A cellular product, dimethylsulphonium propionate (DMSP), is decomposed into acrylic acid and DMS, and the formation of DMSP is probably from methionine which could be utilized by P. pouchelii.

Oxidation of propane to acrylic acid and acetic acid over alkaline earth-doped Mo-V-Sb-O_x catalysts

Alkaline earth metal （Mg,Ca,Sr and Ba）-doped Mo-V-Sb-O x catalysts,prepared by a dry-up method,have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions.The catalysts have been characterized by N2 adsorption-desorption,temperature-programmed desorption （TPD） of NH3,SEM and XRD.Influence of water vapor on the catalytic performance,particularly on the selectivities to acetic acid and acrylic acid,has also been studied.The selectivity to acrylic acid was improved significantly by the doping of alkaline earth metals to Mo-V-Sb-O x catalysts.The surface acidic sites of the catalyst decreased with the doping of the catalyst with alkaline earth metals,which ultimately was found to be beneficial for obtaining high selectivity to acrylic acid.The catalytic activity and product selectivities were found to be influenced by the reaction temperature,C3H8/O2 ratio and space velocity.A significant improvement in the selectivity to acrylic acid has also been observed by the addition of water vapor in the feed of propane and oxygen in the oxidation of propane.

A MORPHOLOGICAL STUDY OF POLY(DIVINYLBENZENE-co-ACRYLIC ACID) IN CROSSLINKING PRECIPITATION POLYMERIZATION

Divinylbenzene-80 （DVB-80） and polar monomer acrylic acid （AA） having hydrogen bonding at a total monomer loading of 5 vol% were precipitated-copolymerized in a variety of organic solvents with 2,2＇-azobis（isobutyronitrile） （AIBN） as initiator. The experiments were investigated from a two-dimensional matrix, i.e., the actual crosslinking degree of DVB varying from 0 to 80% and the solvent composition varying from 0 to 100% of toluene mixture with acetonitrile, when the mixture of acetonitrile and toluene was used as the reaction solvent. Under various reaction conditions, six distinct morphologies including soluble polymers, swellable microgels, coagulum, irregular microparticles, and nano-/micrometer microspheres were formed and the structures of these polymer architectures were described. A morphological map was utilized to discuss the effects of both crosslinking degree of DVB and composition of solvent on the transitions between morphology domains. The results demonstrated that the microspheres are formed by an internal contraction due to the marginal solvency of the continuous phase and the crosslinking of the polymer network through the covalent bonding from DVB as well as the interchain hydrogen-bonding between the carboxylic acid units.

PREPARATION OF POLY(ETHYLENEGLYCOL-co-ACRYLIC ACID) MICROSPHERES WITH DIVINYLBENZNE AS CROSSLINKER BY DISTILLATION-PRECIPITATION POLYMERIZATION

Monodisperse poly（poly（ethyleneglycol） methyl ether acrylate-co-acrylic acid） （poly（PEGMA-co-AA）） microspheres were prepared by distillation-precipitation polymerization with divinylbenzene （DVB） as crosslinker with 2,2＇- azobisisobutyronitrile （AIBN） as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.

Effect of preparation conditions on selective oxidation of propane to acrylic acid

The effects of chemical composition and preparation conditions,especially calcination atmosphere and water content on the catalytic performances of MoVTeNbO mixed oxide catalyst system for the selective oxidation of propane to acrylic acid were investigated.Among the catalysts studied,Mo_(1.0)V_(0.3)Te_(0.23)Nb_(0.12)O_(x) catalyst calcined in inert atmosphere at 600℃shows the best performance in terms of propane conversion and selectivity to acrylic acid.The results reveal that proper chemical composition, calcination atmosphere and water content affect greatly the catalysts in many ways including structure,chemical composition,which are related to their catalytic performances;and 51.0%propane conversion and 30.5%one-pass yield to acrylic acid can be achieved at the same time.

Time Related Influence of α-Mercapto-β-(2-Furyl) Acrylic Acid (MFA) in Cadmium Toxicity

The effect of a-mercapto-β-(2-furyl) acrylic acid (MFA, 200 mg/kg, oral) administered 30 min or 24 h post cadmium (1 mg/kg, i.p.) exposure on cadmium toxicity, was investigated in rats. The Cd induced hepatic metallothionein was reduced by MFA treatment parallel to the depletion of hepatic Cd. However, in renal tissue,MFA caused only redistribution of metal from the paniculate to the soluble fraction. Hepatic and renal Zn and renal Cu were significantly increased on Cd exposure. MFA therapy, however, lowered the hepatic Zn and increased the renal Cu levels. The action of MFA appears to be via metal chelation rather than by MT induction.

Graft Polymerization of Acrylic Acid on a Polytetrafluoroethylene Panel by an Inductively Coupled Plasma

Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE panel through grafting polymerization of acrylic acid （AA）, a transparent poly （acrylic acid） （PAA） membrane was achieved from acrylic acid solution. Grafting polymerization initiating from the active group5 was achieved on the PTFE panel surface after the nitrogen plasma treatment. Utilizing the acrylic acid as monomers, with COO- groups as cross link sites to form reticulation structure, a transparent poly （acrylic acid） membrane with arborescent macromolecular structure was formed on the PTFE panel surface. Analysis meth- ods, such as fourier transform infrared spectroscopy （FTIR）, microscopy and X-ray photoelectron spectroscopy （XPS）, were utilized to characterize the structures of the macromolecule membrane on the PTFE panel surface. A contact angle measurement was performed to characterize the modified PTFE panels. The surface hydrophilicities of modified PTFE panels were significantly enhanced after the plasma treatment. It was shown that the grafting rate is related to the treating time and the power of plasma.

Syntheses and Crystal Structures of Two Complexes with 3-(3-Pyridyl)acrylic Acid

The reaction of 3-（3-pyridyl）acrylic acid （H（3-PYA）） with Co（NO3）2.6H2O or MnCl2.4H2O yielded two new complexes： [Co（3-PYA）2（H2O）4.H2O] 1 and [Mn（3-PYA）2（H2O）4] 2. Complex 1 crystallizes in monoclinic, space group C2/c with a = 9.9473（12）, b = 13.7227（16）, c = 14.7376（18） A, β = 99.043（2）°, V = 1986.7（4） A^3, Z = 4, Dc= 1.549 g/cm^3,μ = 0.921 mm^-1, F（000） = 964, R = 0.0786 and wR = 0.1443. Six types of hydrogen bonds and π-π packing interactions connect the mononuclear units [Co（Ⅱ）（3-PYA）2（H2O）4·H2O] into a three-dimensional supramolecular architecture. Complex 2 crystallizes in monoclinic, space group P21/n with a = 11.3630（16）, b = 7.0346（10）, c = 12.1365（18） A, β = 112.545（3）°, V = 896.0（2） A^3, Z = 2, D, = 1.997 g/cm^3,μ = 0.785 mm^-1, F（000） = 438, R = 0.0787 and wR = 0.1550. The discrete entity Mn（Ⅱ）（3-PYD）2（H2O）4 is extended into a 3-D supramolecular architecture by four kinds of hydrogen bonds.

Reactivity Ratios of Diethyldiallylammonium Chloride with Acrylamide or Acrylic Acid

The compositions of copolymers of diethyldiallylammonium chloride （DEDAAC） with acrylamide （AM）, acrylic acid （AA） or sodium acrylic acid （NaAA） at low conversion were determined by elemental analysis, and the reactivity ratios of monomers in copolymerization were obtained by Kelen-Tudos method. The results showed that the reactivity ratios rDE and rAM are 0.31 and 5.27 for DEDAAC with AM, rDE and rAA are 0.28 and 5.15 for DEDAAC with AA, and roe and rNsAA are 0.40 and 3.97 for DEDAAC with NaAA, respectively. The copolymerizations for DEDAAC with AM, AA or NaAA are non-ideal copolymerization and the products are random copolymers.

The Application of Polytetrafluoroethylene (PTFE) Fiber Grafted Acrylic Acid as a Cation Exchanger for Removing Cu^(12)

The polytetrafluoroethylene fiber grafted acrylic acid was used as a cation exchanger. The exchange capacity of the cation fiber is 3.06 mmol/g. The maximum Cu2+ adsorption capacity is 107.48 mg/g. It could be desorbed completely by 1mol/L HCl.

Radiation Induced Grafting of Acrylic Acid onto Viscose Rayon Fabrics and Its After-Effects

Radiation induced grafting of various polymers with different monomers proved to be an attractive means to modify the physical or chemical properties of polymeric materials or textile fabrics. In the present work, radiation induced grafting of viscose rayon fabrics, consisting mainly of cellulose fibers, with acrylic acid monomer has been carried out. The grafting yields have been thoroughly studied as a function of different applied experimental parameters. The impact of the graft yield on the physical properties of the fabrics such as tensile strength, elongation, swelling, moisture absorption, crease recovery angle and also the dyeing properties of the fabrics has been studied. The effect of increasing the contact time of the fabric and monomer solution, at room temperature, after stopping irradiation has been studied in detail as well as the effect of temperature on the irradiated samples also after stopping irradiation. The best grafting yield was obtained on irradiating viscose rayon fabric in methanol-water solvent containing acrylic acid monomer, at a dose 20 kGys, then heating for 7 hours at 80℃ and finally keeping the samples at room temperature for about 20 hours. That treatment significantly increased the final graft yield.

Graft Polymerization of Acrylic Acid and Acrylamide onto BOPET Corona Films

The graft polymerization of acrylic acid(A) and acrylamide(B) was carried out onto bi-oriented polyester BOPET corona film.The influence of monomer concentration,reducer concentration and reaction time on the graft polymerization was investigated.The surface tension of the films increased with an increase of monomer concentration,till the concentration of monomer A reached 1.5×10^(-2)g/mL and the concentration of monomer B reached 4.0×10^(-2)g/mL.The surface tension of the films reached a maximum value at 7×10^(-4)M of reducer concentration and subsequently decreased with further increase in reducer concentration.The surface tension of the films increased with the increase of the reaction time apparently within 50min.The grafted corona BOPET films were characterized with IR and XPS.The presence of graft on the film surface was confirmed.The attenuation experiments on grafted corona BOPET films in air at 50℃ and in water were carried out to investigate the persistence of graft polymerization of acrylic acid and arylamide onto BOPET corona films.

Concentration of mixed acid by electrodialysis for the intensification of absorption process in acrylic acid production

The absorption process in acrylic acid production was water-intensive.The concentration of acrylic acid before distillation process was low,which induced to large amount of wastewater and enormous energy consumption.In this work,a new method was proposed to concentrate the side stream of absorption column and thus increase the concentration in bottom product by electrodialysis.The influence of operating conditions on concentration rate and specific energy consumption were investigated by a laboratory-scale device.When the voltage drop was 1 V·cP^(-1)(1 cP=10^(-3) Pa·s),flow velocity was 3 cm·s^(-1) and the temperature was 35℃,the concentration rates of acrylic acid and acetic acid could be 203.3%and 156.6%in the continual-ED process.Based on the experimental data,the absorption process combined with ED was simulated,in which the diluted solution from ED process was used as spray water and the concentrated solution was feed back to the absorption column.The results shown that the flow rate of spray water was decreased by 37.1%,and the acrylic acid concentration at the bottom of the tower was increased by 4.56%.The ions exchange membranes before and after use 1200 h were tested by membrane surface morphology(scanning electron microscope),membrane chemical groups(infrared spectra),ion exchange capacity,and membrane area resistance,which indicated the membrane were stable in the acid system.This method provides new method for energy conservation and emission reduction in the traditional chemical industry.

Effect of Dissolved CO_2 and Tetrahydrofuran on the Polymerization of Acrylic Acid

The polymerization of acrylic acid (AA) with dissolved carbon dioxide and tetrahydrofuran (THF) in the monomer is studied. Viscosity measurement. differential scanning calorimetry (DSC). and scanning electron microscopy (SEM) indicate that the conccntration of tctrahydrofuran has pronounced effect on the molecular weight (Mn). glass transition temperature (Tg). and the morphology of the product.

Synthesis and Properties of IPN Hydrogels Based on Konjac Glucomannan and Poly(acrylic acid)

Novel interpenetrating polymer network （IPN） hydrogels based on konjac glucomannan （KGM） and poly（acrylic acid） （PAA） were prepared by polymerization and cross-linking of acrylic acid （AA） in the pre-fabricated KGM gel. The IPN gel was analyzed by FF-IR. The studies on the equilibrium swelling ratio of IPN hydrogels revealed their sensitive response to environmental pH value. The results of in vitro degradation showed that the IPN hydrogels retain the enzymatic degradation character of KGM.

Grafting Copolymerization of Styrene and Acrylic Acid onto Pre-irradiated Polypropylene Fabric

Grafting copolymerization of styrene and acrylic acid onto polypropylene fabric had been studied by using a pre-irradiation technique. The polypropylene fabric Samples were irradiated by Y-ray and electron beam under the conditions of air and nitrogen gas, respectively. The effect of absorbed dose, monomer concentration in solvent, reaction temperature and reaction time on the degree of grafting were determined. The effects of metallic salts and sulphuric acid on the grafting yield of acrylic acid were also examined. The samples irradiated by electron beam give a much higher degree of grafting than those by Y -ray when styrene was grafted to polypropylene fabric. However, the grafting yield of acrylic acid on polypropylene fabric in the presence of metallic salts and sultric acid showed the opposite results from the case of styrene. This effect is reasonably interpreted by assuming that the grafting is dominated by trapped radicals and peroxides in pre-irradiated polypropylene.