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101.
Blending of two polymers in solution is a simple and cost‐effective technique to improve upon the physical and mechanical properties of the component polymers through synergism. To obtain maximum synergy in their properties, the component polymers should be miscible with each other on molecular scale. Polymer blends of complex physicomechanical properties are being actively investigated. Poly(methacrylic acid) (PMAA), a commercial polymer, yields transparent, hard, brittle, and water‐sensitive films. It has been blended with natural polymers like dextran, collagen, and gelatin to obtain films with improved physical and mechanical characteristics. Polyesteramides, which are easily synthesized from vegetable seeds oil, a sustainable resource, have found application in surface coatings. These oligomeric products do not make free standing films in the ambient condition. The polyesteramides from vegetable seeds oil can be used to obtain blend with PMMA of improved mechanical and water absorption properties. In this study, linseed oil polyesteramide (LOPEA) and dehydrated castor oil polyesteramide (DCPEA), the source oils with different unsaturation in their fatty acid chains, were blended with PMAA through mixing in solution in the ratio DCPEA/LOPEA: PMAA as 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, and 20/80. In the first instance, the miscibility of the two components was investigated in solution by viscosity and ultrasonic measurements and in solid phase through differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Moisture absorption by the blend was also studied. DCPEA and LOPEA show immiscibility with PMAA in solution phase while LOPEA with more unsaturation in the fatty acid chain of the oil was found more immiscible than DCPEA. DCPEA shows a narrow miscibility window in the solid phase while LOPEA was found immiscible with PMAA in the solid phase too. Uptake of moisture was found to be markedly reduced in the blends of DCPEA/LOPEA with PMAA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1367–1374, 2007: 相似文献
102.
Peter Van Puyvelde Sachin Velankar Jan Mewis Paula Moldenaers K. U. Leuven 《Polymer Engineering and Science》2002,42(10):1956-1964
The effect of physical compatibilization on the deformation and coalescence of droplets in immiscible polymer blends is discussed. Evidence is provided for the existence of concentration gradients in block copolymers along the interface during deformation. This causes complex changes in droplet shapes during deformation and relaxation. These concentration gradients also result in Marangoni stresses, which stabilize the droplets against deformation and breakup. Coalescence experiments have been performed, varying both the compatibilizer concentration and the shear rate. Existing coalescence models have been evaluated. An empirical extension of Chesters' partially mobile interface model is presented, that treats the effects of Marangoni stresses on the coalescence process as a higher effective viscosity ratio. 相似文献
103.
Graft copolymerization of poly(vinyl chloride) (PVC) partially dehydrochlorinated by heating in nitrobenzene was investigated using styrene as monomer and anhydrous AlCl3 as cationic initiator in the temperature range of 0–35°C. Effect of monomer, catalyst, and PVC concentration on % graft-on was also evaluated. Introduction of labile sites in PVC by partial dehydrochlorination in nitrobenzene resulted in an increase in % graft-on. Intrinsic viscosity of PVC–g–polystyrene in THF initially increased with an increase in % graft-on. At higher % graft-on a decrease in [η] was observed. 相似文献
104.
105.
A crosslink‐able elastomeric polyester urethane (PEU) was blended with a thermoplastic, polyacrylonitrile (PAN), and electrospun into nanofibers. The effects of the PEU/PAN ratio and the crosslinking reaction on the morphology and the tensile properties of the as‐spun fiber mats were investigated. With the same overall polymer concentration (9 wt %), the nanofiber containing higher composition of PEU shows a slight decrease in the average fiber diameter, but the tensile strength, the elongation at break and tensile modulus of the nanofiber mats are all improved. These tensile properties are further enhanced by slight crosslinking of the PEU component within the nanofibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
106.
Results of the heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated TiO2 suspensions in the presence of ammonia are presented. The initial rate of Fe(VI) reduction, R, may be expressed as R = k
Fe(VI)[Fe(VI)]1.25 where k
Fe(VI) = a[Ammonia]+b), a = 6.0 × 103 μm
0.25 s and b = 4.1 × 106 μm
−1.25s−1. The rate constant, k
Fe(VI), increases with the ammonia concentration. The photocatalytic oxidation of ammonia is enhanced in the presence of Fe(VI).
A mechanism involving Fe(V) as a reactive intermediate is presented which explains the faster photocatalytic oxidation of
ammonia in the presence of Fe(VI). 相似文献
107.
M. E. Ladhabhoy M. M. Sharma 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1970,20(9):274-280
The kinetics of absorption of oxygen by 2-ethylhexaldehyde dissolved in 2-ethylhexanoic acid at concentrations up to 1.38 × 10?3 mole/cm3 (20 wt.-%), in the presence of manganese acetate, was studied in a stirred cell and in bubble and packed bubble columns. Diffusion of oxygen was found to play a major role. The reaction was first order in oxygen and second order with respect to the aldehyde, and the overall third-order rate constant was found to be 2.98 × 107 cm6 mole?2 sec?1 at 30°. The effect of cobaltous acetate on the specific rate of absorption of oxygen was also studied and manganese acetate was found to be the better catalyst. 相似文献
108.
Interpolymer complex microparticles based on polymethacrylic acid‐chitosan for oral insulin delivery
In the present study, microparticles composed of polymethacrylic acid‐chitosan (PMAA‐CS) were prepared by a novel interionic gelation method. Free‐radical polymerization of methacrylic acid was carried out in the presence of CS, using a water‐soluble initiator, and application of these microparticles toward oral insulin delivery was evaluated. Microparticles obtained were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) studies. From SEM studies, it was observed that microparticles had an aggregated morphology with size ~20 μm, while FTIR confirmed the presence of ionic interaction between PMAA and CS chains. Protein loading was done by diffusion filling method, and from in vitro release study, it was observed that insulin‐loaded microparticles displayed a pH depended release profile at alkaline/acidic pH. Microparticles exhibited sustained release of insulin for 3–4 h at neutral pH, and enzyme linked immunosorbent assay (ELISA) proved that encapsulated protein maintained 100% biological activity at neutral pH. Preliminary study suggests that these microparticles can serve as good candidate for oral protein delivery. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 506–512, 2006 相似文献
109.
Synthetic, spectroscopic and antimicrobial aspects of some fertility inhibitor heterobimetallic complexes have been carried out. These heterobimetallic chelates [M(C(5)H(5)N(3))(2)M(2)'(R)(4)]Cl(2) (M = Pd or Pt and M' = Si, Sn, Ti and Zr) have been successfully synthesinzed via the reaction of M(C(5)H(7)N(3))(2)Cl(2) with group four or fourteen dichlorides in 1:2 stoichiometric proportions. The products were characterized by elemental analyses, molecular weight determinations, magnetic susceptibility measurements, conductance, and IR multinuclear NMR and electronic spectral studies. A square planar geometry has been suggested for all the complexes with the help of spectral data. Conductivity data strongly suggest that chlorine atoms are ionic in nature due to which complexes behave as electrolytes. All the complexes have been evaluated for their antmicrobial effects on different species of pathogenic fungi and bacteria. The testicular sperm density, testicular sperm morphology, sperm motility, density of cauda epididymal spermatozoa and fertility in mating trails and biochemical parameters of reproductive organs have been examined and discussed. 相似文献
110.