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SynopsisThe grafting of maleic anhydride (MAn) to low density polyethylenes (PEs) dissolved in 1,2-dichlorobenzene ( DCB) has been studied. Grafting was successful a t temperatures of about 160°C both in air without initiator and under nitrogen with the radical initiator 2.5-di ( t-butylperoxy -2,5-dimethyl-3-hexyne (LPO). The presence of succinic anhydride grafts was shown by FTIR spectroscopy of the product; 'H-NMR spectroscopy indicates that the grafts consist of single succinic anhydride units. The graft content was determined by nonaqueous titration, and the extent of crosslinking inferred from the melt flow rates (MFR) of the products. The effects of concentration of initiator, MAn, and PE on the graft content were determined; the influence of PE structure, reaction time, and temperature was also studied. Melt blending of the grafted PE with polystyrene containing oxazoline functional groups (OPS) was investigated using a Rheomix mixer. The interpolymer reaction which occurs during blending was studied by means of FTIR, and the morphology of the blends by scanning electron microscopy (SEM). Information was also gained from the change in torque viscosity during the blending process.

X‐ray diffraction patterns of linear and branched polyethylenes typically show two sharp reflections and an amorphous halo. The position of the halo depends on branch content and temperature. A single curve describes the position of the halo maximum (2θhalo) for a range of liquid hydrocarbons and polyethylenes in the 20–140°C range. At temperatures well below their melting point, branched polymers give 2θhalo values which differ significantly from those observed for the liquid Linear polymers show a greater divergence, indicating that some of the material giving rise to the halo is much better packed than in the liquid.Parallel 13 C NMR spin‐lattice relaxation studies suggest that this relatively ordered material has a trans conformation but a low average T1c value. © 1993 John Wiley & Sons, Inc.

SynopsisMaleic anhydride was grafted to the linear hydrocarbon, n-eicosane, at 165°C in the presence of the free radical initiator, 2,5-dimethyl-2,5-di( t-butylperoxy)-3-hexyne. The anhydride has a low solubility in eicosane and a multiple addition procedure was adopted. Grafted product which separated from the reaction mixture was fractionated and analyzed. The fractions contained on average 2-5.5 anhydride units/eicosane residue. 'H-and 13C-NMR studies show that the grafts consist of single succinic anhydride Mgs. At the concentrations of maleic anhydride chosen for homogeneous reaction (< 0.02M) and at 165OC, poly(maleic anhydride) is above its ceiling temperature, so that succinic anhydride radicals cannot add maleic anhydride to form polymer side chains. Instead, these radicals abstract hydrogen atoms to yield grafts consisting of single anhydride units.

The decomposition of 2-chloroethylphosphonic acid in aqueous solution has been studied at pH values from 6 to 9 and at temperatures in the 30 to 55 C range. The rate of decomposition is estimated from the rate of formation of ethylene. The rate is proportional to the concentration of the phosphonate dianion and is independent of the hydroxyl ion concentration. The rate constant at 40 C is 1.9 x 10-4 sec-I and the activation energy is 29.8 kcal mol-'. The rate of reaction is not affected significantly by the presence of potassium iodide or urea (substances which increase the rate of leaf abscission in trees sprayed by 2-chloroethylphosphonic add). The rate decreases sghtdy in the presence of low concentrations of magnesium and caldum ions.2-Chloroethylphosphonic acid is widely used in regulating plant development. Its plant growth activity is primarily associated with its ability to release ethylene to the plant tissues (2). A number of groups have studied aspects of the breakdown of the acid (1, 4-6). Maynard and Swan (4) showed that the products are chloride ion, ethylene, and phosphate. The yield of ethylene was found to be quantitative (1, 5), and according to Yang (6), the yield of phosphate is also quantitative. Maynard and Swan noted that the decomposition proceeds only at pH values above 4.5 and came to the tentative conclusion that a doubly ionized phosphonate group is required before fragmentation can occur. Edgerton and Blanpied (3) showed that the rate of formation of ethylene in buffered solutions increases rapidly with pH in the S to 7 region, and Warner and Leopold (5) claimed that ethylene evolution proceeds linearly with time for the first 7 hr, the rate increasing with increasing pH. The decomposition has been described as a base-catalyzed elimination reaction (1), and a second order reaction (5). Yang (6) suggests that the mechanism involves the nucleophilic attack of water on the phosphonate dianion and adds that OH-may also serve as a nucleophile in the reaction. Kinetic data for the decomposition under controlled conditions of both pH and temperature do not appear to be available. This note reports such data, together with some information on the effects of certain additives on the rate of decomposition. MATERIALS AND METHODSThe 2-chloroethylphosphonic acid, provided by Amchem Products, Amber, Pa., was of purity >99%; titration with NaOH indicated that it contained 99.8 + 0.4% acid. The material is hygroscopic and was exposed only to dry air. Buffer solutions were prepared by addition of NaOH solution to solutions of reagent grade sodium dihydrogen phosphate, boric acid, or sodium bicarbonate. Urea and KI were of reagent grade.The reaction vessel for the kinetic experiments consisted of a modified 125-ml conical flask with inner and outer compartments. Ten ml 0.1 M 2-chloroethylphosphonic acid solution, whose pH had been adjusted to 4.1 by addition of NaOH, was placed in the central compartment; 25 ml buffer solution was placed in the outer compartment, and the flask was immersed in ...

SO3--CN-CH3NH-gH loN-Solvent Water Methanol Ethanol Dime t h yl formami de Acetone Ethanol Water Chloroform Dimethyl sulphoxide Acetonitrile A, (mt-4 450 425 424 465 464 464 462 437 452 444 A2 (mI-4 475 (sh) 495 497 570 572 565 525

The ki~letics of reaction betireen 2,2-diphellyl-1-picrylhyclrazyl ( D P P H ) and a wide variety of phenols have been studied. 'The rate of disappearance of D P P H is of first order with respect to both the D P P H and the reacting phenol. The rates of reaction can be roughly correlated with the Hammett u value of the phenol substituent in the range -0.4 < u < 0.2, a p value of -6 being obtained. I-Butyl groups in both ortho positions of the phenol give rise to steric hindrance, the reductio~l in rate being largely due to a reduction in the A factor. Hydrogen abstraction fron~ the less reactive phenols is stroilgly retarded by the product, %,2-diphenyl-1-picrylhydrazine.The rate-determining step probably involves the abstraction of a hydrogen atom from the phenol by the DPPM to give diphenylpicryll~ydrazine and a phenoxy radical. The retardation by diphe~~ylpicryll~yclrazi~~e is readily explained if this primary step is reversible.Hydrogen-abstraction reactions involving 2,2-diphenyl-1-picrylhydrazyl ( D P P H ) as the acceptor molecule are relatively easily studied and a number of recent publications have been concerned with the rates of reaction of this radical with hydrogen donors. Inforination has been obtained concerning the reactivities of restricted ranges of donors containing C-IH (I), N-I-I (2, 3), 0-H (4, 5 , G), and S-I-I (7, 8) bonds. Phenols are well suited to an investigation of hydrogen abstraction froin 0-I-I-containing compouilds (3). A wide range of phenols is available and a detailed study of the effect of substituents is possible.During the course of the worli, a paper b y McGowan, Powell, and Raw was published (4) giving rate constants for the second-order reactioils of DPPIH with a large number of phenols, showii~g that substituents inay exert coilsiderable polar and steric influences on the reaction. Their measurements were normally made a t room temperature using carboil tetrachloride as solvent, but with three phenols, n~easurements were made over a teinperature range. In the work described here benzene was used as solvent, activation energies and A factors were obtained for all the phenols studied, and the effect of the product 2,2-diphenyl-1-picrylhydrazine on the rate of reaction was determined. Soine additional evidence was obtained that the primary reaction i~lvolves the hydrogen atom of the 0-H group, and the stoichiometry of the process was investigated.ESPERIRIES?'.AL iWaterials 2,2-Diphenyl-1-picrylhydrazine was prepared by the reaction of picryl chloride and 1,l-diphe11)rlhydrazine (9, 10). DPPIH was prepared by the oxidation of diphenylpicrylhydraziile with lead dioxide (9). Co~nplexed solveilt was re~noved by heating ilz vaci~o a t GO" for several hours.2-h4ethyla1tisole and 1-and 2-~~~ethoxynaphthalene (Eastman Kodali) were used without further purification.Phenols were obtained froin the Aldrich Chemical Coinpany or from the Eastinan I