The soapless emulsion copolymerization of methyl methacrylate (MMA) and n‐butyl acrylate (n‐BuA) at four levels of monomer feed composition (f10) was studied. Conversion (X), average particle diameter (Dp), molecular weight distribution (MWD), surface charge density, and glass transition temperature (Tg) of the copolymer as a function of reaction time (t) were measured. The copolymers obtained even at low conversion, except for the run of (f10) = 90 wt. percent MMA, exhibit two Tgs in their DSC thermograms. Phase separation is found to occur in the latex particles during polymerization. The heterogeneous distribution of monomers in particles, in which a relatively rich MMA region exists in the shell and a relatively rich n‐BuA region exists in the core of the particles, is assumed to arise from phase separation. The average copolymer composition and the fraction of the two domains are estimated. The polymerizatrion course and particle size growth follow the linear X vs. t2 and Dp3/2 vs. t relationships, respectively. Although the coagulation of particles happens after around 30 percent conversion, the polymerization behaviors, except for increasing rates, are not affected.

The instantaneous copolymer composition equation for a binary components system has been used for determining monomer reactivity ratios. Equation (1) has been rearranged in the form by Fineman and Ross' as follows:The monomer reactivity ratios ri are then determined graphically. The ri values are estimated from

In this study, the morphologies and the mechanical properties of the ternary blend of PA (polyamide)b/SEBS(styrene-[ethylene-butylene]-styrene triblock copolymer)/maleated SEBS were investigated. Maleated SEBS compatibilizers of various maleic anhydride (MA) content were prepared in the laboratory. The compatibilizer significantly influenced the dispersion of the rubber as well as the crystalline form and spherulites of the polyamide. The effects of the compatibilizer on mechanical properties were correlated with the observations of morphology and stress-strain behavior. The toughness of the blends was found to be increased for those undergoing additional yielding during cold drawing. Finally, a compatibilization mechanism of maleated SEBS for the blends was proposed.

SYNOPSIS4'-[ Oligo (ethylene oxide) monomethyl ether carbonyl] biphenyl-4-yl4-(alkenyloxy ) benzoate side-chain liquid crystalline (LC) polysiloxane polymers with various lengths of a terminal group and spacer were prepared. The mesophase structure and transition temperature of those polymers were investigated using methods of X-ray diffraction, polarized optical microscopy, and differential scanning calorimetry, respectively. The mesophases of the polymers were smectic ones. The layer spacing d l s and the side-chain distance of d2s obtained were around 29-34 8 and 4.4-4.6 8, respectively. d 1s were much shorter than twice the lengths of the side chains presumed in the fully extended conformation. Hence, the two-layer end-on packings or the packing with overlapping of tails model seemed not able to interpret the mesophase structure of those polymers studied. The effects of temperature on the mesophase microstructure of 4'-[ethylene oxide monomethyl ether carbonyl] biphenyl-4-yl 4-(pentenyloxy ) benzoate side-chain LC polysiloxane polymer were also studied using the X-ray diffraction method. It was found that both d 1 and d 2 of the polymer in the mesophase temperature range became shorter with decreasing temperature and the long-and sbort-range order could remain, to some extent, at temperatures above the isotropic transition temperature and temperatures below the melting temperature. 0 1993

SynopsisPolymerization of acrylamide was thermally initiated by the oxygenated cobalt(II1) triethylenetetramine complex. Rate, conversion, and molecular weights obtained are favorable comparable to those initiated by K2&04 and K2&08 initiators. An induction period is about 3 mins. The value of K d f at 60°C is 6.75 X s-', and the chain transfer to monomer constant is 1.2 xThe rate dependence obtained are a half order on the initiator concentration and a 1.38 order on the monomer concentration. The mole fraction of combination termination occurred in the overall termination reactions evaluated is 0.746.