An experimental study of crystallization kinetics and the influence of nucleating agents on the solidification of poly(p‐phenylene sulfide) (PPS) is described. The effect of molecular weight is considered by investigating PPS samples having different viscosity levels. We studied the effect of a range of nucleating agents including aluminum oxide, calcium oxide, silicon dioxide, titanium dioxide, kaolin, and talc. All of these compounds were found to enhance the rate of crystallization; in particular, silicon dioxide, kaolin, and talc were the most effective nucleating agents. An effort to study particle size effects of the silicon dioxide showed that the nucleation was very sensitive to the source of the material. These studies did, however, show that nucleation rates tended to increase with decreasing particle size and increasing loading of silicon dioxide. Comparison of PPS crystallization rates with those of other polymers indicates that it crystallizes much more slowly than polyethylene or isotactic polypropylene and is slower than polyetherether‐ketone, when comparisons are made on an equivalent basis. PPS crystallizes at similar rates to polyethylene terephthalate (PET). However, our nucleated PPS does not crystallize as rapidly as nucleated PET.

SynopsisAmorphous polfiethylene terephthalate) (PET) and cellulose blends in film form were obtained by room temperature hydrolysis of PET/cellulose trifluoroacetate solution cast films. Evidence is presented indicating that the cellulose, or the water associated with it, nucleates the crystallization of the PET during differential scanning calorimetry (DSC) runs. At about the 50/50 composition, a phase inversion, from continuous PET to continuous cellulose appears.Hydrolysis and/or annealing in water at the boil yields a mixture of cellulose IT and cellulose IV. The nature of the cellulose appears to be different in the case of the room temperature hydrolyzed structures. Hydrolysis appears to proceed more readily when the films are richer in the cellulose component. EXPERIMENTALThe prehydrolyzed films used in this study were those described in the previous paper' and were prepared from the same sources, Whatman cellulose and Goodyear PET with a reported intrinsic viscosity of 0.59. The solvent was a mixture of distilled TFA and methylene chloride in a ratio of 70/30 by volume, and the concentration of polymer was 5% weight on volume. The solutions were cast on a glass plate and rapidly flash dried

An experimental study of structure development in melt spinning polyetherimide (PEI) and polyarylate (PAR) is presented. PEI was melt spun at 320° and 350°C and PAR at 310° and 340°C to drawdown ratios of up to 1 000. The melt spun fibers were found to be totally amorphous but to have significant levels of birefringence which increased with draw-down ratio. The birefringence was found to vary linearly with the spinline stress for both polymers and the data was independent of the melt spinning temperature. The proportionality constants are interpretable as equivalent to stress optical constants for the corresponding melts and have values of 9 400 Brewsters for the PEI and 7 400 Brewsters for the polyarylate. The mechanical properties of the melt spun fibers were determined in uniaxial extension. It was found that Young's modulus and tensile strength increased with spinline stress or birefringence while elongation to break decreased. The mechanical properties were found to be similar to polyether ether ketone, poly-p-phenylene sulfide, and polyethylene terephthalate in similar correlations, but as compared to polypropylene at the same spinline stress had higher Young's modulus and tensile strength but lower elongation to break. We were not able to successfully draw these materials over a hot plate at temperatures above their glass transition temperature.

A study of the development of crystallinity and orientation in the melt spinning and drawing of poly ether ether ketone fibers is presented. Melt spun fibers are characterized by differential scanning calorimetry, biref ringence, and wide angle x-ray diffraction. These fibers were subsequently drawn at 160•‹, 180•‹, and 230•Ž. The drawn fibers were characterized by the same techniques as the melt spun fibers. Uniaxial stress-strain behavior, tensile strength, and elongation to break characteristics have been determined and correlated with fiber struc ture. Particularly important results are that drawdown ratios and spinline stresses can induce significant crystal lization in the spinline. Correlations of fiber mechanical properties are developed with spinline stress and biref ringence.

The development of crystallinity and orientation in melt spun and subsequently drawn poly p phenylene sulfide (PPS) fibers is investigated using differential scanning calorimetry (DSC), birefringence and wide angle x-ray diffraction (WAXS) techniques. The melt spun PPS fibers were found to possess small amounts of crystallinity at moderate draw-down ratios. The fibers may be crystallized to a significant extent by subsequent drawing over a hot plate. The levels of crystallinity and orientation in the largely glassy melt spun PPS fibers has been determined as well as subsequently drawn fibers. Uniaxial mechanical properties were determined as a function of spinning and drawing conditions. In general, elongation to break decreases while modulus and tensile strength increase with an increase of melt spinning draw down ratio and solid draw ratio. The Young's modulus and tensile strengths are increasing functions of fiber birefringence and the elongation to break a decreasing function.