SynopsisWhen extruding a blend of low density polyethylene (LDPE) and a technical grade of sodium lignosulfonate through a capillary it was observed that LDPE formed fibers in a matrix of the lignosulfonate. With short capillaries and low shear rates, short fibers of LDPE with lengths between 0.5 and 5 m and with diameters in the range 2-20 pm can be produced. Since sodium lignosulphonate is water-soluble, the LDPE fibers can easily be isolated. Such fibers can be used for synthetic wood pulp or in nonwoven types of applications.
The concentration and molecular weight distribution (GPC) of polystyrene (PS) in the two phases of the PS‐SO2 (δ)‐system were determined. Typical concentrations of PS in the upper phase were around 30%, while the lower phase contained at most 1% PS. An exception was a PS‐grade with a low molecular weight (MW 3.5 · 103), which dissolved homogeneously. The molecular weight of PS in the lower phase was substantially below an the one found in the concentrated phase. Mechanical agitation was necessary to attain an equilibrium state; during the equilibration the upper phase became more diluted. At the same time the molecular weight of the lower phase PS‐fraction increased, while the MW value in the upper phase remained practically unchanged and equal to that of the virgin sample. The fractionation with regard to the molecular weight between the two phases was also reflected in the Tg‐values of the fractions. The value of X(Flory‐Huggins parameter) determined from vapour pressure data above the concentrated phase was 0.8–1.
SynopsisThe two-phase equilibrium in the system polystyrene (PS)-liquid sulfur dioxide [SOn(l)] was investigated, mainly at room temperature. The system consisted of an upper PS-rich phase, concentration (30-50)% depending on the way of preparation, and a lower phase containing less than 1% PS. The range of molecular weights of the PS samples used was 22,000-350,OOO (mW,). PS with an mu, value of 22,000 dissolved homogeneously in SOn(l). In systems forming two phases a fractionation of PS with respect to molecular weight was observed. The value of the PS fraction dissolved in the lower PS lean phase was always substantially lower than that of the upper phase. When increasing the temperature to 90-95OC, the two phases disappeared and the PS component I'ormed a jellylike mass with a very low solubility in SOp(1). Also in the supercritical dense SO2 gas, the solubility of PS was a few tenths of a percent only. Experiments with Soxhlet extraction indicated an extractability of a few percent.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.