An ethylene-propylene random copolymer (EP) in carbon disulfide, toluene, and cyclopentane was found to convert to a thermoreversible gel at the temperature lower than ca. woe. Sol<=±gel transition temperatures were measured as a function of polymer concentration using several samples with different propylene contents (PC) and molecular weights. PC varies from 22 to 49wt%. The sol--.gel and gel-->sol transition temperatures, where thermal hysteresis was present for each sample, lowered considerably with increasing PC, regardless of differences in molecular weights. The gel-melting behavior was investigated with the aid of the Takahashi theory which is based upon a conjecture that junction points of a gel are fringed micelle crystallites. The theory was well applicable to the present systems. A common linear relation was found to hold between liT;, and In V2N when the samples had similar PC, where is the observed gel-melting temperature, v2 is the volume fraction (concentration) of the polymer in the gel, and N is the weight-average degree of polymerization. Further, results of X-ray diffraction, differential scanning calorimetry, and microscopic observation showed that gelation took place through crystallization and that junction points of an EP gel were made up of microcrystallites such as fringed micelles, particularly for a sample with high content of propylene.

Background: Lymph is pumped through the collecting lymphatic vessels by both intrinsic and extrinsic forces. The intrinsic pump relies on spontaneous lymphatic contraction, which generates the pumping lymph pressure (Plp). Among healthy people with daily leg edema, a considerable number of cases are accompanied with low leg Plp. Herein, a double-blinded controlled trial was conducted in healthy female volunteers with reduced leg Plp to compare the effectiveness of a 15–29 mmHg compression stocking (Stocking A) and a 8–16 mmHg stocking (Stocking B) on elevating Plp.Method and Results: Among 219 healthy female volunteers who underwent measurement of leg Plp, 80 participants (36.5%) had unilateral or bilateral legs with Plp < 20 mmHg (122 legs with Plp < 20 mmHg and 38 legs with Plp ≧ 20 mmHg). These 80 participants were assigned to wear either Stocking A (n = 40) or Stocking B (n = 40) for 16 weeks. Leg Plp was measured using indocyanine green fluorescence lymphography and an occlusion cuff technique while sitting. At 16 weeks, both Stockings A and B resulted in significantly elevated leg Plp, with the effect on elevating Plp being superior for Stocking A. Only Stocking A resulted in decreased prevalence of leg edema and improved Short Form-36 scores.Conclusion: Compression stockings may represent a therapeutic option to elevate leg Plp and ameliorate leg edema, thereby leading to improved quality of life in healthy females with low leg Plp.

ABSTRACT:Gel-melting temperatures (T~) of ethylene-propylene random copolymer gels formed in n-hexane and n-octane were measured as a function of polymer concentration. The copolymers were heterogeneous in both composition and molecular weight. T~ obeyed well the thermodynamic theory derived by Takahashi, in which gel--->sol transition was treated as melting of crystalline junctions with fringed micelle-type morphology: Plots of 1/T~ vs. In V2N according to the theory were scaled on a common straight line when copolymers had similar propylene contents (PC), where V2 is the volume fraction of the copolymer in the gel and Nis the weight-average degree of polymerization. Quantitative analysis of the theory, including measurements of dilute solution properties, led to the results that average size of crystalline junction ( in number of ethylene units per crystalline sequence was ca. 11 for copolymers with PC= 22 wt%, 9 for PC= 26 and 27wt%, and 5 for PC=49wt%, and thus ( decreased with increasing PC. The junction sizes ( were reasonable order as compared with those estimated from X-ray diffractions.