| 1. |
|
|
| 2. |
|
|
| 3. |
- Flodberg, G., et al.
(författare)
-
Barrier properties of blends based on liquid crystalline polymers and polyethylene
- 2000
-
Ingår i: Polymer Engineering and Science. - : Wiley. - 0032-3888 .- 1548-2634. ; 40:9, s. 1969-1978
-
Tidskriftsartikel (refereegranskat)abstract
- Blends of an extrusion-grade polyethylene and two different liquid crystalline polymers of Vectra type were prepared by melt mixing using poly(ethylene-co-methacrylic acid) as compatibilizer. Oxygen and water vapor permeability, transparency and welding strength of compression molded and film blown specimens were studied. The compression molded blends showed gas permeabilities conforming to the Maxwell equation assuming low permeability liquid crystalline polymer spheres in a high permeability polyethylene matrix One of the liquid crystalline polymers with suitable rheological properties formed a more continuous phase in the film blown blends and a substantial decrease in oxygen and water vapor permeability was observed in these blends. The compression molded blends with 50% liquid crystalline polymer and some of blow molded blends showed very high gas permeabilities. It is believed that voids forming continuous paths through the structure were present in these samples. The blends showed significantly higher opacity than pure polyethylene.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Kakonen, S M, et al.
(författare)
-
Development and evaluation of three immunofluorometric assays that measure different forms of osteocalcin in serum
- 2000
-
Ingår i: Clinical Chemistry. - 0009-9147. ; 46:3, s. 332-337
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Circulating human osteocalcin (hOC) has been used as a marker of bone formation. Our aim was to validate three immunofluorometric assays (IFMAs), measuring different forms of hOC. METHODS: The two-site IFMAs were based on previously characterized monoclonal antibodies. Assay 2 recognized intact hOC, assays 4 and 9 measured the NH(2)-terminal mid-fragment and the intact hOC. In addition, assay 9 required hOC to be gamma-carboxylated. RESULTS: A 76-79% increase of serum immunoreactive hOC was found in the postmenopausal group compared with the premenopausal group with all IFMAs. With EDTA-plasma samples, the observed increases were lower (49-65%). The hOC concentration in the postmenopausal group receiving hormone replacement therapy was 42-44% lower than that in the postmenopausal control group in both serum and EDTA-plasma samples. The depressed carboxylation in warfarin-treated patients was accompanied by lower results in assay 9. The ratio of assay 9 to assay 4 totally discriminated the warfarin-treated patients from the controls. Assay 9 showed the smallest decreases in measured hOC after storage of serum or plasma for 4 weeks at 4 degrees C, followed by assay 4 and assay 2. Results from the last assay were <17% of their initial values after 4 weeks of storage. No diurnal variation was observed with assay 9 as opposed to the two other IFMAs. CONCLUSION: The three assays with their distinct specificity profiles (intact vs fragmented and carboxylated vs decarboxylated hOC) may provide valuable tools for investigating the significance of different hOC forms in various bone-related diseases.
|
|
| 10. |
- Krook, M., et al.
(författare)
-
Barrier and mechanical properties of pulp fiber/polymer laminates and blends
- 2000
-
Ingår i: Polymer Engineering and Science. - : Wiley. - 0032-3888 .- 1548-2634. ; 40:1, s. 143-156
-
Tidskriftsartikel (refereegranskat)abstract
- Paperboard laminates coated with two grades of poly(epsilon-caprolactone) (PCL), poly(hydroxy butyrate-co-valerate) (PHBV) or a liquid crystalline copolyester (LCP) were prepared by compression molding, and the influence of the processing conditions and polymer content of the laminate on the laminate properties was studied. Ligno-cellulose fiber/polymer blends were prepared from wet pulps and PCL and PHBV. The morphology, water vapor transmission rates, creasability, curl and twist and mechanical properties of the laminates and blends were studied. LCP and slowly cooled high molar mass PCL laminated paperboards showed the best creasing properties and the paperboards that were penetrated by the polymer showed the smallest degree of curl and twist. Extensive penetration occurred during compression molding of the paperboard with the low molar mass PCL at all temperatures and with PHBV and LCP at the higher molding temperatures. The water vapor transmission rates ranged from 1 to 300 times that of polyethylene depending on the polymer used and on the thermal history. In the case of blends, competitive properties were obtained only in those with a high polymer content. The laminate stiffness decreased and the strength increased in two polymer concentration regions, at similar to 20 wt% due to fiber-fiber separation and at similar to 60 wt% due to phase inversion.
|
|
