| 1. |
- Liu, Xiaohui, et al.
(författare)
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Non-isothermal crystallization behaviors of polyamide 6/clay nanocomposites
- 2002
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Ingår i: European Polymer Journal. - 0014-3057 .- 1873-1945. ; 38:7, s. 1383-1389
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Tidskriftsartikel (refereegranskat)abstract
- The non-isothermal crystallization behaviors of polyamide 6/clay nanocomposite (PA6CN) were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). DSC results showed that the nanometric silicate layers in PA6CN acted as effective nucleation agents. The addition of silicate layers influenced the mechanism of nucleation and the growth of PA6 crystallites. The DSC results also implied an unusual phenomenon, in contrast to PA6, the crystallinity degree of PA6CN increased with increasing cooling rate. XRD results verified this phenomenon and indicated that the addition of silicate layers favored the formation of the γ crystalline form.
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| 2. |
- Liu, Xiaohui, et al.
(författare)
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Phase transition in nylon 6/clay nanocomposites on annealing
- 2002
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Ingår i: Polymer. - 0032-3861 .- 1873-2291. ; 43:6, s. 1933-1936
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Tidskriftsartikel (refereegranskat)abstract
- The γ -> α crystalline phase transition in nylon 6/clay nanocomposite prior to melting was investigated by X-ray diffraction. The phase transition in the nanocomposite took place at 160 °C, 40 °C higher than that of nylon 6 at 120 °C. The transition extent in the nanocomposite was lower than that in nylon 6. This could be caused by the strongly confined spaces between layers, and the favorable environment for the formation of the γ phase in the existence of clay. Besides, the less grown crystallites of the α phase transformed from the γ phase in the nanocomposite began to melt at much lower temperature than its normal melting temperature
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| 3. |
- Liu, Xiaohui, et al.
(författare)
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Phase transition in polyamide-66/montmorillonite nanocomposites on annealing
- 2002
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Ingår i: Journal of Polymer Science Part B. - : Wiley. - 0887-6266 .- 1099-0488. ; 41:1, s. 63-67
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Tidskriftsartikel (refereegranskat)abstract
- The crystalline-phase transition in polyamide-66/montmorillonite nanocomposites before melting was investigated by in situ X-ray diffraction and is reported for the first time in this work. The phase-transition temperature in the nanocomposites was 170 °C, 20 °C lower than that in polyamide-66. The lower phase-transition temperature of the nanocomposites could be attributed to the γ-phase-favorable environment caused by silicate layers. Meanwhile, the addition of silicate layers changed the crystal structure of the polyamide-66 matrix and influenced the phase-transition behavior.
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| 4. |
- Liu, Xiaohui, et al.
(författare)
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Polyamide 66/clay nanocomposites via melt intercalation
- 2002
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Ingår i: Macromolecular materials and engineering. - 1438-7492 .- 1439-2054. ; 287:3, s. 180-186
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Tidskriftsartikel (refereegranskat)abstract
- Polyamide 66/clay nanocomposites (PA66CN) were prepared via a melt compounding method using a new kind of organophilic clay, which was obtained through co-intercalation of epoxy resin and quaternary ammonium into Na-montmorillonite. The dispersion effect of silicate layers in the matrix was studied by means of XRD and TEM. The silicate layers were dispersed homogeneously and nearly exfoliated in the matrix as a result of the strong interaction between epoxy groups and PA66. The mechanical properties and heat distortion temperature (HDT) of PA66CN increased dramatically. The notched Izod impact strength of PA66CN was 50% higher than that of PA66 when the clay loading was 5 wt.-%. Even at 10 wt.-% clay content, the impact strength was still higher than that of PA66. The finely dispersed silicate layers and the strong interaction between silicate layers and the matrix reduced the water absorption, at 10 wt.-% clay content; PA66CN only absorbs 60% water compared with PA66. The addition of silicate layers changed the crystal structure in PA66CN
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| 5. |
- Liu, Xiaohui, et al.
(författare)
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PP/clay nanocomposites prepared by grafting-melt intercalation
- 2001
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Ingår i: Polymer. - 0032-3861 .- 1873-2291. ; 42:25, s. 10013-10019
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Tidskriftsartikel (refereegranskat)abstract
- Polypropylene (PP)/clay nanocomposites (PPCN) were prepared via grafting-melt compounding by using a new kind of co-intercalation organophilic clay which had a larger interlayer spacing than the ordinarily organophilic clay only modified by alkyl ammonium. One of the co-intercalation monomers was unsaturated so it could tether on the PP backbone by virtue of a grafting reaction. The larger interlayer spacing and strong interaction caused by grafting can improve the dispersion effect of silicate layers in the PP matrix, which was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The mechanical properties of PPCN were improved with the addition of clay. The incorporation of silicate layers also gave rise to a considerable increase of the storage modulus (stiffness) and a decrease of the tan δ value, demonstrating the reinforcing effect of clay on the PP matrix. Besides, the glass transition temperature (Tg) of PPCN decreased in the presence of the silicate layers. The addition of clay did not change the crystal structure of PP, however silicate layers acted as nucleating agents for the crystallization of PP.
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| 6. |
- Wu, Chunxia, et al.
(författare)
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Synthesis of tricyclic carbohydrate-benzene hybrids as selective inhibitors of galectin-1 and galectin-8 N-terminal domains
- 2020
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 10:33, s. 19636-19642
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Tidskriftsartikel (refereegranskat)abstract
- As the galactoside binding family of galectin proteins is involved in many physiological and pathological processes, the inhibitors of these proteins are considered to be of significant interest in the treatment of diseases such as cancer and fibrosis. Herein, fused tricyclic carbohydrate-benzene hybrid core structures are reported to be the selective inhibitors of galectin-1 and the N-terminal domain of galectin-8 by a competitive fluorescence polarization assay. The key intermediates mono- or diiodo tricyclic carbohydrate-benzene hybrids were synthesized from protected 2-bromo-3-O-propargyl-d-galactoseviaa domino reaction and subsequently utilized for further derivatization by Stille couplings to achieve derivatives carrying substituents at C10 and/or C11. Several compounds showed affinity for the galectin-1 and galectin-8 N-terminal (8N) domains; however, weak or even no binding was observed for galectin-3. Monosubstituted derivatives at C10 or C11 exhibited better affinity for galectin-8N than di-substituted derivatives at C10 or C11. Especially, a benzyl substituent orp-fluorobenzyl substituent at C11 displayed affinity and selectivity for galectin-1 and galectin-8N over galectin-3. This suggests that tricyclic carbohydrate-benzene hybrids are promising scaffolds for the development of selective galectin-1 and galectin-8N inhibitors.
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| 7. |
- Wu, Qiuju, et al.
(författare)
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A High Strength Nanocomposite Based on Microcrystalline Cellulose and Polyurethane
- 2007
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 8:12, s. 3687-3692
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Tidskriftsartikel (refereegranskat)abstract
- A high-strength elastomeric nanocomposite has successfully been prepared by dispersing microcrystalline cellulose in a polyurethane matrix. The resulting nanocomposites show increased strain-to-failure in addition to increased stiffness and strength compared to the unfilled polyurethane. The optimal composite contained 5 wt % cellulose. The average true strength for this composition was 257 MPa, compared with 39 MPa for the neat polyurethane, and showed the highest strain-to-failure. The improvements of stiffness, strength, as well as strain-to-failure are believed to be due to good interaction, by both covalent and hydrogen bonds, between the polyurethane and the cellulose nanofibrils.
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