| 1. |
- Zhang, L, et al.
(författare)
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Effects of molecular weight of nitrocellulose on structure and properties of polyurethane nitrocellulose IPNs
- 1999
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Ingår i: Journal of Polymer Science Part B-Polymer Physics. ; 37:14, s. 1623-1631
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Tidskriftsartikel (refereegranskat)abstract
- Semi-interpenetrating polymer network (semi-IPN) coatings were prepared by using castor oil-based polyurethane (PU) and nitrocellulose (NC) with various viscosity-average molecular weights (Mη) from 6 × 104 to 42 × 104, and coated on a regenerated cellulose (RC) film to obtain water-resistant film. The PU/NC coatings and coated films, which were cured at 80°C for 5 min and 2 min, respectively, were investigated by infrared (IR) and ultraviolet (UV) spectroscopy, X-ray diffraction, swelling test, strength test, dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results show that the crosslink densities of the PU/NC semi-IPNs were smaller than that of pure PU, and decreased with the decrease of Mη of nitrocellulose (NC Mη), indicating NC molecules cohered intimately with PU, and hindered the PU network formation. The physical and mechanical properties of the films coated with PU/NC coatings were significantly improved. With the increase of NC Mη, the strength and thermal stability of the coated films increased, but the pliability, water resistivity, and optical transmission decreased slowly. The PU/NC coating with low NC Mη more readily penetrated into the RC film, and reacted with cellulose, resulting in a strong interfacial bonding and dense surface caused by intimate blend of PU/NC in the coated films.
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| 2. |
- Zhang, L., et al.
(författare)
-
Method for prepn. of biological degradability regenerative cellulose waterproof film and cellulose products
- 1998
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Patent (populärvet., debatt m.m.)abstract
- A process for preparing water-proof regenerated cellulose film and water-proof cellulose products freatures use of biodegradable water-proof paint which is composed of pre-polymer of polyurthane, nitrocellulose, SO1-17 liquid, ethyl acetate and less N, N -dimethyl ethanolamine. Its technological steps include coating the surface of regenerated fibre film or cellulose product with and solidifying at 70-90 deg. C for 1-5 min. Obtained products have obviousely improved water-proof nature and tension strength over than 350 kg/sq. cm after immersed in water. The water vapour penetrating it is 0.004-0.005 g.sq. cm. d. It is fully biodegradable.
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| 3. |
- Zhang, L, et al.
(författare)
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Water-resistant film from polyurethane/nitrocellulose coating to regenerated cellulose
- 1997
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 36:7, s. 2651-2656
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Tidskriftsartikel (refereegranskat)abstract
- Water-resistant films were obtained from polyurethane (PU)/nitrocellulose coating to regenerated cellulose films, which were prepared by coagulating cellulose cuoxam solution. The PU/nitrocellulose coating layer was cured at 80 degrees C for 2 min and formed semi-interpenetrating polymer networks (semi-IPNs) structure. The tensile strength (sigma(b)), water resistivity (R), water vapor permeability (P), and light transmittance of the coated films changed with nitrocellulose content in the coating, and the best values (such as sigma(b), 679 kg.cm(-2); R, 53%; P, 0.004 g.cm(-2).day(-1)) were attained at 33 wt % nitrocellulose. The TEM, EPMA, DTA, IRI and UV results-showed that the coated films have strong interfacial bonding, which is caused by covalent and hydrogen bonds between the cellulose film and the semi-IPNs coating. The biodegradation half-life t(1/2) of the coated films in soil at 20-30 degrees C was given to be 58 days, and after about 6 months the coated films were almost completely decomposed by microorganisms. SEM and the kinetics of decay studied on the biodegradability were discussed. The water-resistant films coated with PU/nitrocellulose have promising application where biodegradation is important.
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