| The special three-helix structure of collagen endowed it with excellent biology properties. Collagen protein has outstanding low immunogenic properties, biodegradability biocompatibility and hemostasiability. Materials based on collagen can be degraded into products which are safe and hydrophilic. These special properties make collagen have wide application in biomaterial filed. Film is the form which is most familiar to us and also studied wildly.In this paper, collagen I was extracted from fresh pigskin by acid swelling-pepsin digestion method. Effects of concentration of pepsin and extraction time on the efficiency of extraction were mainly studied. IR and UV spectrum were used to identify the structure of the collagen. In this paper, the rheological behavior of the blends of chitosan and collagen, mechanical properties, thermal properties and surface properties of collagen matrix were studied.The main conclusions list below:1. Collagen I was extracted from fresh pigskin by acid swelling-pepsin digestion method. The collagen extracted kept the three helix structure very well, efficiency of extraction increased when the concentration of pepsin value increased. With time flowing, the efficiency of extraction came to a maximum after about 40 or 50 hours.2. Both solution of chitosan and collagen can formed well-proportioned and steady-going blends. The flow curve of both chitosan and collagen solution tallied with the character of pseudo-plasticity liquid, exhibiting pseudo-plasticity liquid when the shear rates increased. Blends of chitosan and collagen had special rheological curve, the blend systems exhibited pseudo-plasticity fluid when the temperature ranged from 20℃to 30℃.But the blend systems exhibited obvious Newtonian fluid when the temperature ranged from 40℃to 50℃. During the area of 30℃to 40℃, the blend systems change from pseudo-plasticity liquid to Newtonian fluid and the change trend will be strengthed with the increasing of quantity of chitosan.3. The more quantity of chitosan, the larger of theηa of the blend systems, the larger of the decrease scope ofηa. With the increasing of shear rates, theηa of the blend systems arrived to a balance value. 4. The flow activation energy of the blend systems is the function of temperature. When the temperature ranged from 30℃to 35℃, the structure of the blend systems changed and a kind of new flow mechanism appeared.5. In the blend systems there strong reciprocity which destroyed the arrange of the molecular chain and then it leaded to the decease of thermal steady properties.6. The introduction of chitosan improved the tensile strength of the blend films. When Glutaraldehyde of 2.2 per was added into the blend systems tensile strength was improved further, arriving to 22.38MPa, increasing about 372.15per, compared to pure collagen film.7. In the blend films, the components had different contributions to the tensile strength. When the quantity of chitosan took up absolute advantage, the composites exhibited mechanical properties of chiatosan. On the contrary, when the quantity of collagen took up absolute advantage, the composites exhibited the mechanical properties of collagen.8. With the increasing of Glutaraldehyde, the tensile strength of sample from 1st to 4th(10%PVA) increased gradually. When the ratio of Glutaraldehyde was 2.2per, the tensile strength came to a maximum value. When Glutaraldehyde was added into sequentially, the tensile strength of the film decreased tardily; the tensile strength of sample from 5th to 7th(30%PVA) increased firstly and then increased.9. The pure collagen film milky and opaque. After modification, the blend films are semitransparent and very flexile.10. The surface of collagen matrix composites are smooth. The blend films had low surface energy and good hydrophilic properties. The static contact angle of the compound films with different ratios ranged from 60oto 70o. |
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