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Preparation and Properties of PVA / collagen hydrolyzate / silica composite materials

Author: NieLei
Tutor: TangKeYong
School: Zhengzhou University
Course: Leather Chemistry and Engineering
Keywords: PVA/CH/SiO2 composite equilibrium degree swelling kinetics nitrogen content properties
CLC: TB332
Type: Master's thesis
Year: 2009
Downloads: 27
Quote: 0
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Abstract


In the paper,Poly（vinyl alcohol）/Collagen hydrolysate（PVA/CH） binary composite materials was synthesized.By the alcoholysis reaction of tetraethyl orthosilicate（TEOS）,SiO2 was obtained to be used to get the composite materials of Poly（vinyl alcohol）/Collagen hydrolysate/Silica（PVA/CH/SiO2）.The effect of testing methods on the swelling behavior of water absorbent polymer was studied.The mechanism of testing method on the swelling behaviors of materials was discussed. Quantitative analysis of the first swelling stage of the composite films was done.The equilibrium swelling degree and swelling kinetics of PVA/CH and PVA/CH/SiO2 composite films were completed.The effect of ultraviolet light（UV） irradiation on the swelling kinetics of binary and ternary composite films was also investigated. Furthermore,the dissolution of the both composite films in buffer solution was included.FT-IR,mechanical properties and SEM were all employed to get the information of structure and properties of composites.It was found that the swelling behavior of water absorbent polymer could be well reflected by multi-sample testing method.With the single-sample method,however, the swelling speed at the first stage was accelerated with the equilibrium degree not affected.The reason is that concentration differences by the alternative staying of samples in air and water might change the dynamic equilibrium among the three states of water molecules in the films.The Ma-t curves of water absorbent polymer fitted the exponential function of y = -a·ex/c + b with a reasonable confidence.Increasing the CH content of the composites may increase the equilibrium swelling degree of PVA/CH composite films,whilst the introduction of silica results in a remarkable decrease in swelling degree because silica changed the internal structures of PVA/CH/SiO2 composite films.The swelling kinetics curves of the both composites may be divided into two parts.The swelling speed was great at the first part,and the swelling curves tums to flat slowly at the second stage.Besides,the composites were dissolved in buffer solution and nitrogen content of films was measured,and the dissolution properties of binary and ternary composite films were studied.The results showed that the dissolution of CH in buffer solution can be hindered by silica.A longer staying in the buffer solution caused the dissolution of small molecules from the composites to decrease the swelling degree of the composites.The decreasing speed of PVA/CH composites materials was found faster than that of PVA/CH/SiO2 composites materials.The thermal degradation behavior of binary and ternary composite materials was also investigated by using thermo-gravimetric thermal analyzer（TG）.The Coats-Redfem method was employed to get the thermal degradation activation energy of the samples.It was found that the thermal degradation activation energy of PVA/CH composite materials decreases with increasing of the CH content,indicating that the composite is easy to be thermal degraded with the introduction of collagen hydrolysate.The thermal stability was improved with the addition of silica.FT-IR curves indicated that a series of peaks between 1000 and 1200 cm-1.They may be caused by the anti-symmetric stretching vibrations of Si-O-Si bridging sequences.The peak around 1200 cm-1 can be assigned to be the vibration mode of Si-C.With increasing of CH concentration,the elongation at break of both composites films increased,but the tensile strength of PVA/CH materials was affected obviously.The addition of silica increased the tensile strength and elongation at break of the composites.Increasing the CH content resulted in a decrease in tensile strength and an increase in elongation at break of PVA/CH/SiO2 composites materials.A very good compatibility between PVA and CH phases of the materials was found by the SEM pictures.The surface structure was changed by the addition of silica.

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