【作者】 陈洁；

【导师】 盛奎川；

【作者基本信息】 浙江大学 ， 生物系统工程， 2012， 硕士

【摘要】 玉米醇溶蛋白作为生物可降解材料的开发与应用越来越受到人们的重视。国内外研究者针对玉米醇溶蛋白开发了生物膜等新型材料,然而,其物理力学性能相对传统的石油基产品较差,性能受环境参数影响较大。因此,研究开发玉米醇溶蛋白利用新技术,拓展其应用途径已成为当前的一个重要研究课题。本文主要研究玉米醇溶蛋白与竹粉复合材料的制备工艺及性能,探讨超高压改性对玉米醇溶蛋白的粘结性、流变性、热特性和微观形态的影响,并研究竹粉的颗粒大小,以及不同浓度NaOH溶液预处理对复合材料性能的影响,最后分析板坯含水率、成型温度、成型时间等工艺参数对玉米醇溶蛋白与竹粉复合材料物理力学性能的影响。主要结论如下：(1)随着压力的增加(100、200、300、400、500、600 MPa),玉米醇溶蛋白与竹粉复合材料的力学性能指标,如静曲强度、弹性模量和抗拉强度均先增加后下降,当压力为400 MPa时,各项力学性能指标最大,分别达到28.4 MPa、2752.58 MPa、15.7 MPa; 2h厚度膨胀率则先下降后增加,当压力为500 MPa时,复合材料的2h厚度膨胀率最小,为5.6%。(2)玉米醇溶蛋白经超高压处理后具有假塑性流体特性,呈现“剪切变稀”现象。超高压压力、剪切温度和剪切速率对玉米醇溶蛋白的流变性有显著影响。随着压力增大,溶液黏度呈现先增加后减小再增加的趋势,当压力为400 MPa时,黏度最高；随着剪切温度的增加,溶液黏度呈现先下降后增加的趋势,当温度为40℃时,黏度最低；随着剪切速率的增加,溶液的黏度降低,但当剪切速率接近100 s-1时,黏度变化不明显。玉米醇溶蛋白粉在400 MPa压力处理后,变性温度Tm升高,蛋白质的热稳定性提高；热焓△H减小,蛋白质分子的聚集程度增大；DSC显示变性峰有变宽的趋势,蛋白质的协同性降低。玉米醇溶蛋白溶液在400 MPa压力处理后,SEM显示蛋白颗粒凝聚成环状或者链状结构。(3)竹粉颗粒大小(20、40、60、80、100目)和NaOH溶液预处理(1%、2%、3%、5%、10%)对复合材料物理力学性能有明显影响。当竹粉颗粒大小为60目时,复合材料的静曲强度和弹性模量达到最大,分别为28.72 MPa和2669.75 MPa;当竹粉颗粒大小为40目时,复合材料的抗拉强度达到最大,为17.5 MPa;当竹粉颗粒大小为80目时,复合材料的2h厚度膨胀率最小,仅为5.8%。随着NaOH浓度的增加,复合材料的静曲强度和弹性模量分别呈现先增大后减小的趋势,2%NaOH预处理的复合材料静曲强度达到最大,为28.84 MPa;3%NaOH预处理的复合材料弹性模量达到最大,为2913.03 MPa; NaOH浓度为2%时,复合材料的抗拉强度达到较高值,为14.5 MPa；处理后的复合材料较未处理的2h厚度膨胀率显著降低,1%时达到最小值,为6.78%。(4)获得含水率及工艺条件对复合材料性能影响的规律,优选出性能较佳的成型工艺条件。结果表明：当板坯含水率X1为14%,成型温度X2为175℃,成型时间X3为12 min时,复合材料的静曲强度Y1达到最大,理论值为31.86 MPa,弹性模量Y2达到最大,理论值为3139.36 MPa;当板坯含水率X1为14%,成型温度X2为170℃,成型时间X3为15 min时,复合材料的抗拉强度Y3达到最大,理论值为15 MPa;当板坯含水率X1为16%,成型温度X2为170℃,成型时间X3为5 min时,复合材料的2h厚度膨胀率Y4达到最小,理论值为11%。更多还原

【Abstract】 The development and application of zein as bio-composites attract more and more attention. Lots of new bio-composites based on zein are developed, such as zein films. However, the physical and mechanical properties are relatively poor compared with traditional petroleum-based products, and their performance is affected by environmental conditions greatly. Therefore, developing effective ways for the utilization of zein has become one of the important research subjects. This study used zein and bamboo powder to generate the composites, discussed the influence of the high pressure on adhesion properties, theological properties, thermal characteristics and micro-structure of zein. Meanwhile, this research explored the inflence of bamboo particle sizes and different NaOH aqueous solution concentrations on mechanical properties of composites, and finally invested the influence of process parameters, such as:moisture content of slab, molding temperature and time on mechanical properties of composites. The results were summarized as the following:(1) With the increase of the pressure (100,200,300,400,500,600 MPa), the modulus of rupture (MOR), modulus of elasticity (MOE) and tensile strength (TS) of composites first increased, and then decreased, when the pressure was 400 MPa, the adhesion properties reached their highest values of 28.4 MPa,2752.58 MPa,15.7 MPa respectively; 2h thickness swelling (2h-ts) of composites first decreased, and then increased, when the pressure was 500 MPa,2h-ts reached their lowest values of 5.6%.(2) The zein solutions with high pressure treatment showed pseudoplastic fluid characteristic, with shear thinning phenomenon. As the pressure increased, the viscosity of solution first increased, and then decreased, and increased again, when the pressure was 400 MPa, the viscosity of solution reached the highest value. With the shear temperature increased, the viscosity of solution first decreased, and then increased, and reached the lowest value at 40℃. With the shear rate increased, the viscosity of solution reduced, and reached a plateau when the shear rate was close to 100 s-1. Zein powder were treated under 400 MPa pressure, denaturation temperature Tm increased and the thermal stability of zein improved; Heat enthalpy△H decreased, the hydrophobic properties and aggregation extent of protein molecules changed; The width of DSC melting peak under high pressure treatment broadened, proving the coordination of zein structure became lower. SEM showed that zein particles under 400 MPa pressure treatment condensed in ring or chain structure.(3) When bamboo particle size was 60 mesh, MOR and MOE of composites reached the highest value of 28.72 MPa and 2669.75 MPa; TS of composites reached the highest value of 17.5 MPa with 40mesh bamboo particle size.2h-ts of composites got the lowest value of 5.8% with 80 mesh bamboo particle size. With the increase of the NaOH aqueous solution concentrations (1%,2%,3%,5% and 10%), MOR and MOE of composites first increased, and then decreased. The value of MOR reached the highest of 28.84 MPa with 2% NaOH aqueous solution treatment on bamboo powder. The highest MOE value of composites was 2913.03 MPa with 3% NaOH aqueous solution treatment. The best TS of composites was obtained with 2% NaOH aqueous solution treatment, the value was 14.5 MPa. The lowest value of 2h-ts of composites was 6.78% with 1% NaOH aqueous solution treatment.(4) When the moisture content of slab (X1) was 14%, molding temperature (X2) was 175℃, molding time (X3) was 12 min. MOR (Y1) and MOE (Y2) of composites achieved maximum value of 31.86 MPa and 3139.36 MPa respectively; When the moisture content of slab (X1) was 14%, molding temperature (X2) was 170℃, molding time (X3) was 15 min, TS (Y3) of composites achieved maximum value of 15 MPa; When the moisture content of slab (X1) was 16%, molding temperature (X2) was 170℃, molding time (X3) was 5 min,2h-ts (Y4) of composites achieved lowest value of 11%.更多还原