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101.
以水为发泡剂,普通玉米淀粉为原料,采用双螺杆挤出机制备淀粉泡沫材料,研究了发泡剂用量及聚乙烯醇的加入量对泡沫材料结构与性能的影响。 用扫描电子显微镜观察了泡沫材料截面的形态,用万能材料试验机测试了泡沫材料的力学性能。 结果表明,水的质量分数为8%时淀粉泡沫径向膨胀率和发泡倍率最高,分别为22倍和17.6倍,压缩模量最高(4.07 MPa)。 加入质量分数10%的聚乙烯醇(PVA)使淀粉泡沫的孔径变大至1.29 mm,壁厚增加至82.43 μm,同时压缩模量增加至9.70 MPa。 相似文献
102.
103.
Morphology and mechanical properties of poly(vinyl alcohol) and starch blends prepared by gelation/crystallization from solutions 总被引:1,自引:0,他引:1
In an attempt to produce biodegradation materials, poly(vinyl alcohol) (PVA)–starch (ST) blends were prepared by gelation/crystallization
from semidilute solutions in dimethyl sulfoxide (Me2SO) and water mixtures and elongated up to 8 times. The content of mixed solvent represented as Me2SO/H2O (volume percent) was set to be 60/40 assuring the greatest drawability of PVA homopolymer films. The PVA/ST compositions
chosen were 1/1, 1/3, and 1/5. The elongation up to 8 times could be done for the 1/1 blend but any elongation was impossible
for blends whose ST content was beyond 50%. When the blends were immersed in water at 20 or 83 °C, the solubility became considerable
for an undrawn blend with 1/5 composition and a drawn 1/1 blend with λ=8. To avoid this phenomenon, cross-linking of PVA chains
was carried out by formalization under formaldehyde vapor. Significant improvement could be established by the cross-linking
of PVA chains. For the 1/1 blend, the amount of ST dissolved in water at 23 °C was less than 3% for the undrawn state and
25% for the drawn film. The decrease in the ST content was enough for use as biodegradation materials. Namely, the water content
relating to the biodegradation in soil is obviously different from such a serious experimental condition that a piece of blend
film was immersed in a water bath. At temperatures above 0 °C, the storage modulus of the formalization blends became slightly
higher than those of the nonformalization blends. The Young's modulus of the drawn films with a draw ratio of 8 times was
2 GPa at 20 °C.
Received: 23 June 2000 Accepted: 30 October 2000 相似文献
104.
于媛 《新疆大学学报(理工版)》2000,17(1):61-64
通过对美国硬红冬麦粉与新疆小麦粉的比较研究,找到了新疆小麦粉的主要特征及弱点,并针对性地制订了改良方案,为研制新疆的面条专用粉提供了新方法。 相似文献
105.
Giordano Raquel L. C. Hirano Paulo C. Gonçalves Luciana R. B. Netto Willibaldo Schmidell 《Applied biochemistry and biotechnology》2000,84(1-9):643-654
This article presents a detailed study on the conditions for achieving a stable biocatalyst to be used in the production of
ethanol from starch. Different pellets were used depending on which characteristic of the biocatalyst was being studied: (a)
Saccharomyces cerevisiae entrapped in pectin or calcium alginate gel particles; (b) silica containing immobilized glucoamylase entrapped in pectin
gel particles; or (c) pectin gel particles, with the silicaenzyme derivative and yeast coimmobilized. The influence of several
variables on the mechanical resistance of the particle, on the viability of the microorganism, and on the rate of substrate
hydrolysis was studied with biocatalyst. The best conditions found were 6% pectin gel, 2-mm particle diameter, and curein
0.2 M CaCl2·2H2O/60 mM acetate buffer, pH 4.2, for gel preparation; and 6.0 g/L of CaCl2·2H2O in the fermentation medium. Biocatalyst (c) was successfully tested for the production of ethanol from liquefield manioc
flour syrup. 相似文献
106.
交联-羧甲基复合变性淀粉的流变与降失水性能 总被引:6,自引:0,他引:6
以马铃薯淀粉和氯乙酸为主要原料,通过交联-醚化制备了交联-羧甲基复合变性淀粉(CCMS),考察了所得CCMS糊液的流变性能和在钻井泥浆中的降滤失水性能,并对其降失水原理进行了探讨。结果表明,在质量分数为0.5%~4.0%、温度为20~60℃的实验条件下,CCMS糊液表现为假塑性流体特征,符合Ostwald-Dewaele的经验公式ηa=Kγn-1;将CCMS与中粘羧甲基纤维素(MV-CMC)进行对比实验,结果发现,在饱和盐水泥浆和4%盐水泥浆中,当其用量分别为MV-CMC质量分数的57%和75%时,就可达到钻井液用MV-CMC的增粘、降滤失水性能指标。 相似文献
107.
以1-乙基咪唑为原料,采用discover环形单模聚焦微波合成仪合成了1-乙基-3-羧甲基咪唑四氟硼酸盐离子液体,对产品结构进行了表征及热性分析,并测定了粘度、密度、表面张力、电化学窗口等物化性能,同时考察了合成离子液体对淀粉的溶解性能.结果表明,单模聚焦微波辐射合成具有速度快、时间短、反应条件温和等优点,产品产率为88.23%,其密度、粘度、表面张力与温度均呈线性关系,且随温度升高而减小.与水溶剂相比,合成的离子液体对可溶性淀粉具有较高的溶解度,为淀粉及其衍生物的均相衍生化反应提供了理论基础. 相似文献
108.
羟乙基丙烯酸酯(HEA)进行游离基型聚合,生成聚羟乙基丙烯酸酯(PHEA)的研究已有报道,但有关该化合物氢转移聚合反应仅有Saegusa等进行过研究,而在钠催化下的氢转移聚合反应却未见报道。本文研究了HEA在钠作用下的氢转移聚合反应,用IR、NMR、VPO和元素分析等手段研究了它的结构和分子量,讨论了反应机理。 相似文献
109.
110.
William J. Orts Geoffrey A. R. Nobes Gregory M. Glenn Gregory M. Gray Syed Imam Bor‐Sen Chiou 《先进技术聚合物》2007,18(8):629-635
Blends of thermoplastic starch with poly(ethylene‐co‐vinyl alcohol) copolymer (EVOH) were melt extruded with water/glycerol as plasticizer and a series of amino acid additives. The biggest factor in end‐use mechanical properties proved to be the relative humidity (RH) during storage. Plasticized starch‐EVOH blends stored at 0 and 50% RH changed significantly over time, with, for example, the tensile strength (TS) of the glycerol‐plasticized blend increasing from 4.7 to 26.3 MPa over 8 weeks when maintained at 0% RH. In contrast, the TS of this same sample stored at 75% RH remained unchanged for 8 weeks. Amino acids provided relatively minor, but significant changes in mechanical properties with time. Based on TS, elongation‐to‐break, and modulus, it may be concluded that β‐alanine, sarcosine, and L ‐proline were more effective than glycerol at maintaining strong flexible blends. Increases in crystallinity and changes in morphology with time, as described by modulated DSC were correlated to these changes in mechanical properties. Published in 2007 by John Wiley & Sons, Ltd. 相似文献