钻井液用交联-接枝淀粉的制备及性能

以N,N′-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,采用“溶剂法”工艺合成了高粘度抗剪切丙烯酸钠接枝淀粉(St),考察了单体、引发剂和交联剂用量、丙烯酸中和度、反应时间及反应温度对合成交联丙烯酸钠接枝淀粉糊液粘度的影响。 结果表明,其优化反应条件为：m(淀粉)∶m(丙烯酸）=1∶1.5,乙醇质量分数为80%,过硫酸铵的用量为单体总质量的1%,交联剂为单体总质量的0.6%,反应时间2.5 h,反应温度为55 ℃,丙烯酸中和度为70%。 该交联接枝淀粉糊液具有良好的触变性,在4%盐水泥浆中的添加量为14.0 g/L时,表观粘度为26.0 mPa·s,滤失量为7.2 mL;在饱和盐水泥浆中添加量为23.5 g/L时,表观粘度为54.5 mPa·s,滤失量为3.1 mL;在80 ℃高温下老化16 h其表观粘度及滤失量等性能基本保持不变,表现出良好的增粘、降失水作用和抗盐、抗老化性能。     

化学交联聚乙烯醇降失水剂的交联度与性能探究

化学交联聚乙烯醇的交联度显著影响其降失水剂的性能及应用,通过调节交联度可以使降失水剂达到所需的效果。本文选择戊二醛作为交联剂与聚乙烯醇反应,探究了反应温度、酸浓度、聚乙烯醇在共聚体系中的质量分数、戊二醛与聚乙烯醇摩尔比对聚乙烯醇交联度的影响。通过运用均匀设计方法,得出60℃、80℃、100℃的最佳交联度为1.29%、1.46%、1.29%,对应的最佳工艺条件为反应温度50℃,酸浓度0.96 mol·L~(-1),聚乙烯醇在共聚体系中的质量分数6%,戊二醛与聚乙烯醇摩尔比1.60/1.68。加有降失水剂的水泥浆的API滤失量均在50 m L以下,且流变性能良好。根据均匀设计方法得出结论,戊二醛与聚乙烯醇摩尔比对聚乙烯醇交联度的影响最大,应重点控制其数值以达到所需交联度。     

交联羧甲基淀粉预富集-悬浮体进样-石墨炉原子吸收法测定水样中铬(Ⅲ)和铬(Ⅵ)

以交联羧甲基淀粉(CCMS)为吸附剂,悬浮体进样-石墨炉原子吸收法(GFAAS)测定环境水样中Cr(Ⅲ)和Cr(Ⅵ)形态。研究了溶液pH值、吸附时间、溶液体积、共存离子等对CCMS吸附Cr(Ⅲ)和Cr(Ⅵ)的影响。结果表明:在pH=6.0时,吸附15 min,CCMS可以选择性地吸附Cr(Ⅲ),对Cr(Ⅵ)不吸附,从而实现Cr(Ⅲ)和Cr(Ⅵ)的分离。将吸附Cr?的CCMS加0.1%的琼脂制成悬浮体直接进石墨炉检测,用1 mL 1%盐酸羟胺将Cr(Ⅲ)还原成Cr(Ⅵ),测总铬。方法对Cr(Ⅲ)的检出限为0.044μg/L,相对标准偏差(RSD)为10.4%(初始浓度CCr(Ⅲ)=1.0μg/L,n=11),富集倍数为50倍。将本方法应用于环境标准样品的测定,测得结果与标准值相符。     

交联羧甲基红薯淀粉降低水中Ca~(2+)含量的研究

以环氧氯丙烷为交联剂,氯乙酸为羧甲基化试剂,合成交联羧甲基红薯淀粉并且研究其降低水中的Ca2+含量的效果.结果显示,交联羧甲基红薯淀粉吸附ca2+的适宜条件为,淀粉取代度0.721、2%淀粉用量、pH 8,吸附时间30min、吸附温度70℃下,交联羧甲基红薯淀粉对水中Ca2+的吸附量可达4.53mmol/L,Ca2+清除率为75.33%.交联羧甲基红薯淀粉吸附Ca2+的行为遵从Langmuir等温吸附方程.     

交联羧甲基壳聚糖对铅离子的吸附研究

以壳聚糖为原料,先在氨基上引入羧甲基制备出N-羧甲基壳聚糖,再和环氧氯丙烷发生交联反应,合成出新型交联羧甲基壳聚糖,FTIR表征其结构。研究了交联羧甲基壳聚糖对Pb2+的吸附性能,探讨了交联剂用量、铅离子溶液的pH值、温度、吸附时间等因素对其吸附性能的影响,并考察了交联羧甲基壳聚糖对铅离子吸附动力学和热力学实验。实验结果表明,交联羧甲基壳聚糖对铅离子的吸附量优于壳聚糖,平衡吸附量可达297.6 mg/g。交联羧甲基壳聚糖对铅离子的吸附符合准二级动力学模型和Langmuier等温吸附,吸附主要依靠结构中的羧基和氨基基团。     

兼有缓蚀与降粘性的聚丙烯酸咪唑啉制备及其性能评价

以原料聚丙烯酸和二乙烯三胺合成聚丙烯酸咪唑啉,利用红外光谱和元素分析对其进行了表征。采用旋转挂片和电化学Tafel极化曲线法评价了其缓蚀性能,采用旋转粘度计测试了其降粘性能。实验结果表明,原料酸胺质量比为3:1时,当产物浓度为0.40g/L,测试时间20min时,产物缓蚀率可达到87.58%,明显优于原料聚丙烯酸;70℃,聚丙烯酸咪唑啉的加入量为100μg/g时,产物对江苏油田韦5-57原油的降粘率为82.21%,净降粘率高于原料聚丙烯酸和丙烯酸十八酯-苯乙烯-马来酸酐聚合物降粘剂的净降粘率。     

用于压裂液改性的耐高温锆硼交联剂的制备及评价

通过优化实验,得到了用于压裂液改性的耐高温锆硼交联剂的最佳条件,即以质量分数为0.5%的二氧化锆乳状液用量为基准,其它试剂用量为:质量分数为4%硼砂,体积分数为50%丙三醇,反应时间为5 h,反应温度60℃,乙酰丙酮体积分数为8%,三乙醇胺体积分数40%。采用傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)和高温流变仪等技术手段表征了产物的结构和性能。结果表明,在交联比为0.5%下,耐高温锆硼交联剂与0.6%的羟丙基胍胶(HPG)基液形成的交联冻胶在160℃、170 s~(-1)的测试条件下恒速剪切2 h,剪切后冻胶的黏度最后保持130 mPa·s以上,弹性模量明显大于粘性模量,表现出良好的应用前景。     

一种新型交联羧甲基葡甘聚糖微球对Cr(Ⅵ)的吸附性能研究

通过Fe3+交联羧甲基葡甘聚糖制得了一种新型羧甲基葡甘聚糖凝胶球,研究了羧甲基葡甘聚糖铁凝胶球对Cr(Ⅵ)的吸附性能。分别考察了吸附时间、羧甲基葡甘聚糖浓度、FeCl3浓度、pH值、温度、Cr(Ⅵ)浓度和微球粒径对吸附的影响,同时用红外光谱初步表征了羧甲基葡甘聚糖铁凝胶球-Cr(Ⅵ)复合物的结构。结果表明,293K时,微球对Cr(Ⅵ)的吸附反应在12h时达平衡,当羧甲基葡甘聚糖质量分数为1.0%,FeCl3质量分数为1.0%,Cr(Ⅵ)浓度为400mg/L时,吸附量达到0.4385mmol/g。根据不同温度下微球吸附Cr(Ⅵ)的等温线,计算了吸附过程的热力学参数,同时用Freundlich方程对实验数据进行了拟合,发现该方程适用于所研究的吸附体系。该体系为自发放热过程,体系熵减少,降温有利于吸附。     

丙烯酸/2-丙烯酰胺基-2-甲基丙磺酸高吸水树脂的反相悬浮聚合及其性能

采用反相悬浮聚合法,通过均匀实验设计,制备了聚(丙烯酸(AA)/2-丙烯酰胺基-2-甲基丙磺酸(AMPS)）(PAAMPS)高吸水树脂,探讨了单体摩尔分数及其中和度、引发剂及交联剂摩尔分数（相对于单体总量）对蒸馏水、质量分数0.9%NaCl水溶液中吸液性能的影响,并经实验数据拟合,得到了二次回归方程,比较了优化配方、单因素实验的模拟值和实验值,结果表明,模拟值与优化值基本接近,其优化工艺参数为：AMPS占单体的摩尔分数8%,中和度为75%,交联剂、引发剂用量与单体的摩尔分数分别为0.035%和0.17%,单体总质量浓度为30%,分散剂用量为单体质量分数的0.5%,反应温度70 ℃,反应时间1.5 h。 此条件下合成的PAAMPS在蒸馏水、0.9%NaCl水溶液中的吸液倍率分别为1.600和130 g/g。     

壳聚糖辅助剥离石墨烯应用于增强聚乙烯醇薄膜

本文以石墨粉为原料,羧甲基壳聚糖(CS)作为助剥离剂和稳定剂,通过湿法机械球磨剥离出具有良好分散性的石墨烯,放置5个月仍无沉降.使用XRD,UV-Vis和SEM等表征手段对其剥离情况及形貌进行分析.并进一步将其作为增强填料改性PVA薄膜,采用流延法制备出一系列不同比例的石墨烯-羧甲基壳聚糖/PVA复合膜,通过SEM、拉伸性能、透湿性能以及透光率等测试对其结构和性能进行分析.结果表明:利用羧甲基壳聚糖成功剥离出大片分散性良好的石墨烯,石墨烯在PVA薄膜中分散均匀,具有良好的相容性.2 g·L~(-1) CS浓度下,石墨烯分散液添加量体积分数为20%时,复合膜的性能得到最大改善,此时拉伸强度为113.26 MPa(相较于纯PVA膜提升了150%),断裂伸长率为128.3%,透光率和雾度分别为91.78%和0.22%,同时其水蒸气透过系数为2.70×10~(-13) g·cm·(cm~2·s·Pa)~(-1),阻湿性良好.     

Thermal stability and degradation of starch derivatives

Thermal behaviour of different starch derivatives, i.e. starch esters and ethers having degree of substitution (DS) in the range of 0.02–0.18 were studied. Potato, maize and wheat starches were used. Measurements were carried out by coupled thermal analysis/ mass spectrometry method (STA-MS) in air atmosphere. The major DTG peak during the investigation for starch derivatives is observed below 300°C. The mass loss up to a temperature of 300°C is about 50%. The most abundant ions found areH₂O⁺ and CO₂ ⁺. For the studied starch derivatives with a low degree of substitution (DS<0.18) no correlation was found between thermal stability and the level of substitution regardless of the nature of substitution.     

Starch Formates: Synthesis and Modification

Starch can be efficiently converted into the corresponding formates homogeneously using N-formyl imidazole obtained by the reaction of 1,1′-carbonyldiimidazole and formic acid in dimethyl sulfoxide as a solvent. Starch formates are soluble in polar aprotic solvents, not susceptible against hydrolysis, and not meltable. Thermoplastics could be generated by conversion of starch formates with long-chain fatty acids exemplified by the conversion with lauroyl chloride in N,N-dimethylacetamide, leading to mixed starch laurate formates. The mixed esters show melting temperatures mainly dependent on the amount of laurate ester moieties.     

Starch Granule Size and Morphology of Arabidopsis thaliana Starch-Related Mutants Analyzed during Diurnal Rhythm and Development

Transitory starch plays a central role in the life cycle of plants. Many aspects of this important metabolism remain unknown; however, starch granules provide insight into this persistent metabolic process. Therefore, monitoring alterations in starch granules with high temporal resolution provides one significant avenue to improve understanding. Here, a previously established method that combines LCSM and safranin-O staining for in vivo imaging of transitory starch granules in leaves of Arabidopsis thaliana was employed to demonstrate, for the first time, the alterations in starch granule size and morphology that occur both throughout the day and during leaf aging. Several starch-related mutants were included, which revealed differences among the generated granules. In ptst2 and sex1-8, the starch granules in old leaves were much larger than those in young leaves; however, the typical flattened discoid morphology was maintained. In ss4 and dpe2/phs1/ss4, the morphology of starch granules in young leaves was altered, with a more rounded shape observed. With leaf development, the starch granules became spherical exclusively in dpe2/phs1/ss4. Thus, the presented data provide new insights to contribute to the understanding of starch granule morphogenesis.     

Synthesis and Properties of Novel Hydrogels from Cross-linked Starch Phosphates

Summary: Starch based stable hydrogels providing high swelling and water storing capacity are not only of certain interest for the cosmetics and hygiene industry but also have the potential to become an effective tool in combating desertification and supporting cultivation in many regions of the world. It has been found that strong water adsorbing covalent networks with free swelling capacity (FSC) of up to 190 g water/g hydrogel can be obtained by cross-linking low-substituted mono-starch phosphates (MSP) in a semi-dry process with di- and tricarboxylic acids such as succinic acid (SA), adipic acid (AA) or citric acid (CA). The linear behaviour over a wide frequency range of the rheological parameters G′ and G″ which were determined by using a shearing disc viscosimeter clearly reveal that the cross-linked starch phosphates are stable hydrogels having stronger elastic than viscous properties.     

热塑性淀粉力学性能的提升途径及作用机理

以可再生资源(如淀粉、纤维素和蛋白质等)为基础发展而来的生物可降解塑料受到人们越来越多的关注,是可降解塑料行业发展的重要方向之一。天然淀粉由于来源广、低成本和可生物降解的特点,广泛用于制备淀粉塑料,并用于农业、食品、医药和包装等行业,有望取代石油基衍生聚合物。淀粉大分子具有结晶结构,所含大量羟基可形成较强的分子间和分子内氢键,使其不能热塑加工,而当加入增塑剂后可破坏其结晶结构,从而用于制备热塑性淀粉。目前,热塑性淀粉的力学性能差,是影响其使用性能的首要问题。近年来国内外开展了大量的研究以试图增强其力学性能。本文主要以不同类型的热塑性淀粉为基础,以淀粉自身改性和外加组分改性两种提高其力学性能的途径为主线,以其力学性能的提升方法和作用机理为重点,系统总结了近年来国内外以提高热塑性淀粉材料的力学性能为目的的研究工作,归纳了影响力学性能的相关因素以及提升途径,并对该领域重点研究的内容进行了总结和展望。     

Mechanical properties and enzymic degradation of thermoplastic and granular sago starch filled poly(ε-caprolactone)

The mechanical, morphological and biodegradation properties of two types of poly(ε-caprolactone)/sago starch (PCL/sago) composites were investigated i.e. dried granulated sago starch and undried thermoplastic sago starch (TPSS). Thermoplastic starch was extruded with a twin screw extruder model Haake Rheomix (TW100 attached to a Haake Rheometer (Haake Rheodrive 5000). The composites were compounded with a Haake internal mixer (Haake Rheomix 3000) attached to the Haake Rheometer. Tensile properties were determined with the Monsanto Tensometer T10. A Shimadzu UV-160A visible UV spectrophotometer was used to monitor the liberation of carbohydrate as a consequence of starch hydrolysis by α-glucoamylase. Determining the weight loss of composites as well as the acid liberated from PCL also monitored biodegradation. The results indicate that dried granulated sago starch function better as fillers in terms of mechanical properties and the ease of biodegradation. However, TPSS imparted better yield strength to the composites. Poor wetting of starch accounts for the decreased mechanical properties at higher starch concentration as agglomeration occurs. While the rigid granular starch retained their shape in the composites, thermoplastic starch that is surrounded by microvoids is easily deformed due to plasticization.     

Synthesis, thermal properties, and biodegradability of propyl-etherified starch

High amylose corn starch (HACS) was etherified with 1-bromopropane in dimethyl sulfoxide. The structure of the products was characterized by infra-red and ¹H-NMR spectroscopy. The degree of substitution (DS) on glucose unit calculated from ¹H-NMR spectrum was varied from 0.9 to 2.7 by changing feed ratio of 1-bromopropane to HACS. Thermogravimetric analysis reveals that the etherified HACS has a higher decomposition temperature than unmodified HACS. Differential scanning calorimetry analysis reveals that the etherified starch has a clear glass transition temperature which decreased with increasing DS, and that no melting point is observed. This result demonstrates that the etherified HACS mainly consists of amorphous region. The biodegradation rate decreases with increasing degree of etherification.     

3,5-二硝基苯甲酸淀粉酯的合成及应用

高分子吸附剂;3;5-二硝基苯甲酸淀粉酯的合成及应用     

Processing and characterization of waxy maize starch films plasticized by sorbitol and reinforced with starch nanocrystals

Nanocomposites films have been processed from a filler and a matrix having the same nature, i.e. waxy maize starch. The filler consists of nanoplatelet-like starch particles obtained as an aqueous suspension by acid hydrolysis of starch granules and the matrix was prepared by plasticization and disruption of starch granules with water and sorbitol. Nanocomposite films were obtained by casting and evaporating the mixture of the aqueous suspension of starch nanocrystals with the gelatinized starch. The resulting films were conditioned before testing and the effect of accelerated ageing in moist atmosphere was investigated. The thermal properties of the nanocomposite films were determined from DSC measurements and the mechanical characterization was performed in both the linear and nonlinear range.