多孔性交联淀粉絮凝剂的制备研究

以玉米淀粉为原料,先用a-耐高温淀粉酶处理,制备多孔玉米淀粉,然后以环氧氯丙烷(ECH)为交联剂,合成具有多孔结构的颗粒态交联淀粉絮凝剂,并对交联工艺进行了初步优化。制备多孔交联淀粉的最佳条件为:25 g多孔淀粉,碱性硫酸钠溶液用量50 mL,环氧氯丙烷用量0.75mL,反应温度25℃,反应时间18 h。     

壳聚糖膜的制备及其性能测试

以天然高分子材料壳聚糖为原料,采用流延法制备了壳聚糖膜。研究了N-乙酰化和交联壳聚糖膜的制备方法及性能特性等。通过FTIR、XRD和SEM方法表征结构,并测试了力学性能。试验结果表明交联和乙酰化可以增加壳聚糖膜的拉伸强度提高膜的性能。     

交联性聚乙烯基吡咯烷酮PVPP的制法及其应用

阐述了交联性聚乙烯基吡咯烷酮的制备方法,以及其在医药行业和其他行业的用途。     

交联壳聚糖微球纯化抑肽酶研究

采用反相悬浮法制备交联壳聚糖微球,共价偶联胰蛋白酶,制成抑肽酶亲和吸附剂,将其直接亲和层析牛肺粗提液,制备高比活抑肽酶。结果表明,制备的亲和吸附剂单位活力1270KIU·g-1,蛋白质偶联率52.4%,酶活性回收率50.8%。制备的抑肽酶比活力达5650KIU·mg-1,并且该吸附剂具有非特异性吸附小、能反复使用、机械强度高、活化简单、价格低廉等优点。     

交联透明质酸钠凝胶的制备工艺研究

以细菌发酵透明质酸(HA)为原料,在室温条件下采用二乙烯基砜(DVS)交联剂制备DVS-HA凝胶,为去除未反应的交联剂进行多方案实验,通过气相色谱法检测凝胶中残留交联剂含量,以期获得较优工艺方案,为进一步开发HA临床应用产品奠定了基础.     

甲氰菊酯的酶促降解

阴沟肠杆菌w10j15中提取到甲氰菊酯降解酶,测定了其对甲氰菊酯的降解特性。研究结果表明,降解酶在40℃、pH7 5时对甲氰菊酯显示最大的降解活性,对甲氰菊酯的降解率为65%。经实验测定,其每毫克酶蛋白质最大降解速率Vmax为48 08 nmol·mL-1·min-1,米氏常数(Km)为332 23 nmol·mL-1。     

脂肪酶N435对PBSA与PBSH的酶催化降解和分子模拟

分别采用2种酸1种醇和2种醇1种酸分别对聚丁酸丁二醇酯（PBS）改性,合成了不同化学结构的共聚酯聚（丁二酸丁二醇酯-co-己二酸丁二醇酯）（PBSA）和聚(丁二酸丁二醇-co-丁二酸己二醇酯)（PBSH）,并在磷酸缓冲液以它们为底物在磷酸缓冲液中,研究了对脂肪酶N435降解反应感受性的异同。采用质量损失率和凝胶渗透色谱评价了降解前后共聚酯相对分子质量的变化;广角X衍射仪和热重分析仪分析了酶降解前后共聚酯结晶度和热性质的变化;偏光显微镜对降解后的材料进行了形貌观测。结果表明,相比于PBS,PBSA和PBSH对脂肪酶的感受性有很大提高,24 h后降解率分别达到90 %和60 %以上,并且PBSA降解速率比PBSH快;降解后两种共聚酯相对分子质量变化不大,但相对分子量分布系数变宽,结晶度增大;降解3 d后PBSA的热稳定性降低,而PBSH的热稳定性提高。     

Mechanical,Water Absorption and Enzymatic Degradation Properties of Sago Starch Filled Linear Low Density Polyethylene

Abstract

Sago starch filled linear low density polyethylene (LLDPE) composites, have been prepared by melt mixing of the granular starch and LLDPE in a HAAKE internal mixer. The tensile, water absorption and enzymatic degradation properties of the composites have been determined. Incorporation of sago starch into LLDPE led to decrease in tensile strength and elongation at break of the composites. Up to 15 wt.% of sago starch could be added to LLDPE without adverse effects on the tensile properties. The water uptake increased with immersion time and the rate of absorption is strongly controlled by the immersion temperatures. Dramatic reduction in tensile properties were observed in the composites that were immersed in water at 90[ddot]C. The recovery of the tensile strength and elongation at break upon redrying is about 37.5 and 1.6% respectively. The permanent damage to the composites was attributed to severe hydrolysis of the starch particles. The enzymatic degradation study using oc-amylase revealed that both tensile strength and elongation at break reduced with time of treatment. Mode of failures of both LLDPE matrix and its sago starch filled composites, assessed by fracto-graphic analysis in a scanning electron microscope (SEM) are discussed.     

京尼平交联明胶多孔支架的制备及降解

采用天然交联剂京尼平,结合相分离技术与冷冻干燥方法,制备不同交联度的明胶多孔支架。结果表明,支架的交联度随着京尼平浓度的增加而升高,最高可以达到65．3％;不同交联度的明胶支架微观呈相互连通的多孔结构,且孔径随交联度的升高而降低;通过调控明胶支架的交联度,可以调控支架的降解时间。     

水溶性交联聚合物微球的制备及性能

采用反相微乳液聚合制备水溶性交联聚合物微球。交联比为0 1%、0 5%、1 0%时,微球平均粒径分别为74 9、151 8、214 9nm。水化时间由0增至144h时,微球平均粒径由106 7nm增大到189 5nm。盐质量分数由0增至0 5%时,微球平均粒径由202 7nm减小到93 5nm。微孔滤膜封堵性能随水化时间无明显变化,随盐质量分数的增加而明显降低。岩心封堵实验表明,交联聚合物微球对气测渗透率为3 058μm2的岩心的流动阻力可达120kPa。     

Fabrication of Polylactide‐Based Biodegradable Thermoset Scaffolds for Tissue Engineering Applications

The fabrication of tissue engineering scaffolds based on the polymerization of crosslinked polylactide using leaching and batch foaming to generate well‐controlled and interconnected biodegradable polymer scaffolds is reported. The scaffold fabrication parameters are studied in relation to the interpore connectivity, pore morphology, and structural stability of the crosslinked PLA scaffold. In vitro cell culture and in vitro degradation are used to analyze the biocompatibility and biodegradability of the scaffolds. The new crosslinked PLA thermoset scaffolds are highly suitable for bone tissue engineering applications due to their complex internal architecture, thermal stability, and biocompatibility.

     

Structural Properties and Enzymatic Degradation Behavior of PLLA and Stereocomplexed PLA Nanofibers

PLLA and stereocomplexed polylactide (sc‐PLA) nanofibers were formed by electrospinning solutions of the polymers in HFIP. A highly semi‐crystalline sc‐PLA nanofiber having only sc crystallites was confirmed by WAXD analysis. The diameters of the nanofibers of both polymers decreased slightly when they were annealed at 60 °C, which was near T_g. Enzyme degradation of both as‐spun PLLA and sc‐PLA nanofibers by proteinase K from Tritirachium album was carried out. The rate of degradation of the nanofibers can be controlled by varying annealing conditions, hence the extent of crystallinity.

     

Dissolution and Enzymatic Degradation Studies Before and After Artificial Ageing of Silk‐ or Linen‐Reinforced Gelatin Laminates, 2

Biodegradable laminates based on gelatin and on gelatin/starch blend reinforced with fabrics (silk or linen) were prepared by melt pressing. Due to crosslinking during the thermal treatment and in some cases, to additional crosslinking with methylenedi(p‐phenyl) diisocyanate, the fresh and artificially aged samples demonstrated improved mechanical properties, as reported previously. In Part 1 of this study on the environmental behavior of these new laminated composites, the simple dissolution in a buffer solution or water of fresh and artificially aged samples was considered. During this treatment soluble, i.e., uncrosslinked molecules were removed leaving a product resulting from addition reactions and consequent crosslinking. These processes take place during the melt pressing at 180 °C and cause a decreased solubility of gelatin. The present Part 2 deals with the enzymatic treatment of the same samples. We have implicitly shown that the gelatin moiety of the laminates undergoes proteolysis and that this process depends on the laminate composition. At the end of the treatment the enzymatic buffer solution contains only peptides and virtually no high‐molecular gelatin. The degrees of degradation vs. time dependencies differ for water and enzymatic treatment of the samples, indicating different processes in either treatment. The time‐course curves of the enzymatic treatment of different laminates and the kinetic parameters derived therefrom were analyzed. Thereby the effect of many factors on the accessibility of the gelatin moiety to proteolysis was shown. These factors are: temperature treatment, artificial ageing, the nature of the reinforcing fabrics, the “additional” crosslinking with methylenedi(p‐phenyl) diisocyanate, etc. The gelatin‐linen laminate is the most sensitive to crosslinking. There is a tendency that the crosslinking smears the differences in the time‐course of the absorption behavior curves of the different samples.

Degree of degradation, β′, (related to only the gelatin) vs. time, t, for laminates: (a) uncrosslinked gelatin‐linen; (b) crosslinked gelatin‐linen; (c) uncrosslinked gelatin‐silk; (d) crosslinked gelatin‐silk.     

聚乙二醇嵌段长碳链二酸共聚物的合成与酶降解研究

采用长碳链癸二酸代替丁二酸与丁二醇以及不同含量的相对分子质量为200的聚乙二醇(PEG)嵌段共聚,得到了聚癸二酸丁二醇酯聚乙二醇嵌段共聚物(PBSe-PEG),并采用核磁共振波谱仪、凝胶渗透色谱仪、差示扫描量分析仪、热重分析仪、广角X射线衍射仪等分析手段表征了嵌段共聚物的结构和性能,并且研究了固定化南极假丝酵母菌脂肪酶(简称脂肪酶N435)对PBSe-PEG的降解性。结果表明,几种PBSe-PEG是预期产物,其数均相对分子质量在5×104左右;PBSe-PEG与纯PBSe相比晶型结构相似;随着PEG含量增加,PBSe-PEG的熔融温度（Tm）和结晶温度（Tc）逐渐下降;相比PBS,脂肪酶N435对PBSe-PEG具有更好的降解性。     

单分散多孔聚合物微球的制备及其反相色谱应用

用分散聚合的方法制得单分散微米级聚苯乙烯微球(PS),以此聚苯乙烯微球作为种子,以邻苯二甲酸二丁酯为溶胀剂,苯乙烯为单体,二乙烯基苯为交联剂,甲苯为致孔剂,采用种子溶胀聚合的方法制得粒径分布较窄的多孔高交联的聚苯乙烯-二乙烯基苯微球(PS-DVB)。研究了交联剂与致孔剂的加入量对微球形貌、粒径及孔结构参数的影响。结果表明,所得多孔微球球形圆整,库尔特测得平均粒径为5.067~5.520μm,粒径分布窄,D90/D10为1.23~1.56,孔结构可控,并以此多孔微球作为反相色谱填料基质,理论塔板数每米可达6 000~15 000,可以用作高效液相色谱(HPLC)填料。     

悬浮聚合法制备PGMA-MMA-EGDMA共聚物交联微球

以甲基丙烯酸缩水甘油酯(GMA)为主单体、甲基丙烯酸甲酯(MMA)为共单体、乙二醇二甲基丙烯酸酯(EGDMA)为交联剂、聚乙烯醇(PVA)为分散剂,采用悬浮聚合法制备了三元共聚交联微球GMA-MMA-EGDMA,采用FT-IR和SEM对其化学结构和微球进行了表征,考察了分散剂用量、搅拌速度、油/水相比、交联剂用量、NaCl用量对交联微球的成球性能及粒度的影响规律. 结果表明,分散剂用量、搅拌速度与油/水相比是影响交联微球制备的主要因素,当分散剂用量<1%、搅拌速度<250 r/min、油/水相比>1:4(j)时,共聚合体系中均不能成球. 在水相中加入电解质NaCl有助于成球,交联微球的粒径随NaCl用量增大而减小. 控制悬浮聚合的反应条件可以制备出球形度好、粒径在100~400 mm范围内可控的交联微球GMA-MMA-EGDMA.     

Enzymatic Desizing of Polyvinyl Alcohol from Cotton Fabrics

Enzymatic degradation of polyvinyl alcohol (PVA) was used for the desizing of cotton fabrics. A mixture of two different PVA-degrading enzyme activities, including PVA oxidizing, was partially purified from the culture filtrate of a PVA-degrading mixed culture by ionic exchange chromatography. Optimum conditions for PVA-degradation by using this enzyme mixture were pH 8·0 and temperatures ranging from 30°C to 55°C. Cotton fabrics sized with a PVA solution (25 g dm⁻³) were desized with the enzyme mixture after a 1 h treatment at 30°C and pH 8·0. In this case, similar amounts of residual PVA in fabrics were detected in comparison with the conventional desizing process which uses hot water (80°C, 30 min). Minimum amounts of residual PVA were found when the enzymatic desizing time was extended to 6 h. Also, the PVA content in the liquid waste from the enzymatic desizing carried out during 4 h was negligible with a 7·4-fold increase in the biochemical oxygen demand as compared with the initial value. © 1997 SCI.     

交联聚乙烯的生产技术及应用

介绍了交联聚乙烯的3种工业化生产技术及其在电线电缆、管材、泡末塑料等领域的应用。     

地聚物多孔轻质高强材料的制备及孔结构特性

为了解决地聚物多孔材料质轻与高强难以取得一致性的问题,本文采用正交试验,对粉煤灰地聚物多孔材料表观密度和强度进行试验,在此基础上,利用超细矿渣粉的独特性,对双氧水发泡剂及辅助稳泡材料进行了优选,制备出抗压强度达到5.9 MPa、表观密度仅为557 kg/m3的地聚物多孔材料.结果表明:当粉煤灰/矿渣比例为1:1,双氧水掺量为2.0％,硬脂酸钙掺量为1.0％,MnO2掺量为0.3％,制备的矿渣-粉煤灰基地聚物多孔材料可以达到质轻高强的目的.采用XRD、SEM和低场核磁共振技术对多孔材料进行了微观测试,并对其抗压强度、表观密度与孔结构之间关系进行了分析.     

细菌纤维素纳米支架材料生物酶解的初步研究

对细菌纤维素的纤维素酶解进行了单因素实验研究,探讨了酶用量、酶解时间及酶解温度等工艺条件对细菌纤维素酶解程度的影响.结果表明:在0.6%～1.6%的酶用量范围内,细菌纤维素的降解程度随酶用量的增加而提高;在0.4%～1.2%的酶用量范围内,细菌纤维素的降解程度随酶解时间的延长而提高,但是在后期增加的程度有所降低;在1～7 d的酶解时间内,细菌纤维素的降解程度随酶解时间的延长而不断提高;在45～55℃的酶解温度范围内,细菌纤维素的降解程度随温度升高呈先升后降的趋势,较适温度为50℃.