医用改性海藻纤维的制备及性能研究

选用海藻酸钠、仙鹤草为原料,添加一定量聚乙烯醇(PVA),配制共混纺丝液,采用湿法纺丝技术制备医用改性海藻纤维,并对其相关性能进行了测试。测试结果表明:添加了PVA和仙鹤草的海藻纤维与纯海藻纤维相比较,其干、湿态下的断裂强度和断裂伸长率均有所增加,纤维水浸液对水的pH值影响较小,纤维吸液能力增强,止血效果显著,抗菌性能符合国家标准。     

聚乙烯醇/聚丙烯酸/腐植酸钠高吸水性树脂的制备及溶胀行为

以N,N＇-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂,采用水溶液聚合法合成了聚乙烯醇/聚丙烯酸/腐植酸钠多功能高吸水性树脂。研究了聚乙烯醇和腐植酸钠含量对树脂吸水倍率的影响,同时考察了树脂的吸水速率、溶液pH值对吸水倍率的影响及反复溶胀性能。结果表明,在体系中引入廉价的腐植酸钠,能够显著提高树脂的吸水能力。在腐植酸钠含量为10wt%时,树脂具有最高的吸水倍率,其吸蒸馏水和0.9wt%NaCl溶液分别达到1020g/g和80g/g。     

Study on superabsorbent composites. XXI. Synthesis,characterization and swelling behaviors of chitosan‐g‐poly(acrylic acid)/organo‐rectorite nanocomposite superabsorbents

A novel chitosan‐g‐poly(acrylic acid)/organo‐rectorite (CTS‐g‐PAA/OREC) nanocomposite superabsorbent was synthesized by aqueous polymerization using N, N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Rectorite was organified with four different degree of hexadecyltrimethyl ammonium bromide, and the organification of rectorite was proved by FTIR and XRD. The effect of organification degree of rectorite on water absorbency of CTS‐g‐PAA/OREC with different organo‐rectorite content was investigated. The swelling behaviors in distilled water and various pH solutions were also studied. The results from IR spectroscopy and XRD data show that acrylic acid had been grafted polymerization with chitosan and organo‐rectorite and formed nanocomposite. Introducing organo‐rectorite into the CTS‐g‐PAA polymeric network can improved water absorbency and swelling rate of CTS‐g‐PAA/OREC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of potassium humate–acrylic acid–acrylamide hydrogel

A novel potassium humate–acrylic acid–acrylamide (KHA–AA–AM) superabsorbent polymer was prepared from the reaction among leonardite potassium humate, acrylic acid and acrylamide by free radical initiating process using ammonium persulfate as the initiator and N, N′-methylene bisacrylamide as the crosslinker. Various effects of synthesis conditions on superabsorbent polymer were studied and the optimal reaction condition was obtained with crosslinker concentration 0.44–0.74 wt%, initiator concentration 1.12–2.22 wt%, n(KOH)/n(AA) 0.51–0.70, monomer concentration 10.95–12.59 wt%, graft reaction temperature 83 ± 1°C, monomer mole ratio of acrylic acid to acrylamide 1.42–2.30, and potassium humate content 17.54 wt%. Under the optimal conditions, the solution absorbency of KHA–AA–AM superabsorbent polymer to deionized water, tap water, 0.5% carbamide solution and 0.9% NaCl solution were 733–756, 161–284, 786–825, and 76–83 g/g, respectively.     

Synthesis and Swelling Behavior of Superabsorbents Cross-Linked with N-Maleyl Chitosan

A kind of superabsorbent based on the monomers maleic anhydride (MA) and acrylic acid (AA) was prepared by solution polymerization using ammonium peroxodisulfate (AP) and sodium bisulfite (NaHSO₃) as initiator, and N-maleyl chitosan (N-MACH) as cross-linker. Effects of process parameters such as the amount of cross-linker, mass ratio of MA to AA, and neutralization degree of AA on the water absorbency of superabsorbents are discussed. The results indicated the water absorbency of superabsorbents increased and then decreased with the increase of MA content, the amount of the N-MACH cross-linker, and the neutralization degree of AA. Under the optimal conditions, the water absorbency of superabsorbents could reach l560.42 g/g and 83.7 g/g in distilled water and in 0.9% NaCl solution, respectively. In addition, to enhance the water absorbency of superabsorbents in 0.9% NaCl solution, polyvinyl alcohol (PVA) was introduced as interpenetrating polymer in the network and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) was introduced as comonomer. It was proved that PVA and AMPS could effectively improve the water absorbency of superabsorbents both in distilled water and 0.9% NaCl solution.     

3,5-二硝基水杨酸比色法测定溶液中还原糖的研究

据相关资料报道,在碱性溶液中3,5-二硝基水杨酸被还原糖还原生成的氨基化合物在540 nm波长下具有最大吸收,在此条件下该方法可测糖的适合浓度为3~4 mg/mL。而对其吸收光谱的测定研究发现,生成的氨基化合物在483 nm处有最大吸收,在该波长下测糖范围是0.1~1.0 mg/mL,并且测量的相对误差为2.2%。     

Cellulose mercerization: Use of amino acid‐glycerol ethers as wetting agents

The action of a new nonconventional series of (tryptophan‐phenylalanine‐histidine and tyrosine)‐glycerol‐ether surfactants as wetting agents in hot cotton mercerization was studied. The mercerization result was evaluated with the barium hydroxide absorption number, water absorbency and moisture regain, and mechanical properties of fibers; the dyeability of the mercerized samples with a direct and reactive dye was also studied. An improvement was observed for all the above parameters in the presence of the aforementioned wetting agents despite their being used in very low concentrations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

空气喷射变形丝的芯吸效应

利用毛细管上升法和液滴吸收法研究了聚酯、黏胶、聚酰胺、聚酯/黏胶和聚酯/聚酰胺空气喷射变形丝的芯吸率和吸湿率。结果表明,空气变形后复丝的芯吸率提高。与聚酰胺和黏胶空气喷射变形丝相比,聚酯空气喷射变形丝显示出较大的芯吸率。黏胶空气喷射变形丝显示出最低的芯吸率。与同样的未变形丝相比,混合的空气喷射变形丝显示出较大的芯吸率。     

嗜酸乳杆菌冻干影响因子的研究

传统的乳酸菌发酵剂因活化过程复杂,极易引起污染而影响发酵乳的质量。目前,多采用冷冻干燥技术制备直投式粉末状乳酸发酵剂。然而,菌种冻干时机的把握和冻干保护剂的选择,将直接影响乳酸菌在冷冻干燥前后的存活率以及存活期。本文研究了嗜酸乳杆菌的生长曲线,选用蔗糖、乳糖、甘油、VC、谷氨酸钠、麦芽糊精、脱脂乳粉等为嗜酸乳杆菌冻干保护剂进行了冻干研究。结果表明:①嗜酸乳杆菌发酵液培养至酸度为100°T、pH值4.8时,OD410nm=0.511为最大,是最佳发酵终止时间;②嗜酸乳杆菌冻干保护剂配方以5%麦芽糊精、2%VC、5%甘油为最佳冻干保护剂组合,此时嗜酸乳杆菌冻干菌粉活菌数为2.34×109cfu/g。     

粘胶基活性碳纤维新工艺研究

本文提出了一种制备活性碳纤维的新工艺———直接活化工艺和一个评价工艺质量的综合指标———有效得率。控制好反应条件 ,粘胶纤维能通过直接活化工艺制成外在和内在性能均良好的活性碳纤维 ,并能大幅降低生产成本。有效得率综合了活化得率与比表面积两个因素 ,能较好地反映生产工艺的优劣。经 6 0 0℃以上温度碳化处理后 ,催化剂基本上全部分解除去。当催化剂含量 >10 %时 ,粘胶纤维的活化得率、收缩率趋于稳定 ,有效得率有上升的趋势。两种工艺制作的产品有相同的化学结构 ,对甲苯和丙酮的吸附性能相近