键合胍盐低聚物的抗菌聚苯乙烯的制备及其抗菌活性

在Haake转矩流变仪中,将盐酸胍与己二胺的低聚物(PHMG)与末端带环氧基的遥爪型聚苯乙烯(PS)进行熔融反应,得到具有抗菌性能的聚苯乙烯(PS-PHMG)。红外(FT-IR)光谱证明胍盐低聚物是以化学键的形式键合到PS分子链上的。分别用扩散法和振荡瓶法测试了抗菌聚苯乙烯对大肠杆菌和金黄色葡萄球菌的抗菌性能。扩散法实验表明,经提纯后的PS-PHMG不存在胍盐低聚物的溶出,但对大肠杆菌和金黄色葡萄球菌均有明显的抑菌圈。振荡瓶法结果表明:当PS中w(PS-PHMG)=0.2%(即w(PHMG)=0.069%)时,与大肠杆菌接触30 mi m后,抑菌率达100%;当w(PS-PHMG)=0.1%(即w(PHMG)=0.035%)时,30 min内对金黄色葡萄球菌的抑菌率也能够达到100%,具有较好的抗菌速效性,杀灭细菌的时间小于30 min。     

三氟甲烷磺酸稀土盐对聚丙烯热稳定性的影响及机理

通过熔融共混将三氟甲烷磺酸镱[Yb(OTf)₃]和三氟甲烷磺酸镧[La(OTf)₃]添加至聚丙烯(PP)中, 制得PP/Yb和PP/La材料, 并对其热稳定性进行表征. 热失重分析(TGA)和差示扫描量热分析(DSC)结果显示, Yb(OTf)₃和La(OTf)₃均可以显著提高聚丙烯的热稳定性. 当Yb(OTf)₃添加量仅为1%(质量分数)时, PP的起始分解温度从275 ℃提高至305 ℃, 最大分解温度从384 ℃提高至405 ℃, 160 ℃下的氧化诱导时间从12.1 min延长至43.0 min, 热焓从1907 J/g降低至483 J/g; 而PP/La1的起始分解温度、 最大分解温度、 160 ℃下的氧化诱导时间和热焓分别为300 ℃, 409 ℃, 18.6 min和633 J/g. 结果表明, La(OTf)₃对聚丙烯热稳定性的改善作用弱于Yb(OTf)₃, 对2种稀土盐产生不同实验结果的原因进行分析并提出机制. 由于阴离子和阳离子的共同作用, Yb(OTf)₃和La(OTf)₃均可提高PP的热氧稳定性. La(OTf)₃中三氟甲烷磺酸根的自由基捕捉能力和稀土离子的配位能力发挥主要作用, 而Yb(OTf)₃中的稀土离子的高反应活性也起到关键作用.     

胍盐离子液体的研究进展

胍盐离子液体由于具有较高的热稳定性、化学稳定性和催化活性而受到关注. 总结了近年来胍盐离子液体的合成、性质和应用三个方面的研究进展.     

胍盐键合型聚氨酯涂料的制备及其抗菌防霉性能

采用化学键合的方式将聚六亚甲基盐酸胍(PHMG)键合到聚氨酯(PU)分子链上,制得抗菌PU涂料PU-PHMG。利用红外光谱(FT-IR)、阿贝折射仪、原子力显微镜(AFM)等对其结构与性能进行了表征,用振荡法、抑菌圈法等对其抗菌性能进行了测试,同时探究了PHMG的质量分数对PU涂料各项性能的影响。研究表明:当PHMG的质量分数为1.0%时,PHMG的键合效率达到93.59%,对大肠杆菌和金黄色葡萄球菌的抑菌率达到99.5%以上,证明PU-PHMG具有优异持久的抗菌性能。此外,该涂料还兼具优异的防霉性能和力学性能。     

一种新型胍盐抗菌剂的制备及其性能研究

采用盐酸胍盐、六亚甲基二胺、二乙基三胺和环氧氯丙烷为原料合成了一种新型的胍盐抗菌剂,使其同时起到抗菌和提高纸页湿强度的作用。用二维核磁共振谱(HH-COSY)对胍盐抗菌剂的结构进行了表征,同时研究了胍盐抗菌剂对大肠杆菌的最低抑菌浓度和对纸张的增湿强效果。通过UV吸收法和激光共聚焦显微镜对胍盐抗菌剂的抗菌机理进行了进一步的研究,结果表明,胍盐抗菌剂主要是通过先破坏细菌的细胞膜,然后引起细胞内的物质流出细胞,从而抑制细菌的生长繁殖。     

硅胶支载的仿生物有机胍盐催化剂在有机合成中的应用

评述了一种新型硅胶支载的有机胍盐的制备方法，结构特点及其在羧酸和氯甲酸酯选择性酯化，羧酸的酰氯化，缩醛的脱保护等有机反应中的应用。     

镧系硅钨杂多酸胍盐的合成及物性研究

合成了LnL(L代表配体)型镧系硅钨杂多配合物K_5[LnSiW_(11)O_(39)],再分别与盐酸胍盐反应,得(CN_3H_5)_5[LnSiW_(11)O_(39)]·nH_2O。阳离子交换试验证明Ln~(3+)居于配合物内界。用IR、UV、DSC-TGA和XRD分析,对杂多配合物进行了表征。     

键合聚六亚甲基胍盐酸盐的聚丙烯蜡的制备及其抗菌活性

在Hakke转矩流变仪中,将聚丙烯蜡（PPw）接枝马来酸酐（PPW—g—MAH）与聚六亚甲基胍盐酸盐（PHMG）熔融反应,得到具有抗茵性能的聚丙烯蜡（PPW—g—PHMG）。透射电镜显示PHMG在PPw一舻PHMG上呈纳米尺度均匀分布。将聚丙烯与PPW—g—PHMG混合,混和物（PP／PPw—g—PHMG）的抑茵圈法和贴膜法抗茵性能测试结果显示：样品对大肠杆菌具有优异的抗菌性能。经过提纯后,PP／PPw—g—PHMG没有出现PHMG的溶出,具有非溶出性的、持久的抗茵功能。     

极少量1,5-己二烯改善聚丙烯树脂热稳定性研究

在Ziegler-Natta丙烯聚合反应中,引入少量1,5-己二烯,在不明显改变聚丙烯链结构的基础上,通过可能的主链环化,提高其热稳定性.聚合反应由9,9-二(甲氧基甲基)芴为内给电子体的Mg Cl2/Ti Cl4催化剂在本体条件下进行,1,5-己二烯浓度控制在1.0 mol%以下.结果显示,在所控制的1,5-己二烯浓度下,虽然催化剂活性和聚合物分子量有一定程度的降低,但聚合物的熔点(Tm)和熔融焓(ΔHf)只略有下降,而结晶温度(Tc)基本保持不变.GPC和流变测试结果表明聚合物的链结构无变化,聚合过程无支化或交联结构生成.热重分析(TGA)结果显示,聚丙烯热稳定性有较大幅度的提高,初始分解温度(Tonset)从纯聚丙烯的460.6℃提高到482.3℃,聚合物在反应釜中呈良好的颗粒形态.     

由N-氯代胍和芳基异腈酸酯合成脲基胍盐的新途经

A new synthetic method for the preparation of N-carbamoyl-N‘,N‘-disubstituted guanidinium salts was developed from the nucleophilic reaction of N-chloroguanidines with aryl isocyanates.     

氟橡胶/改性乙丙橡胶并用胶的热稳定性

采用热分析技术考察了氟橡胶及氟橡胶(FPM)/改性乙丙橡胶(MEPDM)并用胶在氮气中的热稳定性, 通过微分法与积分法两种动力学方法计算出了FPM及FPM/MEPDM并用胶的热分解活化能E和指前因子A. 结果表明, 并用胶的热分解温度稍高于纯的氟橡胶, 但热分解活化能略低于氟橡胶, FPM、FPM/MEPDM(5%)和FPM/MEPDM(10%)的热分解活化能分别为251.74、244.98和219.60 kJ·mol-1; 热分解反应级数n均为0.95. 随着失重百分率的增大, 热分解活化能增大.     

Thermal Stability Evaluation of PA6/LLDPE/SEBS-g-DEM Blends

Summary: The thermal stability of a polyamide-6/low linear density polyethylene blend (PA6/LLDPE) was studied using thermal analysis techniques. The thermogravimetric studies carried out showed that when a diethyl maleate grafted styrene- ethylene/butadiene-styrene terpolymer (SEBS-g-DEM) is added to the PA6/LLDPE blend there is an actual enhancement of the thermal stability due to the increase in the interfacial area within the blend. The Invariant Kinetic Parameter method (IKP) proved to be a qualitative technique unfolding the type of degradation mechanisms taking place in the material vicinity. Nucleation and phase boundary reactions are the kinetic models of thermal decomposition with the most significant probability of occurring.     

EC/CA共混物的相容性和热稳定性

EC/CA共混物的相容性和热稳定性;乙基纤维素;醋酸纤维素;溶液共混;相容性     

Properties of Low Density Polyethylene/Polypropylene Blends

ABSTRACT

The role of di-cumyl peroxide (DCP) as compatibilizer in low density Polyethylene/Polypropylene (LDPE/PP) blends has been explored. Mixtures with varying LDPE/PP ratio were prepared in a Brabender plasticorder and tested for their mechanical properties and calorimetric response. Then peroxide was added at concentrations up to 0.5%, and the mechanical properties of the these new blends were measured. Also, the mixing torque, melt flow index and gel content of the above products were recorded as a function of peroxide concentration. It was found that the incorporation of DCP restricts the thermoplastic characteristics of the melt, which was primarily attributed to branching which occurs in LDPE. This results in an enhancement in the adhesive bonding between the two polymers mainly due to chain entanglements. This was further supported by the fact that mechanical properties of the treated blend were significantly improved.     

Rheological Study on Polypropylene/Cycloolefin Copolymer Blends

Summary: Polypropylene, cycloolefin copolymer and their blends were characterized by means of melt flow analysis and capillary rheometry at temperatures between 190 and 230 °C in order to shed more light on COC fiber formation obtained in injection molding process. Melt viscosity and its activation energy as functions of blend composition show negative deviation from the expected additivity (Negative Deviating Blends). The COC/PP viscosity ratio increases with shear rate, but decreases with temperature. High temperature, low viscosity ratio and high shear rate seem to be favorable for fiber formation. Glass transition (from the reversible heat flow curve of modulated DSC) of dumbbell specimens produced by injection molding at 230 °C with COC minor component was 2–4 °C higher than that of grinded pellets obtained from mixing at 190 °C.     

Dynamically Photocrosslinking of Polypropylene／EPDM Blends as a Thermoplastic Elastomer

The mechanical properties and the crystal morphological structures of the dynamically photocrosslinked polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) blends have been studied by means of mechanical tests, wide-angle X-ray diffraction(WAXD), and differential scanning calorimetry(DSC). The dynamically photocrosslinking of the PP/EPDM blends can improve the mechanical properties considerably, especially the notched Izod impact strength at low temperatures. The data obtained from the mechanical tests show that the notched Izod impact strength of the dynamically photocrosslinked sample with 30% EPDM at -20℃ is about six times that of the uncrosslinked sample with the same EPDM component. The results from the gel content, the results of WAXD, and the DSC measurements reveal the enhanced mechanism of the impact strength for the dynamically photocrosslinked PP/EPDM blends as follows: (1) There exists the crosslinking of the EPDM phase in the photocrosslinked PP/EPDM blends ; (2) The β-type crystal structureof PP is formed and the content of α-type crystal decreases with increasing the EPDM component; (3) The graft copolymer of PP-g-EPDM is formed at the interface between the PP and EPDM components. All the above changes of the crystal morphological structures are favorable for increasing the compatibility and enhancing the toughness of the PP/EPDM blends at low temperatures.     

Miscibility and Thermal Behavior of Pullulan/Polyacrylamide Blends

Blends of Pullulan (PU) and Polyacrylamide (PAM) having biomedical applications were prepared and characterized in order to evaluate the miscibility of natural component with the synthetic one. Blends with different composition ratios were prepared using water as common solvent. Viscosity, ultrasonic velocity and density were measured at 30 and 40°C. Furthermore, the blend films were prepared by a solution casting method and analyzed by DSC, FTIR and TGA methods. Results of ultrasonic and density methods revealed the semi-miscibility of the blend. Using viscosity data, interaction parameters (Chee's ‘μ’ and Sun's ‘α’) were computed. The values confirmed that the blend is miscible when the Pullulan content is less than 20% in the blend. Change in temperature had no effect on the miscibility nature of the blends. Intermolecular interactions of hydrogen bonding type were confirmed by DSC and FTIR methods. Thermal behavior of blends was investigated using TGA method.     

Thermal Dehydration and Miscibility of PHEMA/PMAA Blends

Miscibility and dehydration of poly(2-hydroxyethyl methacrylate) and poly(methacrylic acid) (PHEMA/PMAA) blends were investigated by temperature modulated DSC (TMDSC), TG and solid-state ¹³C NMR methods. TMDSC spectra and ¹H spin-relaxation times showed that the blends are homogeneous on a scale of 5-10 nm for all compositions. From TG and ¹³C NMR, we elucidated that the mass loss of the blends at 300°C is ascribed to the dehydration between the hydroxyl group of PHEMA and the carboxyl group of PMAA. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Control of Thermal and Radiation Stability of Polypropylene Containing Calcium Carbonate Nanoparticles

Thermal and γ radiation stability of iPP containing CaCO₃ nanoparticles were investigated by oxygen uptake procedure at 190 °C. The loading of iPP matrix was maximum 25% (w/w). The behavior on thermal oxidation was investigated for two formulations of iPP compounds differing by the surface characteristics of nanoparticles (i.e. uncoated and stearic acid-coated filler). Three irradiation doses (5, 15 and 25 kGy) were applied. The efficient protection of stabilizers that are present in the as-prepared formulations was emphasized by proper values of the kinetic parameters obtained for oxidation. The contribution of CaCO₃ nanoparticles to the oxidative process of iPP is discussed.