温度对HDPE/MPA共混物阻透性能的影响

分析了溶剂分子透过聚合物共混物的溶解-扩散行为,建立了溶剂分子扩散通量与其表观扩散活化能、偏摩尔混合焓以及温度之间的关系式。并采用多种配方的HDPE/MPA共混物,在不同温度下进行渗透实验,结果表明本文建立的关系式与实验数据吻合良好。     

MPA醇酸树脂的制法及其应用

阐述了用马来海松酸（MPA）为多元酸替代苯酐制备醇酸树脂的新工艺。该工艺简便，所得的MPA醇酸树脂的性能符合要求，且生产成本低于一般醇酸树脂.介绍了MPA醇酸树脂的生产工艺和性能指标，并列举了它在快干醇酸清漆中的应用。也讨论了MPA醇酸树脂相关的工艺条件。     

马来海松酸新戊二醇酯多元醇的制备及性能

马来海松酸酐(MPA)具有良好的耐热性能,被用作制备耐热多元醇的原料而得到广泛研究.实验将含有耐热基团的新戊二醇(NPG)和MPA制备多元醇酯,以进一步提高产品的耐热性能.研究了反应体系的酸值变化,通过改变NPG与MPA的摩尔比,得到了具有较大羟值范围的系列产品.对产品进行了红外和热重表征.结果表明,MPA的三个羧基均发生了酯化反应,且反应较为彻底.酯化产物具有较高的初始失重温度,可作为耐热原料使用.     

改性尼龙6纤维的制备与性能研究

采用MAH-g-PE与增塑剂邻苯二甲酸二辛酯(DOP)对尼龙6进行改性制得了改性尼龙6纤维(MPA),研究了MAH-g-PE和DOP用量对MPA流变性能、热性能、热延伸及比强力性能的影响.结果表明:MPA样品流动性随着DOP含量的增加而增强,说明增塑剂对于尼龙6的增塑效果比较明显.DSC分析表明,MAH-g-PE的加入...     

辐照交联PVC/环氧树脂固化复合发泡材料的制备及性能

采用熔融共混法和辐照交联工艺成功制备了一系列聚氯乙烯(PVC)/环氧树脂(E-12)/马来海松酸酐(MPA)复合发泡材料。通过傅里叶变换红外光谱仪(FTIR)和核磁共振仪(¹H-NMR、¹³C-NMR)表征了MPA的化学结构;通过凝胶含量、力学性能、扫描电子显微镜(SEM)和吸水率等试验,探究了E-12/MPA(EM)固化物含量对PVC/E-12/MPA复合发泡材料性能的影响。结果表明,当EM固化物含量为10%(质量分数,下同)时,PVC/E-12/MPA复合发泡材料的凝胶含量为42.3%,较改性前提高了9.9%,拉伸强度提高了23.4%,压缩强度提高了26.7%,压缩模量提高了32.5%;断裂伸长率从286.11%降至217.68%,吸水率从改性前1.5%增至3.4%,同时具有优异的泡孔结构。     

生物基阻燃剂与三聚氰胺氰尿酸盐在低密度聚乙烯中的协同阻燃性能研究

为了探究新型生物基阻燃剂的适用范围和协同阻燃效果，利用氢氧化镁（MH）和植酸（PA）反应制备新型生物基阻燃剂（MPA）。将MPA与三聚氰胺氰尿酸盐（MCA）加入低密度聚乙烯（LDPE）中制备LDPE阻燃复合材料，并测试复合材料的阻燃性能和热稳定性。结果表明：当MPA加入量为40 g,MCA加入量为20 g,LDPE-3复合材料的热释放速率峰值降至702.6 kW/m2,CO和CO2的释放量也受到有效抑制，残留物含量大幅提升，从0.2%提升至14.2%。MCA的加入可以有效提升LDPE/MPA复合材料的热稳定性，抑制LDPE/MPA复合材料的早期分解，使LDPE-3的起始热分解温度（T5%）从273.2℃提升至329.8℃。MPA与MCA同时在LDPE使用时能够产生良好协同阻燃作用，有效提升LDPE复合材料的阻燃性能以及热稳定性。     

模流分析技术应用（五）

在上一期我们介绍了MPA7．0的一些新增功能，本期我们将提供一些用MPA分析解决问题的案例，希望能给大家一些帮助。     

醋酸甲羟孕酮诱导结肠癌SW480细胞凋亡及其差异表达蛋白的分析

目的对醋酸甲羟孕酮(Medroxyprogesterone acetate,MPA)诱导结肠癌SW480细胞凋亡时的差异表达蛋白进行分析。方法以不同浓度(25、50、75μmol/L)的MPA作用SW480细胞24、48和72h,MTT法检测细胞增殖水平。以上述浓度的MPA作用SW480细胞48h,流式细胞术分析细胞的凋亡率及细胞周期各时相比例的变化。以50μmol/L MPA作用SW480细胞48h,透射电镜观察细胞结构的变化;应用双向电泳技术分离细胞总蛋白,PDQUEST8.0软件分析凝胶图谱,选择差异表达蛋白,以Agilent1100HPLC-Chip/MS系统进行MS/MS分析,搜索UniProtKB/SWISS-PORT,Homo Sapiens(Human)数据库筛选目标蛋白质。结果透射电镜下观察经MPA作用的SW480细胞可见明显的凋亡形态学变化;不同浓度的MPA对SW480细胞均有明显的抑制增殖和诱导凋亡作用,且呈剂量依赖性,细胞凋亡率最高可达56.15%;细胞周期分析表明,MPA诱导结肠癌细胞凋亡的作用可能与细胞周期的阻滞相关,此阻滞作用具有剂量依赖性;共鉴定出泛素、只含LIM结构域蛋白质3、热休克蛋白10、有机阴离子转运蛋白4、泛素羧基末端水解酶2、核苷二磷酸激酶-A、层黏连蛋白受体1共7种SW480细胞凋亡相关蛋白。结论 MPA具有诱导SW480细胞凋亡的作用,SW480细胞凋亡相关蛋白可能作为MPA抗结肠癌的潜在生物标志物。     

pH对MPA改性大豆蛋白胶粘剂性能的影响

MPA(改性聚酰胺)交联剂是一种环保型水溶性热固性树脂,具有可增溶豆粉、提高胶接耐水性等特点。以NaOH(氢氧化钠)和TEA(三乙醇胺)溶液分别作为pH调节剂,着重探讨了不同pH对MPA适用期、大豆蛋白胶粘剂性能(如pH、黏度及胶接强度等)的影响。研究结果表明:NaOH溶液与TEA溶液相比,前者调节pH的用量是后者的22.4%,说明前者的效率高于后者。当pH=4~5时,MPA的黏度适宜,由此配方胶粘剂制备的胶合板能耐受28 h的煮-烘-煮循环处理;当pH过高时,MPA的适用期明显缩短,相应胶粘剂的胶接耐水性变差。用NaOH调节pH=5时,MPA的氮杂环结构增多、反应活性增强,相应胶粘剂的胶接耐水性明显提高。     

松香基环氧固化剂的合成、性能及其在各向同性导电胶中的应用

以可再生资源松香为原料,经与二烯体马来酸酐进行加成反应,合成了马来海松酸酐(MPA)环氧树脂固化剂,在一定条件下,对环氧树脂128/MPA体系固化反应进行探讨,固化产物的力学性能、耐热性能     

Permeation barrier properties of polyethylene/modified blends of polyamide and polyvinylalcohol containers against methanol/gasoline fuels

One commercial grade of polyamide and/or polyvinylalcohol resins were modified by a compatibilizer precursor to make various compositions of modified polyamide (MPA) and/or modified blends of polyamide/polyvinylalcohol (MPAPVA) through reactive extrusion. Good methanol/gasoline fuel permeation resistance together with clearly defined MPAPVA and MPA laminar structures were found on containers blow‐molded from the blends of polyethylene PE/MPAPVA and PE/MPA, respectively. The compositions of MPAPVA and MPA resins were found to exhibit a significant influence on the methanol/gasoline fuel permeation resistance and morphology of PE/MPAPVA and PE/MPA containers, respectively. Possible mechanisms are proposed to explain these interesting phenomena. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2158–2169, 1999     

注塑共混阻透容器成型技术

高密度聚乙烯（ＨＤＰＥ）／改性尼龙（ＭＰＡ）共混物经注塑用具有阻透性能的容器,该类容器可用于贮存以烃类作溶剂的农药、涂料等。研究了成型工艺、配方、成型设备及模具对容器阻透性能的影响。     

Gasoline Permeation Resistance of Containers of Polyethylene,Polyethylene/Modified Polyamide and Polyethylene/Blends of Modified Polyamide and Ethylene Vinyl Alcohol

An investigation of the gasoline permeation resistance of polyethylene (PE), polyethylene/modified polyamide (MPA), and polyethylene/blends of modified polyamide and ethylene vinyl alcohol (MPAEVOH) bottles is reported. The gasoline permeation resistance improves slightly after blending EVOH barrier resins in PE matrices during blow‐molding, wherein only broken and less demarcated EVOH laminas were found on the fracture surfaces of the PE/EVOH bottle. In contrast, much better permeation resistance and more clearly defined MPA and MPAEVOH laminas were found for PE/MPA and PE/MPAEVOH bottles, respectively. The gasoline barrier properties and MPAEVOH laminar structures of PE/MPAEVOH bottles improve and become more demarcated, respectively, as the MPA contents present in MPAEVOH resins increase. In fact, by using the proper composition, the gasoline permeation rate of PE/MPAEVOH bottles is about 450 and 3 times slower than that of the PE and PE/MPA bottles, respectively. These interesting gasoline barrier and morphological properties of PE, PE/MPA and PE/MPAEVOH were investigated in terms of melt shear viscosities and thermal properties of the base resins, and the chemical and physical amorphous phase structure present in their corresponding bottles.     

连四甲苯液相氧化过程热力学分析及动力学模拟

连四甲苯（PR）液相氧化制备苯偏四甲酸（MPA）是合成聚偏苯四甲酰亚胺单体的关键步骤。本文首先采用基团贡献法对MPA的热力学参数进行了估算,进一步分析了PR氧化过程热力学参数随温度的变化。结果表明,在研究温度范围内,该氧化过程为强放热反应,反应过程中需要及时移除反应热以控制温度的波动。通过间歇实验研究了不同催化剂浓度和温度对反应的影响,动力学实验结果表明,保持催化剂总浓度不变,改变催化剂配比对PR氧化速率影响不大,但是提高Mn浓度对MPA生成速率的提升效果最佳;升高温度能够明显提升目标产物MPA的选择性。基于自由基链式反应机理,建立了简化的PR氧化集总动力学模型,拟合回归得到苯环上首个甲基氧化的活化能为57.20 kJ·mol^-1;但是苯环上部分甲基被氧化为羧基后,其他甲基氧化的活化能增加为120.30 kJ·mol^-1,说明羧基的存在使甲基活性变弱,被进一步氧化的难度增加。论文相关研究成果可为MPA生产新工艺的开发和工业反应器设计提供参考依据。     

储存超临界流体容器的安全泄放量计算方法

超临界流体(SCF)已无相变可言,也就无潜热可言。储存液化气体容器的安全泄放量计算方法不适用于储存超临界流体的容器。本文简要回顾了容器安全泄放的基本理论,进而探讨基于"伪潜热"计算法的储存超临界流体容器的安全泄放量计算方法。     

High Capacity Anion-Exchange Resin as a Solid-Phase Extraction for Determination of Methylphosphonic Acid

A highly sensitive and accurate method for the preconcentration and determination of ultratrace amounts of methylphosphonic acid (MPA) in water samples is proposed. The method is based on the solid phase extraction with an ion exchange anion resin. The high capacity anion-exchange was prepared from the reaction of polyvinylbenzyl chloride and 2,3,4-tris((dimethyl amino)methyl)phenol in dioxane. The ion-exchange capacity was estimated by the potentiometric titrations and calculated as 8.6 meq/g-dry. The extraction efficiency and the influence of the type and least amount of eluent for the stripping of MPA from the cartridge, pH, flow rates of sample solution and eluent, resin stability and reproducibility, and the breakthrough volume were evaluated. The limit of detection of the method was 0.5 µg L^?1 for MPA and also an enrichment factor of 100 was obtained.     

Association between Serum Biomarkers and Peripheral Neuropathy in Microscopic Polyangiitis

This study aimed to elucidate the pathomechanism of peripheral neuropathy (PN) in microscopic polyangiitis (MPA) and to identify biomarkers useful for diagnosis and severity assessment. Patients with MPA (n = 37) and other non-inflammatory neurological diseases (ONDs; n = 12) were enrolled, and the peripheral nerves of all patients were evaluated using nerve conduction studies. We compared the clinical characteristics and 14 serum biomarker profiles among patients with MPA and PN, MPA without PN, and ONDs. Patients with MPA had a higher prevalence of motor neuropathy than patients with ONDs. Among the patients with MPA, those with motor neuropathy had significantly higher total Birmingham Vasculitis Activity Scores and serum levels of C-reactive protein (CRP), tissue inhibitor of metalloproteinase-1 (TIMP-1), and interleukin-6 than patients without motor neuropathy. Multivariable analyses adjusted for age, serum CRP level, and diabetes mellitus showed that high serum levels of TIMP-1 were independently related to a diagnosis of motor neuropathy in MPA. Additionally, there were significant negative correlations between the serum levels of TIMP-1 and compound muscle action potential amplitudes. Serum levels of TIMP-1 may be associated with the pathomechanism of motor neuropathy in MPA and could be a useful biomarker for diagnosing and evaluating the severity of motor neuropathy in MPA.     

Effects of polyethylenes on the morphology,barrier, and impact properties of polyethylene/modified polyamide blends

An investigation of the influence of the melt shear viscosities of polyethylenes (PE) on the morphology, barrier, and impact properties of polyethylene/modified polyamide PE/MPA bottles is reported. The melt shear viscosities of polyethylenes exhibited a significant influence on the deformation and morphology of MPAs during the blow molding of polyethylene/modified polyamide (PE/MPA) blends. Some obscure MPA laminars were observed in PE/MPA bottles as the value of melt shear viscosity ratio of MPA to PE (VR) deviated significantly from the “optimum” range. In contrast, clear and elongated laminar structures of MPAs were found as the value of VR reached the “optimum” range. Similarly, the total impact energies (Ets) and permeation barrier properties of PE/MPA samples improved with the value of VR until it reached the “optimum” range, after which value Ets and permeation barrier properties of PE/MPA samples reduced significantly with further increasing VR. Possible mechanisms accounting for these interesting behaviors are presented in this study.     

Effects of composition of modified polyamide on barrier properties of polyethylene/modified polyamide blends

A systematic study on the effects of types and contents of compatibilizer precursors (CPs) on degrees of crystallinity (W_c), melt shear viscosities (η_s), and permeation barrier properties of modified polyamides (MPAs) and on their corresponding morphology and barrier properties of bottles blow-molded from polyethylene (PE)/MPA blends is reported. Two alkylcarboxyl-substituted polyolefins were selected as CPs to modify PA and to improve its permeation resistance to xylene by the “reactive extrusion” process. The barrier improvements of MPAs prepared in this study depend significantly on the type and content of CP present in the MPA. A maximum improvement in barrier properties of each MPA series samples were found as the contents of CP reached an “optimum” value. On the other hand, it is interesting to note that bottles blow-molded from PE/MPA series samples exhibited better barrier properties because the MPAs used were associated with better permeation resistance to xylene. The melt shear viscosities of MPAs were found to depend on the type of CP used and increase with increasing CP contents. In contrast, the W_c of MPAs decreased with increasing CP contents. Further analysis of the fracture surfaces of bottles blow-molded from PE/MPA blends also indicated that the morphology of MPA laminas depended on the type of CP present in the MPA, and these MPA laminar structures became clearer as the contents of CPs increased. Possible mechanisms accounting for the interesting behaviors described above are discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1531–1540, 1997