聚甲醛的热重分析研究

由均聚和共聚甲醛在氮气和空气中的热重分析曲线，探讨了聚甲醛的链结构和聚甲醛的各种降解方式同热失重的关系，并利用Ｃｏａｔｓ－Ｒｅｄｆｅｒｎ方法计算了共聚甲醛在空气中的动力学参数，对聚甲醛的热稳定性作了讨论．     

聚甲醛结晶动力学研究

用解偏振光强法和差示扫描量热法（ＤＳＣ）分别研究了聚甲醛和聚甲醛助剂Ｐ的等温结晶动力学和非等温结晶动力学。探讨了助剂Ｐ对聚甲醛的结晶成核作用。     

聚甲醛的改性研究进展

聚甲醛作为常用工程塑料,因具有较高的强度、良好的耐磨、绝热、绝缘性能及优异的可加工性能使其广泛应用于机械工业、汽车、电子电气及精密仪器等领域,但冲击韧性低和稳定性差限制了聚甲醛在工业上的应用,因此近几年聚甲醛的改性研究颇受重视。本文综述了聚甲醛的改性方法,详细论述了不同改性工艺对聚甲醛力学性能、摩擦性能、绝热绝缘性能及稳定性的影响,并对聚甲醛工业应用的发展方向做出了展望。     

聚甲醛与热塑性酚醛树脂相容性研究

考察了聚甲醛(POM)与热塑性酚醛树脂(Novolak)的相容性;浊点法研究结果表明,POM/Novolak共混物存在一个低位临界相转变温度.DSC测试表明,POM与Novolak共混后,共混物的熔点下降;通过DSC测试得到数据,采用Hoffman-Weeks平衡熔点外推法和Flory熔点下降方程推算出POM与Novolak的相互作用参数(χ)约为-0.032.FTIR研究表明,Novolak的羟基能够与POM的醚氧基形成氢键,导致共混物中Novolak的羟基峰向高频偏移.研究结果表明,POM与Novolak能够达到热力学相容.     

聚甲醛自润滑材料的发展概况

聚甲醛是一种综合性能优良的自润滑工程材料，广泛应用于汽车，机床，化工和电气等领域。本文对聚甲醛自润滑材料的类型与特点及其发展状况作了陈述与归纳，并提出了聚甲醛自润滑材料今后研究的工作重点和发展方向是改善聚甲醛的成型性和抗冲性，制了以综合性能优异的聚甲醛自润滑材料，开展聚甲苯自润滑材料的磨损图研究。     

玻纤增强聚甲醛复合材料性能研究

本文采用玻璃纤维(GF)增强聚甲醛,考察不同玻纤添加量及退火对POM流变行为、力学性能及热性能的影响.研究结果表明:玻纤的加入使聚合物基体的结晶度提升,熔体的储能模量、耗能模量及复数粘度明显提升;同时,玻纤的加入,尤其是退火后处理,能有效提高基体的拉伸强度、弯曲强度和弯曲模量;但是,玻纤的加入对基体的冲击性能的改善效果...     

聚甲醛结晶过程的流变学方法探索

使用流变学方法小振幅振荡剪切跟踪了聚甲醛降温结晶和升温熔融的动力学过程,结果表明流变学方法也是测定结晶、熔融温度的有效手段.转变温度可由动态储能模量的起始偏折点进行标识;而对于恒温结晶过程,流变学方法可由动态储能模量对时间的演进得到结晶过程中的相对结晶度,进而使用Avrami方程拟合获取结晶动力学参数,还可将结晶过程视为物理凝胶化过程而使用凝胶化时间标示结晶过程的快慢.     

聚甲醛合成的研究进展

从聚甲醛的制备出发,综述了引发剂、共聚单体的研究成果,进而概述了聚甲醛的结构以及性能方面的研究进展。重点强调了聚甲醛的高性能化研究,即在合成过程中通过共聚单体来引入侧基,以改善聚甲醛的韧性、热稳定性等性能。通过优化共聚单体的分子结构,调节共聚单体的含量来合成高性能化的聚甲醛树脂,以适应高速、高温、高压的工作环境。     

扫描电镜用于PTFE拉伸微孔膜的形态结构研究--研制中PTFE拉伸微孔膜的SEM鉴定

运用扫描电镜(SEM)图像研究了聚四氟乙烯(PTFE)粉料经过推挤、辊压和拉伸得到的微孔膜的形态结构,观察到膜是由网状纤维及由它所连接的结点所组成.单相和双向拉伸显著影响到膜结构的改变,而未经热处理的拉伸膜的丝状纤维在放置中收缩改变了膜的微孔形态结构,但在孔径测定中没有显著变化.认为纤维丝是PTFE粉料在推挤和辊压中形成的结点在拉伸中伸展引出的并产生孔隙,而由于从SEM仅能观察到1 nm深度的膜表面层,厚度达数十微米多孔膜的孔径分布应是很错杂的.     

POM／EVA共混物的研究

用力学测试、扫描电镜（ＳＥＭ）、热分析（ＤＳＣ）等手段研究了聚甲醛（ＰＯＭ）与乙烯－醋酸乙烯酯共聚物（ＥＶＡ）共混物（ＰＯＭ／ＥＶＡ）的力学性能及其微同形态；用聚甲醛与马来酸二丁酯（ＤＢＭ）的接枝物（ＰＯＭ－ｇ－ＤＢＭ）作相溶剂，能改变共的两相间的粘结力，从而提出了共混物的力学性能，ＳＥＭ观察表明接枝物的加入改变了ＰＯＭ／ＥＶＡ共混物的断裂方式，微观形态及结晶性能，对其热性能影响不大；通过改变ＰＯ     

Rheological behavior of POM polymer melt flowing through micro-channels

Determination of the rheological behavior of the polymer melt within micro-structured geometry is vital for accurate simulation modeling of micro-molding. The lack of commercial equipment is one of main hurdles in the investigation of micro-melt rheology. In this study, a melt viscosity measurement system for POM melt flowing through micro-channels was established. For measured pressure drop and volumetric flow rate, both capillary and slit flow models were used for the calculation of viscosity. The calculated results were also compared with those of PS resin to discuss the effect of morphology structure on the viscosity characteristics of polymer within micro-channels. It was found that the measured POM viscosity values in the test ranges are significantly lower (about 29-35% for a channel size of 150 μm) than those obtained with a traditional capillary rheometer. Meanwhile, the percentage reduction in the viscosity value and the ratio of slip velocity relative to mean velocity all increase with decreasing micro-channel size, but less significantly when compared with PS resin. In the present study we emphasize that the rheological behavior of the POM resin in microscopic scale is also different from that of macroscopic scale as PS resin but displays a less significant lower. It also revealed that the wall slip occurs more easily for the PS resin within micro-channels than POM resin due to enlarge the effect of molecular weight.     

宝石样品的扫描电镜研究

用扫描电镜对马来西亚天然玉石、玻璃样品的表面微观形貌和结构进行观察研究，研究结果为宝石真伪及宝石类型与价值的昨别提供了简便，快速，可靠的无损检测方法及有效信息。     

丁腈橡胶对聚甲醛树脂的增韧机理研究

研究了丁腈橡胶（ＮＢＲ） 对聚甲醛（ＰＯＭ） 树脂的增韧机理,并比较了ＰＯＭ／ＮＢＲ 体系和ＰＯＭ／ 热塑性聚氨酯（ＴＰＵ） 体系的异同．结果表明,高丙烯腈（ＡＮ） 含量的ＮＢＲ 有着和ＴＰＵ 相近的溶度积参数,且其分子上的氰（ＣＮ） 基或双键对ＰＯＭ 分解时产生的甲醛及大分子自由基的捕捉作用,有利于改善ＮＢＲ 和ＰＯＭ 之间相容性,因而可和ＰＯＭ 树脂形成良好的合金体系;当ＮＢＲ 含量达４０ｗｔ％ 时,ＰＯＭ／ＮＢＲ 体系出现脆 韧转变,从逾渗机制、剪切带机制、类互穿网络（ＩＰＮ） 作用机制等角度进行考察的结果证明,ＮＢＲ 对ＰＯＭ 树脂的增韧行为以及ＰＯＭ／ＮＢＲ 共混合金体系的脆 韧转变规律与ＰＯＭ／ＴＰＵ 体系相一致．     

紫外可见分光光度计测定POM塑料中甲醛含量的不确定度评价

建立了分光光度法测定POM塑料中甲醛含量的不确定度评定数学模型。根据JJF 1059.1-2012标准要求与VDA 275-1994方法进行测定,从试样质量称量、重复性试验、试样水溶液的甲醛浓度、吸收液体积以及含水率测试五个方面分析测定过程中不确定度来源,并分别对其进行量化和和合成。结果表明,POM塑料中甲醛含量为5.015 mg/kg,扩展不确定度为0.254 mg/kg(k=2)。测定结果的不确定度主要来源于试样水溶液的甲醛浓度测试引入的不确定度,占比90.82%,其中线性拟合分量引入的不确定度贡献最大,占75.58%,其次是标液配制和仪器引入的不确定度分量,分别占13.41%和7.62%。因此在实际测量过程中,应重视仪器和量具的检定与核查,增加标准工作曲线的更新频次,以及规范试验操作步骤以提高测试结果的准确性;另一方面,称量、标液、含水率测试所引入的不确定度非常小,可忽略不计。     

双酚A型聚碳酸酯自然老化的XPS研究

利用Ｘ－射线光电子能谱研究了双酚Ａ型聚碳酸酯经自然化老后的表面化学组成与结构变化。结果表明，表面光降解反应可以分成两个主要阶段：在老化前期，主要是碳酸酯基的分解；之后主要是偕二甲基基团和芳环的氧化。而前期碳酸酯基的分解对其力，学性能的影响最为显著。     

Synthesis and supramolecular features of hybrid POM/onium solid-state assemblies

Abstract

Polyoxomolybdate-based organic?inorganic hybrid architectures were synthesised and characterised by X-ray crystallography. The supramolecular assemblies present rows of metallic clusters H-bonded by ammonium cations, with a 1:2 molybdate/ammonium ratio. The organic moieties of the ammonium cations establish hydrophobic contact among them such as van der Waals, C–H?π and π?π interactions that stabilise the supramolecular architectures. In particular, for compound 5 the n-alkyl tails pack closely together giving a lipid-like bilayer. In compound 6, the aromatic phenyl rings of the organic cation allow the stabilisation of the supramolecular architecture by C–H?π and π?π interactions. Regarding the X-ray structure of the compound 11, the tetraanionic octa-molybdate [Mo₈O₂₆]^4? cluster is surrounded by four ethyl-triphenyl-phosphonium cations. Running along the b-axis open channels are occupied by DMF solvent molecules. Interestingly, a soaking experiment in n-pentane with the corresponding crystals of compound 11 afforded to a crystal structure very different from the native one.     

Bioassay-guided isolation and POM analyses of a new immunomodulatory polyphenolic constituent from Callistemon viridiflorus

Chromatographic separation of 80% EtOH extract of Callistemon viridiflorus leaves led to the isolation of six known constituents (1–6) along with a new polyphenolic compound 7 identified as apigenin 4′-O-β-d-glucopyranosyl-(1″′ → 4″)-O-β-d-glucopyranoside. The ethanolic extract of C. viridiflorus leaves and isolated compounds were evaluated for in vitro immunomodulatory activity by means of RAW 264.7 macrophages proliferation (MTT) assay. Ethanolic extract of leaves and compounds 1, 3, 4, 6 and 7 caused a significant increase in macrophage proliferation; these findings may suggest that this medicinal plant could be utilised as an excellent source of compounds for immunomodulatory activity.     

Effects of clay and surface plasma‐treated carbon fiber on wear behavior of thermoplastic POM composites

In engineering applications, experimental data and insight from scientific investigations on wear properties of polyoxymethylene (POM) composites are important for engineers to understand how to design and formulate POM materials with high resistance to wear. In this work, clay and carbon fiber were utilized and incorporated into POM and the mechanical and wear properties, in specific wear rate, were then assessed. The experimental results suggested that the addition of clay increased the tensile modulus and strength. The mechanical and wear properties of POM composites were found to improve with the addition of the carbon fiber. Carbon fiber/clay/POM composite exhibited the lowest specific wear rate and friction coefficient.     

PP/尼龙66/聚碳酸酯/ABS共混高聚物的SEM样品制作

讨论了PP／尼龙66／聚碳酸酯／ABS共混高聚物的扫描电子显微镜样品制作中存在的问题,通过实验,探讨了出该材料最佳的样品制作条件。