聚甲氧基二甲醚合成工艺研究

以甲缩醛和三聚甲醛合成聚甲氧基二甲醚的反应体系为研究目标,筛选了HZSM-5分子筛为催化剂,考察了原料配比、反应温度、反应时间、催化剂用量对反应结果的影响。优化的反应条件为:甲缩醛和三聚甲醛质量比为2/1、反应温度为70℃、反应时间为2~4 h、催化剂用量为1.5%。在此条件下,三聚甲醛转化率大于95%,柴油有效添加组分DMM3-4的选择性为42%以上。循环实验表明,该催化剂结构稳定、性能优良,在5次循环使用中原料转化率和产物选择性未见有明显下降。     

Phonons and heat capacity of polyoxymethylene

Using Wilson's GF matrix method as modified by Higgs for an infinite system, we report normal modes and their dispersion for polyoxymethylene using the Urey‐Bradley force field. Heat capacity has been evaluated as a function of temperature from dispersion curves via density‐of‐states. The results obtained agree well with the experimental data reported in the literature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

膜盒热流道注射模设计

针对聚甲醛材料的膜盒塑件收缩变形大、成型稳定差的特点,详细分析了塑件成形工艺,介绍了模具结构、热流道系统结构、滑块结构及冷却系统的设计,模具设计合理,取得了较好的经济效益,对盒型类塑件的注射模设计有一定的参考价值。     

玻璃纤维,碳纤维填充聚甲醛的摩擦磨损性能研究

利用ＲＦＴ－Ⅲ往复摩擦磨损试验机测试了玻纤，碳纤填充聚甲醛所形成复合材料的摩擦磨损性能，并利用ＳＥＭ和ＸＰＳ研究了其磨损机理，研究发现，填加一定量玻纤，碳纤均可降低聚甲醛的磨损，但填加碳纤效果更好，ＸＰＳ分析发现钢对偶面上的Ｆｅ向玻纤，碳纤复合材料表面发生转移，并生成Ｆｅ２Ｏ３。     

Polyoxymethylene/polyurethane/alumina ternary composites: Structure,mechanical, thermal and dielectric properties

Ternary composites composed of polyoxymethylene (POM), polyurethane (PU), and boehmite alumina were produced by melt blending with and without latex precompounding. Latex precompounding served for the predispersion of the alumina particles. The related masterbatch (MB) was produced by mixing the PU latex with water‐dispersible boehmite alumina. The dispersion of the alumina was studied by transmission and scanning electron microscopy techniques (TEM and SEM, respectively) and discussed. The crystallization of POM was inspected by means of differential scanning calorimetry (DSC) and polarized optical microscopy (DSC and polarized light microscopy, respectively). The mechanical and thermomechanical properties of the composites were determined in uniaxial tensile, dynamic‐mechanical thermal analysis (DMTA), short‐time creep tests (performed at various temperatures), and thermogravimetric analysis (TGA). The melt flow of the composites was characterized in a plate/plate rheometer. In addition, the dielectric response of the nanocomposites was investigated by means of broadband dielectric spectroscopy at an ambient temperature. The composites produced by the MB technique outperformed the direct melt (DM) compounded composites in respect to the thermal and mechanical characteristics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

三聚甲醛与甲醇在SO_4~(2-)/Fe_2O_3固体超强酸上的开环缩合反应研究

对SO42-/Fe2O3固体超强酸上三聚甲醛与甲醇开环缩合反应制备聚甲醛二甲基醚(DMMn)的反应条件进行了研究。其中,醇醛比、反应温度和反应时间对产物分布的影响较大。当甲醇与三聚甲醛的物质的量比(即醇醛比)为1.2、反应温度130℃、反应时间2h、反应压力0.1MPa、催化剂用量为总反应物质量的1.5%时,柴油添加组分DMM3-8收率可达22%,同时,SO42-/Fe2O3具有较好的循环使用性能。并运用XRD、SEM、NH3-TPD、IR等表征手段对反应前后催化剂进行了分析。     

聚甲醛二甲醚合成催化剂的筛选及工艺条件优化

以甲醇和三聚甲醛为原料催化合成聚甲醛二甲醚(DMMn)。在高压反应釜中对金属氧化物、离子交换树脂和分子筛三类固体酸催化剂进行了筛选,并采用吡啶吸附-红外光谱法和BET对活性较好的几种分子筛进行了表征,以得到的较佳催化剂进行优化条件实验。结果表明,HMCM-22分子筛具有较好的催化活性和最佳的DMM2-8的选择性。在最佳反应反应条件:n(甲醇)∶n(三聚甲醛)=1.5∶1,w(cat.)为3%,150℃,反应8 h,DMM2-8的选择性达到63.35%。     

Preparation of core–shell nanoparticle‐based hindered amine stabilizer and its application in polyoxymethylene

Core–shell nanoparticles chemically functionalized by hindered amine stabilizer (HAS), poly(BA‐MMA‐co‐PMPA) (PBMP), were prepared by two‐stage emulsion polymerization from butyl acrylate, methyl methacrylate, and 1,2,2,6,6‐pentamethylpiperidin‐4‐yl acrylate. The incorporation of HAS into the particles was confirmed by nuclear magnetic resonance (¹H‐NMR) and the core–shell microstructure of PBMP particles was revealed by transmission electron microscopy. Furthermore, PBMP capable of one‐step toughening and photostabilizing, was melt‐blended with polyoxymethylene (POM), and its dispersion in POM was investigated by scanning electron microscope. The results showed that the core–shell nanoparticles could be well dispersed in POM matrix, indicating its good compatibility with POM. The UV resistance and impact resistance of POM were obviously improved by the HAS‐functional core–shell nanoparticles simultaneously. In addition, the core–shell nanoparticles could confer excellent protection to the surface of POM from UV‐light damage, regardless of the adverse effects on the thermal‐oxidative stability of POM, as investigated by thermogravimetry analysis under aerobic condition. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

聚甲醛产业中国专利分析

以聚甲醛(POM)的中国专利数据为分析样本,从中国专利申请的地区分布、时间分布、申请人、技术构成等多角度详细剖析了国内POM专利技术的整体发展状况。结果表明,我国POM产业的技术基础薄弱,研究主要集中于POM共混改性的个别方向,而日本、美国、德国则掌握了从POM合成到POM改性的全面技术,在各个方面对我国POM产业的发展造成压力。建议我国企业和研究机构加大研发力度,尽快开发出具有自主知识产权的POM生产工艺,并继续积极开展改性POM的技术攻关。