阴离子聚合制备聚乙烯-g-聚氧化乙烯接枝共聚物

聚烯烃 (聚乙烯 ,聚丙烯等 )的化学改性一直是科学研究和实际生产的一个热点 ,改性过的聚烯烃可以广泛应用到高分子共混物和复合材料中 .在众多聚烯烃中 ,聚乙烯产量最大 ,但因其惰性也最难于化学改性 .我们采取的改性方法是在聚合物中引入反应性基团 ,可以在温和条件下进行有选择的而且高效的化学改性 .由于两亲性共聚物可用作乳液聚合和悬浮聚合中的表面活性剂及稳定剂 ,塑料的表面改良剂和聚合物的共混相容剂等[1,2 ] ,因此人们对该共聚物的研究越来越多 .过去 ,多数两亲性共聚物的研究局限于聚苯乙烯 (ＰＳ)和聚氧化乙烯 (ＰＥＯ)接枝共…     

茂金属 乙烯的流变性与加工性

研究了丁烯－１共聚的茂金属聚乙烯（mＰＥ）的流变性,发现茂金属聚乙烯的窄分子量分 布导致它在挤出加工剪切范围里熔体粘度高、对剪切敏感性差以及熔体从牛顿型转为非牛顿型所需的剪切速率、转变应力高,在挤出加工条件下流动性差,加工困难。对茂金属聚乙烯（mＰＥ）进行改性制得ＭmＰＥ,ＭmＰＥ熔体对温度、剪切速率的敏感性提高,在加工温 度、加工剪切范围里的天观粘度降低,加工流动性得到了显著的改进,可在普通聚乙烯加工     

茂金属聚乙烯的流变性与加工性

研究了丁烯 １ 共聚的茂金属聚乙烯（ｍＰＥ） 的流变性,发现茂金属聚乙烯的窄分子量分布导致它在挤出加工剪切速率范围里熔体粘度高、对剪切敏感性差以及熔体从牛顿型转为非牛顿型所需的剪切速率、转变应力高,在挤出加工条件下流动性差,加工困难．对茂金属聚乙烯（ｍＰＥ） 进行改性制得ＭｍＰＥ,ＭｍＰＥ 熔体对温度、剪切速率的敏感性提高,在加工温度、加工剪切速率范围里的表观粘度降低,加工流动性得到了显著的改进,可在普通聚乙烯加工设备上,制备性能优良的茂金属聚乙烯薄膜制品．     

阻燃共聚酯的热降解动力学研究——Ⅰ.含磷共聚PET和PET的比较

1　前言ＰＥＴ(聚对苯二甲酸乙二醇酯 )由于具有优良的综合性能 ,被广泛地应用于合成纤维、薄膜和工程塑料等领域 ,但由于它的可燃性 ,在火灾事故中 ,由其着火所致占有较大比例 ,因此它的阻燃化更加引起了世界范围内学者的广泛关注[1 ] 。由于磷是对聚酯的最有效阻燃元素 ,采用共聚法制备含磷ＰＥＴ的报道较多 ,也有关于其热降解动力学研究的报道[2～ 1 0 ] 。但本文所采用的单体羟基苯氧膦丙酸 (ＣＥＰＰ)和ＰＥＴ共聚所得产物的热降解动力学研究 ,尚未见报道。研究该种含磷ＰＥＴ的热稳定性和热降解行为对研究该材料的使用范围和成型加工…     

可紫外光固化的聚乙烯基硅氮烷合成与表征

采用带丙烯酸酯基团的烯丙基溴化合物(4-溴丁烯酸乙酯)和聚乙烯基硅氮烷发生取代反应,实现了丙烯酸酯基团在聚乙烯基硅氮烷主链上的链接.采用质子核磁共振谱(1H-NMR)和二维质子核磁共振谱(2D-1H-1H-NMR)对分子结构进行了表征,采用光学差热分析仪(Photo-DSC)和傅立叶转换红外光谱仪(FT-IR)测试了改性高分子的光敏性能,用热重分析仪(TGA)分析了产物在高纯氮气氛围下的陶瓷收率.结果表明,通过分子改性,交联固化时间从改性前的20min减少到1min之内,功能化的聚乙烯基硅氮烷可以在光刻蚀工艺中作为负性光刻胶使用.     

接枝聚乙烯/GMS接枝SiO_2共混物的制备和性能

合成了单硬脂酸丙烯酸甘油二酯(AGMS)和改性纳米SiO_2的接枝物(SiO_2-g-PAGMS),将AGMS、SiO_2-g-PAGMS、聚乙烯、接枝聚乙烯和改性纳米SiO_2等物质按比例挤出,吹膜. 60℃加速流滴实验结果表明,SiO_2-g-PAGMS与聚乙烯及接枝聚乙烯混合膜加速流滴期最高可达36 d,是同等条件下AGMS与聚乙烯及接枝聚乙烯混合膜的1. 50倍,是只添加SiO_2-g-PAGMS/聚乙烯膜的2. 25倍.接枝聚乙烯/SiO_2-g-PAGMS共混物在降低雾度的同时,结晶温度降低,熔融温度升高,膜拉伸强度变化小于11%.     

FTIR及Py-GC/MS定性分析高聚物单体

红外光谱反应出的是特征化学基团的振动 ,对于高聚物的具体单体组成分析 ,只能借助于紫外光谱、核磁共振及质谱进行综合判断才能得到圆满的鉴定结果[1,2 ] 。本工作针对在红外光谱仪不能分辨的情况下通过气相色谱 质谱联用技术进行综合分析鉴定 ,结果可为其它高聚物分析研究提供实验依据。1　实验1 1　仪器及试验条件未知高聚物试样为白色颗粒状 (晨光化工二厂 )。ＳＹＳＴＥＭ2 0 0 0ＦＴＩＲ ,ＰＥ公司造ＩＲ谱仪 ;ＣＤＳ2 0 0 0铂金丝裂解器 ,裂解室温度 2 5 0℃ ,裂解温度 6 0 0℃ ,升温速率 1 40℃ ｍｓ;ＨＰ6 890型 ,Ｃｏｍｐｏｎｄ…     

聚乙烯醇与硬脂酸酯化反应及性能的研究

聚乙烯醇 (ＰＶＡ)具有良好的成纤成膜性能 ,膜的阻氧性、透明性、抗静电性、韧性、印刷性和耐化学性能优异 ,用途广泛 .ＰＶＡ的缺点是吸湿性大 ,耐水性差 ,熔融加工困难和热稳定性低 .吸湿后 ,ＰＶＡ的强度仅为其干强度的 55%～ 60 % ,膜的阻氧性下降 .ＰＶＡ在 1 60℃开始分子内脱水 ,2 30℃时开始分子间脱水变脆 .由于分子内和分子间有大量氢键存在 ,ＰＶＡ熔融温度高 ,不能熔融加工 ,而溶液成型工艺复杂、成本高、难于制备厚壁和形状复杂的制品 .降低熔融温度、提高热稳定性能是实现ＰＶＡ熔融加工成型的必要条件 .国内外在采用马来酸…     

接枝共聚物氯化聚乙烯－苯乙烯对聚苯乙烯的共混改性

用氯化聚乙烯接枝苯乙烯共聚物（ＣＰＥ－ｇ－Ｓｔ）和氯比聚乙烯（ＣＰＥ）对聚苯乙烯（ＰＳ）进行共混改性．当ＣＰＥ含量为２５％时，用ＣＰＥ－ｇ－Ｓｔ改性的共混物的冲击强度为１８．５ｋＪ·ｍ￣（－２），是用ＣＰＥ改性的共混物冲击强度的２．１倍；其拉伸强度不低于３４ＭＰａ．     

接枝共聚物氯化聚乙烯—苯乙烯对聚苯乙烯的共混改性

用氯化聚乙烯接枝苯乙烯共聚物（ＣＰＥ－ｇ－Ｓｔ）和氯化聚乙烯（ＣＰＥ）对聚苯乙烯（ＰＳ）进行共混改性。当ＣＰＥ含量为２５％时，用ＣＰＥ－ｇＳｔ改性的共混物的冲击强度为１８．５ｋＪ．ｍ＾－＾２，是用ＣＰＥ改性的共混物冲击强度的２．１倍；其拉伸强度不低于３４ＭＰａ。     

Thermal decomposition of amide and imide derivatives of maleated polyethylene

The thermal decomposition behavior of six derivatives of maleated polyethylene was investigated by high‐resolution pyrolysis gas chromatography–mass spectrometry. The results revealed that substituents attached to maleated polyethylene as amides formed from secondary amines were significantly less stable than imides formed from primary amines. Morpholine amide and N‐methylaniline amide derivatives of maleated polyethylene underwent significant decomposition at 160 °C and substantial decomposition at 200 °C. In contrast, the imide derivatives of maleated polyethylene were stable for long periods of time at elevated temperatures. Following 2 min of heating, the first traces of decomposition were detected at 200 °C for the 2‐aminoanthrancene imide derivative, at 255 °C for the 2‐phenethylamine imide, and at 280 °C for the 9‐aminomethylphenanthrene imide. With the exception of the 9‐aminomethylphenanthrene imide, all other derivatives decomposed to form the corresponding amine as the single most significant volatile product. The most likely explanation for this result is that the polymer contained small amounts of succinamic acid that did not close to form the imide. We concluded that the imide was stable even to 315 °C and that the amine was lost from β‐carboxyamide groups present in the sample. In the 9‐aminomethylphenanthrene imide derivative, we observed no loss of amine. Instead, we observed an alternative fragmentation process yielding 9‐methyl phenanthrene. The dependence of the thermal stability of these various derivatives of maleated polyethylene has important implications for the design of reactive‐blending strategies for polyolefins with other functional polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 730–740, 2000     

Thermal decomposition behavior of naphthalene-labeled polyethylene

Pyrolysis–GC/mass spectrometry experiments reveal that naphthalene groups attached to maleated polyethylene as the 1-naphthylethyl ester are stable for relatively long periods of time at 170°C. Decomposition can be detected for samples heated for 2.0 min at 200°C, but even at that temperature, the extent of decomposition is very small. At higher temperatures, two of the decomposition products from the labeled polymer are readily understood: 1-vinylnaphthalene and 1-naphthylethanol can form by reactions that are well-precedented in the organic chemistry literature. At 200°C, only naphthalene is formed, which requires scission of the bond between the naphthyl ring and the C₁ carbon of the ethyl group. We suggest two possible pathways for this reaction. © 1996 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 34:2045–2049, 1996     

Preparation and characterization of PE and PE-g-MAH/montmorillonite nanocomposites

Polyethylene (PE) was chemically modified with grafting maleic anhydride (MAH) monomer on its backbone at first. Then the melt-direct intercalation method was employed to prepare two kinds of nanocomposites, polyethylene (PE)/organic montmorillonite (Org-MMT) and maleic anhydride grafted polyethylene (PE-g-MAH)/Org-MMT nanocomposites. X-ray diffractometery (XRD) was used to investigate the intercalation effect and transmission electron microscopy (TEM) to observe the dispersion of Org-MMT interlayers in matrixes. The results show that an intercalated structure would be acquired on mixing the PE and Org-MMT; and an almost exfoliated system would be obtained by mixing the PE-g-MAH and Org-MMT. Moreover, further measurements via thermogravimetric (TGA) and differential scanning calorimetry (DSC) showed that both of the nanocomposites had a higher thermal decomposition temperature and a higher crystallization temperature when compared to the original matrix. At the same time, the thermal and crystal properties for the PE-g-MAH prepared in this experiment are also discussed.     

甲基丙烯酸双酯改性真丝的热性质

众所周知 ,真丝绸因具有柔和的光泽、细腻的手感、良好的舒适性和保健性而素有“纤维皇后”的美称 .但其极易起毛起皱 ,尤其是湿态下更为严重 ,这大大影响了它的实用价值 .70年代以来 ,人们就开始用化学整理的方法提高和改善真丝绸的各种性能 ,但所用整理剂含有游离甲醛 ,或经其整理后织物会释放对人体有害的甲醛 .随着人们生活水平的提高 ,人们对“绿色纺织品”的需求越来越迫切 ,要求整理向低甲醛、无甲醛方向发展 .近年来 ,人们对用单烯类和环氧化合物对真丝进行改性的研究作了大量的工作[1～ 4] ,这些改性在某种程度上能够改善真丝的性…     

Synthesis of straight and helical carbon nanotubes from catalytic pyrolysis of polyethylene

Straight and helical carbon nanotubes with diameter from 20 to 60 nm have been synthesized through catalytic decomposition of polyethylene in autoclave at 700 °C. The X-ray power diffraction pattern indicates that the products are hexagonal graphite, and transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) images reveal the morphologies and structures of carbon nanotubes. The effects of reaction temperature, catalyst and maleated polypropylene on the growth of the carbon nanotubes were also discussed, and the growth mechanism of the CNTs was proposed. Pyrolysis of polyethylene is a promising green chemical method for economically producing carbon nanotubes.     

Effect of conductive particles on the mechanical,electrical, and thermal properties of maleated polyethylene

Inclusion of conductive particles is a convenient way for the enhancement of electrical and thermal conductivities of polymers. However, improvement of the mechanical properties of such composites has remained a challenge. In this work, maleated polyethylene is proposed as a novel matrix for the production of conductive metal–thermoplastic composites with enhanced mechanical properties. The effects of two conductive particles (iron and aluminum) on the morphological, mechanical, electrical, and thermal properties of maleated polyethylene were investigated. Morphological observations revealed that the matrix had excellent adhesion with both metal particles. Increase in particle concentration was shown to improve the tensile strength and modulus of the matrix significantly with iron being slightly more effective. Through‐plane electrical conductivity of maleated polyethylene was also substantially improved after adding iron particles, while percolation was observed at particle contents of around 20–30% vol. In the case of aluminum, no percolation was observed for particle contents of up to 50% vol., which was linked to the orientation of the particles in the in‐plane direction due to the squeezing flow. Inclusion of particles led to substantial increase (over 700%) in the thermal conductivities of both composites. The addition of high concentrations of metal particles to matrix led to the creation of two groups of materials: (i) composites with high electrical and thermal conductivities and (ii) composites with low electrical and high thermal conductivities. Such characteristics of the composites are expected to provide a unique opportunity for applications where a thermally conductive/electrically insulating material is desired. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal decomposition of immobilized compounds for the generation of gaseous standard mixtures containing ammonia and amines

The thermal decomposition of phthalamic acid derivatives chemically bonded to the surface of silica gel was examined and utilized for the generation of single-component gaseous standard mixtures of ammonia, methylamine, diethylamine and triethylamine. The conditions of the thermal decomposition (temperature, time, diluent gas flow rate) were optimized to ensure complete liberation and rapid elution of the compounds from the bed of modified silica gel. The total amounts of these four compounds that can be released from unit mass of the modified silica gel are in the range of several mg.     

杯芳烃交联聚硅氧烷热稳定性能研究

聚有机硅氧烷是一类主链由硅-氧键连接而成,侧链为有机基团的聚合物,兼具有机聚合物和无机聚合物的特性,性能优异,尤以卓越的耐高温性能而著称,在大气中于-50~250℃可以长期使用[1].为了进一步提高聚有机硅氧烷的热稳定性,主要有以下几种方法,(1)添加各种耐热性添加剂,或可与聚     

Synthesis and thermal behavior of gem-dinitro valerylated polystyrene

Commercial polystyrene has been chemically modified with 4,4-dinitro valeryl chloride by use of Friedel–Crafts acylation reaction in the presence of anhydrous aluminum chloride in a mixture of 1,2-dichloroethane and nitrobenzene. The modified polystyrene containing –COCH₂CH₂C(NO₂)₂CH₃ fragments in side phenyl rings, named gem-dinitro valerylated polystyrene (GDN-PS), was characterized by an Ubbelohde’s viscometer, FTIR, and ¹H NMR spectroscopy. Simultaneous thermogravimetry–differential thermal analysis and differential scanning calorimetry (DSC) have been used to study thermal behavior of the polymer. The results of TG analysis revealed that the main thermal degradation for the GDN-PS occurs during two temperature ranges of 200–300 and 300–430 °C. The DTA curve of GDN-PS is showing a visible exothermic peak at 253.8 °C corresponding to the decomposition of gem-dinitro valeryl groups. The decomposition kinetic of the gem-dinitro groups for GDN-PS with degree of substitution (DS) 11 % was studied by non-isothermal DSC under various heating rates. Kinetic parameters such as activation energy and frequency factor for thermal decomposition of GDN-PS with DS 11 % were evaluated via the ASTM E698 and two isoconversional methods.     

Thermal decomposition of various alkyl onium organoclays: Effect on polyethylene terephthalate nanocomposites' properties

The thermal stability of organically modified layered silicates is determinant for processing polymer nanocomposites and is believed to play a key role on their properties. In this work, alkyl phosphonium, alkyl pyridinium and dialkyl imidazolium surfactants were used as intercalating agents for the preparation of highly thermally stable organophilic montmorillonites. The thermal decomposition of the surfactants and of their organoclays was studied by combined thermogravimetric analysis (TGA) and mass spectroscopy (MS), which allowed the identification of specific volatile compounds issued from the degradation. In order to investigate the influence of the thermal decomposition of the intercalating agent during processing, the various organoclays were incorporated in a polyethylene terephthalate (PET) matrix. The color of the nanocomposites was significantly affected by the thermal decomposition of the intercalating agent. In the case of the alkyl pyridinium modified clay, the degradation of the intercalating agent during processing was found to alter the clay dispersion. Finally, the crystallization was analyzed by differential scanning calorimetric (DSC) analysis and polarized optical microscopy (POM): it was demonstrated that the kinetics of nucleation and growth is not only affected by the dispersion state of the clay, but also depends on the clay/polymer interface properties, and therefore on the nature of the intercalating agent.