PET／PA66／液晶共聚酯酰胺共混体系的流变性能

采用ＳＥＭ１、热偏光显微研究了聚对苯二甲乙二酯（ＰＥＴ）／聚酰胺６６（ＰＡ６６）／热致液晶共聚酯酰胺（ＬＣ３０）三元共混物的形态结构;利用Ｉｎｓｔｒｏｎ３２１１型毛细管流变仪研究了共混物的流变性能,结果表明：ＰＥＴ／ＰＡ６６／ＬＣ３０共混物为一热力学不相容的多相聚合物体系,ＬＣ３０的加入提高了ＰＥＴ／ＰＡ６６的相容性,有效地改善了ＰＥＴ／ＰＡ６６共混物的流变性能,ＰＥＴ／ＰＡ６６／ＬＣ３０三元共混     

热致液晶聚酰胺的溶解性能和热性能

采用直接缩聚法,用自制的新型二元酸PEG3与芳香二胺进行缩聚反应,合成出较高分子量(比浓对数粘度为1.063 dL/g)的热致液晶聚酰胺,对其热性能和溶解性能进行了研究。结果表明,柔性链的引入,降低了聚酰胺的熔点(Tm=307.8℃),有利于液晶相的形成。而苯环的引入,平均分配了聚酰胺的刚性,既保持了聚酰胺耐热的特性,又提高了液晶相的稳定性(液晶显示范围ΔT=Ti-Tm=66.1℃),有利于该液晶高分子的应用。热失重(TGA)曲线显示了合成的聚酰胺具有较好的热稳定性(温度在400℃以上的质量损失为5%)。合成的聚酰胺具有较强的耐溶剂性,不溶于非极性溶剂,只能部分地溶解于强极性的纯溶剂或溶解于加盐(LiCl,或CaCl2)的复合溶剂中。     

热致液晶共聚酯酰胺／PET共混物的流变性能和原位增强特性

采用Ｉｎｓｔｒｏｎ３２１１型毛细管流变仪研究了ＰＥＡ／ＰＥＴ共混物的流变性能，据此探讨共混物熔体的可纺性，讨论了共混物配比与复合纤维力学性能的关系，并且偏光显微镜，扫描电镜研究纤维的结构。结果表明，共混物的表观粘度低于ＰＥＴ的粘度，当ＰＥＡ为１０％，共混物的表观粘度达到最小值；且ＰＥＡ含量低于１０％时，共混物的可纺性即，表现出良好的原位增强效果。     

Influence of Layered Aluminoborophosphate on Flame Retardance,Crystallization Behaviors and Mechanical Properties of Polyamide 66 Systems

A layered aluminoborophosphate(LABP-DDA) was hydrothermally synthesized using dodecylamine as a structure-directing agent, and was added into polyamide 66(PA66) to obtain nanocomposites, PA66/LABP-DDA, via melt intercalation method. The characterization results of transmission electron microscopy(TEM) and small angle X-ray scattering (SAXS) indicate that LABP-DDA has been successfully exfoliated into nano-layers of PA66 matrix. The unstable γ phase of PA66 was found in the composites with the help of X-ray diffraction(XRD) and differential scanning calorimetry(DSC). The heterogeneous nucleation effect of LABP-DDA resulted in an increasement of about 10℃ in melting temperature and an increasement of about 7% in crystallinity when compared with those of neat PA66. The introduction of LABP-DDA did not significantly affect the toughness and strength of PA66. The results of flammability test indicate that LABP-DDA possesses positive synergistic flame retarding effect in the presence of melamine polyphosphate(MPP) and the 77%PA66/(23-x)%MPP/x%LABP-DDA(x=1, 2) samples in thickness of 1.6 mm reached from Fail to V-1 rating based on UL94, compared with 77%PA66/23%MPP.     

Miscibility and interfacial property studies of the blends of ethyl cellulose with copolyamide6/66/1010

Interfacial properties governing reverse osmosis separations were studied by using liquid chromatography data with respect to ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends. The miscibility of ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends was investigated by using differential scanning calorimetry (DSC) and Fourier transform infrared, while the interfacial properties of the blends, including the interfacial adsorption, hydrophobicity, polar and non-polar parameters and β-parameters, were studied by using liquid chromatography. The results show that EC and PA-130 are miscible at compositions of (80/20), (70/30) and (50/50). The hydrophobicity of EC/PA-130 increases with the of PA-130 content. The EC/PA-130(70/30) is superior to the other blends for separating non-dissociable polar organic solute and is more suitable for use as desalting membrane material. It seems that liquid chromatography is an effective tool for studying the interfacial properties of polymer blend materials and selecting high performance of membrane materials.     

COMPARISON OF POLYAMIDE 66/MONTMORILLONITE NANOCOMPOSITES PREPARED FROM POLYAMIDE 6 AND POLYAMIDE 66 BASED MASTER-BATCHES

Two master-batches,polyamide 66 (PA66)/organo-montmorillonite (OMMT) and polyamide 6 (PA6)/OMMT, prepared by melt compounding with methyl methacrylate (MMA) as co-intercalation agent,have been used to prepare nearly exfoliated PA661montmorillonite (MMT) nanocomposites.The resulting nanocomposites are compared in view of their morphology and properties.Nano-scale dispersion of OMMT is realized in both types of nanocomposites,as revealed by XRD,TEM and Molau tests.PA66/MMT nanocomposites having superior me...     

热致液晶性序列嵌段共聚酯

用1，10-癸二醇、聚四氢呋喃二醇（分子量为1050）与含液晶基元的缩聚单体2－甲基对苯撑双（4－氯甲酰）苯甲酸酯，通过溶液缩聚反应合成了一系列序列嵌段共聚酯。当取四氢呋喃二醇与癸二醇的重量配比小于70／30时，共聚物具有明显的液晶性。共聚物的液晶性用偏光显微镜、DSC和X射线衍射进行了表征。     

PET-HBT嵌段热致性液晶共聚酯的合成

液晶高分子材料具有相当高的强度和模量，被誉为当代超级工程塑料．以对羟基苯甲酸甲酯、1，4-丁二醇为主要原料，经熔融酯交换合成双-对羟基苯甲酸丁二醇酯(BBHB)；以四氯乙烷为溶剂，采用溶液缩聚法将过量的BBHB与对苯二甲酰氯(TPC)合成端基为BBHB的齐聚物(PHBT)；以对苯二甲酸二甲酯与乙二醇为原料，经熔融酯交换合成对苯二甲酸双β-羟乙酯(BHET)，然后采用溶液缩聚法将BHET与少量的TPC合成端基为TPC的齐聚物(PTET)；最后以PHBT与PTET为原料，以四氯乙烷为溶剂，采用溶液缩聚法合成目标共聚酯(PET-HBT)。研究了共聚酯的双折射现象及热行为；用偏光显微镜观察了试共聚酯的织态结构并用FTIR表征了共聚酯的微观结构．     

Synthesis and Characterization of Thermotropic Liquid Crystalline Polyesters

Abstract

Synthesis and characterization of polyesters of 4,4′-dihydroxy biphenyl with succinic, adipic, suberic and sebacic acids were carried out. Initially the diacids were converted to the corresponding acid chlorides in dimethyl formamide (DMF). 4,4′-dihydroxy biphenyl was prepared from 4-hydroxy biphenyl by bromination and subsequent hydrolysis. The low molecular weight polyesters were prepared by the condensation of diacid chlorides with 4,4′-dihydroxy biphenyl in DMF at appropriate temperature. All the polymers were characterized by ¹H NMR, FT-IR, DSC and hot stage polarizing microscope. Thermotropic liquid crystalline behaviour was established by high temperature X-ray (HTXRD) at various temperature intervals. It was found that among the four compounds prepared, three of them showed nematic phase liquid crystallinity with the exception of the ester of succinic acid.     

Thermal and crystallization studies of nano-hydroxyapatite reinforced polyamide 66 biocomposites

The thermal and crystalline behaviour of nano-hydroxyapatite (n-HA) reinforced polyamide 66 (PA66) biocomposites was studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). The thermal properties of PA66 and n-HA/PA66 composites were analysed by TG. The effect of hydroxyapatite on the melting and crystallization of PA66 was evaluated by DSC. DSC measurements exhibited an increase in the crystallization temperature, however, decrease in crystallinity with the addition of n-HA to the PA66 matrix, which was attributed to the hydrogen bonds between the n-HA surface and polyamide 66 molecules. With increase of n-HA content, the melting peak of the PA66 component shifted to higher temperature, suggesting constrained melting. The addition of n-HA to PA66 played the role of nucleating agent and enhanced the crystallization rate. Non-isothermal parameter a measured by Liu method varies from 1.13 to 1.18, from 1.02 to 1.07, and from 1.18 to 1.21 for PA66, 30 wt% n-HA/PA66 and 40 wt% n-HA/PA66, respectively, and the values of K_(T) systematically increase with rise in relative degree of crystallinity.     

含氧化偶氮苯介晶基元共聚醚的合成与液晶行为

以1,6-二溴己烷(A)和1,10-二溴癸烷(B)为共缩聚单体,按不同摩尔配比与4,4'-二羟基氧化偶氮苯经相转移催化共聚醚化反应,合成了一系列主链上含有氧化偶氮苯介晶基元的共聚醚,它们均有好的液晶性,其取向膜观察到条带织构,当A/B的摩尔比为1时液晶态范围最宽。     

三元无规芳—脂族聚酯酰胺的热致液晶行为

采用低湿溶液缩聚的方法合成了对苯二甲酰氯，二甲基联苯胺和己二醇为单体的芳酯族液晶聚酯酰胺。用ＤＳＣ，Ｘ光衍射分析和偏光显微镜等手段研究了该系列聚酯酰胺的热致液晶行为，确认了二甲基联苯胺单体用量在２０％（ｍｏｌ）的情况下，所得聚酯酰胺仍为向列型液晶聚合物。由于聚酯酰胺分子间聚酰胺链段之间的氢键作用，随着二甲基联苯胺用量增加至６０ｍｏｌ％时，所得的聚酯酰胺己无液晶转变温度，其液晶区间即从熔融温度直至分     

Mechanism of the temperature-dependent degradation of polyamide 66 films exposed to water

Experiments were performed to elucidate the degradation mechanism of hot-pressed polyamide 66 upon exposure to water. For films exposed to water over the temperature range 25 °C-90 °C, degradation was monitored using FTIR and solid-state ¹³C NMR spectroscopies. The data are consistent with a mechanism in which (1) a radical is formed on the methylene carbon adjacent to the amide nitrogen, (2) this radical reacts with oxygen to form a hydroperoxide, and (3) the hydroperoxide decomposes to form an imide or a hydroxylated amide, both of which may cleave leading to chain scission. Water appears to facilitate degradation by increasing the flexibility of the polymer matrix through swelling rather than acting as a reactive species, at least at the early stages of the process. An apparent activation energy of 15 ± 2 kJ/mol is observed for the early stages of degradation, suggesting that segmental motions in the polymer associated with water and oxygen sorption or inter-chain radical reactions are indeed key components of the degradation process.     

SYNTHESIS AND CHARACTERIZATION OF ORGANOMONTMORILLONITE AND POLYAMIDE 66/MONTMORILLONITE NANOCOMPOSITES

The montmorillonites (MMTs), layered, smectite-type silicates, were premodified by two different methods priorto the polymer melt intercalation. In one case MMTs were modified with cetyltrimethylammonium bromide (CTAB), andtermed as organomontmorillonites (OMMTs); in the other case MMTs were modified by nylon, and the products were calledmodified montmorillonites (MMMTs). The effects of CTAB and nylon on the MMTs were investigated by using TG andWAXD. The results show that interlayer spacings of CTAN and nylon modified MMTs are larger than that of sodium MMTs.Then, polyamide 66 (PA 66)/MMT nanocomposites were obtained through the method of melt intercalation of polymers. Thenanocomposites were characterized by WAXD, TEM and Molau experiments. The results indicate that the MMTs dispersehomogeneously in the PA 66 matrix. The mechanical properties of nanocomposites, such as tensile properties and flexuralproperties, were also measured and show a tendency to increase with increase of MMT content and reach the maximumvalues at 5phr MMT content. The heat distortion temperature (HDT) of the nanocomposites (7 phr) is about 32 K higher thanthat of pure PA 66.     

Melamine integrated metal phosphates as non-halogenated flame retardants: Synergism with aluminium phosphinate for flame retardancy in glass fiber reinforced polyamide 66

An integrated multicomponent molecule, Melamine-poly(aluminium phosphate) (Safire^®200), its zinc and magnesium analogues namely Safire^®400 and Safire^®600 respectively were used as flame retardants for glass fiber reinforced polyamide 66 in combination with aluminium phosphinate. Characterisation, thermal stability, combustion properties, glow-wire flammability index and glow-wire ignition temperature and cone calorimetry results are reported. Lower threshold of loading of flame retardants that pass V0 rating in UL-94 vertical burning test have been determined. Effect of Zinc borate (Firebrake^®500 grade) in these formulations was investigated. Influence of additives on endothermic and exothermic transitions of polyamide 66 in these formulations were studied by differential scanning calorimetry. The formulations were evaluated against the properties and fire performances of classical commercial combination of aluminium phosphinate and melamine polyphosphate. All the new formulations down to 15% of additives loading achieve V0 rating according to UL-94 protocol. This synergistic combination of additives significantly reduces the peak of heat release rate (pHRR) and total heat release (THR) in formulations exhibiting various degrees of intumescence.     

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.     

热致液晶聚酯共混物与复合材料研究

评述了热致液晶聚酯的共混物与复合材料的研究新进展,揭示了热行为与相容性、流变性与加工性以及形态结构与多种性能之间的内在联系,展望了应用于高强高模纤维与塑料、低热膨光纤涂层及低透气包装膜等高性能材料的前景.     

固态缩聚尼龙66的熔化行为

固态缩聚尼龙６６的熔化行为沈百拴，张喜亮，李新法（郑州大学材料工程系郑州４５００５２）关键词尼龙６６，固态缩聚物，熔化行为，差示扫描量热注关于固态缩聚反应的研究国内外已有报道［１～４］，叵未见固态缩聚尼龙６６（ＳＳＰＰＡ６６）熔化行为的报道。本文用Ｄ...     

Thermal Oxidative Stability of Heat-Stabilised Polyamide 66 by Differential Scanning Calorimetry

The thermal stability of heat-stabilised polyamide 66 in an oxidative environment is evaluated by DSC. The oxidative stability of the polyamide decreases as a result of repeated injection moulding. The results also indicate that the presence of glass fibres in the polyamide has a negative influence on the oxidative stability. Both isothermal and dynamic DSC measurements seem to be useful tools for assessing the stability of polyamides and there is a relationship between data determined using both procedures. This revised version was published online in July 2006 with corrections to the Cover Date.