聚对苯甲酰胺薄膜的结构

聚对苯甲酰胺溶于ＤＭＳＯ ＮａＨ系中，变成聚合物阴离子，形成均相溶液．从此溶液中蒸发掉ＤＭＳＯ，用有机溶剂再生后获得再生薄膜．室温下干燥的薄膜基本上是无定形的，１３０℃的热处理对薄膜的结构几乎不发生大的影响，２５０℃或者３００℃的热处理后，薄膜的结构由无定性变成结晶１型及新的结晶２型．与结晶１型相比，结晶２型的ｄ＝０４９ｎｍ与ｄ＝０２８ｎｍ的反射强烈出现，而且相对于结晶１型的ｄ＝０３１ｎｍ的反射看不见或者看不清楚     

超支化聚磷酸酯阻燃剂对尼龙6的成炭促进作用

以三氯氧磷和双酚A为原料制备了具有超支化结构的聚磷酸酯阻燃剂(HPPEA),通过红外(FTIR),核磁(1H-NMR,31P-NMR)及热重分析表征了产物的结构和热稳定性.将HPPEA与三聚氰胺聚磷酸盐(MPP)进行复配,通过熔融共混法制备阻燃尼龙6,通过氧指数法和垂直燃烧法测试了其阻燃性能,采用热重分析(TGA)研究...     

高岭土填充尼龙6的结晶行为

利用差示扫描量热仪（ＤＳＣ）研究了未处理高岭土和经γ－缩水甘油醚氧丙基三甲氧基硅烷（ＫＨ５６０）处理的高岭土对尼龙６等温和非等温结晶行为的影响．结果表明，未处理的高岭土和ＫＨ５６０处理的高岭土在尼龙６基体中都起到异相成核作用．但是，与未处理高岭上相比，ＫＨ５６０处理的高岭土更有效地提高了尼龙６的结晶速率．这一方面归因于ＫＨ５６０处理的高岭土在尼龙６中的分散性好，增大了成核密度；另一方面归因于高岭土经ＫＨ５６０处理后，与尼龙６的相容性增强，从而提高了尼龙６的晶体生长速率．     

尼龙1212/尼龙6共混体系的非等温结晶行为

用DSC研究了尼龙 12 12 ,尼龙 6及其共混体系的非等温结晶行为 .结果表明 ,加工历史对尼龙的结晶和熔融行为影响很大 .经双螺杆挤出机挤出的尼龙 12 12和尼龙 6 ,由于应力诱导分子链取向 ,其结晶温度都有不同程度的提高 ,且表现出多重熔融现象 .在共混体系中 ,尼龙 12 12分子在共混物的界面上异相成核结晶 ,提高了其结晶温度 ,但酸酐化SEBS的加入抑制了分子链的运动又使其结晶温度降低 .共混体系降低了尼龙12 12的熔融温度 ,并使得其高熔点的熔融峰逐渐消失 ;而尼龙 6的熔融行为基本上没有变化 .     

浇铸尼龙—6的结晶与熔融

用ＤＳＣ法研究了Ｌａ２Ｏ３和Ｙ２Ｏ３对浇铸尼龙－６（ＭＣ尼龙－６）结晶与熔融的影响，二者都使ＭＣ尼龙－６熔体等速降温的结晶温度Ｔｅ升高，等速升温的溶点Ｔｍ降低，结晶度Ｘｃ降低，拉伸过程的断裂能密度及断裂伸长率提高，Ｌａ２Ｏ３使ＭＣ尼龙－６平衡熔点Ｔｍ降低，结晶速率增加，结晶完善程度变差，Ｙ２Ｏ３使ＭＣ尼龙－６的Ｔｍ升高，它可显著改善ＭＣ尼龙－６的耐热性。     

PC/尼龙6共混合金的结晶结构与性能

聚碳酸酯(PC)由于具有突出的冲击韧性、良好的透明性、尺寸稳定性和电气绝缘性而广泛应用于电子电气、仪器仪表、汽车、机械、医疗、照明和建筑等领域,是一种综合性能优良的工程塑料.但也存在着加工流动性差和耐药性差、易应力开裂及对缺口敏感等缺陷,且价格昂贵,因而限制了它的应用范围.对PC进行合金化,提高PC的性能,降低成本是PC改性的重要研究方向,开发成功的PC合金有PC/ABS,PC/PET,PC/PBT[1]和PC/PE[2]等.制备高性能PC/尼龙6(PA6)合金是目前国内外PC改性的热点.PA6的加入可以改善PC的耐药性、耐应力开裂性及加工性能,降…     

多组分单体接枝聚丙烯/尼龙6反应共混物结晶行为研究

用多组分熔融接枝的方法将甲基丙烯酸缩水甘油酯 (GMA)和苯乙烯 (St)共同接枝到聚丙烯 (PP)上 ,制得具有较高GMA接枝率的多单体接枝聚丙烯 ,PP g (GMA co St) .将PP g (GMA co St)与尼龙 6 (PA6 )进行共混 ,利用扫描电镜 (SEM) ,差示扫描量热计 (DSC)和广角X射线衍射 (WAXD)对共混物的形态和结晶进行了研究 .在共混过程中 ,PP g (GMA co St)与PA6反应原位生成了PP g PA6 ,有效改善了共混物的相容性 ,分散相尺寸明显减小 .在PP g (GMA co St) PA6为 3 7的体系中 ,PP g (GMA co St)出现分级结晶现象 ,其在较低温度下的结晶属于均相成核结晶 .在PP g (GMA co St) PA6为 7 3的体系中 ,由于PA6相分散细微 ,在通常结晶温度下不结晶 ,而是在低温下均相成核与PP g (GMA co St)同时结晶 .WAXD证实体系中接枝PP ,PA6为分别结晶 ,无共晶或新的晶型产生     

浇铸尼龙－6的结晶与熔融

用ＤＳＣ法研究了Ｌａ＿２Ｏ＿３和Ｙ＿２Ｏ＿３对浇铸尼龙－６（ＭＣ尼龙－６）结晶与熔融的影响。二者都使ＭＣ尼龙－６熔体等速降温的结晶温度Ｔ＿ｃ升高、等速升温的溶点Ｔ＿ｍ降低、结晶度Ｘ＿ｃ降低，拉伸过程的断裂能密度及断裂伸长率提高。Ｌａ＿２Ｏ＿３使ＭＣ尼龙－６平衡熔点只降低，结晶速率增加，结晶完善程度变差。Ｙ＿２Ｏ＿３使ＭＣ尼龙－６的升高，它可显著改善ＭＣ尼龙－６的耐热性。     

尼龙6/蒙脱土纳米复合材料的结晶行为

用广角Ｘ 射线衍射（ＷＡＸＤ）、差示扫描量热仪（ＤＳＣ）、小角激光散射（ＳＡＬＳ）等手段研究了尼龙６／蒙脱土纳米复合材料的结晶行为．结果表明分散在尼龙６基体中的蒙脱土纳米粒子起成核剂的作用．蒙脱土的表面改性增加了蒙脱土和尼龙６分子之间的界面粘接，它具有阻碍尼龙６结晶的作用，使结晶活化能增加     

聚对苯二甲酰对苯二胺/尼龙6复合物

随着材料科学的发展，纤维增强塑料已由纤维与树脂的复合，扩展到以刚性链高分子与柔性链高聚物在分子水平上的微观复合．棒状、刚性的液晶高分子是一种超高强度和超高模量的高分子材料，同时还具有在某种条件下易于自发取向形成微纤的特性．基于这些性能，液晶高分子自然成为代替无机纤维作增强剂，与柔性链高聚物进行微观复合最理想的材料．在与柔性链高聚物复合时，如何使之在基体中形成有很高的长径比（Ｌ／Ｄ）的液晶纤维，并在基体中又能起到强的增强效果，来获得高强度、高模量的复合材料．多年来一直是国际上研究的热点，有关这方面…     

解偏振光法测定装置的改进及高聚物结晶速度的测定

试制成功了热平衡时间短的解偏振光强度测定装置,用该装置测定了尼龙66,尼龙6和PET的结晶动力学数据,得到了满意的结果,     

聚醚酯/蒙脱土复合材料的结晶动力学和结晶形态

有机－无机复合材料是近来材料科学发展的热点,无机物对基体的结晶行为有很大的影响［１,２］．聚醚酯嵌段共聚物的高弹性依靠硬段结晶形成的物理交联点［３,４］,因而任何影响结晶的因素必然导致其性能的变化．通过聚醚酯与蒙脱土的复合,研究聚醚酯的结晶行为的变化...     

Melt crystallized polyamide 6.6 and its copolymers, Part II. Crystallization mechanisms in the homopolymer

The crystallization kinetics of polyamide 66 have been studied using polarized optical microscopy. The growth rate data for positively birefringent spherulites in polyamide 66 show a distinct change of slope, which would be identified as a regime I/II transition based on secondary nucleation theory. However, recent data for the same specimens crystallized isothermally, from small angle X-ray scattering found the lamellar thickness to be constant at approximately 2.0 chemical repeat units, but with an internal crystalline core and a substantial innerlayer. The crystal core increases in size to 2 chemical repeat units with both time and temperature at the expense of the inner layer. This evidence is totally inconsistent with secondary nucleation theory, where a lamellar thickness which varies significantly with supercooling is an integral part of the derivations.A calculation of the dimensions of the critical nucleus is reported here, using surface free energies, which found it to be impossibly large at a value between 14 and 360 stems in size, further suggesting that another crystallization mechanism is operating. Calculations of the surface free energy of the hydrogen-bonded surface suggest that it is the high energy surface, rather than the folded surface, which normally occurs as the high energy surface in polymers. As the high energy surface, the hydrogen-bonded surface would be expected to be the growth face, as occurs in non-polymeric materials. An earlier model of Lovinger, which placed the fold direction into the melt, generating a rough surface, is consistent with these results.It is suggested that crystallization in polyamide 66, if not in all polyamides, occurs through a surface roughening mode of growth. This is a natural consequence of the presence of H-bonding in the direction of growth. In one sense, polyamide 66 is conventional in its growth behavior, relative to non-polymeric materials, as the growth face is the highest energy surface. As such, the lamellar thickness would no longer be a morphological variable related to the supercooling in any direct way as an essential part of any crystallization theory for polymers. Such behavior is impossible in other polymeric systems as the fold surface is the highest energy surface and the presence of folds prohibits growth on that surface. However, models of surface roughening, which were developed as an alternative explanation for the behavior of, principally, polyethylene, predict the conventional lamellar thickness - supercooling relation to exist, which is inconsistent with the observed existence of a constant lamellar thickness with variable crystal core dimensions.It is suggested that polyamide 66 be taken as a paradigm for a different kind of polymer crystallization than that normally encountered. That is crystallization in which the growth face is the highest energy surface, not the folded chain surface, having much in common with the behavior of non-polymeric materials. The energetic changes occurring in this case, however, are governed by a combination of entropic and enthalpic barriers to crystallization, rather than being dominated by enthalpic considerations, as in metals. This is a direct result of the entropic effects of the long chain nature of polymers combined with the enthalpic effects of the hydrogen-bonding.     

生物可降解材料聚乳酸结晶行为研究进展

聚乳酸是一种具有良好生物相容性、可生物降解的热塑性脂肪族聚脂,是一种环境友好材料。聚乳酸的结晶性能对其力学性能和降解速率有着重要的影响,因而其结晶行为也逐渐成为人们研究的热点。本文针对聚乳酸的结晶行为综述了聚乳酸及其共混、共聚体系的最新研究进展。     

左旋聚乳酸的结晶行为研究

用DSC, WAXD和POM对Zn催化剂制备的左旋聚乳酸(PLLA)的熔体结晶行为进行了研究. 在95~125 ℃范围内, PLLA熔体结晶生成厚度约(14±1) nm的片晶, 该片晶不易发生熔体等温增厚. 对实验数据分别用Avrami方程和Arrhenius方程进行了计算, Avrami指数n=3±0.3, 表明PLLA以球晶形式生长, 其最大结晶速率温度为(105.0±0.5) ℃, t1/2约为5.2 min. 利用Lauritzen-Hoffmann（LH）理论对PLLA结晶机理进行了分析, 发现PLLA结晶的Regime Ⅱ和Regime Ⅲ的转变温度为107 ℃. Kg(Ⅱ)和Kg(Ⅲ)分别为4.57×105 K2和1.115×106 K2, 且Kg(Ⅲ)/Kg(Ⅱ)=2.4, 与LH理论值一致.     

导向剂法合成低硅X型沸石(LSX)

利用导向剂法(CDA)合成低硅[n(SiO₂)/n(Al₂O₃)≈2.0]X型沸石,用XRD,X射线荧光光谱测定样品的晶相及化学组成,并利用电子衍射对导向剂在老化过程中的结构变化进行了研究.结果表明,导向剂法合成速度快、杂晶极少.在晶化过程中的导向作用是一个持续过程,其活性不仅与配方、老化时间和温度有关,而且与其晶面的生长有关.     

Crystallization behavior of biodegradable poly(ethylene adipate) modulated by a benign nucleating agent: Zinc phenylphosphonate

Zinc phenylphosphonate (PPZn), a benign and biocompatible nucleating agent, was prepared and incorporated into the biodegradable poly(ethylene adipate) (PEA) to investigate its effect on the crystallization behavior, crystallization kinetics and spherulite morphology of PEA. Upon addition of PPZn, the crystallization temperature and crystallinity of PEA in the non-isothermal crystallization process increased significantly. Analysis of crystallization kinetics by Avrami equation suggests that the crystallization time shortened greatly and crystallization rate increased markedly after addition of PPZn. In the presence of PPZn, the spherulite size decreased and spherulite density increased significantly. It suggests that PPZn is an efficient nucleating agent for the crystallization of PEA. The accelerated crystallization in the presence of PPZn is mainly attributed to the epitaxial nucleation of PEA crystals on the surface of PPZn crystals, that is, a perfect lattice matching between PEA crystal and PPZn crystal occurs.     

基于聚乙二醇结构调控高分子量聚乳酸立构复合体系的结晶行为

设计合成了梳形聚(聚乙二醇甲醚丙烯酸酯)(PPEGA)及其与聚乙二醇(PEG)的嵌段共聚物(PEG-b-PPEGA).通过与高分子量左旋聚乳酸(PLLA)和右旋聚乳酸(PDLA)共混探究了PEG不同的结构对PLA立构复合体系(sc-PLA)结晶的影响.结果 表明线形PEGA和PEG能与sc-PLA完全相容,两者均能促进...     

苯乙烯—丙烯酸钠共聚物改性PET结晶行为的研究

本文用DSC和FT-IR方法研究了PET/苯乙烯-丙烯酸钠共聚物共混体系的相溶性、等温结晶动力学、组成、温度等因素对结晶速率、结晶度等结晶行为的影响,并初步探讨了离聚物对PET的作用。