长碳链聚醚酰胺弹性纤维开发及其弹性机理

以长碳链聚酰胺弹性体为原料,通过熔融纺丝技术制备了高性能化新型长碳链聚醚酰胺(LPAE)弹性纤维.该弹性体是以基于生物来源单体的长碳链聚酰胺为硬段,以聚醚为软段,其弹性可通过调节软硬段比例有效调控.测试结果表明,与目前市场上应用广泛的氨纶莱卡(LYCRA)相比,软段含量较高的LPAE纤维具有高断裂伸长,低初始模量的特点;在200%伸长范围内,其弹性回复率与氨纶相当,耐热性优于氨纶.分析得知,LPAE纤维的高弹性源于硬段聚酰胺存在强氢键相互作用且结晶度高,同时硬段充当物理交联点;软段具有良好的柔性,可以发生大变形,这种软硬段交替的嵌段分子链结构形成三维网络.大应变下,LPAE纤维弹性回复率降低是由分子链滑移及软段拉伸诱导结晶共同造成的.     

长碳链聚酰胺基热塑性弹性体研究进展

长碳链聚酰胺基热塑性弹性体(LCPAE)是一种高性能热塑性弹性体,它是由长碳链聚酰胺(LCPA)硬段以及聚醚软段构成的一种嵌段共聚物,通过调节聚酰胺硬段以及聚醚软段的分子量以及相对含量,可以获得一系列的嵌段共聚物,邵氏硬度从25D到70D。由于两种链段在热力学上互不相容,使得该类弹性体具有微相分离的聚集态结构,同时具备LCPA树脂耐磨、强度高、热稳定性好、加工性好以及聚醚材料的低温柔软性、回弹性高等诸多优点。本文综述了1970年以来LCPAE的发展历程、市场现状、国内外研究进展以及相关专利分析,并简要总结了借助原位X射线衍射技术研究LCPAE微观结构与性能的部分进展,其在单轴拉伸外场作用下的聚集态结构演化对于理解其结构性能关系、指导分子结构设计有着重要意义。本文还简要介绍了本实验室使用具有自主知识产权的长碳链聚酰胺PA1012原料设计合成系列LCPAE的工作。文章最后结合已有研究进展,对LCPAE面临的重要科学问题以及产学研协作实现国产化所需解决的实际问题进行了总结与展望。     

长链碳烯-聚丁二烯涂覆二氧化锆固定相的制备及评价

通过在聚合诱导胶体凝聚法制备的二氧化锆微球表面上沉积、交联长链碳烯和聚丁二烯,制备了复合型二氧化锆固定相.探索了影响反应的主要因素,并对其色谱性能进行了评价.用分离实例说明该固定相对中性,特别是碱性化合物具有优良分离性能,显示反相色谱特征.     

长链正烷烃的受限结晶研究进展

聚合物的结晶过程和最终凝聚态结构直接影响材料的加工使用性能.作为高分子材料的最大品种,聚烯烃由于分子量大,分子量分布较宽,结晶过程中形成多种亚稳态,因而从分子水平上阐明其结晶机理存在困难.与聚乙烯链结构相似的长链正烷烃可作为聚烯烃的模型化合物,研究其受限结晶行为能为复杂的聚合物受限结晶提供理想的模型体系.长链正烷烃的受限空间可以分为一维受限薄膜、二维受限微孔、三维受限微乳液或微胶囊等.相对于本体,长链正烷烃在每个受限体系中的结晶行为各不相同,这主要来源于受限体系对成核、结晶以及相转变的影响.本文重点综述了长链正烷烃在3种受限体系中的结晶特点,并结合各个体系中聚合物的结晶特点,阐述了长链正烷烃作为聚合物模型化合物的合理性.     

弹性体拉伸取向和应变诱导结晶研究进展

橡胶拉伸取向和应变诱导结晶被公认为是天然橡胶和一些合成橡胶(如氯丁橡胶、丁基橡胶、氢化丁腈橡胶等)高效自增强的关键所在,研究该现象和行为规律对理解橡胶增强机理具有十分重要的意义.本文总结了常用于研究橡胶拉伸取向和应变诱导结晶的表征方法,对其原理、特点和适用范围进行了对比分析;综述了纳米填料(炭黑,二氧化硅,黏土,碳纳米...     

一维新型碳的同素异形体:碳链

碳链是一种完全一维的、具有电子轨道sp杂化结构的新型碳的同素异形体.正是由于碳链的独特的一维结构,使其拥有区别于富勒烯、石墨烯和碳纳米管的化学键,从而表现出更加优异的性能,如:理论预言碳链的机械强度是石墨烯的几倍;碳链的导热也类似于石墨烯和碳纳米管;碳链是具有直接带隙的半导体材料,且带隙的大小可以通过其长度来调控,其长...     

PET/PC共混体系的酯交换反应对其高压结晶行为的影响

利用转矩流变仪、DSC、SEM及WAXD等表征手段研究了PET/PC共混体系的酯交换反应对其高压结晶行为的影响.SEM观察表明,PET和PC熔混时的酯交换反应有利于PET/PC体系在高压结晶时生成厚度较大的伸直链晶体,且可以促进其高压下酯交换反应的发生.楔形伸直链晶体和弯曲伸直链晶体的存在证明链滑移扩散和酯交换反应两种机制对体系中聚酯伸直链晶体的增厚有贡献.拟合分峰法和War-ren-Averbach傅里叶分析法的计算结果表明,随PET/PC体系熔混时酯交换反应程度的增加,高压结晶共混物的结晶度降低,PET的平均微晶尺寸增大,点阵畸变平均值则减小,而微晶尺寸分布变宽.提出了在共聚物组分都具备结晶能力时,结晶诱导化学反应和化学反应诱导结晶两种过程在一定条件下可同时发生的观点.     

环氧丙烷聚醚三元醇/左旋聚乳酸三枝链嵌段共聚物的结晶行为

采用DSC对环氧丙烷聚醚三元醇/左旋聚乳酸三枝链嵌段共聚物(PPO-b-PLLA)的熔体结晶行为进行了研究. 在388～407 K范围内, 分别采用Avrami方程和Arrhenius方程进行了结晶动力学计算. Avrami指数n值约为2.2, 表明共聚物以二维生长方式进行晶体生长. 基于LH结晶理论, 对三枝链嵌段共聚物的结晶机理进行了探讨. 实验发现该体系共聚物的Regime II和Regime III转变温度随着n(PO)∶n(LA)的增大而变化, Kg (III)/Kg (II)＝2.0～2.2, 与LH理论预期值吻合. 实验结果表明三枝链的PPO链段对PLLA链段的结晶有很大影响, 使其成核较均聚物困难. 链折叠自由能σe和链折叠功q均高于PLLA的值.     

含长氟链丙烯酸酯共聚物的合成及应用展望

采用传统自由基共聚合方法合成了新型的含氟大分子单体PFMA-MA,并将其与甲基丙烯酸甲酯(MMA)、丙烯酸异丁酯(IBA)和γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPTS)进行自由基共聚合成了长氟链丙烯酸酯共聚物(ACLC)。对该聚合物的表面性能以及本体性能进行了研究。结果表明,少量的PFMA-MA便可使得到的共聚物ACLC的憎水性大幅度提高。通过X射线光电子能谱(XPS)研究大幅提高憎水性的机理,结果表明ACLC中的长氟链段具有强烈的迁移特性,氟原子富集于表面,使得材料憎水性得到提高。ACLC具有优异的附着力、硬度和低吸水率。含长氟侧链梳形丙烯酸酯共聚物有望应用在疏水、防水涂层材料等领域。     

拉伸状态下弹性聚醚酯聚集态结构和分子运动的固体高分辨核磁共振研究

用固体高分辨核磁共振碳谱方法对不同拉伸比的聚醚酯嵌段共聚物的聚集态结构和分子运动进行了研究,发现共聚物中的聚四氢呋喃(PTMO)链段在拉伸比为2 0时开始就出现结晶,且结晶度和晶片厚度都随着拉伸比增加而明显增加,而样品中未结晶部分的高频分子运动随拉伸比的变化则不明显,拉伸导致的PTMO结晶主要发生在“纯”的PTMO非晶区.通过1 H自旋扩散实验,估算出在拉伸比为4 . 0倍时,PTMO非晶区与结晶区的界面层厚度为1 .1nm ,PTMO非晶区与硬段的结晶区的界面厚度约为3 .1nm .     

MODIFICATION OF POLYAMIDE 6 WITH POLYAMINOAMIDE-g-POLY(ETHYLENE GLYCOL) VIA HYDROLYTIC POLYMERIZATION

To enhance the impact strength of polyamide 6,hydrolytic polymerization modification by the polyaminoamide-gpoly (ethylene glycol)(PAAEG)derivatives with poly(ethylene glycol)(PEG)molecular weight of 400-10000 was studied. Amide groups of polyaminoamide segments were postulated to form hydrogen bonding with polyamide 6,and hydroxy groups of PAAEG units were expected to react with carboxylic acid groups of polyamide 6 forming copolymers during the polymerization.The improved compatibility in amorphous reg...     

Effects of different composition ratio on the dielectric relaxation and dynamic mechanical properties of poly(ω‐dodecalactam‐co‐ε‐caprolactam‐co‐propylene oxide) copolymers

The molecular dynamics of new poly (ω‐dodecalactam‐co‐ε‐caprolactam‐co‐propylene oxide) copolymers (DL/CL/PAC) has been investigated by using dynamic mechanical thermal analysis (DMTA) and dielectric relaxation spectroscopy (DRS) measurements. The copolymers were synthesized via anionic polymerization of relevant lactams activated with carbamoyl derivatives of telechelic hydroxyl terminated polypropylene oxide with isophorone diisocyanate (PAC). The calorimetric, X‐ray diffraction, and DMTA measurements were performed to recognize the influence of the composition ratio and the type of PAC on the physical, thermal, and mechanical properties of the synthesized copolymers. The DRS was used to study the frequency dependence of the dielectric permittivity of some isotherms from ?110 to 145 °C. Copolymerization of ε‐caprolactam with about 10 wt % ω‐dodecalactam results in a copolymer that has lower water absorption, a melting point close to that of polyamide 6 and has a high enough degree of crystallinity in respect to high storage modulus. Five dielectric relaxations have been observed in the dielectric spectra, three at lower temperature and two at higher temperature. The copolymers have two glass transition temperatures for polyamide segments and polyether blocks, indicating microphase separation in the copolymers. Other studies directed toward molecular dynamics of polyamide DL/CL/PAC copolymers have not been reported. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

On the effect of the polyketone structure on the strength properties of thermoplastic-matrix fiber glass composites

The physical, mechanical, and structural-relaxation properties of composite microplastics based on thermoplastic (polyethylene and polyamide) matrices, in which the alternating ethylene-CO, diene-CO, and ethylene-CO-α-olefin copolymers are used as a finish, were studied. An important role of the interface between the components in the formation of the mechanical properties of thermoplastic-matrix composites and the possibility of controlling adhesive interactions by means of polymeric finishes based on poly(diene-ketone)s and aliphatic polyketones with different side-chain lengths are shown.     

Copolyesteramides—III. Anionic copolymers of ε-caprolactam with ε-caprolactone. Crystalline character and mechanical properties

The crystalline character of anionic copolymers of ε-caprolactam with ε-caprolactone and of some alternatingly-sequenced analogues has been studied and investigations made of the mechanical and dynamic mechanical properties of the anionic copolymers. The anionic copolymers are crystalline over the whole range of compositions. Depending on the proportions of NH(CH₂)₅CO and O(CH₂)₅CO units and the thermal history of the copolymers, the crystalline phases present are either wholly of polyamide type or composed of co-existing and mutually incompatible polyamide and polyester entities. However, the constituents appear to be miscible in the amorphous phase. The mechanical properties of the copolymers (like their crystalline melting temperatures) change discontinuously with composition, showing minima in the values of initial modulus, yield stress and breaking stress at ca 25–40% amide-group content where dual crystallinity exists. In addition to their variation with composition, the properties are also affected by changes in the procedure of anionic copolymerisation.     

Molecular weight control in polycondensation of hydroxyl diesters with hexamethylenediamine by polymer matrices

Polycondensation reactions of hydroxyl diesters such as dimethyl tartrate (DMT) and diethyl mucate (DEM) with hexamethylenediamine (HMD) were carried out in the presence of poly(vinyl pyridine) (P-VPy) and its copolymers with styrene of different compositions as matrix polymers in order to investigate the difference in interaction forces with monomers or the resulting polyamides owing to hydrogen bonding. It was found that matrix effects of poly(4-vinyl pyridine) (P-4VPy) on the rate enhancement and solution viscosity of the resulting polyamide became more pronounced with decreasing solvent polarity. This result suggests that the matrix effects of P-4VPy on polycondensation are due to hydrogen bonding interactions between hydroxyl diesters and P-4VPy. The addition of P-4VPy increased the molecular weight of the resulting polyamide to a higher extent than poly(2-vinyl pyridine) (P-2VPy), and the molecular weight of the resulting polyamide could be controlled according to the molecular weight of P-4VPy. Copolymer composition of 4-vinyl pyridine–styrene (4VPy/St) copolymers as matrix polymers also affected the molecular weight of the polyamide, which increased with increasing P-4VPy unit contents in the copolymers.     

Synthesis and properties of multiblock copolymers based on polydimethylsiloxane and polyamides from dicarboxylic acid and diisocyanate terminated functionalities

Polydimethylsiloxane (PDMS)–polyamide multiblock copolymers were successfully synthesized via diisocyanate route by two different procedures, i.e., the one-step and two-step methods, In the two-step method, α, ω-diisocyanate-terminated polyamide oligomers, which were prepared in situ from a mixture of isophthalic acid (IPA) and azelaic acid (AZA) with 4,4′-methylenedi (phenyl isocyanate) (MDI) in 1,3-dimethyl-2-imidazolidone (DMI) in the presence of 3-methyl-1-phenyl-2-phosopholene 1-oxide catalyst, were reacted with α, ω-bis (10-carboxydecyl) polydimethylsiloxane (PDMS-diacid) leading to the formation of multiblock copolymers. In the one-step method, the reaction components, MDI, IPA, AZA, and PDMS-diacid were reacted all together in DMI in the presence of the catalyst. These polymerizations gave multiblock copolymers having inherent viscosities in the range of 0.36–1.12 dL/g in N,N-dimethylacetamide (DMAc). These multiblock copolymers were soluble in amide-type solvents, and transparent (or translucent) and ductile films could be cast from the solutions in a mixture of DMAc and bis(2-ethoxyethyl) ether. The multiblock copolymers prepared by the two-step method had better-defined, microphase-separated morphology than those obtained by the one-step method. The mechanical properties of PDMS–polyamide multiblock copolymer films were found to be highly dependent on the PDMS content; the tensile strength and modulus of the films decreased with increasing the PDMS content.     

Improved Compatibility of Blends between Recycled Polypropylene and Polyamide 6 by the Products of Degradation

The compatibilization of recycled polypropylene in blends with polyamide 6 prepared via twin screw extruder was investigated. Reactive compatibilization between the recycled polypropylene and polyamide 6 was studied by “Molau test” and FTIR, the results showed the formation of copolymers during blending. Morphology analysis revealed the diameter of recycled polypropylene dispersed in polyamide 6 matrix decreased markedly and the boundary was obscure compared with the uncompatibilized blends by scanning electron microscopy. Moreover, enhanced interfacial adhesion between the blends components was also investigated by the tensile behavior and dynamical mechanical analysis.     

Compatibilization of polyethylene/polyamide 6 blends with functionalized polyethylenes prepared with metallocene catalyst

Metallocene catalyst technology was utilized to prepare functionalized polyethylenes, which were used as compatibilizers in polyethylene/polyamide 6 (40/60) blends. Polymerization of ethylene with 10-undecen-1-ol, 10-undecenoic acid, or N-methyl-10-undecenylamine resulted in ethylene copolymers with a small amount (0.2–1.2 mol %) of functionalized side chains. The blends were prepared in a twin-screw midiextruder, and injection molded with a mini-injection molding machine. The effect of the new compatibilizers on morphology and mechanical and thermal properties was studied. Toughness as well as stiffness and strength increased significantly with an addition of 10 wt % compatibilizer. Morphology became much more uniform, and crystallization and melting behavior changed. The Molau test with FTIR analysis was used to determine that the desired reactions between the compatibilizer and polyamide had actually taken place. The results showed functionalized polyethylenes prepared with metallocene catalysts to act as effective compatibilizers in polyethylene/polyamide 6 blends. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3099–3108, 1999     

尼龙6/高岭土界面相互作用对其复合材料力学性能和流变行为的影响

<正> 无机填料填充复合材料的性能,除了依赖于聚合物基体和填料固有的内在性质外,很大程度上依赖于它们之间的界面性质。因此,研究聚合物/填料界面相互作用,对合理地设计具有优良性能的复合材料具有十分重要的意义。 目前,还很难对粉末填料与聚合物基体之间界面相互作用进行定量的研究,而且关于这方面的报道也较少。本文利用接触角法测定了高岭土填料和尼龙6基体的表面自由能、界面张力、粘附功等热力学参数,对高岭土与尼龙6之间界面相互作用与复合材料力学性能、流变行为的关系进行了分析和探讨。