Modification of nylon-6 with poly (m-phenylene isophthalamide) via MDI as a chain extender

Reinforcement of flexible nylon-6 by using poly (m-phenylene isophthalamide) PmIA (Nomex) using (MDI) 4,4-diphenylene methane diisocyanate as a chain extender was studied. Observation by scanning electron microscopy showed that the multiblock copolymer had a homogeneous texture. From the differential scanning calorimetry measurements, the multiblock copolymers were shown to have only one melting point, T _m, which is higher than that of nylon-6. The wide-angle X-ray diffraction pattern shows that nylon-6 has two diffraction peaks at 2=20° and 23.8°. However, the multiblock copolymer has only one peak at 2=20°, indicating a different crystal structure of multiblock copolymers. The copolymers appear to have a significant reinforcing effect on the mechanical properties.     

多壁碳纳米管的处理及其在芳纶1313中的分散

为了改善多壁碳纳米管(MWNTS)在溶剂N,N-二甲基乙酰胺(DMAc)中的分散性,提高MWNTs与芳纶1313(PMIA)基体界面的结合性能,用混酸对MWNTs进行了处理,用FT-IR对处理前后的MWNTs进行了表征,发现处理后的MWNTs表面接上了羧基.通过溶液共混的方法制得了PMIA/MWNTs纳米复合薄膜,并用SEM和TEM对其进行了表征,发现处理后的MWNTs在PMIA基体中的分散更为均匀.     

Lightweight poly(m-phenylene isophthalamide)/CF/GO@Fe3O4 composites for enhanced shielding of electromagnetic pollution

Journal of Materials Science: Materials in Electronics - In this work, ferroferric oxide (Fe3O4) microspheres with a diameter of?~?150 nm were in situ grown on the surface of...     

Modification of nylon-6 with semi-rigid and wholly-rigid aromatic polyamides

Nylon-6 was reinforced by two semi-rigid aromatic polyamides, poly(p-diphenylmethyl terephthalamide) (PMA), and poly(p-diphenyloxide terephthalamide) (POA), and also one wholly-rigid aromatic polyamide, poly(m-phenylene isophthalamide) (PmlA) by physical blending and chemical copolymerization usingp-amino phenyl acetic acid (P-APA) as a coupling agent. From the results of differential scanning-calorimetry, it was shown that both the polyblends with semi-rigid and wholly-rigid polyamides exhibited a glass transition temperature,Tg, higher than that of nylon-6 homopolymer. It also showed that theT _gs of wholly-rigid polyblends were higher than those of semi-rigid polyblends. Nevertheless, the multiblock copolyamides appeared to have even higherT _g andT _m, and better thermal stability. Morphological observations revealed that all the polymer alloys (polyblends and copolymers) were a dispersed phase structure, although the multiblock copolyamides were more homogeneous and compatible. Based on wide-angle X-ray diffraction, it was found that the polyblends had two diffraction peaks, i.e. 2 = 20.5 ° and 24 °. However, the multiblock copolyamides had only one peak at 2 = 20 °, evidently indicating a new crystal structure of the multiblock copolyamides formed. For the mechanical properties, it was found that the multiblock copolyamides had a more significant reinforcing effect than those of polyblends, especially those copolymerizing with wholly aromatic polyamides.     

常压法间位聚芳硫醚酰胺酰胺的合成及表征

通过合成一种新的含二酰胺键的单体,将其与硫化钠进行常压溶液缩聚,合成出了间位聚芳硫醚酰胺酰胺(m-PPSAA),通过红外、核磁证实了其化学结构,用DSC、TG等手段对m-PPSAA的热性能进行了表征,结果表明聚合物具有优良的热性能,通过X射线衍射表明m-PPSAA为结晶型聚合物,通过溶解性试验表明m-PPSAA能溶解于DMF、DMSO、NMP等溶剂,比PPS的溶解性好.     

聚乳酸的增塑改性

采用溶液共混法,以聚乙二醇(PEG)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二辛酯(DOP)作为增塑剂,对聚左旋乳酸(PLA)进行增塑改性.用综合热分析仪对改性PLA的热性能进行了表征.讨论了不同的增塑剂及其用量对改性PLA性能的影响:当增塑剂的含量增加时,改性PLA的强度下降,伸长率增加,并逐渐由脆性向韧性转变;玻璃化转变温度(Tg)和熔点(Tm)下降.当增塑剂的质量比≤20%时,共混物各组分间有较好的相容性.PEG400改性的PLA效果较好.     

Modification of oxidized graphite edge surface with poly(vinyl chloride)

An oxidized edge surface of pyrolytic graphite (PG) has been prepared by electrochemical treatment. A thin layer of poly(vinyl chloride) (PVC) was coated on the oxidized edge surface, and the PVC-coated sample heat treated at 300, 400, and 500 °C, respectively. The influence of the PVC coating on the structural change of the oxidized edge surface of PG caused by the heat treatment was studied by laser Raman and Fourier transform-infrared attenuated total reflection spectroscopies. For the electrochemical treatment, the formation of oxygen-containing functional groups proceeds over the edge surface of PG. With increasing degree of oxidation, the functional groups are formed in the following order; hydroxyl groups, carboxyl groups, lactone groups, quinones, and acid anhydrides. Acid anhydrides are formed on the outermost surface and completely eliminated by heat treatment up to 300 °C. The other functional groups remain even after heat treatment up to 500 °C. However, the functional groups are eliminated by the PVC coating, the elimination temperature depending on the type of functional groups: quinones, lactone groups, and carboxyl groups are eliminated at 300, 400, and 500 °C, respectively. PVC coated on the edge surface is found to play an important role in the complete elimination of oxygen-containing functional groups with >C=O through heat treatment at 500 °C.     

Phase separation in blends of oligo (caprolactone glycol)-based polyurethane with poly(vinyl chloride)

The structure of o!igo (caprolactone glycol)-based polyurethane-poly(vinyl chloride) (PVC) blends obtained from tetrahydrofuran solution was studied by X-ray diffraction and electron microscopy. The system is characterized by a oornp!ex phase diagram with two types of equilibria: (1) crystal-liquid equilibrium in the region of blend compositions up to 40 wt% PVC; (2) liquid-liquid equilibrium in the region of man compositions. The crystallization kinetics of oligo(caprolactone) polyurethane blocks from an initially compatible amorphous blend was investigated. Small-angle X-ray cattering (SAXS) studies provide evidence that the amorphous component (PVC) is incorporated in the interlamellar crystalline regions of the compositions. The amorphous blends are characterized by the presence of modulated structures at two scale levels, this being explained as e result of the process in which the bulk samples were obtained from a three-component polymer-polymer-solvent system.     

聚醚腈型阳离子水性聚氨酯乳液的制备与性能

采用端羟基聚醚腈(HPEC),甲苯二异氰酸酯(TDI),1,4-丁二醇和三乙醇胺(TEA)为主要原料制备了聚醚腈型阳离子水性聚氨酯乳液.讨论了制备过程中对水性聚氨酯乳液性能的影响因素.实验结果表明,三乙醇胺对乳液的稳定性影响很大,采用该工艺制备的聚醚腈型阳离子水性聚氨酯乳液具有良好的贮存稳定性,且涂膜的机械性能良好;当聚醚腈型阳离子水性聚氨酯乳液和固化剂的质量比在100:6到75:6之间时,产品的强度最好.     

Linear poly(ethylene oxide)-based polyurethane hydrogels: polyurethane-ureas and polyurethane-amides

Over the last 30 years, water-swellable and water-insoluble hydrogels have been extensively investigated and developed, leading to a large family of materials which have found uses in a wide range of biomedical applications. While hydrogels usually present a crosslinked structure, linear polyurethane-ureas (PUUs) based on poly(ethylene oxide) have been shown to be able to absorb and swell with aqueous media without dissolving. This behavior is due to the phase separated domain morphology, where hydrogen bonded urethane/urea hard segment domains are dispersed in a PEO soft segment domain. This work investigates the possibility of obtaining linear poly(ethylene oxide)-based polyurethane-amide (PUA) hydrogels using two amide diols as chain extenders, a mono amide diol (AD) and a diamide diol (DD), and a dicarboxylic acid (maleic acid, MA). Poly(ethylene oxide) based PUAs were obtained using a “one-shot” bulk polymerization technique. The chemicophysical characterization and water-solubility tests showed that these materials, while having molecular weights similar to the PUUs, do not possess sufficient phase separation, hydrogen bonding and hydrophobicity of the hard segment domains to exhibit hydrogel behavior. Crosslinked PUAs using maleic acid as chain extender show interesting hydrogel properties. © 1999 Kluwer Academic Publishers     

肝素化水性聚氨酯改性医用聚氯乙烯表面的研究

以N 甲基二乙醇胺为扩链剂合成了阳离子水性聚氨酯 (ACPU) ,将其固定在医用聚氯乙烯管内壁并对其进行肝素化。通过全血凝固时间实验证明 ,改性后的医用聚氯乙烯管的抗凝血性明显提高。另外使用红外光谱分析了阳离子水性聚氨酯的结构及其肝素化处理后聚合物结构的变化 ,并考察了MDEA含量对阳离子水性聚氨酯乳液及其涂膜性能的影响。     

Fracture toughness of exponential layer-by-layer polyurethane/poly(acrylic acid) nanocomposite films

This paper characterizes the fracture toughness of layer-by-layer (LBL) manufactured thin films with elastic polyurethane, a tough polymer, and poly(acrylic acid) as a stiffening agent. A single-edge-notch tension (SENT) specimen is used to study mode I crack propagation as a function of applied loading. Experimental results for the full-field time histories of the strain maps in the fracturing film have been analyzed to obtain R-curve parameters for the nanocomposite. In particular, by using the strain maps, details of the traction law are measured. A validated finite strain phenomenological visco-plastic constitutive model is used to characterize the nanocomposite film while a discrete cohesive zone model (DCZM) is implemented to model the fracture behavior. The LBL manufactured nanocomposite is found to display a higher fracture toughness than the unstiffened base polymer.     

Modification on crystallization of poly(vinylidene fluoride) (PVDF) by solvent extraction of poly(methyl methacrylate) (PMMA) in PVDF/PMMA blends

The crystallization modification of poly(vinylidene fluoride) (PVDF) was investigated for the blend films of PVDF and poly(methyl methacrylate) (PMMA). The mass crystallinity (χ_c) and further, the β-phase content (F_(β)) of PVDF, were studied for the as-prepared blend films with different mass ratios. In addition, the variations of χ_c and F_(β) were systematically probed once the PMMA component was removed from the related blend systems. DSC, FTIR and XRD measurements all indicated that 1) χ_c, F_(β) and even the content of α-phase (F_(α)) decreased with the addition of PMMA; 2) with the extraction of PMMA, both χ_c and F_(β) increased while F_(α) decreased. It is worth noting that the increase of χ_c and F_(β) depended on the relative amount of extracted PMMA (E_PMMA), i.e., the more PMMA was removed, the more χ_c and F_(β) increased. These results reveal the hindrance effect from the PMMA constituent to the crystallization of PVDF, and consequently, this restriction would be released when the PMMA was extracted.     

PU/PVDF共混中空纤维膜结构与性能

采用熔体纺丝后拉伸的方法制备了聚氨酯(PU)/聚偏氟乙烯(PVDF)共混中空纤维膜,研究了拉伸对共混膜形态结构的影响,通过测定水通量随透膜压力的变化讨论了PU/PVDF共混中空纤维膜的压力响应性能,并对不同拉伸倍数所得膜压力响应性能差异进行了研究.结果表明,拉伸过程增大了聚合物间界面微孔的通透性,有效地提高了膜的水通量;且随拉伸倍数的提高,PU/PVDF共混中空纤维膜界面微孔的回复性有所提高.     

Investigation of a novel poly (lactic acid) porous material toughened by thermoplastic polyurethane

Journal of Materials Science - Poly (lactic acid)/thermoplastic polyurethane (PLA/TPU) ductile fibrous porous material was obtained by electrospinning, which has better mechanical properties than...