Relations between structure and property of polyamide 11 nanocomposites based on raw clays elaborated by water‐assisted extrusion

Bio‐based polymers and polymer nanocomposites have known an increasing interest during the past few years. This work is focused on the elaboration and the characterization of bio‐based nanocomposites made from polyamide 11 (PA11) and nonorganomodified montmorillonite. To elaborate these materials an original elaboration process, consisting in injecting water during the extrusion, was used. Results show that thanks to this process, a well exfoliated morphology is obtained for clay contents as high as 10% wt. This was explained on the one hand by the fact that the clay is soluble in water and on the other hand by the fact that water and PA11 are miscible at high pressure and high temperature. Moreover, the morphology analyses have revealed that from 10% wt of clay, the platelets were not totally randomly distributed but they were rather organized at a mesoscopic scale. The obtaining of such clay's dispersion involves an enhancement of thermomechanical properties. For example, for a clay content of 10% wt, the Young's modulus of the material can be doubled and its degradation temperature increased. The role of the elaboration conditions on the morphology and subsequent properties of the nanocomposites are also carefully analyzed. Finally, it has been evidenced that the presence of the filler infers on both the crystalline form induced and the crystallization kinetics. In summary, this study demonstrates that, in the case of PA11 nanocomposites, the water‐assisted injection process leads to the achievement of an exfoliated morphology for clay contents as high as 10% wt that allows to obtain high performance materials and to be free from using organomodified clays. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

改性聚酰胺树脂的合成及其在热熔胶领域的应用

以国产低分子聚酰胺树脂为基本原料 ,经过接枝、交联改性 ,在不同合成条件下 ,合成出适应于不同应用场合的三种电性能优异的韧性难燃聚酰胺树脂。该产品可作为热熔粘合剂广泛应用于电子电器、汽车、热缩材料等领域。由于合成中采用来源丰富的国产原料 ,并适量加入废聚酯 ,大大降低了原料成本。测试和应用试验表明 ,产品性能已达到进口同类产品水平。因此该产品具有较大的应用潜力 ,其经济效益和社会效应显而易见     

丝胶改性聚酯和聚酰胺纤维吸放湿性的研究

本文表明用丝胶改性聚酯纤维、聚酰胺纤维以提高改性纤维的吸放湿性是有效的。理论分析与实验结果统一。     

Novel composite nanofibers based on polyamide 66/graphene oxide- grafted aliphatic- aromatic polyamide: preparation and characterization

New polyamide 66/graphene oxide (GO)-grafted aliphatic-aromatic polyamide (polyamide-imide) (PAI) (PA66/GOF) composites nanofibers were successfully prepared via electrospinning method for the first time. An polyamide imide (PAI) was synthesized using polycondensation reaction from a dicarboxylic acid and a diamine based on 4,4′-(4,4′-isopropylidenediphenyl-1,1′-diyldioxy) dianiline, and characterized by ¹HNMR and FTIR. Morphological, structural, thermal and mechanical characteristics of the nanocomposite fibers were investigated by means of SEM, TEM, WAXD, DMTA and TGA techniques. Composites nanofibers of PA66/GO, PA66/PAI and PA66/GOF with smooth surface, uniform structure as well as with diameter ranging from 195 to 784 nm were obtained. The GO incorporation caused a reduction in the nanofibers diameters. The TEM images showed that the GO was well dispersed in the PA66 nanofibers without significant aggregation. An approximately 10 °C temperature increase in the glass transition temperature of PA66 was achieved by addition of 0.5 wt% of PAI, resulting from aliphatic-aromatic structure of PAI. By the TGA results, an increase about 40 °C was observed in the thermal stability of PA66/PAI composite nanofibers in comparison with that of pure PA66 nanofibers.     

溶剂沉淀法制备的聚酰胺粉末之溶剂与粉末结构和热稳定性的关系

使用粒度分布仪、白度仪、电子显微镜和差热仪测定四种溶剂沉淀法制备的聚酰胺粉末发现：每种方法所获得的粉末粒径、比表面积、白度均不相同；以乙醇 氯化钙混合溶剂制备的粉末内部具有多孔结构；以乙醇 盐酸 水混合溶剂制备的粉末热稳定性较高     

Polyamide hydrolysis accelerated by small weak organic acids

It is well known that acidity, pH, of a solution accelerates the hydrolysis of soluble amides. Here we describe the unexpected result that weak small organic acids at low concentrations hydrolyze a polyamide at rates approximately twice that of a water HCl solution of the same pH. The effect of three small organic acids in dilute solutions, acetic, propanoic, and butanoic was studied. It is observed that the effect on the hydrolysis rate increases as the organic acid gets weaker. Butanoic, the weakest acid, has the strongest effect on increasing the hydrolysis rate. Measurements on the concentration of these acids in the polyamide reveal that there is a selective desire for these weak organic acids to diffuse into the polyamide. The concentration of these acids in the polyamide is found to be several multiples of the concentration in the water environment. And the acid concentration is highest for butanoic. The hydrolysis rate is shown to be governed by solubility, not pH of the water environment. The longer hydrocarbon tail on the carboxylic group increases its compatibility with the polyamide's monomer structure. Results are reported on the hydrolysis of polyamide-11 polymerized from aminoundecanoic acid, both neat and a commercial plasticized composition, placed in water at 100 °C and 120 °C under anaerobic conditions in high pressure glass tubes.     

Multiple thermosetting of semicrystalline polymers: Polyamide 66 and poly(ethylene terephthalate) fibers

Polyamide 66 fibers were thermoset in a torsion-bending deformation at various temperatures up to 240 °C. Some of the fibers were heat-set at constant length prior to the deformation at presetting temperatures of 150 °C and 200 °C to vary the structural state of the starting material. Fractional recovery was measured after various combinations of temperature and time. It was found that heat setting of PA66 is dominated by time-dependent stress relaxation exhibiting time-temperature equivalence. Increased crystallinity, and/or other molecular rearrangements occurring during presetting, impose additional constraints on molecular mobility, which delay onset of the flow regime and increase the time constant of relaxation at a given temperature. The thermosetting characteristics of PA66 fibers are very similar to those of poly(ethylene terephthalate) fibers. For both polymers, superposing the curves of fractional recovery vs. setting time at different temperatures produce satisfactory master curves, without the need for vertical shifting of the data. Arrhenius plots yield approximate activation energies for the thermosetting flow process of 35-65 kcal/mol in PA66 and 95-115 kcal/mol in PET.     

Fracture resistance of mineral reinforced polyamide 6

Tensile tests have been carried out over a wide range of test speeds on compact tension specimens of polyamide 6 containing spherical silica particles, whose size and content had been adjusted to give optimum impact performance in conventional impact tests after conditioning at 50% relative humidity. The tensile test results confirmed there to be a significant improvement in the high speed crack initiation resistance at room temperature and at high moisture contents on addition of the silica particles. However, at low moisture contents and/or temperatures well below the glass transition temperature, the crack initiation resistance was reduced. It is hence inferred that for the chosen silica particle distribution, toughening requires a certain minimum level of matrix ductility in order to be effective.     

涤锦超细纤维碱性染色研究

采用HG-3、磷酸二氢铵、AD-95三种助剂，对涤锦复合超细纤维染色作应用研究。通过对染物K/S值、表面色泽均匀度S值染色牢度的测试，认为HG-3是分散染料碱性染色的优良助剂。     

特达~在户外运动服中的运用

特达 ○R纤维是尼龙 6 6的改良产品 ,是通过异形、复合、混纤、变形等纺丝技术开发的差别化产品。不仅改善了尼龙的性能 ,而且赋予尼龙更好的功能。特达 ○R具有良好的强度和韧性、优良的耐磨性、弹性回复性以及染色性能 ,是用于户外运动服的好面料。