聚酰胺系热塑性弹性体

介绍了聚酰胺系热塑性弹性体的发展历程，叙述了ＴＰＡＥ的合成方法，优异性能，应用领域及研究状况，并探讨了ＴＰＡＥ今后的发展趋势。     

Rheological characterization of filled polyamide 11 and polyamide 12 solutions in polyols

A thorough understanding of the rheological properties of real-world, formulated polymer melts and solutions is important to fabricate articles via typical melt processing techniques. Polyamides have been studied extensively in the area of water purification applications. In this work, the viscosity of these homogeneous polyamide 11 and polyamide 12 solutions in specific polyols was measured in the single phase region as a function of shear rate and temperature via capillary rheometry. In addition, the viscosity of the same polyamide solutions containing various levels of dispersed, nanoscale calcium carbonate particles was characterized in order to understand the rheology of the filled systems. Viscosity-reduced shear rate master curves were constructed by applying the principle of time–temperature superposition, and the activation energies were measured for the polyamide-polyol solutions. The observed increase in viscosity caused by the addition of nanofiller could not be explained by simply applying a vertical shift to the master curve, and a density exponent was required to account for the stiffening mechanism. Also, the dependence of the relative viscosity on the filler loading was shown to be consistent with the hypothesis that the filler particles were organized in the form of small fractal aggregates. The filled polyamide 11 systems exhibited higher relative viscosities than the filled polyamide 12 systems, indicating a higher level of particle aggregation and larger mean cluster size for the filled polyamide 11 systems. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48244.     

Investigation of structure development in polyamide 11 and polyamide 12 tubular film extrusion

The processability of single bubble polyamide 11 and polyamide 12 films was investigated. The development of crystalline structure and chain orientation of polyamide 11 and polyamide 12 films in single bubble film blowing was studied by differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXS), infrared (IR) spectroscopy, and birefringence. DSC measurements of both films revealed a spontaneous increase in glass transition temperature (T_g) and cold crystallization temperature (T_c) during aging at room conditions, with crystallinity and melting point remaining constant. Single bubble polyamide 11 and polyamide 12 films exhibited triclinic α and monoclinic γ crystals, respectively. The level of biaxial orientation was evaluated by calculating White‐Spruiell biaxial orientation factors with pole figure data. We were not able to produce biaxially oriented double bubble films with either polyamide 11 or polyamide 12.     

抗静电聚酰胺纤维制备方法

介绍了抗静电聚酰胺纤维的几种制备方法。重点阐述在纤维表面涂覆表面活性剂法 ,亲水性高分子聚合物与聚酰胺 6共混纺丝法 ,导电纤维法。指出采用多种方法配合使用 ,可获得满意的抗静电效果。     

010聚酰胺树脂的改性

采用本体聚合法 ,进行接枝、交联 ,对国内大量生产的 0 10树脂进行改性。经过正交实验 ,优选出 3个条件作为合成目的产品的最佳条件。其产品的软化点、粘度、韧性等性能与 0 10树脂相比有了大幅度提高 ,并已达到国外进口同类产品指标 ,可作为热熔胶粘剂广泛用于彩电、汽车、热缩材料等领域。该合成路线原料立足国内 ,来源丰富 ,工艺简单易行 ,无环境污染 ,为 0 10类树脂的应用开辟了一条新途径 ,具有良好的经济效益和社会效益     

Continuous polyamidation of polyamide 6

Translated from Khimicheskie Volokna, No. 4, pp. 25–28, July–August, 1994.     

Organo-soluble aromatic polyamide films

To make stable isotropic aramid solutions and films, 6-amino-2-(4-aminopheyl)-4-phenyl quinoline (QDA) was used as base diamine, and copolymerized using terephthaloyl chloride (TPC) with p-phenylene diamine (PPD), 2,2′-bis(trifluoromethyl)benzidine (PFMB), and oxydianiline (ODA) as second diamine, respectively. Homogeneous viscous polymerization solutions based on QDA were obtained, and films prepared from them were transparent and amorphous. The reactivity of QDA with TPC was almost equal to that of PPD; the reactivity of PFMB was low due to the electron withdrawing groups (? CF₃) attached to the ortho positions of the benzene rings. Bulkiness and flexibility of the monomer structure widened the of stable conditions in polymer solution. A rod-like structure of the monomer caused drawbility to decrease. QDA/ODA copolymer films could be drawn well, probably as a result of the flexible linkage of ODA, and had high tensile strength (86 kg/mm²). High modulus, 3.1 × 10³ kg/mm², was obtained in QDA/PPD copolymer films. Tensile strength and modulus increased with draw ratio. T_g and T_m were not seen by DSC and T_d of the polymers was as high as c. 500°C. Excess drawing caused the films to be fibrillated, affecting their tensile properties.     

Creep of aromatic polyamide fibres

Creep of Kevlar 29, Kevlar 49 and PRD 49-III fibres was investigated. The fibres exhibited transient creep and the strain-time relationship was represented by a logarithmic time law. The creep strain recovered with time when the load was removed. Upon reloading to the same creep stress the strain-time relationship was again logarithmic but the creep rate was reduced. Modulus measurements were made during the creep test and these showed that the modulus increased with time. This result indicated a crystallite rotation mechanism which could account for the experimentally observed creep strain. Creep in PRD 49-III fibres exhibited a small temperature dependence over the temperature range 20°C to 150°C. The apparent creep activation energy was consistent with the range of values reported for hydrogen bonding. This suggests one possible creep mechanism in which the combined action of stress and thermal activation causes rearrangement of intercrystalline bonds in the crystallite boundaries resulting in boundary creep. Boundary creep allows crystallite rotation which produces the macroscopic creep strain. Boundary creep is discussed in terms of the fibre morphology and a model of delayed elasticity.     

Fusion bonding of polyamide 12

The strength of fusion bonds between polyamide 12 plaques has been investigated as a function of processing conditions, using the double cantilever beam geometry to measure the mode I critical strain energy release rate, G_c. Bonding was carried out using an instrumented press, which allowed systematic variation of the bonding time, the holding pressure, the interface temperature and the initial difference in temperature between the plaques. G_c was generally found to increase with hold time and interface temperature. However, for a given hold time, hold pressure and estimated interface temperature, the highest G_c were obtained under nonisothermal conditions, that is, when the initial temperatures of the plaques were different. Based on fractographic analysis and observations of the effect of the hold pressure, it is concluded that enhanced wetting is an important factor in the improved efficiency of non‐isothermal bonding.     

Synthesis of novel alkyl-aryl polyamide

A laboratory procedure for synthesizing an alkylaryl polyamide curing agent for liquid epoxy resins from commercially available, low cost materials is given. The various chemical reactions required to obtain the desired end-product are described, and several properties of the novel polyamide are listed. This agent was found suitable for producing foamed or frothed epoxy products.     

Effects of composition of modified polyamide on barrier properties of polyethylene/modified polyamide blends

A systematic study on the effects of types and contents of compatibilizer precursors (CPs) on degrees of crystallinity (W_c), melt shear viscosities (η_s), and permeation barrier properties of modified polyamides (MPAs) and on their corresponding morphology and barrier properties of bottles blow-molded from polyethylene (PE)/MPA blends is reported. Two alkylcarboxyl-substituted polyolefins were selected as CPs to modify PA and to improve its permeation resistance to xylene by the “reactive extrusion” process. The barrier improvements of MPAs prepared in this study depend significantly on the type and content of CP present in the MPA. A maximum improvement in barrier properties of each MPA series samples were found as the contents of CP reached an “optimum” value. On the other hand, it is interesting to note that bottles blow-molded from PE/MPA series samples exhibited better barrier properties because the MPAs used were associated with better permeation resistance to xylene. The melt shear viscosities of MPAs were found to depend on the type of CP used and increase with increasing CP contents. In contrast, the W_c of MPAs decreased with increasing CP contents. Further analysis of the fracture surfaces of bottles blow-molded from PE/MPA blends also indicated that the morphology of MPA laminas depended on the type of CP present in the MPA, and these MPA laminar structures became clearer as the contents of CPs increased. Possible mechanisms accounting for the interesting behaviors described above are discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1531–1540, 1997     

Thermal and mechanical behavior of polyamide 6/polyamide 6I/6T blends

The thermal and mechanical properties of blends, obtained by mixing polyamide 6 (PA6) and an amorphous aromatic copolyamide G21 (ISO nomenclature PA 6I/6T), were investigated by differential scanning calorimetry, dynamic mechanical analysis, and mechanical tensile tests. Quenched blends show a single glass transition temperature; the T_g-composition trend was interpreted by means of the Gordon–Taylor equation. The half-time of crystal-lization decreases by increasing the G21 content and this indicates a depression of the overall crystallization rate. A small decrease in the equilibrium melting temperature of PA6 in the blends was observed; this finding suggests that the interaction parameter in PA6/G21 blends is probably very small. The dynamic mechanical analysis of crystallized blends suggests the presence of a homogeneous amorphous phase even if the crystallization of PA6 occurred. The tensile mechanical properties reveal that G21 acts as stiffener of PA6. The collected experimental data suggest that PA6 and G21 are miscible in the composition range investigated. © 1996 John Wiley & Sons, Inc.     

Characterization and properties of polyphthalamide/polyamide blends and polyphthalamide/polyamide/polyolefin blends

Polyphthalamide(PPA)/polyamide(PA) blends were analyzed to determine the effect of PA addition to PPA on melting point, glass transition temperature, dynamic modulus, and heat distortion temperature. Results indicate that the choice of PPA and the choice of PA for the blend systems affects not only the above properties but also the miscibility of the blend systems. In general, PA addition to PPA lowers the melting point and glass transition, which potentially makes these blend materials easier to process. Also, the PPA/PA blends were observed to have dynamic modulus curves with transitions shifted to lower temperatures and crystalline plateaus shifted to lower modulus. PPA/PA/polyolefin(PP) systems were investigated to determine if a useful balance of properties could be obtained, even though the blend components would have to be processed at unusually high processing temperatures (in excess of 320°C). Morphological characterization indicates that small dispersed domains of PP are obtained. The modifiers utilized in these systems were either found at the interface of the PP domain or dispersed within the PP domain. The properties of PPA/PA/PP blends indicates that these systems are ductile and have a good balance of strength, stiffness, impact, and thermal performance.