Water and toluene barrier properties of a polyamide 12 modified by a surface treatment using cold plasma

CF₄ and CO₂ plasma treatments have been used to modify the barrier properties of a polyamide 12 (PA12) towards permeant molecules, which present opposing characteristics: water and toluene. The surface modifications were observed by atomic force microscopy, X-ray photoelectron spectroscopy and surface Gibbs function measurements. Both treatments lead to different surfaces; one is rather hydrophobic (with CF₄) whereas the other is more hydrophilic (with CO₂. The effect of this modification on permeametric properties has been investigated by liquid water and liquid toluene permeation measurements. Our results show opposite effects of the two treatments. CF₄ plasma treatment leads to a reduction of water and toluene permeability. With CO₂ plasma treatment, in terms of permeation, two different behaviours were observed, an increase and a decrease of permeancy for water and toluene respectively. These results are in full agreement with those obtained for the surface characterization, and confirms change in the polymeric surface affinity for the permeant leading to a variation of the materials permeancy.     

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.     

低分子聚酰胺热熔粘合剂的性能调节

为了适应不同聚酰胺热熔粘合剂用户的不同要求 ,避免改变合成条件带来的操作不便 ,探索了一条以本实验室合成的低分子聚酰胺热熔粘合剂为基本原料 ,用少量调节剂在局部范围内调节粘合剂性能的操作路线。从而进一步提高了产品的适应性     

The investigation on the flame retardancy mechanism of nitrogen flame retardant melamine cyanurate in polyamide 6

Melamine cyanurate (MCA) flame retardant polyamide 6 (PA6) shows good flame retardancy, but the corresponding mechanisms have not been completely understood. In this paper, Fourier transform infrared spectra (FTIR), elemental analysis (EA), scanning electronmicroscope (SEM), energy dispersive scanning (EDS), thermogravimeric analysis (TGA) and pyrolysis-gas chromatogram-mass spectrometer (Py-GC-MS) were conducted to investigate the processes including melt-drip phase, gaseous phase and condensed phase of MCA/PA6 system. Compared with original PA6, it is found that MCA flame retardant PA6 mainly undergoes predominant weak bond-breakage degradation forming oligomers rather than oxidative degradation producing low-boiling point fuel as original PA6 does. The produced oligomers can accelerate the formation of the melt drips which effectively removes the combustion heat and latent fuel, also the self-condensation of these oligomers is advantageous to form stable cross-linking structure, thus greatly consolidating the char layer.     

Structure characterization of heat set and drawn polyamide 66 fibers by FTIR spectroscopy

Structural changes that occur during thermally induced and strain induced crystallization of polyamide 66 fibers were studied by infrared spectroscopy, density measurement and optical microscopy. Two bands at 924 and 1136 cm^–1 were shown to arise from the amorphous phase and assignment of the bands at 936 and 1200 cm^–1 to the crystalline phase were confirmed. We demonstrated that two different infrared spectroscopic methods could be used to determine the total crystallinity of polyamide 66 fibers. One is a calibration method in which the band ratio of 1200 and 1630 cm^–1 is plotted against the crystallinity measured by density measurements. The other one is an independent infrared method. Crystallinity obtained by the independent infrared spectroscopic method showed good agreement with crystallinity observed by density measurement. Infrared dichroism was used to obtain the crystalline orientation using the band at 936 cm^–1. The transition moment angle of 48° was found for the band at 936 cm^–1 with respect to chain axis. Amorphous orientation was obtained using Stein’s equation. Received: 18 September 2000 / Reviewed and accepted: 20 September 2000     

R型及KE型活性染料在锦／棉染色中的应用

R型／中性－浴染色可将染色时间从原来的10h缩短为4－5h，修色可降温后直接加料。由于中性条件固色，避免碱性条件下的锦纶手感损伤。KE型活性染料染色后，在染锦纶时pH值不可太低，以6－7为宜，避免酸性条件下染料－纤维键断裂。     

塑料斜齿轮注塑模具设计与分析

以聚酰胺6(PA6)斜齿轮塑件为对象,进行了一模四腔的注塑模具结构设计与分析,并实现了斜齿轮塑件的顺利脱模。     

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。     

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