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排序方式: 共有488条查询结果,搜索用时 15 毫秒
481.
This paper describes an attempt to develop a durable finishing method in order to improve the fire performance of polyamide 66 fabrics. Hydroxymethylation with a 36% formaldehyde aqueous solution in association with a pad‐curing process to enable the fabric to react with flame‐retardant solutions was used in the finishing process. The fire performance of treated samples was characterized by limiting oxygen index (LOI) and vertical flammability tests, and the results show that the LOI value can increase from 21.6% to 46.2%. The thermal behavior of untreated and treated polyamide 66 fabrics was investigated by using thermogravimetic analysis and differential scanning calorimetry. Furthermore, residual char of treated fabric sample is much higher than that of untreated fabric sample. Fourier transform infrared spectroscopy proves that the substituted hydroxymethyl groups do exist on the molecular chain of polyamide fabric sample after surface modification. The morphology of residue char of polyamide 66 fabric samples was analyzed by scanning electron microscope, and the mechanical properties were also investigated and discussed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
482.
483.
为提高双向拉伸尼龙薄膜的拉伸性能及薄膜性能,本文研究了不同成核剂、润滑剂及芳香尼龙对高黏度尼龙性能的影响.添加剂改性尼龙6后,冲击性能和断裂伸长率均有不同程度的提高,注塑样品表现为α晶型结构.尼龙6流延骤冷时形成不稳定的α晶型,经过双向拉伸后,转变为稳定的α晶型,在X射线衍射图谱中表现为较强的单峰.改性尼龙制备的双向拉伸薄膜具有较高的力学性能和较低的雾度,综合性能较好;润滑剂Incromold-T具有更好的综合效果.加入少量的半芳香尼龙MXD6,尼龙6结晶能力下降,薄膜光学性提高,但力学强度明显下降. 相似文献
484.
How Wei Benjamin Teo Van Thai Tran Kaijuan Chen Kim Quy Le Hejun Du Jun Zeng Kun Zhou 《先进技术聚合物》2023,34(2):748-757
Crystallization of polyamide 12 (PA12) is an essential process requiring thorough investigation for evaluating the mechanical properties after the polymer parts are manufactured. The change in crystallization temperature results in different crystallization behaviors for PA12. Hence, the crystal morphology of PA12 achieved provides important information about crystallization behavior, especially for those produced through additive manufacturing due to its heterogenous cooling rate in a single print bed. Considering the need of investigating PA12 crystallization using phase-field modeling, this paper aims to simulate the spherulite morphology of PA12 undergoing isothermal crystallization. This model is compared with the spherulite morphologies obtained from the optical microscopy test. The model shows that PA12 spherulites have thicker dendrites when the isothermal temperature is higher. The present phase-field model can determine the spherulite morphologies of bulk printed PA12 based on the crystallization condition and be used to evaluate the properties of the printed part. 相似文献
485.
Azman Hassan Norhayani Othman Mat Uzir Wahit Lim Jian Wei Abdul Razak Rahmat Zainal Ariffin Mohd Ishak 《Macromolecular Symposia》2006,239(1):182-191
A series of polyamide 6/polypropylene (PA6/PP) blends and nanocomposites containing 4 wt% of organophilic modified montmorillonite (MMT) were designed and prepared by melt compounding followed by injection molding. Maleic anhydride polyethylene octene elastomer (POEgMAH) was used as impact modifier as well as compatibilizer in the blend system. Three weight ratios of PA6/PP blends were prepared i.e. 80:20, 70:30, and 60:40. The mechanical properties of PA6/PP blends and nanocomposite were studied through flexural and impact properties. Scanning electron microscopy (SEM) was used to study the microstructure. The incorporation of 10 wt% POEgMAH into PA6/PP blends significantly increased the toughness with a corresponding reduction in strength and stiffness. However, on further addition of 4 wt% organoclay, the strength and modulus increased but with a sacrifice in impact strength. It was also found that the mechanical properties are a function of blend ratio with 70:30 PA6/PP having the highest impact strength, both for blends and nanocomposites. The morphological study revealed that within the blend ratio studied, the higher the PA6 content, the finer were the POEgMAH particles. 相似文献
486.
Hermes Farina Cui Ming Yuan Marco Ortenzi Giuseppe Di Silvestro 《Macromolecular Symposia》2004,218(1):51-60
Linear and star-branched polyamide 12 were prepared in the presence of mono- and multifunctional acid agents. Molecular masses and molecular mass distributions are discussed according to our model recently presented and are compared with the data obtained by Flory's model. End group titration and SEC data are discussed. Oligomerisation data confirm the general validity of our model. 相似文献
487.
Barbara Bulleri Massimo Genoni Giuseppe Gallone Augusto Marchetti 《Macromolecular Symposia》2004,218(1):363-371
The replacement of metals with plastics in piping systems is a well established practice in a vast range of public and industrial applications. However, difficulties still exist, mainly related to the limited chemical resistance of the polymers commonly used in pipe manufacturing to some conveyed fluids. This prevents using plastic pipes in important applications such as the transport of liquid hydrocarbons, particularly in oil fields. The use of chemically resistant polymers, such as fluorinated polyolefins, is precluded by high cost and poor mechanical properties. Co-extrusion of multi-layer pipes carrying an internal chemically resistant liner can be a viable alternative capable to extend the use of plastic pipes to refining and chemical industries. An experimental PE/PA multi-layer pipe has been developed whose resistance to diffusion and mechanical properties have been tested. Tests in real oil fields confirm the good performance of the new pipes. 相似文献
488.
The compatibilization of blends of polyamide 6 with a nitrile butadiene rubber has been investigated. The procedure consists of two steps: modification of the nitrile groups of the rubber into oxazoline in the melt through condensation of ethanolamine with formation of a molecule of ammonia, followed by use of the modified rubber as a compatibilizing precursor which is melt mixed with the polyamide to produce the compatibilized blend. The modification reaction has been detected by NMR analysis and a rheological, mechanical and thermomechanical characterization has been carried out on the all the blends. The results indicate that the modification reaction occurs but the conversion of nitrile into oxazoline is relatively low. Use of the modified rubber in the preparation of binary polyamide/rubber blends, leads to an increase in viscosity, which is typical of compatibilized systems, and to enhanced tensile, impact and thermomechanical properties. These phenomena can be explained by the formation of in situ rubber/polyamide copolymers that act as compatibilizers, due to the reaction between oxazoline and the end groups of the polyamide. The presence of residual low molecular compounds, from the modification or from the purification of the rubber worsens all of the properties and inhibits the compatibilizing effect of the modified rubber. 相似文献