选择性激光烧结用尼龙12覆膜Cu粉的制备

提出了溶剂沉淀法制备选择性激光烧结(SLS)用尼龙12覆膜Cu粉复合粉末材料,利用扫描电镜(SEM)观察了复合粉末材料的微观形貌,通过差示扫描量热分析(DSC)、热重分析(TGA)对复合粉末材料的熔融、结晶行为,烧结温度窗口及热稳定性进行了研究,并测试了其烧结件的力学性能。结果表明,复合粉末材料的熔点、结晶速度及热稳定性较纯尼龙粉末有所提高,烧结温度窗口变宽,因而烧结性能优于纯尼龙粉。复合粉末材料烧结件的弯曲强度、弯曲模量、硬度均高于纯尼龙粉的烧结件。     

热分解动力学在含能材料中的应用

文章主要介绍了热分解动力学在含能材料中的重要性,列举了热分解动力学的主要分析方法及几种常用的反应机理,并对其进行简要分析。热分析技术具有快捷简便、准确度高以及适用范围广的特点,在含能材料的热分解动力学中发挥重要作用。热分解动力学广泛应用于含能材料的动力学参数的求解、反应机理的推断以及动力学补偿效应的确定,为其有效使用寿命的预测以及安全性能的评定等提供科学依据。同时,热分析技术的自身完善以及与其他技术的联机使用将促进热分解动力学的不断发展。     

SA型透明尼龙的热性能

首次以直链脂肪族二元胺与对苯二甲酸和间苯二甲酸等为单体,采用多元共缩聚方法制备了半芳香透明尼龙（SATPA）,通过DSC、TG和DTG对其热性能进行了表征,并对其耐热性、热稳定性以及热分解机理进行了分析讨论.实验结果表明,SA型透明尼龙的玻璃化转变温度为102 ℃左右,具有良好的耐热性能;其起始平衡热降解温度为427 ℃,热稳定性优异;它的热降解反应为一步反应,热降解机理初步推断为扩散控制机理。     

尼龙612的结晶及熔融行为

用X射线衍射(WAXD)研究了尼龙612的晶型转变,低温下结晶得到尼龙612的β晶型,随结晶温度的升高,β晶型转变为α晶型。通过差示扫描量热(DSC)对尼龙612的熔融行为进行了研究,尼龙612样品经过不同的热处理后,其熔融行为发生较大的变化,出现了两个熔融峰,低温熔融峰与退火温度相近。在熔融过程中,当温度升高到退火温度时即发生熔融,出现一熔融峰。     

高热稳定性蜜胺聚磷酸盐（MPOP）阻燃剂的合成

蜜胺聚磷酸盐（MPOP）由于分子中同时含有氮、磷两种阻燃元素，具有良好的阻燃效果，是蜜胺衍生物阻燃剂中的重要一种，主要用于防火涂料、阻燃涂料以及聚烯烃、聚氨酯、聚酯和尼龙等高分子材料中。20世纪90年代荷兰DSM公司成功开发了蜜胺聚磷酸盐，并且在阻燃增强尼龙中获得商业应用，其商品牌号为Melapur200。我国也有一些生产厂家生产MPOP。但是产品的热分解温度相对比较低，     

有机化蒙脱石填充尼龙66复合物的结晶与热力学行为研究

通过熔融共混法制备了有机化蒙脱石填充的尼龙66复合材料,通过示差扫描量热分析（DSC）,偏光显微镜照片（POM）和动态力学分析（DMA）等手段研究了复合材料的非等温结晶过程,结晶形态和球晶尺寸,动态力学行为等,并与普通尼龙66进行了比较,发现经过有机化蒙脱石填充的尼龙66的结晶速率比较快,球晶尺寸较小,弹性模量较大。     

热分析法在聚烯烃树脂开发中的应用

介绍了多种热分析方法（包括示差扫描量热（DSC）分析、热重（TG）分析、动态热机械分析（DMA））在聚烯烃树脂开发中的应用。采DSC、TG、DMA等方法可以测量聚烯烃树脂的熔点、结晶温度、热分解温度、维卡软化点等,在聚烯烃树脂开发中具有重作用。     

热致液晶聚酰胺的热分解动力学及寿命

利用热重分析法,在不同升温速率下,对热致液晶聚酰胺热分解动力学进行研究。采用Friedman、Kissinger、Ozawa以及Coats-Redfern等方法对其动力学数据进行分析说明,确定其在氮气中反应机理函数是Avrami-Erofeev法则,活化能E≈208 kJ/mol;其在空气中初始热分解反应机理函数为Mempel Power法则,活化能E≈172 kJ/mol,后期热分解反应机理函数为反Jander法则,活化能E≈111 kJ/mol。并以失重5%作为寿终指标,计算热致液晶聚酰胺在不同温度的寿命,结果表明,其在尼龙加工温度范围内不会失效,适于与尼龙进行复合加工。     

激光烧结尼龙12/ 累托石复合材料的结构与性能

将尼龙12 与有机累托石的混合粉末进行激光烧结成型, 利用X 射线衍射(XRD) 、差示扫描量热分析(DSC) 、扫描电镜(SEM) 等手段对烧结试样的材料结构进行了表征, 并对其力学性能及热性能进行了研究。结果表明: 尼龙12 在激光烧结过程中插入到累托石层间, 形成了尼龙12/ 累托石纳米复合材料。复合材料的力学性能及热稳定性能同尼龙12 烧结试样相比均有不同程度的提高, 有机累托石质量分数为10 %时, 复合材料的拉伸强度、弯曲强度和冲击强度分别提高了10.7 %、15.9 %和38.7 % , 热分解温度提高了27 ℃。      

尼龙46

尼龙46是一种新颖工程塑料,由于其独特的性能,引起了人们的关注。本文介绍尼龙46的制法、特性、成型加工及其应用。尼龙46是荷兰DSM公司开发的新型尼龙材料,其商品名为Stanylo与尼龙6和66相比,它具有较高的熔点、韧性和高温尺寸稳定性,已引起人们的关注,但直到前几年仍未能大批量生产,其原因在于:采用传统方法难以合成高分子量尼龙46。尼龙46的熔点高,采用高温熔融聚合易发生氧化分解和热分解反应,且可能发生丁二胺环合等副反应;采用溶液聚合,则反应很慢,用制备尼     

聚吡咯涂层织物的介电性能研究

采用原位聚合法以棉机织物、尼龙为基布,以吡咯为单体,制备了具有良好介电性能的柔性聚吡咯涂层棉织物和聚吡咯涂层尼龙织物,探讨了掺杂剂种类、掺杂剂浓度对聚吡咯涂层棉织物、聚吡咯涂层尼龙织物介电性能和表面电阻的影响.结果表明,掺杂剂对聚吡咯复合材料的介电性能和表面电阻的影响较大.所制备的聚吡咯涂层棉织物、聚吡咯涂层尼龙织物均具备良好的介电性能和导电性,为最终开发出较为实用的多功能吸波复合材料奠定了基础.     

极性可调高聚物接枝氧化石墨烯相容剂的制备及在MC尼龙中的应用

设计制备了极性可调控的反应型相容剂乙烯-辛烯共聚物-甲醛缩多乙烯多胺-g-氧化石墨烯(POE-TEPAF-GO),并将其应用于铸型尼龙(MC尼龙)/马来酸酐接枝乙烯-辛烯共聚物(MAPOE)共混体系中。同时,调节TEPAF相对分子质量大小,考察不同极性的相容剂对共混材料MC尼龙/MAPOE的影响。研究结果表明,POE-TEPAF-GO对MC尼龙/MAPOE共混体系增容效果较为理想,并且可作为多功能填料对共混材料实现增韧和增强,其中共混材料韧性提高最为显著,较纯MC尼龙提高93%,拉伸强度、热稳定性也有所改善,此外在一定程度上改变了晶型。当TEPAF的Mw=931时,材料的综合性能最优。     

增塑型超韧尼龙11的力学性能和增塑机理

增塑后尼龙１１的冲击强度及断裂伸长率大幅提高,但断裂强度并未大幅降低。尼龙１１的增塑机理是,增塑剂破坏了尼龙１１的分子间氢键作用。研究表明,增塑型超韧尼龙１１的断裂面具有独特的形态,这是一种首次发现的新型断裂现象。本文首次将上述现象归结为“多重裂延”机理。     

Natural silica fiber as reinforcing filler of nylon 6

Short silica fiber (SF) content on the mechanical and morphological properties of composites based on nylon 6 and rubber-toughened nylon 6 matrices was examined. Binary nylon 6/SF and ternary [nylon 6/EPDM-g-MA (ethylene–propylene–diene grafted with maleic anhydride)/SF] composites containing 0–20 wt% SF were formulated. The flexural modulus increased with the SF content at all fiber compositions investigated; however, the value of this property gradually diminished when 20 wt% rubber was added to the polymer. Notched Izod impact strength of 80/20 nylon 6/EPDM-g-MA blend was reduced up to 50% with the addition of 5 wt% SF. However, these composites still retained good stiffness and toughness and presented a good interfacial adhesion between the phases. The results suggest that silica fibers can be employed as an alternative reinforcement of nylon 6 matrices, resulting in materials with useful properties.     

Thermal properties of automotive polymers III – Thermal characteristics and flammability of fire retardant polymers

Thermal properties and flammability behavior of two grades of fire retardant polypropylene and nylon 66, and their base resins were determined. A nylon 6 base polymer and a nano-composite based on that polymer were also analyzed. Thermal gravimetric analysis showed more complex degradation patterns for the fire retardant grades as compared to the base resin. This was attributed to decomposition of ingredients present in the fire retardant. Degradation of polypropylene in air started at about 100°C lower temperature than degradation in nitrogen. For nylon, the degradation in both atmospheres occurred at approximately the same temperature. Modulated Differential Scanning Calorimetry (MDSC) measurements were used to determine melting and glass transition temperatures, heats of fusion, heat capacity and thermal conductivity. Both phosphorus-based and halogen-based fire retardants modified the ignition, propagation, and melt-dripping behavior of nylon and polypropylene during burning. Incorporation of a nano-filler was found to be ineffective in imparting fire retardancy to nylon 6. Performance of these materials will have to be evaluated in actual vehicle applications and fire exposures before use on a broad scale basis. Received: 25 August 2000 / Reviewed and accepted: 28 August 2000     

Fabrication and mechanical properties of aramid/nylon plain knitted composites

The presence of fibre/matrix interfaces strongly influences the overall mechanical properties of composites. In order to produce fully recyclable fiber reinforced composites with improved adhesion properties, polyethylene and polypropylene materials were previously used as single-polymer composite materials. In this paper, another breed of single-polymer composite material has been defined as the ‘one-unity’ composite. Polyamide materials were chosen and combined with aramid fibre in an attempt to achieve better interfacial bonding. Weft-knitting technique was used to produce textile reinforcements for aramid/nylon composite processing. Aramid/epoxy knitted composites were also fabricated to compare them with aramid/nylon thermoplastic composites. Mechanical properties of aramid/nylon and aramid/epoxy composites and their relationships to the fibre/matrix interfacial adhesion and interactions have been investigated. With the increase in processing time, tensile modulus and strength of aramid/nylon composites have increased and decreased, respectively. Furthermore, scanning electron microscopic observations clearly indicated that longer molding time has resulted in stronger adhesion property between fiber and matrix. Aramid/nylon knitted composites have revealed comparable strength property in the course direction, albeit they have inferior tensile strength in the wale direction when compared to that in aramid/epoxy composites. In aramid/nylon knitted composites, while tensile modulus exhibited an increasing trend, there were clear drops in tensile strengths with longer molding time. This indicates that there could be an optimum molding condition at which maximum tensile properties can be obtained. Aramid/nylon knitted composites exhibited relatively better interfacial bonding properties than Aramid/epoxy composites, which suffered fibre/matrix debonding.     

碳纤维增强尼龙1010的力学性能及其对摩擦磨损的影响

用碳纤维填充尼龙1010制备了碳纤维增强尼龙复合材料,并对碳纤维增强尼龙复合材料的力学性能和摩擦学性能进行了实验研究。力学实验结果表明:碳纤维增强使尼龙复合材料的拉伸强度、表面硬度增大,碳纤维增强尼龙材料的拉伸强度在20%碳纤维含量时达到最大值;碳纤维表面处理对尼龙复合材料的拉伸强度有很大影响,碳纤维表面氧化处理提高了碳纤维增强尼龙复合材料的拉伸强度。摩擦磨损实验表明:碳纤维增强尼龙复合材料的摩擦系数和磨损率与其拉伸强度和硬度有密切关系。随着拉伸强度和硬度的提高,尼龙复合材料摩擦系数和磨损率降低;摩擦系数和磨损率与拉伸强度具有反比关系,与材料硬度具有二次方程关系,与碳纤维填充量之间存在负指数变化规律。      

Evaluation of airliner cabin textile materials after vapour phase hydrogen peroxide decontamination

Abstract

Decontamination of airliner cabins may be required, for example, in the event of an epidemic or pandemic. To be performed safely, decontamination must be compatible with aircraft materials and systems. This paper examines the suitability, with respect to cabin textiles, of vapour phase hydrogen peroxide for airliner decontamination applications. The effect of vapour phase and liquid hydrogen peroxide on common airliner interior textile materials, namely wool, nylon, polyester, and Nomex, has been studied by examining the physical and chemical changes and the resulting effect on mechanical properties caused by decontamination. The physical changes induced by the sorption of moisture had an effect on the mechanical properties of all of the materials examined. However, only wool attacked chemically by hydrogen peroxide experience a significant effect on its mechanical properties.     

UV Excimer laser modification on polyamide materials: effect on the dyeing properties

Polyamide (nylon 6) fabrics were irradiated with 193 nm ArF Excimer Laser and then dyed with commercially available acid, disperse and reactive dyes. The morphology of the irradiated surfaces was examined by scanning electron microscopy (SEM). Chemical surface changes of the materials were characterized by X-ray photoelectron spectroscopy (XPS) and change in crystallinity was examined by differential scanning calorimetry (DSC). Polyamide materials irradiated with laser developed ripple-like structures of micron size on the surface. These structures are strictly perpendicular to the stress direction of the fiber. It is worth noting that the dyeing properties of all dyes on polyamide fabrics changed remarkably after the treatment. The change in color is believed to be closely related with the appearance of ripple-like structures. Changes in chemical properties of the treated materials may also be one of the reasons for dyeability changes. This work suggests that the dyeing properties of disperse and reactive dyes on nylon can be improved after laser modification. Electronic Publication     

Recycling of waste nylon 6/spandex blended fabrics by melt processing

A unique approach for reclaiming waste nylon 6/spandex blended fabrics was demonstrated by melt processing through mixing and molding. Spandex from the waste fabrics was removed by hydrolysis under controlled conditions. Morphological analysis showed that the fracture surface was homogeneous for samples of neat nylon 6 and treated fabrics, and voids were observed for samples from untreated fabrics. Thermal analysis indicated that the materials from waste fabrics exhibited both similar melting temperature (around 220 °C) and similar crystallization temperature (around 185 °C). Infrared spectroscopy showed nearly the same main absorption peaks of neat nylon 6 and samples from nylon 6/spandex fabrics. The viscosity of treated fabric samples was lower than that of untreated fabric composites at low and medium frequencies, as an effect of the spandex removal after treatment. The recycled plastics from treated fabrics exhibited good mechanical properties with a tensile strength of 46.6 MPa and a Young's modulus exceeding 2.4 GPa.