阻燃抗滴落PA6纤维的性能研究

采用聚合方法制备抗滴落PA6切片,添加阻燃剂共混纺丝得到阻燃抗滴落PA6纤维。用差示扫描量热法、X射线衍射、透射电镜、极限氧指数法等方法对所得产物的热性能、结晶结构、添加剂的分散性能、阻燃性能及力学性能等进行表征。结果表明,抗滴落剂的加入引起了PA6结晶行为的变化,由α晶型转变成α晶型与γ晶型共存;PA6的热稳定性得到了提高;添加剂在聚合物中分散较均匀,阻燃抗滴落PA6纤维的极限氧指数可达26．6%～28．6%,燃烧时产生的熔融滴落物明显减少。阻燃抗滴落PA6纤维的力学性能较PA6约降低10%。     

Syntheses of intrinsically flame-retardant polyamide 6 fibers and fabrics

In this study, flame-retarded polyamide 6 (FR-PA6) was prepared via the direct co-condensation of ε-caprolactam with two different organophosphorus compounds in a typical melt-polymerization process. Polymer microstructures, especially the incorporation of the phosphorus-containing comonomers, as well as the thermal and physical properties of the resulting copolyamides have been studied in detail. The phosphorus-modified PAs have a P-content of 0.10–0.30 wt %, possess high relative viscosities of 2.2–2.4 and good thermal stability. FR-PA6 multifilaments were prepared by melt spinning and show tensile strengths up to 40 cN/tex and tenacities up to 0.5 GPa. Knitted fabrics of FR-PA6 exhibit high limiting oxygen index values around 35%. Due to the very low phosphorus content, there is no impairment of the material properties of PA6. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47829.     

Effect of flame-retardant melamine and dispersants on the mechanical,thermal, and foaming properties of flexible polyurethane foam

The objective of this study was to investigate the effect of adding flame-retardant melamine and five different dispersants on the precipitation, foaming, mechanical, and thermal properties of flexible polyurethane foam (FPUF). Precipitation experiments were conducted to analyze the effect of dispersant on the separation of flame retardant and polyol, and the foaming characteristics of polyurethane (PU) foam after adding dispersant were analyzed. The effect of adding a dispersant on mechanical strength was characterized by measuring tensile strength, tearing strength, and hardness, and scanning electron microscopy analysis was performed to analyze morphological characteristics. Thermogravimetric analysis (TGA) was performed to analyze the thermal properties of PU foam. A horizontal flame test, limiting oxygen index test, and cone calorimeter tests were conducted to examine the flame retardancy of PU foam with flame retardant melamine and dispersant added. The dispersant ANTI-TERRA-U is a solution of a salt of unsaturated polyamine amides and low-molecular acidic polyesters. And, the dispersant BYK-220S is a solution of a low molecular weight, unsaturated acidic polycarboxylic acid polyester with a polysiloxane copolymer. The dispersants ANTI-TERRA-U and BYK-220S improved the density, tensile strength, tear strength, and hardness of FPUF. TGA of the top and bottom portions of the foam showed less weight difference for samples containing dispersants, indicating better homogeneity due to improved dispersibility. Therefore, we conclude that dispersants are beneficial additives to improve the mechanical properties and dispersibility of PU foam.     

Review on nano-and microfiller-based polyamide 6 hybrid composite: Effect on mechanical properties and morphology

Polyamide 6 (PA6)-based composites are of evolving interest due to its high strength, wear resistance, and barrier properties. The use of binary composites mostly with nanomaterial and glass fibers has been reviewed and presented in literature. However to obtain a balance of properties like stiffness, toughness, and strength along with cost reduction, ternary composites of PA6 have been designed. To achieve the balance, PA6 blend-based composites, with combination of microfiller/nanofiller or PA6 with combination micro-microfiller, PA6 with microfiller/nanofiller and fiber have been designed. The properties of PA6-based ternary hybrid composites depend on type of dispersed phase used, presence of compatibilizer, type of filler used (nanofiller or microfiller or fiber or hybrid) and combination of fillers used. However, a review in this direction is not available in literature. Here, in this study, an overall understanding of various fillers, dispersed phase, and their combinations can be understood along with the discussion on effect of these on tensile properties and morphology of hybrid composite. In this study, an attempt has been made to review the various fillers and dispersed phase and their combinations which have been used in designing the PA6 hybrid composite with good balance of stiffness, toughness, and strength.     

Experimental investigation of mechanical,thermal, and ablation performance of ZrO2/SiC modified C-Ph composites

In this study, an effort has been made to improve the mechanical, thermal, and ablation performance of carbon-phenolic (C-Ph) composites. The ZrO₂, SiC, and ZrO₂/SiC hybrid fillers were synthesized using sol-gel method followed by individual incorporation into C-Ph composites. The thermal stability and flexural strength of these C-Ph composites were analyzed using thermogravimetry analysis and three-point bending test, respectively. A significant improvement in the flexural strength and modulus of the reinforced C-Ph composites was observed and also exhibited the higher thermal stability. The oxyacetylene flame test was conducted to measure the ablation behavior of these filler reinforced C-Ph composites under a heat flux of 4.0 MW/m² for 60 seconds. ZrO₂/SiC0.5 reinforcement in the C-Ph composite decreased the linear and mass ablation rates by 46% and 22%, respectively when compared with pure C-Ph composite. The surface morphology analysis revealed that the burnt composite covered with the ZrC ceramic phase and SiO₂ bubble-like structure, which could have improved the ablation resistance of composites. These results were found well within the acceptable range when using the surface energy dispersive spectroscopy and X-ray diffraction analysis.     

一种磷氮系阻燃剂的合成、表征及对尼龙6的阻燃性能研究

以五氯化磷、氯化铵、苯酚、氢氧化钠为原料,合成磷氮系阻燃剂六苯氧基环三磷腈,通过红外光谱、核磁、热重分析等手段对其结构进行了表征。将其与尼龙6按比例共混后测试了其氧指数和力学性能等指标。结果表明,当该化合物含量提高时,其氧指数升高,力学性能有所下降,但在一定含量范围内,对力学性能影响不大,表明六苯氧基环三磷腈可以有效改善尼龙6的阻燃性能,是一种高效的磷氮系阻燃剂。     

阻燃防水多功能PET纤维的制备

分别采用环境友好型的磷氮系列新型阻燃剂和聚偏氟乙烯(PVDF)对聚酯(PET)进行改性,通过皮芯复合纺丝制备阻燃防水多功能PET纤维,对纤维的制备工艺及其阻燃性能和防水性能进行了研究。结果表明:添加环氧树脂包覆磷酸铵(CK-APP105)质量分数为6%时,纤维极限氧指数值高达30.7%,具有良好的阻燃效果;CK-APP105/三聚氰胺脲酸盐(CK-MCA)质量比为7/3时,协同阻燃效果最佳;芯层料添加质量分数5.6%的CK-APP105和2.4%的CK-MCA,皮层料添加质量分数6%的PVDF,所制得纤维的断裂强度为3.25 cN/dtex,断裂伸长率为67.32%,极限氧指数为30.9%,与水的接触角大于90°;改性PET纤维具有较好的阻燃性能和防水性能。     

Morphology and mechanical property changes in compatibilized high density polyethylene/polyamide 6 nanocomposites induced by carbon nanotubes

Addition of carbon nanotubes to immiscible polymer blends with co‐continuous morphology features to improve the electrical conductivity has attracted much attention in recent years; however, less attention has been paid to the effect of carbon nanotubes on the morphology and corresponding physical properties of immiscible polymer blends with typical sea‐island morphology. In this work, therefore, functionalized multiwalled carbon nanotubes (FMWCNTs) were introduced into an immiscible high density polyethylene/polyamide 6 (HDPE/PA6) blend which was compatibilized by maleic anhydride grafted HDPE (HDPE‐MA). The distribution of FMWCNTs and the phase morphologies of the nanocomposites were characterized using scanning electron microscopy and transmission electron microscopy. The crystallization and melting behaviors of the components were analyzed by differential scanning calorimetry, which is thought to be favorable for an understanding of the distribution of FMWCNTs. It is interesting to observe that the morphology of PA6 particles is very dependent on the method of preparation of the nanocomposites. Correspondingly, FMWCNTs exhibit an apparent reinforcement effect and/or an excellent toughening effect for the compatibilized HDPE/PA6 blend, depending upon their distribution state and the variation of PA6 morphology. This work proves that FMWCNTs have a potential application in further improving the mechanical properties of compatibilized immiscible polymer blends. Copyright © 2012 Society of Chemical Industry     

PA6－PEG共聚纤维和PA6－PEG／PA6共混纤维的物理与力学性能

研究了ＰＡ６－ＰＥＧ共聚纤维以及不同组成比的ＰＡ６－ＰＥＧ／ＰＡ６共混纤维的各项性能。得到了平衡吸湿率可达８％左右的改性纤维。纤维的染色性和手感也有显著改善，力学性能可满足纺织加工的要求。     

Microstructures and mechanical properties of polypropylene/polyamide 6/polyethelene-octene elastomer blends

A series of polymer blends were designed and manufactured. They are composed of three phases: polypropylene (PP), polyamide-6 (PA6) and polyethylene-octene elastomer (POE) grafted with maleic anhydride. The weight fraction of PA6 was adjusted from 0 to 40% by increments of 10%, and the weight fraction of POE was systematically half that of PA6. The morphology, essentially made of PA6 particles dispersed in the PP matrix, was characterised by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the extruded plates prepared with the blends, the shape of the dispersed PA6 particles showed an elongated ellipsoidal shape, whose aspect ratio increased somehow with alloying content. The POE modifier was observed both as a thin interlayer (less than 100 nm thickness) at the PP/PA6 interface, and as a few isolated particles. The elastic modulus and yield stress in tension are nearly constant for PP and blends. By contrast, the notched Izod impact strength increases very much with alloying content. This remarkable effect is interpreted in terms of POE interphase cavitation, enhanced plastic shear deformation and resistance of PA6 particles to crack propagation.     

PA6－PEG共聚纤维和PA6－PEG／PA6共混纤维的物理与力学性能

研究了ＰＡ６－ＰＥＧ共聚纤维以及不同组成比的ＰＡ６－ＰＥＧ／ＰＡ６共混纤维的各项性能。得到了平衡吸湿率可达８％左右的改性纤维。纤维的染色性和手感也有显著改善，力学性能可满足纺织加工的要求。     

Modification of melt,light, and heat stability of polyamide 6 by hindered piperidine amine and tertiary amine

Hindered piperidine amine (HPA) and tertiary amine (TA) were introduced into hydrolytic polymerization of caprolactam, and polyamide 6 (PA 6) modified by additives [HPA/TA = 1 : 1 (w/w)] was obtained. The effects of additives on the melt, light, and heat stability of PA 6 were studied. The results showed that with an increase in additive content, the viscosity of PA 6 increased and the elastic response decreased. Thus, the drawing property of PA 6 fibers during melt spinning was improved. With the addition of 0.1%–0.2% additives, the degree of variation in amino end group content and relative viscosity decreased during the process going from resin to fiber, indicating the modified PA 6 had improved melt stability. During light and heat aging, the ratio of retained fracture strength of PA 6 filament increased after modification by 0.1%–0.4% additives. Scanning electron microscopy showed that the surface morphology of the modified fiber remained almost the same, whereas that of the unmodified fiber was seriously destroyed when exposed to xenon light for 8 days or heated to 180°C in air for 1.5 h. The degree of variation of relative viscosity of the PA 6 fiber also decreased after modification by 0.1%–0.2% additives under oxidative degradation. All these results indicate PA 6 had better melt, light, and heat stability when modified by additives. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 538–544, 2007     

Influence of nano silica hybrid expandable graphite on flammability,thermal stability,and mechanical property of polypropylene/polyamide 6 blends

Silica (SiO₂) nanohybrid expandable graphite (nEG) particles fabricated through one-step method are used as an efficient flame retardant for polypropylene (PP)/polyamide 6 (PA6) blends. The effect of nEG on the flammability, thermal stability, crystallization behaviors, and mechanical properties of PP/PA6 composites is investigated by using limit oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared, scanning electron microscopy, and mechanical tests. Compared with pure expandable graphite (EG), nEG improves the flame retardancy of composites. The results of LOI show that LOI of PP/PA6/nEG10 and PP/PA6/nEG15 composites are 26.0% and 27.2%, respectively. But the LOI values of PP/PA6/EG10 and PP/PA6/EG15 composites are 25.7% and 26.9%, respectively. The UL-94 test results show that PP/PA6/nEG10 composites reach V-1 level when the nEG content is only 10%. However, the PP/PA6 composites with 10% EG does not pass the UL-94 test. In addition, PP/PA6 composites with 15% nEG can reach V-0 level. The CCT results further show that nEG has a higher flame-retardant efficiency than pure EG for PP/PA6 blends. The thermal stability of PP/PA6/nEG composites is better than that of PP/PA6/EG composites. The mechanical property tests indicate that nEG is more conducive to maintain the tensile and impact strengths of PP/PA6 blends than EG due to the enhanced compatibility and interfacial adhesion.     

Polylactic acid flame-retardant composite preparation and investigation of flame-retardant characteristics

Polylactic acid (PLA) is a new type of biodegradable material with good mechanical properties, and is widely used in many fields. However, as PLA is highly flammable, it is necessary to conduct flame-retardant modification research on PLA. Phosphorus heterophilic flame retardants are low smoke, non-toxic and have high flame-retardant efficiency, and also have broad application prospects. In this study, a phosphazene flame retardant, 9,10-dihydro-9-oxa-10-phosphazene-10-yl-hydroxy-phenol (abbreviated as DOPO-PHBA), was synthesized. The PLA/ECE/DOPO-PHBA flame-retardant composites were prepared by adding DOPO-PHBA and epoxy chain extender (ECE) into PLA. Thermal, mechanical, and flame-retardant properties, as well as microscopic morphology of the PLA flame-retardant composites were characterized and analyzed, and the flame-retardant mechanism was discussed. Results show that when the flame-retardant DOPO-PHBA is added at 5 wt%, the PLA composites can reach the V-0 level of combustion, and the corresponding LOI value is 30.0% at this time, and the LOI value increases from 22.5% to 33.6% with the increase of the flame-retardant content. In addition, PLA composites still have good mechanical properties, and the cone heat, carbon residue and the thermal decomposition process shows that the flame-retardant causes a two-phase flame-retardant mechanism on PLA with the gas and condensed phases acting in synergy. High flame retardancy is mainly attributed to free radical quenching, gas dilution, and the thermal barrier caused by the carbon layer. This work provides a simple and scalable method for the preparation of high-performance flame-retardant PLA materials.     

Studies on jute-reinforced composites,its limitations,and some solutions through chemical modifications of fibers

Jute, unlike other natural fibers, absorbs moisture and its moisture regain property is quite high. Water migration and subsequent degradation of jute-based composites can be a problem. Because jute is hydrophilic and the matrix resins are mostly hydrophobic, wetting of the fibers with resins is poor, for which high resin consumption may occur that would increase the cost of composites. To reduce the moisture regain property of jute fiber, it is essential to pretreat the jute fiber so that the moisture absorption is reduced and the wettability of the resin is improved. Jute fiber in the form of nonwoven jute has been pretreated with precondensate like phenol formaldehyde, melamine formaldehyde, cashew nut shell liquid-formaldehyde, and polymerized cashew nut shell liquid. The moisture content of the pretreated nonwoven jute has been determined by conventional methods and by a differential scanning calorimetric technique. Treatment of jute with precondensate causes the reduction of water regain property in jute. Pretreated nonwoven jute has been impregnated with phenol formaldehyde resin, and the composite board has been prepared therefrom. The jute composite board has been tested for bending strength, tensile strength, thickness swelling, and water absorption. Thermal analyses, such as differential scanning calorimetry and thermogravimetry, have also been conducted on jute and pretreated jute fibers. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1093–1100, 1998     

氯乙烯-丙烯腈共聚阻燃纤维的性能研究

采用乳液聚合方法制备氯乙烯-丙烯腈共聚物,得到的共聚物本身具有良好的阻燃性能。将共聚物通过湿法纺丝,得到了阻燃纤维。用热重分析法和电子单纱强力仪对纤维的热稳定性能和机械性能进行了表征,并用扫描电镜对纤维的表面进行观察,同时测定了该纤维的极限氧指数。结果表明:氯乙烯-丙烯腈共聚纤维的极限氧指数可达28.8%～32.5%,燃烧时无滴落现象,且离火即熄;氯乙烯-丙烯腈共聚物阻燃纤维的力学性能较普通腈纶略低。     

OMMT -卤-锑阻燃体系对 PA6／LGF 复合材料的影响

利用有机蒙脱土（ OMMT）协同溴代环氧树脂（ BER）、三氧化二锑（ Sb2 O3）通过熔融插层法制备OMMT-卤-锑阻燃长玻纤增强尼龙6复合材料（OMMT/FR/PA6/LGF）,通过极限氧指数（LOI）、垂直燃烧（UL-94）、锥形量热分析（CONE）、热失重分析（ TGA）、扫描电镜（ SEM）等方法研究了不同质量比的OMMT-卤-锑阻燃体系对OMMT/FR/PA6/LGF复合材料成炭、阻燃、燃烧、力学性能以及热稳定性的影响。结果表明,当OMMT添加量为2％, BER/Sb2 O3添加量为10％时,二者表现出优异的协同阻燃效应,不仅能促使OMMT/FR/PA6/LGF复合材料生成的炭层结构最为致密、均匀、连续,氧指数值最高且能保持FV-0级,还对复合材料的力学性能影响相对最小。     

Improving mechanical and thermal properties of short carbon fiber/polyamide 6 composites through a polydopamine/nano-silica interface layer

Carbon fiber (CF) reinforced matrix composites have been applied widely, however, the interfacial adhesion of composites is weak due to smooth and chemically inert of CF surface. To solve this problem, A polydopamine/nano-silica (PDA-SiO₂) interfacial layer on carbon fiber surface was constructed via polydopamine and nano- SiO₂ (CF-PDA-SiO₂) by a facile and effective method to reinforce polyamide 6 composites (CFs/PA6). The effects of PDA-SiO₂ interfacial layer on crystallization structure and behavior, thermal properties, and mechanical properties of CFs/PA6 composites were investigated. Furthermore, interfacial reinforcement mechanism of composites has been discussed. This interfacial layer greatly increased the number of active groups of CF surface and its wettability obviously. The tensile strength of CF-PDA-SiO₂/PA6 composites increased by 28.09%, 19.37%, and 26.22% compared to untreated-CF/PA6, CF-PDA/PA6, and CF-SiO₂/PA6 composites, respectively, which might be caused by the increased interfacial adhesion between CF and PA6 matrix. The thermal stability, crystallization temperature, crystallinity, and glass transition temperature (T_g) of CF-PDA-SiO₂/PA6 composites improved correspondingly, attributing to the heterogeneous nucleation of nano-SiO₂ in the crystalline area and hydrogen bonds with molecular chains of PA6 in the amorphous area. This work provides a novel strategy for the construction of interfaces suitable for advanced CF composites with different structures.     

Investigation of thermal behaviour and mechanical property of the functionalised graphene oxide/epoxy resin nanocomposites

ABSTRACT

Graphite oxide (GO) and functionalised graphite oxide (FGO) were successfully prepared with -NH₂-terminated GO in the paper, and their chemical structures were characterised with Fourier transform infrared (FTIR), Energy-Dispersive X-ray Spectroscopy (EDS), UV spectrum analysis and XRD, their microstructures were researched by a scanning electron microscope (SEM) and a transmission electron microscope (TEM), and their thermal properties were characterised by TG. The result showed the carbon residue of FGO was 82.1% and the residual char of GO was 48%, the composite materials were prepared with curing for epoxy resin. The thermal stability, mechanical properties, and morphology after impacting tests of composite materials were investigated using thermogravimetric analysis, tensile and charpy impact tests and SEM. The result showed when the 0.2% FGO was filled into the epoxy, the tensile strength was 55.4?MPa, the impact strength was 17.3?KJ/m², the flexural strength was 82?MPa, and the flexural modulus was 2760?MPa. The mechanical properties of composite materials were higher than those of pure epoxy and improved the strength and toughness of epoxy nanocomposites.     

Effects of interface on the dynamic mechanical properties of PET/nylon 6 bicomponent fibers

Three types of drawn bicomponent fibers were investigated to find out the effects of interface on the crystallinity and the dynamic mechanical properties. They are in the form of side‐by‐side, alternating‐radial, and island‐sea types, and the core or island component is PET, and the sheath or sea component is nylon 6. From the results it is observed that the storage moduli of these fibers are higher and the maximum values of the loss tangent are lower than the values calculated by the Takayanagi parallel model. Also, the decrease of interfaces between the two components improves the crystallinity of the PET component in the bicomponent fibers compared with the single‐component PET fiber. With the decrease in interfacial area, the maximum loss tangent decreases and the crystallinity increases at the same composition ratios. Among three types of bicomponent fibers, the side‐by‐side type—with the smallest interfacial area—has the highest crystallinity and the lowest maximum loss tangent. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2083–2093, 1999