Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements

Reactive extrusion was used to modify virgin polyamides 6 (v-PA6) and to prepare chain extended PA6 (CE-PA6) and long-chain branched PA6 (LCB-PA6) for the melt foaming process. This was done using a twin-screw extruder and the following modifiers: a chain extender ADR-4368 and a branching agent maleic anhydride grafted polypropylene. A reaction mechanism was proposed to explain the chain extension and long-chain branching reactions and was verified by the Fourier transform infrared spectroscopy data. The analysis of the gel permeation chromatography data showed that LCB-PA6 presented a strong increase in the molecular weight and in the dispersity index. Moreover, the rheological properties of the v-PA6 and modified PA6 resins were characterized by a dynamic shear test. The LCB-PA6 compared with CE-PA6 showed much higher shear viscosity and longer characteristic relaxation times, indicating the presence of an LCB structure. A uniaxial elongation test showed that the LCB-PA6 had the highest melt viscosity and melt strength as well as most obvious strain-hardening behavior. A high-pressure differential scanning calorimeter under compressed CO₂ was used to investigate the PA6's crystallization properties so as to analyze its minimum temperature of foaming windows. The melt foamability of the CE-PA6 and the LCB-PA6 was verified by batch melt foaming experiments with CO₂ as the blowing agent and maximum temperature of foaming windows was also quantitatively determined by numerical simulation of bubble growth based on the rheological measurements. The results showed that the LCB-PA6 foams had a smaller cell diameter, a larger cell density, a greater expansion ratio, and wider foaming temperature window than the CE-PA6. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48138.     

一种PA/ABS合金的新型相容剂

以南通日之升研发的新型相容剂CMG7000与尼龙/丙烯腈-丁二烯-苯乙烯(PA/ABS)合金常用的相容剂:马来酸酐接枝丙烯腈-丁二烯-苯乙烯(ABS-g-MAH)与进口PA/ABS专用相容剂SAN-co-A和SAN-co-B进行对比分析;研究了不同种类相容剂对PA/ABS合金材料力学性能、热稳定性以及微观形貌的影响。结果表明,CMG7000加入5%时,能够显著提高PA/ABS合金冲击韧性,同时并未明显降低材料的拉伸强度和弯曲模量。由于CMG7000特殊的多组分协同效应,能够改善两相结构的相容性和微观形貌,其具有更高的增韧效率。     

TiO2表面改性对聚酰胺6纤维强度及染色性能的影响

将TiO2表面包覆无定形TiO2,再经复配偶联剂改性后,分散在己内酰胺-水体系中乳化,于聚合釜中水解开环聚合,得到全消光聚酰胺6(PA6)切片。PA6切片经熔融纺丝制得PA6全消光纤维,并织成PA6全消光织物。用热重分析仪、纳米激光粒度仪、沉降试验等研究了改性TiO2的性能及在己内酰胺-水体系中的分散性;用差示扫描量热仪、扫描电子显微镜等研究了PA6全消光纤维结晶性能和截面形貌。结果表明：经复配偶联剂改性的TiO2在树脂基体中有很好的分散性;PA6全消光纤维的可纺性好;加入改性的TiO2后,PA6纤维的强度提高了25 %,但对PA6纤维的熔融温度没有影响;改性PA6全消光织物的上染率提高了10 %。     

影响锦纶6拉伸变形丝染色性能的主要因素

从原料、工艺、设备等方面入手,对影响锦纶6拉伸变形丝(DTY)染色性能的主要因素进行分析和试验论证。实践证明:切片是影响DTY染色性能的关键因素,纺丝温度及速度、DTY热箱温度、拉伸比对DTY丝上染率影响较大,预取向丝(POY)、DTY质量稳定性对染色均匀性影响也较大。     

碳纤维增强尼龙66复合材料的制备及性能

采用双螺杆挤出机熔融共混法制备了碳纤维(CF)增强尼龙66复合材料(PA66/CF),对其结构进行了表征,并研究了其力学性能。扫描电镜照片显示,在PA66/CF复合材料中,CF与PA66基体充分粘结在一起,其微观形貌表明,体系中碳纤长度为0.5~0.7 mm。力学性能测试发现,与尼龙66相比,PA66/CF复合材料各项力学性能指标均有大幅度提高。当加入4束碳纤维时,PA66/CF复合材料力学性能最佳,该复合材料的拉伸强度为200.2 MPa,与PA66相比提高了113.2 MPa;弯曲强度为280.2 MPa,比PA66提高了190.3 MPa;弯曲模量为13560.8 MPa,比PA66提高了10628.7 MPa;冲击强度为14.8 kJ/m^2,比与PA66提高了6.3 kJ/m^2。该PA66/CF复合材料密度较小、力学性能优良,可以广泛应用于风电叶片、发动机罩盖、仪表盘、车尾门等产品当中。     

阻燃型鳞片石墨/尼龙6导热复合材料

为了使树脂基导热复合材料兼具优异导热性能和阻燃性能,分别选用RPM/Mg(OH)2、BPS/Sb2O3、HS-PNPAZ/Mg(OH)2作为阻燃剂,鳞片状石墨作为导热填料,PA6作为基体树脂,采用双螺杆挤出机制备了阻燃型鳞片状石墨/PA6导热复合材料。对比了不同阻燃剂体系对复合材料导热和阻燃性能的影响。结果表明,不同阻燃剂对复合材料导热系数的影响较小,复合材料的导热系数主要受鳞片状石墨的影响。当鳞片状石墨含量为40份时,复合材料的导热系数均大于2.0 W/(m·K)。BPS/Sb2O3和HS-PNP-AZ/Mg(OH)2在鳞片状石墨/PA6复合材料中无阻燃效果,不适合用于鳞片状石墨/PA6复合材料体系的阻燃。RPM/Mg(OH)2在鳞片状石墨/PA6导热复合材料中具有优异的阻燃效果,可使复合材料的阻燃性能达到UL 94~1.6 mm V-0级别。     

高填充尼龙6基复合材料非等温结晶行为的研究

采用熔融共混法制备了高填充尼龙6(PA6)基复合材料,使用差示扫描量热仪研究了复合材料的非等温结晶动力学,并采用不同方法对测试结果进行了分析,结果表明:Avrami-Ozawa方程联用能够较为准确地描述体系的结晶行为。     

夹套式磁力泵在苯酐装置中应用

在使用机械密封离心泵和无密封磁力泵输送高熔点、有毒介质苯酐的过程中,通过对其生产操作、运行费用、环境污染等方面的对比,确认了使用无密封磁力泵的优点,并进一步将其推广到类似产品的生产中。     

尼龙66耐光、耐热性能研究

通过聚合反应合成耐光、耐热尼龙66,讨论了不同分子量、端基、防老化剂的加入对产品性能的影响。     

电位滴定法测定PA6中端氨基和端羧基含量的不确定度评定

通过电位滴定法测定PA6中端氨基和端羧基含量,分析并找出测定过程中影响不确定度的因素,并对各不确定度分量进行评定。结果表明:标准滴定溶液的浓度和消耗标准滴定溶液的体积所引入的不确定度对总不确定度贡献最大,其次是测量的重复性。