不同种类环氧树脂对PA6/CaCl_2体系性能的影响

利用熔融挤出法研究了两种不同环氧值的环氧树脂(E20,E06)对PA6/CaCl2复合体系的结晶、力学、耐热性能的影响。结果表明,在相同环氧树脂含量下,PA6/CaCl2/E20复合材料的熔融温度、起始结晶温度、结晶峰温度、结晶度大体上低于PA6/CaCl2/E06复合材料的值,PA6的结晶受限程度也较大。当EP含量为9份时,PA6/CaCl2/E20与PA6/CaCl2/E06复合材料的拉伸强度均达到最大值(92.7,87.0 MPa),与PA6/CaCl2(47.0 MPa)相比提高了97%和85%。当E20,E06含量分别为3份、5份时,PA6/CaCl2/EP复合材料的冲击强度分别达到最大值8.7,8.7 kJ/m2,与PA6/CaCl2(6.0 kJ/m2)相比提高了45%。另外,加入适量E20,E06后,复合材料耐热性能均有显著提高,且热稳定性降幅不大。综合得知,加入适量的环氧值较高的E20可以得到力学性能优良、耐热性能较好的PA6/CaCl2/E20复合材料。     

环氧树脂对低熔点PA6结构与性能的影响

采用熔融挤出的方法,制备环氧树脂(EP)/CaCl2/尼龙6(PA6)复合材料,研究了不同EP含量对EP/CaCl2/PA6复合材料的结晶熔融行为及性能的影响。结果表明:EP的加入一方面破坏了体系中Ca+与酰胺基团络合配位作用,另一方面,环氧基团与PA6的端氨基及端羧基反应,PA6的摩尔质量局部增大,结晶末端受限。随着EP含量的增加,EP/CaCl2/PA6复合材料熔融温度及结晶度逐渐降低。适量的EP能对PA6起到很好的扩链作用,使得复合材料的多项性能均大幅度提高。复合材料的透光率随EP的增加略有降低,在EP含量9份时透光率仍能达到60.6%,透明性良好。     

熔融挤出温度对PA6/CaCl2复合材料结构与性能的影响

采用熔融挤出的方法,制备了PA6/CaCl2复合材料,研究了熔融挤出温度对PA6/CaCl2复合材料的结晶行为和性能的影响。实验结果表明：随熔融挤出温度的提高,CaCl2与PA6的络合反应程度越大,PA6/CaCl2复合材料的结晶度越小,结晶不完善程度越大,复合材料的粘度越大,熔体流动速率越小。随熔融挤出温度的提高,复合材料的拉伸强度先增大后减小,最后近似趋于定值,冲击强度、弯曲强度随熔融挤出温度的提高总体呈增加趋势。     

CaCl_2含量对PA1010/CaCl_2复合材料结构与性能的影响

采用熔融挤出的方法制备了PA1010/CaCl2复合材料,研究了CaCl2含量对PA1010/CaCl2复合材料的结晶行为、力学性能及流动性能的影响。结果表明:CaCl2的加入提高了PA1010的结晶速率和结晶温度,降低了PA1010的结晶度;随着CaCl2含量的增加,拉伸强度及断裂伸长率先增大后减小,弯曲强度先减小后增大,缺口冲击强度逐渐增大,熔体质量流动速率及热变形温度逐渐减小。     

CaCl2含量对PA6/CaCl2复合材料结构与性能的影响

采用熔融挤出的方法,制备PA6/CaCl2复合材料,研究CaCl2含量对PA6/CaCl2复合材料结构与性能的影响.结果表明:随CaCl2含量的增加,PA6/CaCl2复合材料的结晶度越小,结晶不完善程度越大;复合材料的黏度越大,熔体指数越小.PA6/CaCl2复合材料的拉伸强度,冲击强度随CaCl2含量的增加存在极值现象,弯曲强度随CaCl2含量的增加而增加.     

良好分散尼龙6/多壁碳纳米管复合材料的研究

采用柔和混合法制备纳米粒子良好分散的尼龙-6/多壁碳纳米管(PA6/MWNTs)复合材料,采用差示扫描量热仪(DSC)和广角X射线衍射法(XRD)研究了MWNTs对PA6基体结晶熔融行为的影响。DSC结果表明,MWNTs的加入大幅度地提高了PA6的结晶温度(最高提高约20℃),基体的结晶度也有所提高,说明良好分散的MWNTs在PA6结晶过程中呈现明显的异相成核作用;XRD结果证实,分散良好的MWNT促进PA6形成α晶型,抑制γ晶型的形成。同时,MWNT的加入导致复合材料出现熔融双峰现象,其形状随MWNT含量的变化而改变,双峰结构可能是由于熔融过程中伴随着重结晶而引起的。     

PA6/SMA/LGF复合材料的制备及其性能研究

采用熔融共混法制备了聚酰胺6/苯乙烯-马来酸酐共聚物/长玻璃纤维(PA6/SMA/LGF)复合材料,利用差示扫描量热法(DSC)、热重分析(TGA)、热变形温度及力学性能测试等手段研究了LGF含量对PA6/SMA/LGF复合材料熔融结晶行为、热性能及力学性能的影响。结果表明:随着LGF含量的增加,PA6/SMA/LGF复合材料的结晶温度、结晶度以及熔融焓均先升高再降低,而且复合材料的最大分解温度较纯PA6显著提高;另外,随着LGF含量的增加,PA6/SMA/LGF复合材料的热性能及力学性能均明显改善,其中当LGF含量为27%时,复合材料的热变形温度、弯曲强度、弯曲模量、拉伸强度和冲击强度分别增至206.0℃、227.8 MPa、7 335 MPa、180.6 MPa和18.7 kJ/m2。     

加料顺序对PA6/CaCl2/SMA复合材料结构与性能的影响

通过熔融共混的方法制备PA6/CaCl2/SMA复合材料,研究SMA、CaCl2加入顺序对复合材料结晶行为、力学性能及其洛氏硬度的影响。研究结果表明:在两种不同加工条件下复合材料的熔点和结晶度都要低于SMA/PA6、Cacl2/PA6体系,复合材料的熔点最低降至194.63℃;PA6/SMA/Cacl2加工顺序下复合材料的力学性能要优于先PA6/Cacl2/SMA加工顺序下复合材料的力学性能。     

CaCl2的粒度分布对PA6/CaCl2复合材料结构与性能的影响

采用熔融挤出的方法,制备了PA6/CaCl2复合材料,研究了CaCl2的粒度分布对PA6/CaCl2复合材料的结晶过程和性能的影响.实验结果表明:当CaCl2的粒度在74～150 μm时,PA6/CaCl2复合材料的络合反应程度最大,熔点和结晶度最小,复合材料的各项力学性能指标最好.     

加料方式对PA6/CaCl_2/GF复合材料性能的影响

制备了不同含量玻纤增强的PA6/CaCl2/GF(聚酰胺6/氯化钙/玻璃纤维)复合材料。通过差示扫描量热仪(DSC)、动态力学分析(DMA),研究了不同加料顺序下玻纤含量对复合材料结晶性能、动态力学性能和维卡软化温度的影响。结果表明:先加入玻纤再加入CaCl2的加料方式下,复合材料的结晶度、储能模量、玻璃化转变温度、拉伸强度和弯曲强度更高;不同加料方式下,随着玻纤含量的增加,PA6/CaCl2/GF复合材料的缺口冲击强度和维卡软化温度都大幅度增加。     

Crystallization and melting behavior of multi‐walled carbon nanotube‐reinforced nylon‐6 composites

The crystallization and melting behavior of neat nylon‐6 (PA6) and multi‐walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt‐compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (T_{CC, 1} and T_{CC, 2}) for PA6/MWNTs composites instead of a single exotherm (T_{CC, 1}) for the neat matrix. The formation of the higher‐temperature exotherm T_{CC, 2} is closely related to the addition of MWNTs. X‐ray diffraction (XRD) results indicate that only the α‐phase crystalline structure is formed upon incorporating MWNTs into PA6 matrix, independently of the cooling rate and annealing conditions. These observations are significantly different from those for PA6 matrix, where the increase in cooling rate or decrease in annealing temperature results in the crystal transformation from α‐phase to γ‐phase. The crystallization behavior of PA6/MWNTs composites is also significantly different from those reported in PA6/nanoclay systems, probably due to the difference in nanofiller geometry between one‐dimensional MWNTs and two‐dimensional nanoclay platelets. The nucleation sites provided by carbon nanotubes seem to be favorable to the formation of thermodynamically stable α‐phase crystals of PA6. The dominant α‐phase crystals in PA6/MWNTs composites may play an important role in the remarkable enhancement of mechanical properties. Copyright © 2005 Society of Chemical Industry     

Surlyn对PET及其共混体系流变与结晶性能的影响

通过熔融共混法制备了聚对苯二甲酸乙二醇酯 (PET)/聚酰胺6 (PA6)/Surlyn与PET/均苯四甲酸酐 (PMDA)/Surlyn共混材料,研究了Surlyn对共混体系的形貌以及共混体系中PET流变性能与结晶性能的影响。并使用扫描电子显微镜 观察了PET/PA6/Surlyn共混物的低温淬断断面,使用旋转流变仪与差示扫描量热仪研究共混物的流变性能与结晶性能。结果表明,Surlyn可以提高PET/PA6/Surlyn共混体系的熔体强度,促进共混体系中PET的结晶,使PET结晶温度提高10 ℃,过冷度与结晶半高宽显著下降,明显改善PET的流变性能与结晶性能,而对于PMDA扩链后的PET,Surlyn对其结晶性能的影响影响较小;Surlyn可以降低PA6分散相的粒径,提高PET与PA6两相之间的相容性。     

聚酰胺6/丙烯酸酯橡胶共混物热性能和结晶行为研究

采用熔融共混法制备了聚酰胺6/环氧型丙烯酸酯橡胶(PA6/ACM)共混物,并通过差示扫描量热仪(DSC)、X射线衍射仪(XRD)和偏光显微镜(PLM)对PA6/ACM共混物的热性能和结晶行为及晶体形貌进行了研究。结果表明,随着ACM含量的增加,共混物的融熔温度(Tm)和结晶温度(Tc)均略有下降;由于环氧型ACM的加入,PA6的晶型也由γ晶型转化为 α晶型,且随着橡胶加入量的增加,结晶度逐渐降低,晶粒逐渐变小,结晶也越来越不完善;共混物的缺口冲击强度明显提高。     

Influence of fibrillated poly(tetrafluoroethylene) on microcellular foaming of polyamide 6 in the presence of supercritical CO2

In this article, PA6/poly(tetrafluoroethylene) (PTFE) composites were prepared by internal mixer with high rotor speed. The existence of PTFE nano-fibrillation network structure was observed by scanning electron microscopy (SEM) analysis. The effect of PTFE on crystallization and rheological behavior of PA6 was evaluated. The result showed that the PTFE fibrils improved the crystallization properties of PA6 and do not change the crystal structure. The PTFE effectively enhanced the melt strength of PA6 by fibrillation. The PA6/PTFE composites were then foamed assisted by supercritical CO₂. The PTFE was used as cell nucleating agent, crystal nucleating agent and melt strength enhancement agent in the foaming process. Finally, the microcellular PA6 foams were successfully obtained with the cell density higher than 10⁹ cells/cm³, the cell size of ca. 14 μm and the volume expansion ratio of 16.     

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.     

尼龙6/聚酯(PET)共混体系结晶相分离的研究

用差示扫描量热（ＤＳＣ）考察尼龙６／聚酯（ＰＥＴ）共混体系的结晶行为，表明是结晶相分离的。不同条件下，结晶相分离的过程和形成的结晶态不同，反映在热行为上，如熔融过程和相应特征参数值，便随着处理的条件、组成比等而改变。研究结果还表明，当尼龙６组分的质量分数Ｗ ＰＡ－６＜ ０．１ 时，它被ＰＥＴ 阻隔而不再结晶，因两者形成部分氢键，酯基对尼龙６ 结晶影响的结果，尼龙６／聚酯（ＰＥＴ）共混体系中尼龙６ 的熔融峰温，随组成比的变化呈现波浪形曲线。