关于纳米蒙脱土影响聚己内酰胺结晶行为及流变行为的研究

通过双螺杆挤出机熔融挤出生产有机改性纳米蒙脱土(MMT)增强聚己内酰胺(PA6)。使用差示扫描量热仪开展自成核试验及非等温结晶行为研究,了解纳米MMT含量对PA6结晶行为的影响,结果表明:少量的纳米MMT可以明显提高成核效率和结晶速率,但继续增加纳米MMT会抑制PA6结晶生长,降低结晶速率和结晶度。使用广角X射线衍射仪研究PA6的结晶行为,结果表明:纯PA6同时存在α及γ晶型,添加纳米MMT的PA6发生α-γ晶型转变,证实纳米MMT与PA6的作用可以改变PA6的结晶行为。使用毛细管流变仪分析纳米MMT含量对PA6熔体受剪切时流变行为的影响,结果表明:纳米MMT含量影响PA6熔体的黏度及非牛顿流体特征,尤其是高纳米MMT含量的PA6在不同剪切速率下表现出明显的黏度变化。     

立体缺陷分布对iPP/CNC复合材料等温结晶动力学的影响

采用两种立体缺陷分布均匀性不同的等规聚丙烯(iPP),制备了两种等规聚丙烯/纤维素纳米晶(iPP/CNC)复合材料,研究了纯iPP和iPP/CNC复合材料的等温结晶动力学行为及结晶形态。结果表明,与立体缺陷分布更加均匀的PP-B相比,PP-A表现出更高的结晶温度、熔点和结晶度,球晶尺寸明显更小,等温结晶速率更快;加入CNC后,PP-A/CNC和PP-B/CNC的结晶温度变高、结晶峰宽变窄、熔点及结晶度上升、晶体尺寸显著降低、等温结晶速率进一步提高,且二者之间在结晶速率上的差距明显缩小,反映出CNC对于iPP的结晶能力同样具有较为显著的提升效果。对于i PP/CNC复合材料,iPP的立体缺陷分布和CNC对其等温结晶动力学及晶体形态都有十分显著的影响。     

功能化纤维素纳米晶在聚丙烯中的应用

在酸解法制备纤维素纳米晶(CNC)的基础上,通过两步改性将原儿茶酸(PA)引入到CNC表面,得到功能化CNC(CPA).X射线光电子能谱(XPS)证明PA成功接枝到CNC表面上;反滴定法表明CPA中酚羟基含量可达3.604 mmol/g;采用X射线衍射仪(XRD)和透射电子显微镜(TEM)测试表明改性后CNC的结晶度有...     

热致液晶聚酰胺对聚酰胺66结晶行为的影响

利用差示扫描量热仪（DSC）、广角X射线衍射（WAXD）和偏光显微镜（POM）等仪器研究了热致液晶聚酰胺（TLCP）对聚酰胺66（R％6）结晶行为的影响。结果表明：随TLCP的添加量从0增加到30％，共混物的结晶温度和结晶度分别从PA66的235．83℃和39．8％逐步下降为224．7℃和30．8％，PA66的结晶明显受到抑制；共混物中PA66衍射峰的强度随TLCP含量的增加而下降，（100）、（010）晶面间距分别从0．43667nm和0．37139nm增加到0．4414nm和0．37793nm；共混物球晶尺寸明显大于PA66，并且随TLCP含量增加PA66的球晶变得越来越不完善。     

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。     

纤维素纳米晶对聚乳酸结晶行为的影响

聚乳酸(PLA)因具有良好的生物相容性和生物降解性而受到广泛的关注,但其结晶速率慢和结晶度低,大大地限制了PLA的使用。基于此,本文从结晶改性入手,通过改进后的两步法将纤维素纳米晶(CNC)均匀分散到PLA中。利用透射电镜(TEM)、傅里叶红外光谱(FTIR)、差示扫描量热仪(DSC)、偏光显微镜(POM)、力学性能测试、X射线衍射测试(XRD)等表征手段测试了CNC的加入对PLA复合材料结晶行为的影响。结果表明,加入质量分数3%的CNC,PLA的结晶度提高到47.5%,复合材料的拉伸强度也提高了10%,并且在145℃等温结晶的晶核数量明显增多,晶粒尺寸明显减小,球晶生长速率提高。     

热塑性聚氨酯对尼龙6结晶行为的影响

使用X射线衍射法分析了热塑性聚氨酯（TPU）对PA6结晶行为的影响,研究了TPU软段类型。邵氏硬度对PA6的结晶行为的影响。结果表明：TPU含量越高,尼龙6的结晶度越小,但TPU邵氏硬度对结晶基本上没有影响。相同含量的TPU,随着软段分子量的提高,尼龙6的结晶度提高．即95S的TPU对尼龙6的结晶性影响最大。     

酰胺化纳米晶纤维素提高乙烯-醋酸乙烯酯共聚物薄膜阻透性的研究

合成了三种酰胺化纳米晶纤维素,并采用溶液共混成膜法制备了酰胺化纳米晶纤维素（CNC）/乙烯醋酸乙烯醋共聚物(EVA)复合膜材料。通过紫外-可见分光光度计、电子万能试验机和透湿仪研究了酰胺化CNC/ EVA复合膜的光学性能、力学性能以及水蒸气阻隔性,并通过原子力显微镜研究热压处理的EVA复合膜的表面形貌。结果表明,添加三种不同碳链的酰胺化CNC都使 EVA膜的透光率有所降低,当添加量为5 %时,EVA膜透光率仍高达90%。一定程度的热压能够让酰胺化纳米晶纤维素在EVA基体中分散更均匀,使EVA复合膜的透光率提高了2%～3%;随着纳米晶纤维素含量的逐渐增加,三种酰胺化CNC/EVA膜的拉伸强度均逐渐增强,透湿率（WVTR值）均减小;酰胺化CNC含量相同时, 十六胺改性的纳米晶纤维素(CNC-N16)/EVA复合膜的力学性能和水蒸气阻隔效果优于相应的十二胺和正辛胺。     

PP/PA6/EPDM-g-GMA合金性能的研究

在聚丙烯（PP）中加入10％～40％（质量分数）的PA6及反应增容剂EPDM—g—GMA对PP进行共混改性．观察和分析了共混合金的形貌及等温结晶形态，测试了合金的力学性能。结果表明：PP／PA6体系中加入EPDM—g—GMA后相容性改善；PP球晶尺寸随PA6的混入而减小，且PA6结晶相分布PP晶区内和PP晶区之问，加入EPDM—g—GMA后PA6结晶相尺寸减小；PP／队6体系中加入EPDM—g—GMA可起到反应增容和橡胶增韧的协同效应，使材料的韧性比纯PP明显提高；PP／PA6体系的杨氏模量高于PP，加入EPDM-g-GMA后杨氏模量比未增容体系提高不显著；PP／PA6体系的屈服强度随PA6用量的增加而下降，加入EPDM—g-GMA后屈服强度高于未增容体系但略低于PP。     

PA6/蒙脱土纳米复合材料力学性能与结晶行为的研究

陈述了纳米MMT直接加入到PA6中对力学性能的效应;阐明了用不同的MMT的处理方法和不同的载体树脂所制成的母料对PA6复合材料力学性能和结晶行为的影响;还研究了母料中纳米分散程度对PA6复合材料力学性能和结晶行为的影响。DSC研究表明:纳米蒙脱土的加入加快了PA6的结晶过程,促使了γ晶的生成,起到了异相成核作用。     

PA66/PET共混物的结晶行为

用ＤＳＣ分析方法研究了ＰＡ６６／ＰＥＴ共混物的结晶行为,结果表明,两种共混物配比与相容剂种类对其结晶行为有着显著的影响。当共混物中ＰＥＴ含量较低,融体冷却时,先固化的ＰＥＴ在ＰＡ６６连续相中具有成核剂的作用,加快了结晶速度,在有些相容剂存在下还增加了结晶度。     

Confined crystallization phenomena in immiscible polymer blends with dispersed micro- and nanometer sized PA6 droplets, part 3: crystallization kinetics and crystallinity of micro- and nanometer sized PA6 droplets crystallizing at high supercoolings

Crystallization kinetics and crystallinity development of PA6 droplets having sizes from 0.1 to 20 μm dispersed in immiscible uncompatibilized PS/PA6 and reactively compatibilized (PS/Styrene-maleic anhydride copolymer=SMA2)/PA6 blends are reported. These blend systems show fractionated crystallization, leading to several separate crystallization events at different lowered temperatures. Isothermal DSC experiments show that micrometer-sized PA6 droplets crystallizing in an intermediate temperature range (T_c∼175 °C) below the bulk crystallization show a different dependency on cooling rate compared to bulk crystallization, and an athermal crystallization mechanism is suggested for PA6 in this crystallization temperature region. The crystallinity in these blends decreases with PA6 droplet size. Random nucleation, characteristic for a homogeneous nucleation process, is found for sub-micrometer sized PA6 droplets crystallizing between T_c 85 and 110 °C using isothermal DSC experiments. However, crystallization in the PA6 droplets is most likely initiated at the PA6-PS interface due to vitrification of the PS matrix during crystallization. Very imperfect PA6 crystals are formed in this low temperature crystallization region, leading to a strongly reduced crystallinity. These crystals show strong reorganization effects upon heating.     

Crystallization behavior of PA66/SiO2 organic‐inorganic hybrid material

The poly 2‐hydroxy propylmethacrylate‐methyl methacrylate (PHPMA‐MMA)/SiO₂ composite, derived from 2‐hydroxy propylmethacrylate (HPMA), methyl methacrylate (MMA), and tetraethoxysilane (TEOS), was used to synthesize polyamide 66(PA66)/SiO₂ organic‐inorganic hybrid material. X‐ray diffraction (XRD) was used to investigate the lattice spacing change of the PA66/SiO₂ hybrid material. It was found that the addition of PHPMA‐MMA/SiO₂ composite nearly did not change the crystal form of PA66. The nonisothermal crystallization kinetics of PA66 and PA66/SiO₂ hybrid material was investigated by differential scanning calorimetry (DSC) with various cooling rates. At every given cooling rate, the start crystallization temperature of the PA66/SiO₂ hybrid material was higher than that of PA66, while the crystallization temperature range was narrower than that of PA66. Avrami analysis modified by the Jeziorny method, the Ozawa method, and a method developed by Liu were employed to describe the nonisothermal crystallization process of the samples. The results showed that the Jeziorny method and the Ozawa method were not suitable to describe the nonisothermal crystallization process of PA66/SiO₂ hybrid material; however, when the relative degree of crystallinity X (t) was less than 1 ? 1/e, ln [? ln (1 ? X (t))] was still linear to lnt. The Liu method was successful to describe the nonisothermal crystallization processes for both PA66 and the PA66/SiO₂ hybrid material. It was confirmed that the presence of PHPMA‐MMA/SiO₂ composite could increase the crystallization rate and had a hetero phase nucleation effect on the PA66 matrix. Moreover, the introduction of PHPMA‐MMA/SiO₂ could improve the crystallization active energy ?E calculated by the Kissinger equation, attributing to the strong interaction between the polyamide chains and the PHPMA‐MMA/SiO₂ composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 810–817, 2006     

聚(苯乙烯-丙烯酰胺)/蒙脱土核壳结构材料改性聚酰胺6的性能研究

用自制的以有机蒙脱土（OMMT）为核、聚苯乙烯为次外层、聚丙烯酰胺为外层的新型聚(苯乙烯-丙烯酰胺)/OMMT核壳结构,通过熔融共混法制备了含3 %（质量分数,下同）核壳结构的改性聚酰胺6（PA6）。研究了改性PA6的力学性能、加工流动性能、结晶性能和热稳定性能。结果表明,核壳结构改性PA6能明显提高材料的弯曲性能,其弯曲强度较纯PA6提高了1.44 %,弯曲模量提高了3.46 %;核壳结构对PA6的结晶有成核作用,材料的结晶温度提高了8.5 oC,结晶度提高了3.3 %;核壳结构改性PA6与纯PA6具有基本一致的热稳定行为;核壳结构还能有效提高PA6的加工流动性,其熔体流动速率是纯PA6的2.18倍。     

Stress photo‐oxidative aging behaviour of polyamide 6

The long‐term stress accelerating aging behaviour of polyamide 6 (PA6) was studied by exposure to UV irradiation. The aging behaviour and mechanism were investigated in terms of creep behaviour, mechanical properties, chemical structure, crystallization and orientation behaviour. It was found that the creep deformation of PA6 under stress/UV irradiation was lower than that of the sample aging only under stress, resulting from crosslinking and low mobility of molecules under UV irradiation. The tensile strength of PA6 under stress and stress/UV irradiation substantially increased at the primary aging stage due to stress‐induced molecular orientation. The oxidation of PA6 may also be inhibited by orientation, leading to a relatively low content of carboxylic groups. Under UV irradiation, stress accelerates the degradation of PA6, resulting in strengthening UV absorption due to formation of isolated carbonyl groups. The melt temperature and crystallinity both showed an increase with time, which were much higher for the sample aged under stress/UV irradiation than for that aged only under UV irradiation. Wide‐angle X‐ray diffraction analysis also showed that the orientation factor and crystallinity of PA6 increased with aging time before 16 days, indicating a clear orientation and crystallization of molecules induced by stress. The UV‐induced crosslinking reduced the mobility of PA6 chains, resulting in a lower crystallinity and orientation factor of the sample aged under stress/UV irradiation compared with that under stress aging only. Copyright © 2011 Society of Chemical Industry     

Synthesis and properties of hydroxyapatite nanorod‐reinforced polyamide 6 nanocomposites

BACKGROUND: Polyamide 6 (PA6)/hydroxyapatite (HA) nanocomposites, which combine the bioactivity and biocompatibility of HA and the excellent mechanical performance of PA6, have emerged as new biomaterials with potential applications in the clinical setting. It has been shown that these nanocomposites show good similarity to natural bone in terms of chemistry and mechanical properties. RESULTS: In this study, highly crystallized hydroxyapatite nanorods (HANR) were used to fabricate PA6/HA nanocomposites via in situ hydrolytic ring‐opening polymerization of ε‐caprolactam. The effect of the HANR on the thermal stability, crystallization behavior and hydrogen bonding of PA6 was investigated using thermogravimetric analysis, differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy, respectively. It was found that HANR can obviously increase the crystallization temperature and decrease the degree of supercooling. In addition, the thermal degeneration temperature of PA6 is also increased by the incorporation of HANR. FTIR analysis of the hydrogen bonded N? H stretching vibration revealed that, with increasing HANR loading, the hydrogen bonded N? H stretching band shifts to higher frequency and decreases in intensity. CONCLUSION: The thermal stability and crystallization ability of PA6 are improved considerably by the incorporation of HANR. However, the hydrogen bonding strength is weakened and the degree of ordering of hydrogen bonding is reduced by the incorporation of HANR, which can be explained by the formation of hydrogen bonds at the interface between ? OH groups of HANR and the ? N? H or ? C?O groups of PA6. Copyright © 2009 Society of Chemical Industry     

环氧改性剂对PA6/EVOH共混物性能的影响

介绍了不同环氧改性剂对聚酰胺6（PA6）/乙烯?乙烯醇共聚物（EVOH）共混物的拉伸性能、流变性能、结晶性能的影响,并研究了甲基丙烯酸缩水甘油酯（GMA）与共混物的反应机理。使用转矩测试、红外光谱、氢核磁共振、拉伸测试、旋转流变测试和差示扫描量热法对共混物进行了表征。结果表明,随着改性剂环氧值的增加,共混物的共混转矩、拉伸强度、复数黏度和储能模量均增加,共混物的结晶度和结晶温度降低,断裂伸长率呈先升高后降低的趋势;考虑到加工过程的流动性,GMA改性的共混物性能最佳,拉伸强度提高了8.5 %,断裂伸长率提高了26.6 %;红外光谱和氢核磁共振表明,GMA可以在高温下发生自聚合反应,形成多环氧低聚物,进而与PA6和EVOH反应,提高共混物的性能。     

Structure of polyamide 6 and poly (p-benzamide) in their rod-coil-rod triblock copolymers investigated with in situ wide angle X-ray diffraction

A series of rod-coil-rod triblock copolymers containing polycaprolactam (PA6) as the coil block and poly (p-benzamide) (PBA) as the rod block were synthesized by a two-step polycondensation reaction. Proton nuclear magnetic resonance (¹H NMR), UV-vis spectrophotometry (UVS) and differential scanning calorimetry (DSC) were performed to determine the fundamental molecular structure and thermal property of copolymers. UV-vis spectrophotometry results revealed that the content of PBA homopolymer increased with the block length (number of monomer) of PBA and reached a plateau value ranging from 22 to 40 monomers of PBA. The wide angle X-ray diffraction (WAXD) measurements indicated that the crystallization of PA6 blocks was strongly suppressed due to the stretching from rods after annealed at temperature above the melting point of PA6. Only a few imperfect crystals of PA6 existed in the samples with low volume fraction of PBA. Moreover, the variation of PA6 block length hardly affected the crystallinity of PBA, which was dominantly controlled by the block length of PBA as diffusion was the control step for PBA crystallization at the annealing temperature.     

半芳香族耐热性共聚酰胺的合成及性能

以癸二胺、己二胺和对苯二甲酸为主要原料,通过一步熔融缩聚法合成了半芳香族共聚酰胺聚对苯二甲酰癸二胺/己二胺(PA10T/6T),采用核磁共振碳谱确认了其结构。在此基础上,通过差示扫描量热仪、X射线衍射仪和热重分析仪对其熔融温度、结晶温度、晶体生长方式、结晶活化能、结晶度以及热稳定性进行了测试分析研究。结果显示,PA10T/6T具有较宽的加工窗口,当PA6T链段的物质的量分数达到10%,30%和50%时,PA10T/6T熔融温度较PA10T分别下降了10.97,37.41,7.8℃;PA6T链段的引入并没有改变聚合物的晶体生长方式且对聚合物的热稳定性没有明显影响;随着PA6T链段含量的增加,聚合物的结晶温度、熔融温度、结晶活化能的绝对值以及结晶度均呈先降低后升高的趋势,这是聚合物分子链结构和聚合物晶体完整性综合影响的结果。     

PA6/LDPE/PE-g-MAH共混纳米纤维的制备及结构研究

采用共混海岛纺丝法制备聚酰胺6/低密度聚乙烯/聚乙烯接枝马来酸酐(PA6/LDPE/PE-g-MAH)共混纤维,溶解剥离出LDPE基体相,可制备出PA6纳米纤维;研究了共混物的组成和纺丝条件对共混纤维的相结构、结晶、力学性能及PA6纳米纤维直径的影响。结果表明:随着共混物中PA6分散相含量增加,PA6纳米纤维的直径逐渐增大;PA6质量分数从30%增加至60%时,PA6纳米纤维平均直径由107 nm增至149nm;PA6质量分数为70%时,由于相逆转无法得到PA6纳米纤维;在PA6质量分数为55%条件下,提高拉伸倍数,PA6纳米纤维的直径进一步降低,且结晶度、力学性能增加。