PP/POE共混物的热行为与晶态结构

采用双螺杆挤出机熔融共混制备了不同组成的聚丙烯(PP)/乙烯-辛烯弹性体(POE)共混物,利用差示扫描量热仪、偏光显微镜和广角X射线衍射系统研究了共混物的热行为与晶态结构。结果表明PP与POE之间具有一定的相容性,POE的异相成核作用提高了共混物中PP的结晶温度和结晶速率,有效地诱导β晶型PP的形成,增大了共混物中α晶型和β晶型PP的晶面表观厚度。另一方面,由于POE与PP之间存在较强的相互作用,POE大分子链使PP分子链的扩散和堆积受阻,从而导致PP/POE共混物总结晶度的降低。     

热氧老化对尼龙6结晶行为与性能的影响

通过熔融共混法制备了添加稳定剂的稳定化尼龙6和不加稳定剂的尼龙6。采用差示扫描量热(DSC)、X射线衍射(XRD)、动态力学性能(DMA)、红外光谱等方法研究了尼龙6在160℃高温环境中热氧老化不同时间后结晶行为及性能的变化。结果表明,随着热氧老化时间延长,尼龙6的结晶温度、结晶度及拉伸强度呈先上升后下降趋势,冲击韧性下降,储存模量提高;稳定剂的存在提高了尼龙6的结晶温度、结晶度及力学性能保持率,但对其玻璃化转变温度影响不大;热氧老化36h以后,尼龙6以γ晶型为主,稳定化尼龙6以α晶型为主。     

母料中弹性体不同配比对HDPE/E-TMB共混物热性能及结晶形态的影响

用自制增韧母料(E-TM B)与HDPE热机械共混制得HDPE/E-TM B共混物。通过DSC分析仪和偏光显微镜研究了共混物的熔融、结晶行为和结晶形态,并将其结晶形态与简单共混对照样加以对比研究。结果表明,和纯HDPE相比,共混物的熔点降低、结晶温度升高,成核速率和结晶速率增大;随母料中乙丙弹性体含量的增加,共混物的熔点逐渐降低、结晶温度逐渐升高,结晶细化程度增大、数目增多;共混物的结晶比原料HDPE及简单共混对照样都显著细化。     

PA66/PA6I6T共混物非等温结晶动力学及性能

将PA66与PA6I6T以不同配比进行熔融共混,通过差示扫描量热分析对所制备的尼龙66 (PA66)与半芳香尼龙(PA6I6T)共混物在不同降温速率下的非等温结晶行为进行了研究。利用Jeziorny法及Mo方法对共混物的非等温结晶动力学数据进行了分析,并采用Kissinger方法计算了共混体系的结晶活化能;考察了PA6I6T含量对共混物力学性能、耐热性及加工流动性的影响。研究发现,PA66与PA6I6T具有良好的相容性,少量的PA6I6T会促进PA66的结晶,随着PA6I6T含量的进一步增加,PA66的结晶速率及结晶度呈下降趋势,PA66的结晶活化能的绝对值随PA6I6T含量的增加表现为先增大后减小。共混物的拉伸强度和冲击强度随PA6I6T含量的增加而增加,其中拉伸强度在PA6I6T达到一定含量后趋于平缓。PA6I6T的引入提高了共混物的耐热性和热稳定性,但加工流动性较纯PA66材料有一定程度降低。     

聚丙烯/尼龙6共混物的X射线衍射研究EI

用广角 X射线衍射 (WAXD)方法研究了不同接枝聚丙烯对聚丙烯 /尼龙 6 (PP/PA6 )共混物结晶行为的影响。结果表明 ,与简单机械共混物相比 ,由于增容剂的加入 ,PP的结晶行为发生变化——不同晶面的生长速率不同 ,且在所研究的范围内有随增容剂含量的增加 。     

尼龙6/粘土与聚乙烯醇共混物中尼龙6的晶型转变

主要研究了在尼龙6/粘土(NYC)与聚乙烯醇(PVA)共混复合物中尼龙6的晶型转变。在差示扫描量热(DSC)和X射线衍射的表征中发现,当PVA的含量小于16.7%时,PVA的α晶型消失。随着NYC/PVA体系中NYC含量的增加,原来存在于NYC中尼龙6主要的γ晶型逐渐转变为α晶型;当PVA的含量等于或大于50%时,在NYC/PVA体系中只存在α晶型的尼龙6结晶。用扫描电镜(SEM)进一步分析经离子束刻蚀的NYC/PVA样品发现,随PVA含量的增加所产生尼龙6晶型的转变现象,主要是由粘土迁移行为造成的。     

尼龙1212/SEBS-g-MA/DIDP/BSBA共混体系的结晶行为

用W AXD、PLM及DSC研究了尼龙1212/SEBS-g-M A/D IDP/BSBA共混体系的结晶行为。W AXD结果显示,增韧剂的加入改变了尼龙1212的晶型。PLM观察表明共混体系中由于M A与尼龙之间的相互作用,增韧剂充当了成核剂,使得尼龙1212球晶向细晶化发展。用修正A vram i方程的Jez iorny法研究共混体系的非等温结晶动力学,发现共混体系的半结晶时间t1/2缩短,增韧剂对尼龙1212有明显的异相成核作用。     

增韧尼龙6的力学性质和形态EI

尼龙由于在干态和低温下冲击强度较低而限制了其应用,本文进行了用聚烯烃弹性体接枝物(E-g-MA)增韧尼龙6的研究,并讨论了增韧的机理。     

氧化石墨烯/尼龙6复合材料的等温结晶行为

采用液相共混法制备氧化石墨烯(GO)/尼龙6(PA6)复合材料,利用差示扫描量热(DSC)和偏光显微镜(POM)表征该体系的等温结晶行为。结果表明,Avrami方程可较好地描述PA6和GO/PA6复合材料的等温结晶行为,氧化石墨烯对尼龙6起到成核剂作用,使其结晶速率增大,结晶活化能减少。等温结晶温度升高,PA6和GO/PA6的绝对结晶度和结晶速率减少。偏光显微镜观察证实,添加氧化石墨烯后的尼龙球晶细化。     

PTT/TPEE共混合金的热性能和结晶形态

采用冲击试验机、差示扫描量热仪和热台偏光显微镜研究了聚对苯二甲酸丙二醇酯(PTT)/热塑性聚酯弹性体(TPEE)共混合金的抗冲击性能、结晶熔融行为和晶体形态。结果表明,TPEE可以提高共混材料的缺口冲击强度;共混物只有一个玻璃化转变温度,且随着TPEE含量的增加而降低,两组分具有良好的相容性;共混物在玻璃态结晶时,随着TPEE含量增加,冷结晶热焓降低,结晶峰温度降低。共混物熔体的起始结晶温度降低,但在低温时结晶速率加快,TPEE对PTT的结晶化具有促进作用。共混物中PTT形成球晶,但由于TPEE的干扰而使PTT的球晶尺寸减小,晶体形态完善程度下降。     

Impact fracture behaviour of nylon 6-based ternary nanocomposites

This study focuses on achieving high stiffness/strength and high fracture toughness in nylon 6/organoclay nanocomposites prepared via melt compounding by incorporating a maleic anhydride grafted polyethylene–octene elastomer (POE-g-MA) as a toughening agent. Mechanical test results indicated that the ternary nanocomposites exhibited higher stiffness than nylon 6/POE-g-MA binary blends at any given POE-g-MA content. More importantly, the brittle–ductile transition of nylon 6/POE-g-MA blends was not impaired in the presence of organoclay for the compositions prepared in this study. TEM analysis shows that organoclay layers and elastomer particles were dispersed separately in nylon 6 matrix. In the binary nanocomposite, no noticeable plastic deformation was observed around the crack tip. In the ternary nanocomposites, the presence of organoclay in the matrix provided maximum reinforcement to the polymer, while their absence in the elastomer particles allowed the latter to promote high fracture toughness via particle cavitation and subsequent matrix shear yielding. The partially exfoliated clay layers also delaminated and hence, adding to the total toughness of the nanocomposites.     

Thermal properties of nylon6/ABS polymer blends: Compatibilizer effect

Nylon6/ABS binary blends are incompatible and need to be compatibilized to achieve better performance under impact tests. Poly(methyl methacrylate/maleic anhydride) (MMA-MA) is used in this work to compatibilize in situ nylon6/ABS immiscible blends. The MA functional groups, from MMA-MA copolymers, react with NH₂ groups giving as products nylon molecules grafted to MMA-MA molecules. Those molecular species locate in the nylon6/ABS blend interfacial region increasing the local adhesion. MMA-MA segments are completely miscible with the SAN rich phase from the ABS. The aim of this work is to study the effects of ABS and compatibilizing agent on the melting and crystallization of nylon6/ABS blends. This effect has been investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Incorporation of this compatibilizer and ABS showed little effect on the melting behavior of the PA6 crystalline phase, in general. DMTA analysis confirmed the system immiscibility and showed evidence of compatibility between the two phases, nylon6 and ABS, produced by MMA-MA copolymer presence. The nylon6/ABS blend morphology, observed by transmission electron microscopy (TEM), changes significantly by the addition of the MMA-MA compatibilizer. A better dispersion of ABS in the nylon6 phase is observed.     

Morphological, mechanical and rheological properties of nylon 6/acrylonitrile-butadiene- styrene blends compatibilized with MMA/MA copolymers

The morphological, mechanical and rheological properties of nylon 6/acrylonitrile- butadiene-styrene blends compatibilized with MMA-MA [poly(methyl methacrylate-co- maleic anhydride)] copolymers were studied. A twin screw extruder was used for melt-blended the polymers and the injection moulding process was used to mold the samples. The main focus was on nylon 6/ABS blends compatibilized with one MMA-MA copolymer. This copolymer has PMMA segments that appear to be miscible with the styrene-acrylonitrile (SAN) phase of ABS and the anhydride groups can react with amine end groups of the nylon 6 (Ny6) to form graft copolymers at the interface between Ny6 and ABS rich phases. Tensile and impact and morphological properties were enhanced by the incorporation of this copolymer. Transmission electron microscopy (TEM) observations revealed that the ABS domains are finely dispersed in nylon 6 matrix and led to the lowest ductile-brittle transition temperatures and highest impact properties. It can be concluded that the MMA-MA copolymer is an efficient alternative for the reactive compatibilization and can be used as a compatibilizer for nylon 6/ABS blends.     

热空气老化对LDPE/POE共混物结晶行为和力学性能的影响

在70℃条件下,对低密度聚乙烯(LDPE)/聚烯烃弹性体(POE)共混物进行八周热空气老化试验,通过差示扫描量热法(DSC)和宽角X射线衍射(WAXD)表征了共混物结晶行为的变化,研究了热空气老化对共混物力学性能的影响。w(POE)为30%的共混物具有优异的耐热氧老化性能,在老化前期,其断裂伸长率有所增加,在老化后期才略有下降,而拉伸强度则基本不变。热空气老化对共混物结晶行为产生明显的影响,且结晶行为的变化主要在老化前期完成。经过热空气老化,部分在制备过程中形成的不完善晶体重新结晶,晶粒尺寸逐渐变大,提高了LDPE结晶的完善性。     

聚酯含量对PBT/PET/PA-6三元共混物性能影响

采用ＤＳＣ、ＳＥＭ等方法对ＰＢＴ／ＰＥＴ／ＰＡ６三元共混物中聚酯含量的变化与共混物性能之间的关系进行了研究。实验结果表明,共混物中ＰＥＴ含量的增加有利于提高该三元共混物的热性能和结晶性能;另外,ＰＢＴ含量的增加则大大提高了共混物的抗冲击能力。     

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。     

聚醚醚酮与酚酞型聚芳醚酮的共混研究

借助DSC、FTIR、PLM(偏光显微镜)、SEM技术研究了聚醚醚酮(PEEK)/酚酞型聚芳醚酮(PEK-C)共混物的相容性特征及结晶行为、结晶形态。结果表明该共混物是部分相容的,其相容程度与共混物的组分比及热历史有关;共混物中PEK-C对PEEK的结晶有阻碍,其阻碍与共混物的组分比及结晶条件有关;共混物的结晶形态对共混组分比有较大的依赖,同时还与结晶温度有关。