PLA/Lyocell纤维复合材料结构与性能研究

以聚乳酸(PLA)为基体,新型纤维素纤维Lyocell纤维为增强材料,通过熔融共混及注塑成型制备了PLA/Lyocell纤维可生物降解复合材料,并采用扫描电镜(SEM)、力学性能测试、差示扫描量热法(DSC)和维卡软化温度测试等手段,探讨了Lyocell纤维含量对复合材料结构和性能的影响。结果表明:随着Lyocell纤维含量的增加,PLA/Lyocell纤维复合材料的结晶度、弯曲模量和维卡软化温度均随之提高,而拉伸强度和冲击强度则呈现先上升后下降的趋势。其中当Lyocell纤维含量达到6%时,其在复合材料中的分布较为均匀,所对应复合材料的力学性能相对较好,其拉伸强度、缺口冲击强度和弯曲模量比纯PLA分别提高了15.3%、12.3%和13.0%。     

ABS/MMT纳米复合材料的制备及性能的研究

文章采用丙烯腈-丁二烯-苯乙烯(ABS)/氨基蒙脱土(MMT)进行熔融共混得到不同含量MMT的ABS/MMT纳米复合材料。用扫描电子显微镜、拉伸试验机、冲击试验机研究ABS/MMT的力学性能及断面结构。结果得出:在ABS/MMT纳米复合材料中,随着MMT含量的增加,ABS/MMT复合材料的拉伸强度呈先上升后下降,且当MMT含量在3份时性能较好,缺口冲击强度呈线性下降趋势。ABS/MMT冲击断面中,出现了许多网孔结构,橡胶粒子被蒙脱土的的片层包裹着,不能发生塑性变形,其为ABS/MMT复合材料缺口冲击强度降低的主要原因之一。     

聚丙烯-蒙脱土纳米复合材料性能的研究

采用熔融插层法制备了聚丙烯-蒙脱土纳米复合材料,并对复合材料的力学性能及晶形结构进行研究.结果表明:添加少量的纳米蒙脱土(<5%,质量分数),能够明显改善PP/MMT纳米复合材料的力学性能,当其质量分数达到4%～5%时,复合材料的冲击强度、断裂伸长率、拉伸强度及弹性模量均达最佳值.同时,随着蒙脱土含量的增加,聚丙烯的晶形结构会发生转变,其晶体尺寸呈不断减小趋势.     

PP/OMMT纳米复合材料制备技术研究

对潍坊某地的膨润土(MMT)原料进行提纯、用碳酸钠作为钠化剂进行钠化改型及有机改性,制备出与聚合物相容性较好的有机膨润土(OMMT),将之与聚丙烯(PP)复合制备出PP/OMMT纳米复合材料。重点研究了不同改性剂对MMT层间距的影响以及OMMT用量对复合材料力学性能的影响。结果表明:在十八烷基苄基二甲基溴化铵(1827)和己内酰胺复合改性剂的作用下,MMT的层间距扩大到2.44 nm;在一定范围内,随着OMMT用量的增加,PP/OMMT纳米复合材料的冲击强度和拉伸强度呈现先提高再降低的趋势,OMMT用量为2%时,复合材料的缺口冲击强度达到6.65 kJ/m2,拉伸强度达到24.53 MPa。     

聚乳酸/聚烯烃弹性体/蒙脱土复合材料的制备与性能研究

以聚乳酸(PLA)为基材,在聚烯烃弹性体(POE)的增塑作用下,搀杂不同比例的蒙脱土(MMT),采用熔融共混法,制备出一系列的PLA/POE/MMT复合材料。通过拉伸及冲击测试、差热扫描量热仪(DSC)、熔指仪对复合材料的力学性能、热性能和流动性能进行表征。结果表明:随着MMT的加入,PLA/POE/MMT复合材料的拉伸性能和冲击性能总体上比纯PLA差,复合材料的玻璃化转变温度(Tg)和熔点(Tm)总体上比纯PLA要低,只有当MMT含量为1 wt.%时,才使PLA体系的冲击强度有所提高,Tg和Tm有所提高。随着MMT的加入,PLA体系的流动性变好。     

聚丙烯/BA原位聚合改性MMT纳米复合材料的DSC分析与力学性能

通过原位聚合制备了聚丙烯酸丁酯 (PBA )改性蒙脱土 (MMT ) ,与聚丙烯 (PP)熔融复合制成PP/MMT纳米复合材料 ,系统地研究了复合材料的熔融、结晶行为和力学性能。结果表明 :随着处理MMT的BA用量的增加 ,PP/MMT纳米复合材料中PP相的结晶度、熔点和结晶温度明显提高 ,结晶速度加快 ;复合材料的拉伸强度变化不大 ,但拉伸模量和冲击强度有显著提高。当BA/OMMT质量比为 1/ 12左右时 ,复合材料的韧性趋于平衡值 ,而拉伸模量出现最大值     

3D打印用聚乳酸/松木粉/纳米二氧化硅木塑复合材料性能研究

以化学改性松木粉(PWF)为增强材料、聚乳酸(PLA)为基体,同时添加少量纳米二氧化硅(nano-SiO_2),通过熔融挤出制备了适用于熔融沉积成型(FDM)3D打印技术的木塑复合材料,并对该木塑复合材料的力学性能和3D打印性能进行了研究。结果表明:添加nano-SiO_2可以显著提高木塑复合材料的力学性能,随着nanoSiO_2用量的增加,PLA/PWF/nano-SiO_2木塑复合材料的各项力学性能均呈现逐渐上升的趋势,且在nanoSiO_2用量为5%时达到最佳。PWF用量对PLA/PWF/nano-SiO_2木塑复合材料各项力学性能的影响呈现先上升后下降的趋势,且材料性能在PWF用量为15%时达到最佳,此时弯曲强度为101.6 MPa、弯曲模量为4 652 MPa、拉伸强度为92.81 MPa、拉伸模量为3 845 MPa、冲击强度为4.31 kJ/m~2,相对于PLA/PWF木塑复合材料均提高了50%以上。该PLA/PWF/nano-SiO_2木塑复合材料可应用于FDM型3D打印,具有良好的打印性能。     

凹凸棒石/聚乳酸纳米复合材料的力学性能和流变性能

采用熔融共混法制备凹凸棒石(ATT)质量分数分别为1%、3%和5%的ATT/聚乳酸(PLA)纳米复合材料,研究了ATT/PLA纳米复合材料的力学性能和流变性能。红外光谱分析结果表明:ATT与PLA基体之间存在较强的相互作用,使得二者之间具有较好的相容性。当ATT含量低于5%时,其可均匀分散在PLA基体中,而达到5%时,则会发生部分团聚。添加ATT后,PLA基体从脆性材料变为韧性材料,ATT起到增韧作用,并显著提高了复合材料的力学性能。当ATT含量为3%时,断裂伸长率达到26.36%,比纯PLA增加了297.6%,并且复合材料的冲击强度也比纯PLA增加了19.7%。ATT/PLA纳米复合材料的复数黏度、储能模量和损耗模量随ATT含量的增加呈先增大后减小趋势。由于ATT与PLA之间有良好的结合力,ATT的加入增大了复合材料的弹性和黏性,且低频区的变化明显高于高频区的变化。     

PLA协同纳米CaCO3增韧PP的研究

通过熔融共混制得聚丙烯/聚乳酸/纳米碳酸钙（PP/PLA/CaCO3）复合材料,考察了PLA和纳米CaCO3对复合材料力学性能、热性能、流变性能与结晶形态的影响及其作用机理。结果表明,复合材料中形成连续空间网络结构的PLA有助于改善PP的性能,PLA含量为20 %（质量分数,下同）时复合材料综合力学性能最佳;与纯PP相比,加入PLA后的复合材料拉伸强度和冲击强度分别提高5.1 %和54.4 %,断裂伸长率降低62.5 %;纳米CaCO3通过“滚珠增韧”和“异相成核”作用明显改善复合材料力学性能,纳米CaCO3含量15 %时产生的晶粒细化作用效果最为显著,复合材料综合力学性能达到最佳,拉伸强度、断裂伸长率和冲击强度分别比未添加CaCO3时提升了15.2 %、2.7 %和5.6 %。     

聚氯乙烯/蒙脱土纳米复合材料的研究

采用熔融插层法制备了聚氯乙烯(PVC) /蒙脱土(MMT)纳米复合材料并进行了表征,研究了PVC/MMT纳米复合材料的力学性能。结果表明:PVC进入到有机MMT的片层间形成了纳米复合材料,但PVC不能进入钠基MMT的片层间,形成纳米复合材料;蒙脱土的加入提高了PVC的力学性能,而且PVC/有机MMT纳米复合材料的拉伸和冲击强度总是优于PVC/钠基MMT复合材料;对PVC/有机MMT纳米复合材料而言,复合材料的V型缺口冲击比U型缺口冲击敏感,其力学性能随热处理时间延长而降低,但PVC/有机MMT复合材料比PVC/钠基MMT的抗热性好。     

Effects of thermoplastic poly(ether-ester) elastomer and bentonite nanoclay on properties of poly(lactic acid)

This work presented the influence of thermoplastic poly(ether-ester) elastomer (TPEE) and bentonite (BTN) on improving the mechanical and thermal properties of poly(lactic acid) (PLA). PLA was initially melt mixed with TPEE at six different loadings (5–30 wt%) on a twin screw extruder and then injection molded. The mechanical tests revealed an increasing impact strength and elongation at break with increasing TPEE loading, but a diminishing Young's modulus and tensile strength with respect to pure PLA. The blend at 30 wt% TPEE provided the optimum improvement in toughness, exhibiting an increase in the impact strength and elongation at break by 3.21- and 10.62-fold over those of the pure PLA, respectively. Scanning electron microscopy analysis illustrated a ductile fractured surface of the blends with the small dispersed TPEE domains in PLA matrix, indicating their immiscibility. The 70/30 (wt/wt) PLA/TPEE blend was subsequently filled with three loadings of BTN (1, 3, and 5 parts by weight per hundred of blend resin [phr]), where the impact strength, Young's modulus, tensile strength and thermal stability of all the blends were improved, while the elongation at break was deteriorated. Among the three nanocomposites, that with 1 phr BTN formed exfoliated structure and so exhibited the highest impact strength, elongation at break, and tensile strength compared to the other intercalated nanocomposites. Moreover, the addition of BTN was found to increase the thermal stability of the neat PLA/TPEE blend due to the barrier properties and high thermal stability of BTN.     

异氰酸酯对聚乳酸/热塑性聚氨酯共混物性能的影响

以4,4^′-二苯基甲烷二异氰酸酯（MDI）为反应增容剂，采用熔融共混法制备了不同MDI含量的聚乳酸/热塑性聚氨酯（PLA/TPU）共混物，采用傅里叶变换红外光谱仪（FTIR）、万能试验机、冲击试验机、扫描电子显微镜（SEM）、差示扫描量热仪（DSC）和旋转流变仪对共混物力学性能、微观形态、热性能和流变性能进行了研究。结果表明：MDI可以有效改善共混物的力学性能，当MDI质量分数为1%时，共混物力学性能最佳，缺口冲击强度为40.0kJ/m²，断裂伸长率为214.1%，与未加MDI的共混物相比，分别增加了4.3倍和5.8倍，拉伸强度稍有下降（47.6MPa）；SEM表明，MDI的加入提高了共混物的相容性，加入MDI后，共混物的断面由海-岛结构变为核-壳包覆结构，相界面作用力增强；DSC测试表明，共混物的玻璃化转变温度、冷结晶温度和熔融温度随着MDI含量的增加而升高；流变测试表明，MDI质量分数的增加，共混物呈现更显著的剪切变稀行为，推测共混反应机理为：MDI质量分数的增加，体系内依次发生PLA的扩链、支化和TPU的交联。     

Toughening of polylactide with epoxy-functionalized methyl methacrylate–butyl acrylate copolymer

Glycidyl methacrylate-functionalized methyl methacrylate–butyl acrylate (GACR) core–shell structure copolymers were synthesized to toughen polylactide (PLA). With an increase in GACR content, the PLA/GACR blends showed decreased tensile strength and modulus; however, the elongation at break and the impact strength were significantly increased compared with that of PLA. The brittle fracture of neat PLA was gradually transformed into ductile fracture by the addiction of GACR. From dynamic mechanical analysis, the rigidity of the PLA/GACR blends was decreased with the increase of GACR content. The addition of GACR decreased the degree of crystallinity of PLA. The GACR was found to aggregate to form clusters with size increasing with increasing GACR content by transmission electron microscope analysis. The clusters dispersed in PLA matrix uniformly. It was found that PLA demonstrated large area, plastic deformation (shear yielding) and cavities in the blend upon being subjected the tensile and impact tests, which was an important energy-dissipation process and led to a toughened and transparent blend.     

Effect of clay modification on the morphological,mechanical, and thermal properties of polyamide 6/polypropylene/montmorillonite nanocomposites

Polyamide 6/polypropylene (PA6/PP = 70/30 parts) blends containing 4 phr (parts per hundred resin) of organophilic montmorillonite (OMMT) were prepared by melt compounding. The sodium montmorillonite (Na‐MMT) was modified using three different types of alkyl ammonium salts, namely dodecylamine, 12‐aminolauric acid, and stearylamine. The effect of clay modification on the morphological and mechanical properties of PA6/PP nanocomposites was investigated using x‐ray diffraction (XRD), transmission electron microscopy (TEM), tensile, flexural, and impact tests. The thermal properties of PA6/PP nanocomposites were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and heat distortion temperature (HDT). XRD and TEM results indicated the formation of exfoliated structure for the PA6/PP nanocomposites prepared using stearylamine modified montmorillonite. On the other hand, a mixture of intercalated and exfoliated structures was found for the PA6/PP nanocomposites prepared using 12‐aminolauric acid and dodecylamine modified montmorillonite. Incorporation of OMMT increased the stiffness but decreased the ductility and toughness of PA6/PP blend. The PA6/PP nanocomposite containing stearylamine modified montmorillonite showed the highest tensile, flexural, and thermal properties among all nanocomposites. This could be attributed to better exfoliated structure in the PA6/PP nanocomposite containing stearylamine modified montmorillonite. The storage modulus and HDT of PA6/PP blend were increased significantly with the incorporation of both Na‐MMT and OMMT. The highest value in both storage modulus and HDT was found in the PA6/PP nanocomposite containing stearylamine modified montmorillonite due to its better exfoliated structure. POLYM. COMPOS., 31:1156–1167, 2010. © 2009 Society of Plastics Engineers     

Preparation and characterization of poly(lactic acid)/recycled polypropylene blends with and without the coupling agent,n-(6-aminohexyl)aminomethyltriethoxysilane

Blends of polylactide (PLA) and recycled polypropylene (rPP) were prepared by melt-processing using a corotating twin-screw extruder and subsequent pelletizing of the extrudates for injection molding. The PLA/rPP blends were characterized by Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), rheometer (MCR-102), scanning electron microscopy(SEM), tensile tests, and impact measurements. The results indicate that the PLA/rPP blend is immiscible and has a two-phase structure. TGA revealed enhancement of the thermal stability of the blends upon addition of rPP. The storage modulus, loss modulus, and complex viscosity of the blends increased with rPP concentration. Mechanical studies showed that introduction of rPP results in a decrease in tensile strength and modulus and enhancement of the impact strength of PLA in the blends. The effects of a silane coupling agent on the morphology and on the tensile and impact properties of the rPP blends of silane-modified PLA were also examined. SEM studies suggest that silane is an effective interfacial modifier. Thus, better interfacial adhesion was observed with silane-modified blends as compared with unmodified blends. Silane also improved the mechanical properties of the modified blends. The blends reached maximum tensile strength at 1.5 wt.% silane (relative to modified PLA content), and impact strength increased with increasing silane concentration. These results confirm the enhancing effect of silane on modified PLA/rPP blends.     

Comparison of polylactide/nano-sized calcium carbonate and polylactide/montmorillonite composites: Reinforcing effects and toughening mechanisms

Semicrystalline polylactide (PLA) exhibits high tensile strength and modulus but very low strain-at-break and toughness. In this study, PLA nanocomposites with nano-sized precipitated calcium carbonate (NPCC) and organically modified montmorillonite (MMT) clay were prepared by melt extrusion. Morphologies, tensile mechanical properties, dynamic mechanical and rheological properties, polymer–nanoparticle interactions, and toughening mechanisms of the PLA/NPCC and PLA/MMT nanocomposites were compared. MMT and NPCC showed significantly different effects on the strength, modulus and elongation of the PLA nanocomposites. Different toughening mechanisms were first elucidated for the two types of nanocomposites based on the evidence from both macroscopic and microscopic observations. Under uniaxial tension, large quantities of microvoids were created in both PLA nanocomposites. The microvoids in PLA/NPCC caused massive crazing, while in PLA/MMT they resulted in shear yielding, particularly in the nanocomposite with 2.5 wt% MMT. The MMT stacks and platelets were found to be located between the microvoids in the extended specimens and prevented them from collapsing and coalescing.     

聚乳酸／醋酸淀粉共混物性能形态研究

采用双螺杆挤出机制备聚乳酸（PLA）／醋酸淀粉（AS）复合材料,研究不同螺杆结构和加工次数对复合材料流变-性能-形态的影响。测试结果表明：通过螺杆Ⅱ、二次挤出后的复合材料的力学性能最优,As含量为60％的复合材料拉伸强度达到27．91MPa。动态流变和SEM的结果表明采用螺杆Ⅱ可以提高PLA与As的共混效果。本文也考察了AS含量对复合材料的力学性能和动态流变性能的影响,结果表明当AS质量含量从45％提高到70％时,复合材料的拉伸强度从36．7MPa降低到16．4MPa;其复数黏度和储能模量则随着AS含量的增加而增加。     

MMT的有机改性及其在PLA中的应用

介绍了蒙脱土（MMT）的一次有机改性和二次有机改性方法,并重点介绍了其在聚乳酸（PLA）中的应用。二次改性能有效改善有机改性蒙脱土（OMMT）在PLA中的分散状况,使之尽可能多地形成剥离结构;在性能改善方面,OMMT的添加能有效改善PLA的结晶性能、拉伸模量和冲击强度、热稳定性、阻透性能以及流变性能等。     

丙烯酸酯接枝改性天然橡胶增韧聚乳酸

通过在天然橡胶(NR)分子链上接枝甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA),制备了三种丙烯酸酯接枝改性NR:NR-g-PMMA,NR-g-PBA和NR-g-(PMMA,PBA)。采用核磁共振氢谱对三种接枝物进行了化学结构鉴定。将接枝改性后的NR和未改性的NR与PLA采用哈克密炼机熔融共混,分别制备了PLA/NR,PLA/NR-gPMMA,PLA/NR-g-PBA和PLA/NR-g-(PMMA,PBA)共混物,研究了接枝改性NR和未改性NR含量对共混物力学性能和热性能的影响。各共混物的拉伸弹性模量和拉伸强度均随接枝改性NR和未改性NR含量的增加而降低,断裂伸长率和缺口冲击强度随接枝改性NR和未改性NR含量的增加而提高。其中,PLA/NR-g-PBA共混物的断裂伸长率和缺口冲击强度比其它共混物提高的幅度大,当NR-g-PBA的质量分数为5%时,PLA/NR-g-PBA共混物的断裂伸长率达到78%,缺口冲击强度为5.2 k J/m2,而纯PLA的断裂伸长率仅为7.7%,缺口冲击强度为2.5 k J/m2,说明NR接枝分子柔顺性较高的BA更有利于促进其与PLA共混物的韧性提高。热分析结果表明,PLA/NR-gPBA共混物的热稳定性相比于纯PLA也有所提高。     

Blends of polyacetal and ethylene-octene elastomer: Mechanical,dynamic mechanical and morphological properties

Polyacetal (POM) and ethylene octene copolymer(EOC) elastomers form immiscible blends with extremely low compatibility. In order to improve the dispersion, stability and properties of these blends, dynamic vulcanization was carried out in a twin screw extruder using dicumyl peroxide. The tensile strength decreased with increase in % elongation at break for both blend systems. There was a drastic decrease in impact strength for unvulcanized blends as the elastomer content increased and this was attributed to the coalescence of the elastomer particles as their content increased. In the case of dynamically vulcanized blends there was a significant increase in impact strength as the levels of elastomer increased. Dynamic mechanical analysis has been carried out to investigate the effect of blend composition and dynamic vulcanization on dynamic mechanical parameters such as storage modulus, loss modulus and loss factor. The results indicate gross incompatibility of POM and EOC blends. However, dynamically vulcanized blends show better adhesion between component polymers. The morphological studies reveal that the particle size and coalescence of elastomer was significantly reduced in comparison to unvulcanized bends. The phase adhesion was improved by dynamic vulcanization. Hence, it was observed that dynamic vulcanization effectively improves the morphology of the blend system and enhances the properties of polyacetal.