马来酸酐/二乙烯基苯接枝聚乳酸对微晶纤维素/聚乳酸复合材料性能的影响

研究了马来酸酐(MAH)/二乙烯基苯(DVB)接枝聚乳酸(PLA-g-DVB/MAH)对微晶纤维素(MCC)/聚乳酸(PLA)复合材料性能的影响。首先采用熔融接枝法,将DVB作为MAH的共聚单体接枝到PLA分子链上制备PLA-g-DVB/MAH接枝聚合物,然后以PLA-g-DVB/MAH为相容剂,采用注射成型法制备MCC/PLA复合材料。利用FTIR对PLA-g-DVB/MAH进行表征,探究了PLA-g-DVB/MAH对MCC/PLA复合材料流变及力学性能的影响。结果表明,MAH成功接枝到PLA上,并得到接枝聚合物PLA-g-DVB/MAH;添加PLA-g-DVB/MAH后,MCC/PLA复合材料的储能模量、复数黏度、平衡扭矩以及剪切热都有明显升高;PLA-g-DVB/MAH的添加有利于改善MCC和PLA的界面相容性,进而提高了MCC/PLA复合材料的力学性能。     

MCC对PLA/PPC复合材料力学性能与热稳定性的影响

以微晶纤维素(MCC)作为改性剂,马来酸酐接枝聚乳酸(PLA g MAH)为界面相容剂,聚乳酸(PLA)、聚碳酸亚丙酯(PPC)为基体,通过熔融共混法制得PLA/PPC/MCC三元复合材料。采用控温拉伸、动态热分析、扫描电子显微镜以及热失重分析等方法研究了MCC对PLA/PPC的力学性能和热稳定性。结果表明,PLA/PPC/MCC三元复合材料的拉伸强度提高了12.7 %,玻璃化转变温度（Tg）提高了9.8 ℃;PLA g MAH的加入可以改善PLA/PPC/MCC三元复合材料的界面性质,从而提高力学性能和热稳定性;当PLA g MAH的添加量为5 %（质量分数,下同）时,三元复合材料在常温下的拉伸强度、弯曲强度和冲击强度分别提高了53.7 %、43.1 %和18.5 %;在60 ℃下三元复合材料的断裂强度提高了80 %;热降解温度以及最大失重温度与PLA/PPC相比分别提高了25.31 ℃和61.83 ℃。     

PLA-g-MAH的制备及其对PLA/PBS复合材料性能影响

在聚乳酸(PLA)与马来酸酐(MAH)熔融过程中添加引发剂过氧化二苯甲酰(BPO),成功制备出MAH接枝的PLA(PLA-g-MAH),研究了PLA-g-MAH作为相容剂对PLA/聚丁二酸丁二醇酯(PBS)/PLA-g-MAH复合材料性能的影响。结果表明:PLA-g-MAH一定程度上改善了PLA/PBS体系的力学性能、热稳定性以及结晶性能;流变结果表明,加入的PLA-g-MAH增强了体系的相容性;扫描电镜(SEM)显示PLA和PBS之间的界面从粗糙变模糊,表明PBS与PLA之间附着力得到增强。     

用于3D打印的微晶纤维素/聚乳酸复合材料制备与性能研究

以微晶纤维素（MCC）为增强材料、聚乳酸（PLA）为基体,通过高温熔融共混、挤出、拉丝等流程,制备适用于熔融沉积成型（FDM）3D打印技术的MCC/PLA复合材料,并通过FDM型3D打印机打印出成品。讨论了MCC添加量对该复合材料的力学性能、热性能、微观结构以及3D打印性能的影响。研究结果表明,随着MCC添加量的增加,复合材料的力学性能呈现先增高后下降的变化趋势,当MCC添加量为3%时,其拉伸强度和弯曲强度达到最高,分别为54.55 MPa和64.25 MPa。红外分析证实了微晶纤维素与聚乳酸在熔融时发生了接枝共聚反应。热性能分析表明,添加少量MCC,可以提高复合材料的热稳定性和PLA的结晶度。MCC添加量为3%的MCC/PLA复合材料其力学性能、打印性能和外观达到最佳,可应用于FDM型3D打印技术。     

马来酸酐接枝聚乳酸增容聚碳酸亚丙酯/聚乳酸共混体系的结构与性能研究

采用熔融接枝技术将马来酸酐(MAH)接枝到聚乳酸(PLA)上,制备不同MAH含量的PLA-g-MAH接枝共聚物,将聚碳酸亚丙酯(PPC)、PLA、PLA-g-MAH熔融共混,制备PPC/PLA/PLA-g-MAH共混物,分析接枝物中MAH含量对PPC/PLA/PLA-g-MAH共混体系的热学性能以及力学性能的影响。结果表明:PLA-g-MAH可以改善PPC与PLA二者的相容性,使PLA在降温过程中更容易结晶。引入接枝物后,共混物的起始分解温度及完全分解温度分别提高30℃和60℃。共混物的力学性能随着接枝物中MAH含量的增加呈现先增加后减小的趋势,当MAH的加入量为3%,共混体系力学性能最佳,冲击断面塑性形变程度更加显著,呈现褶皱状韧性断裂特征,拉伸强度达到42.8 MPa,断裂伸长率为120%左右,同时冲击强度最大。     

纳米SiO_2包覆微晶纤维素对PLA/PBS复合材料性能的影响

以纳米二氧化硅(nano-SiO_2)表面包覆的微晶纤维素(MCC)为填料,采用熔融共混的方法制备了聚乳酸/聚丁二酸丁二醇酯(PLA/PBS)复合材料。运用扫描电子显微镜、热重分析仪、差示扫描量热仪、动态热力学分析仪等方法研究了nano-SiO_2对PLA/PBS/MCC复合材料的力学性能、热稳定性以及结晶行为的影响。结果表明,nano-SiO_2包覆在MCC表面后与PLA/PBS熔融共混提高了nano-SiO_2在聚合物材料中的分散性,改善了MCC与树脂基体的相容性;添加5%(质量分数,下同)MCC的PLA/PBS/MCC复合材料,与同样添加量的PLA/PBS/nano-SiO_2-MCC复合材料相比,其储能模量、冲击强度以及结晶度分别提高了13.04%、11.70%、71.92%。     

纳米SiO2包覆微晶纤维素对PBS/PLA复合材料性能的影响

以纳米二氧化硅(nano-SiO2)表面包覆的微晶纤维素(MCC)为填料,采用熔融共混的方法制备了聚乳酸/聚丁二酸丁二醇酯（PLA/PBS）复合材料。运用扫描电子显微镜、热重分析仪、差示扫描量热仪、动态热力学分析仪等方法研究了nano-SiO2对PLA/PBS/MCC复合材料的力学性能、热稳定性以及结晶行为的影响。结果表明,nano-SiO2包覆在MCC表面后与PLA/PBS熔融共混提高了nano-SiO2在聚合物材料中的分散性,改善了MCC与树脂基体的相容性;添加5 %（质量分数,下同）MCC的PLA/PBS/MCC复合材料,与同样添加量的PLA/PBS/nano-SiO2-MCC复合材料相比,其储能模量、冲击强度以及结晶度分别提高了13.04 %、11.70 %、71.92 %。     

剑麻纤维/聚乳酸复合材料的制备及性能研究

采用蒸馏水、Na OH溶液、干法接枝马来酸酐(MAH)、酰化接枝月桂酸(GML)四种方式处理剑麻纤维(SF),用压制成型法制备纤维/聚乳酸(PLA)复合材料。利用红外光谱表征处理后的剑麻纤维。通过力学性能测试和扫描电镜分析表明,复合材料随着纤维含量的增多、层数增加,冲击强度与拉伸强度明显提高。加入70%的同向交错四层纤维时,SF/PLA复合材料的拉伸强度提高到104.5 MPa、冲击强度提高到135.86 J/m。纤维表面处理可以明显改善复合材料的界面相容性。     

碳酸钙对聚乳酸/酯化纤维素复合材料性能的影响

采用熔融共混工艺制备了聚乳酸(PLA)/酯化纤维素/CaCO3复合材料,通过力学性能测试、热重分析、凝胶渗透色谱和红外光谱分析,研究了CaCO3对复合材料力学性能和热稳定性的影响。结果表明:CaCO3能够与酯化纤维素相互作用,并在一定程度上改善复合材料的力学性能,提高复合材料的热稳定性,减缓PLA的热降解。     

PP-g-(MAH-St)对PP/木粉复合材料力学性能的影响

在聚丙烯中(PP)中添加马来酸酐(MAH)和共单体苯乙烯(St),通过熔融挤出法制备了高接枝率的PP-g-(MAH-St),红外光谱分析证明了St和MAH成功接枝到PP主链上。研究了PP-g-(MAH-St)对PP/木粉复合材料力学性能的影响,并用扫描电镜观察了复合材料冲击断面的微观形貌。结果表明,与现有PP-g-MAH相比,只要添加少量PP-g-(MAH-St)就能有效改善PP/木粉复合材料的界面相容性,从而提高材料的力学性能;PP-g-(MAH-St)中MAH的接枝率对复合材料力学性能影响显著,当MAH接枝率为2.8 %时,能使木塑复合材料力学性能达到最佳。     

Mechanical properties of biodegradable composites from poly lactic acid (PLA) and microcrystalline cellulose (MCC)

Biodegradable composites were prepared using microcrystalline cellulose (MCC) as the reinforcement and polylactic acid (PLA) as a matrix. PLA is polyester of lactic acid and MCC is cellulose derived from high quality wood pulp by acid hydrolysis to remove the amorphous regions. The composites were prepared with different MCC contents, up to 25 wt %, and wood flour (WF) and wood pulp (WP) were used as reference materials. Generally, the MCC/PLA composites showed lower mechanical properties compared to the reference materials. The dynamic mechanical thermal analysis (DMTA) showed that the storage modulus was increased with the addition of MCC. The X‐ray diffraction (XRD) studies on the materials showed that the composites were less crystalline than the pure components. However, the scanning electron microscopy (SEM) study of materials showed that the MCC was remaining as aggregates of crystalline cellulose fibrils, which explains the poor mechanical properties. Furthermore, the fracture surfaces of MCC composites were indicative of poor adhesion between MCC and the PLA matrix. Biodegradation studies in compost soil at 58°C showed that WF composites have better biodegradability compared to WP and MCC composites. The composite performances are expected to improve by separation of the cellulose aggregates to microfibrils and with improved adhesion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2014–2025, 2005     

Synthesis of new compatibilizers to poly(lactic acid) blends

In this study, the effectiveness of three random copolymers based on blocks of poly(lactic acid) and polyethylene (PLA‐PE) used as compatibilizer in PLA and high density polyethylene blends (PLA/HDPE) was evaluated in terms of thermal and mechanical properties. The compatibilizers were synthesized by different ways: reactive extrusion (C1), ring opening polymerization of lactide with PE with —OH substituent group (PE‐OH) as initiator (C2) and polycondensation of lactic acid in presence of PE grafted with maleic anhydride (PE‐g‐MAH) (C3). The compatibilizers were used in two different proportions (5 and 15 wt%) and their efficiency was compared with a commercial compatibilizer (C0). The blends with C2 compatibilizer exhibited the highest tensile toughness (350% of increment compared with neat PLA/PE) because of the morphology attained. However, it was found that a relationship exists between the improvement of the compatibility and the loss of the thermal stability (?28°C) in PLA/HDPE blends. POLYM. ENG. SCI., 54:522–530, 2014. © 2013 Society of Plastics Engineers     

Study on the effect of dispersion phase morphology on porous structure of poly (lactic acid)/poly (ethylene terephthalate glycol-modified) blending foams

A methodology for blending foam of poly (lactic acid) (PLA)/poly (ethylene terephthalate glycol-modified) (PETG) was proposed. PLA/PETG blends were prepared through a melt blending method, using multiple functionality epoxide as reactive compatibilizer. The effects of blending ratio and compatibilizer content on the dispersion morphology, molecular structure, mechanical properties, and rheological behavior of PLA/PETG blends were studied. Then PLA/PETG blends were foamed using supercritical CO₂ as physical blowing agent, and their porous structure, pore size, as well as pore density were investigated. The results showed that the mechanical properties and rheological parameters such as melt strength and melt elasticity, as well as the porous structure of the foams dispersion morphology of PLA/PETG blends were affected strongly. The melt elasticity of PLA/PETG blends increased with increasing compatibilizer content. Dispersion phase morphology of PLA/PETG blends also had a significant effect on the pore density of all the samples. The results indicated that homogeneous and finer porous morphology of PLA/PETG foams with high expansion ratio could be achieved with a proper content of compatibilizer in the blends.     

Effectiveness of the preparation of maleic anhydride grafted poly (lactic acid) by reactive processing for poly (lactic acid)/carbon nanotubes nanocomposites

An effective strategy to increase the properties of poly (lactic acid) (PLA) is the addition of carbon nanotubes (CNT). In this work, aiming to improve the surface adhesion of PLA and CNT a new compatibilizer agent was prepared by reactive processing, PLA grafted maleic anhydride (PLA-g-MA) using benzoyl peroxide and maleic anhydride. The effectiveness of the PLA-g-MA as a compatibilizer agent was verified for PLA/PLA-g-MA/CNT nanocomposites. PLA and PLA-g-MA samples were characterized by Fourier transform infrared spectroscopy (FT-IR) to confirm the grafting reaction of maleic anhydride on PLA chains and by rheological analysis to prove the changes in the matrix PLA after the graphitization reaction. Thermal (differential scanning calorimetry and thermogravimetric analysis), mechanical tests (Izod impact strength and tensile test), and morphological characterization were used to verify the effect of the compatibilizer agent. The preparation of PLA-g-MA by reactive extrusion processing proved satisfactory and the nanocomposites presented good thermal and mechanical properties. The addition of the PLA-g-MA also contributed to the greater distribution of CNT and can be used as an alternative for the production of PLA/CNT nanocomposites.     

Preparation of acylated microcrystalline cellulose using olive oil and its reinforcing effect on poly(lactic acid) films for packaging application

A novel poly(lactic acid) (PLA) based composite, reinforced by microcrystalline cellulose (MCC) was prepared. MCC was modified by esterification reaction using olive oil for improving the compatibility with PLA matrix. The acylated microcrystalline cellulose (AMCC) exhibited reduced polarity in comparison to unmodified MCC. AMCC/ PLA composite films were prepared using solvent casting technique. The effects of the MCC surface modification on morphological, mechanical, physical, thermal, biodegradability and barrier properties of the PLA based MCC composites were studied. FTIR analysis confirmed acylation reaction of MCC. Scanning electron microscopy analysis exhibited a uniform distribution of AMCC in PLA matrix. Barrier properties of AMCC based composites were improved as compared to MCC based composites. The tensile strength and tensile modulus of composite films (at 2 wt.% AMCC) were improved about 13% and 35% as much as those of the pure PLA films, respectively. These biodegradable composite films can be a sustainable utilization of olive oil and microcrystalline cellulose in the food packaging application.     

Toughness improvement of poly(lactic acid) with poly(vinyl propionate)-grafted natural rubber

Natural rubber (NR) grafted with poly(vinyl propionate) (NR-g-PVP) was prepared by emulsion polymerization. The monomer content was set at 5, 10, 20, and 30 wt%. The chemical structure of NR-g-PVP was confirmed by ¹H-NMR and FTIR techniques. The grafting parameters of purified NR-g-PVP were evaluated. Binary (PLA/NR and PLA/NR-g-PVP) and ternary (PLA/NR/NR-g-PVP) blends were prepared by melt blending using a twin-screw extruder. The percentage of grafted PVP on NR affected morphology, thermal and mechanical properties of the blends. In binary blends, 5% grafting showed the greatest improvement of toughness and ductility with PLA, whereas there was no improvement in the mechanical properties of PLA/NR blend from using NR-g-PVP as a compatibilizer. The mechanical properties of the blends are related to mutual compatibility of the components. Good interfacial adhesion and proper particle size of NR were the key factors contributing to mechanical properties.     

The synthesis of poly (lactic acid)-fulvic acid graft polymer and its effect on the crystallization and performance of poly (lactic acid)

ABSTRACT

The poly (lactic acid)-fulvic acid graft polymer (PLA-FA) was synthesized with lactic acid and fulvic acid (FA). The optimum parameters were determined by orthogonal experiment. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy exhibited that FA was successfully grafted onto PLA. Then, PLA/PLA-FA composites were prepared with PLA-FA as fillers by melt blending. The structure characterization and performance tests demonstrated that PLA-FA effectively enhanced the comprehensive performance of PLA composites. The rheological analysis demonstrated that PLA-FA had plasticization effect. The non-isothermal crystallization kinetics demonstrated that PLA-FA promoted the crystallization rate of PLA composites, improving toughness of PLA composites.     

Using maleic anhydride grafted poly(lactic acid) as a compatibilizer in poly(lactic acid)/layered‐silicate nanocomposites

The goal of this work was to prepare exfoliated poly(lactic acid) (PLA)/layered‐silicate nanocomposites with maleic anhydride grafted poly(lactic acid) (PLA–MA) as a compatibilizer. Two different layered silicates were used in the study: bentonite and hectorite. The nanocomposites were prepared by the incorporation of each layered silicate (5 wt %) into PLA via solution casting. X‐ray diffraction of the prepared nanocomposites indicated exfoliation of the silicates. However, micrographs from transmission electron microscopy showed the presence of intercalated and partially exfoliated areas. Tensile testing showed improvements in both the tensile modulus and yield strength for all the prepared nanocomposites. The results from the dynamic mechanical thermal analysis showed an improvement in the storage modulus over the entire temperature range for both layered silicates together with a shift in the tan δ peak to higher temperatures. The effect of using PLA–MA differed between the two layered silicates because of a difference in the organic treatment. The bentonite layered silicate showed a more distinct improvement in exfoliation and an increase in the mechanical properties because of the addition of PLA–MA in comparison with the hectorite layered silicate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1852–1862, 2006     

Borassus powder-reinforced poly(lactic acid) composites with improved crystallization and mechanical properties

This article reports on the development of biocomposites based on polylactic acid (PLA) and borassus powder. Borassus powder was treated with alkali to remove hemicelluloses and lignin. The treated borassus improved the homogeneous mixing with PLA and increased the crystallinity of PLA. Dispersibility of the borassus was studied by scanning electron microscopy (SEM) and X-ray MicroCT. PLA/borassus composites were prepared by melt mixing of PLA with 5, 10, and 15 wt % treated/untreated borassus. Composites were examined for mechanical properties and crystallization. Composites showed enhanced tensile strength compared to neat PLA. The PLA/treated borassus powder composites displayed higher crystallinity than PLA. The isothermal cold crystallization study showed increase in the crystallization rate of PLA in the presence of treated borassus. The spherulitic growth was studied using polarized optical microscopy. The enhanced performance of the PLA-borassus composites was observed in the presence of borassus. This study demonstrates that the PLA-borassus composites show great promise for bioplastics applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47440.     

聚乳酸/竹粉复合材料的改性及性能研究

采用甲基丙烯酸缩水甘油酯接枝乙烯辛烯共聚物（POE?GMA）作为相容剂，TPW604作为润滑剂，利用XSS?300转矩流变仪熔融制备聚乳酸（PLA）/竹粉（BF）复合材料。通过热失重、拉伸、冲击 、扫描电子显微镜、旋转流变等方法研究BF、POE?GMA、TPW604添加量对PLA/BF复合材料性能的影响。结果表明，当BF添加量为35 %、POE?GMA添加量为10 %、TPW604添加量为1 %时，复合材料的相容性和流动性均显著提升，复合材料的力学性能达到最优。