Synthesis of poly(butyl acrylate)—laponite nanocomposite nanoparticles for improving the impact strength of poly(lactic acid)

This work aims at preparing and characterizing poly(butyl acrylate) (PBA)—laponite (LRD) nanocomposite nanoparticles and nanocomposite core (PBA‐LRD)‐shell poly(methyl methacrylate) (PMMA) nanoparticles, on the one hand, and the morphology and properties of poly(lactic acid) (PLA)‐based blends containing PBA‐LRD nanocomposite nanoparticles or (PBA‐LRD)/PMMA core–shell nanoparticles as the dispersed phase, on the other hand. The PBA and (PBA‐LRD)/PMMA nanoparticles were synthesized by miniemulsion or emulsion polymerization using LRD platelets modified by 3‐methacryloxypropyltrimethoxysilane (MPTMS). The grafting of MPTMS onto the LRD surfaces was characterized qualitatively using FTIR and quantitatively using thermogravimetric analysis (TGA). The amounts of LRD in the PBA‐LRD nanocomposites were characterized by TGA. The PBA/PMMA core–shell particles were analyzed by ¹H‐NMR. Their morphology was confirmed by SEM and TEM. Mechanical properties of (PBA‐LRD)/PLA blends and (PBA‐LRD)/PMMA/PLA ones were tested and compared with those of the pure PLA, showing that core–shell particles allowed increasing impact strength of the PLA while minimizing loss in Young modulus and tensile strength. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Properties of silanized nypa fruticans filled polylactic acid/recycled low density polyethylene biocomposites

The biocomposites of Nypa Fruticans (NF) and Polylactic acid (PLA)/recycled low density polyethylene (rLDPE) were prepared using Brabender EC PLUS. The effect of NF content and silane coupling agent on mechanical, thermal, and morphological properties were studied. The results show that addition of NF in PLA/rLDPE biocomposites have decreased the tensile strength, elongation at break, and crystallinity of biocomposites. The Young's modulus of biocomposites and thermal stability increased with the increasing NF content. The surface of NF fillers were silanized to improved the interfacial adhesion between the NF filler and PLA/rLDPE matrix. It was found that the tensile strength, Young's modulus, crystallinity of PLA, and thermal stability of silanized biocomposites higher as compared to untreated biocomposites. The enhancement of the properties of biocomposites with silane treatment was proven by SEM studied. The silanized biocomposites showed better interfacial interaction and adhesion between NF and PLA/rLDPE matrix. POLYM. ENG. SCI., 55:1733–1740, 2015. © 2014 Society of Plastics Engineers     

Influence of functionalized reduced graphene oxide and compatibilizer on mechanical,thermal and morphological properties of polypropylene/polybutene-1 (PP/PB-1) blends

Polypropylene/Polybutene-1 (PP/PB-1) blends and nanocomposites containing pristine partially reduced graphene oxide (rGO) and chemically functionalized rGO (FrGO) with silane, and silane grafted with 1,12-dodecanediamine and 1,12-dodecanediol were studied. The effects of the chemical treatments on structure and thermal stability of rGO were first thoroughly investigated. Attenuated total reflectance Fourier infrared (ATR-FTIR) spectroscopy analyses of FrGO evidenced the existence of functional groups on rGO after each chemical treatment, while X-ray diffraction (XRD) results confirmed the effectiveness of the interlayer grafting process through shifting of the basal spacings as witnessed by increased d₀₀₂ values. Furthermore, thermogravimetric analysis (TGA) revealed that the functionalization of rGO resulted in improved thermal stability of rGO demonstrated by its increased thermal degradation temperature. The PP/PB-1 blends and their rGO and FrGO based nanocomposites were prepared by melt blending masterbatch process in the presence of an acrylic acid modified polypropylene compatibilizer (PP-g-AA). Mechanical testing showed that Young’s modulus and tensile strength of the PP/PB-1 blends significantly improved after co-addition of FrGO and PP-g-AA to form the nanocomposites, but it also endowed a drastic decrease in their elongation at break and especially in their impact strength. XRD analyses attested the successful formation of intercalated nanocomposites, and scanning electron microscopy (SEM) examinations disclosed a two-phase morphology consisting of PB-1 dispersed droplets in the PP matrix. SEM also indicated that the incorporation of PP-g-AA into the blends and the nanocomposites contributed to enhanced adhesion and dispersion of PB-1 phase and FrGO nanoparticles within the polymer matrix.     

High-performance poly(lactic acid)/starch materials prepared via starch surface modification and its in situ enhancement

High-performance modified poly(lactic acid) (PLA)/starch (ST) blends were prepared by incorporating silane coupling agent. The coupling agent acted as a bridge between PLA and ST components, enhancing their interfacial compatibility during the melt blending. The addition of epoxy-functionalized silane coupling agent improved the interfacial adhesion between PLA and ST phases, as evidenced by the decreased number and spacing of gaps between the ST particles and PLA matrix. The coupling agent also filled the surface crack of the ST particles, improving their dispersion in PLA matrix. The tensile strength of the modified PLA/ST blend increased from 19.6 MPa for the neat PLA/ST blend to 53.4 MPa, exceeding that of neat PLA. The modified blend also showed improved hydrophobicity and thermal stability. This research presented an effective approach to reducing the cost of PLA-based materials and improving the performance of ST-filled PLA materials by enhancing the interfacial adhesion between ST and PLA through surface modification with silane coupling agent. It provided a simple and feasible strategy for the high-performance modification of polyester/ST materials.     

聚己内酯对聚乳酸/PBAT共混物增容作用的研究

研究了聚己内酯(PCL)作为增容剂对聚乳酸(PLA)与聚己二酸-对苯二甲酸丁二酯(PBAT)的共混物力学性能、热性能、动态力学性能和相容性的影响。结果表明,加入PCL可以改善PLA与PBAT的相容性,提高共混物的冲击强度、拉伸强度和拉伸弹性模量;在PCL含量为2份时共混物两相之间具有良好的相容性。     

Thermal,mechanical, and morphological properties of polylactic acid toughened with an impact modifier

Polylactic acid (PLA) was melt‐blended with different amount (0 to 50 wt %) of a commercially available ethylene acrylate copolymer impact modifier. PLA/impact modifier blends were prepared via an internal mixer and compression molded into test specimens. The thermal, mechanical, and morphological properties of the blends were investigated. The addition of impact modifier decreased the ability of PLA to crystallize and/or recrystallize. The degree of crystallinity of PLA decreased while the cold crystallization temperature shifted to higher temperatures with increasing the impact modifier content. PLA/impact modifier blends were partially miscible. This was confirmed by the dynamic mechanical analysis (DMA) tests. With increasing the impact modifier content, the blends showed some improvement in the elongation at break and notched impact strength indicating the toughening effects of the impact modifier. In contrast, the yield stress and tensile modulus decreased with the increase in the impact modifier content. Scanning electron microscopy (SEM) micrographs revealed that the toughening mechanisms among others involved shear yielding or plastic deformation of the PLA matrix induced by interfacial debonding between the PLA and the impact modifier domains. PLA with 30 wt % impact modifier showed comparable yield stress and tensile modulus and better elongation at break and impact strength (+90%) than those of polypropylene (PP). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123:2715–2725, 2012     

Morphology and property changes in PLA/PHBV blends as function of blend composition

PLA/PHBV blends were prepared by melt mixing. The morphology and physical properties of the blends and neat polymers were investigated. Scanning electron microscopy (SEM) studies provided evidence of interfacial cavities and weak interfacial interaction between the two polymers, and no obvious co-continuous morphology was observed in any of the investigated blends. Positron annihilation lifetime spectroscopy (PALS) indicated the presence of open-volume cavities with sub-nanometre diameters; far smaller than observed from the SEM images. The mean size and relative concentration of these cavities increased with increasing PHBV content. A weak negative deviation in the mean size for low PHBV content possibly indicates some degree of partial miscibility. The glass transition temperature of PLA in the blends decreased with increasing PHBV content, and offers support to some PHBV being miscible with the PLA. The degree of crystallinity in the blends show interesting behaviour that may be explained in terms of the complex morphology observed for these blends. The thermal conductivity of the samples varied with composition, but increased with increasing PHBV content, which was probably related to the increasing crystallinity. Both the tensile strength and Young’s modulus decreased with increasing PHBV content for the sequence of blends, and both parameters exhibited maximum values for 10 wt.% PHBV. For samples between 50/50 and 10/90 PLA/PHBV the tensile strength and Young’s modulus were comparable to or lower than those for both the neat polymers.     

Reactive compatibilization of PLA/PBS bio-blends via a new generation of hybrid nanoparticles

Poly(butylene succinate) (PBS) is a worthy biodegradable thermoplastic polyester for blending along with other biopolymers, especially with poly (lactic acid) (PLA), to overcome its inadequacies in mechanical and thermal characteristics. Since binary blends of PLA and PBS showed that they are incompatible, compatibilization is required. In this work, multi-epoxide polyhedral oligomeric silsesquioxane (Glycidyl POSS) was added to PLA and PBS using the melt blending method to make them compatible. The blends were prepared at different weight ratios having different amounts of compatibilizer. SEM analysis showed that the Glycidyl POSS impacted the interfacial adhesion and other properties of PLA and PBS blends. Noticeable improvements in mechanical properties were revealed by tensile and impact test results. Tensile strength and Young's modulus were improved when epoxy-POSS was added up to 1 and 3 wt% into ternary blends, but further increasing POSS concentrations resulted in lower values. FTIR analysis showed a strong interaction between the epoxide group of POSS and the end groups of PBS or PLA. The thermal properties of samples were analyzed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The shifts in glass transition temperatures of the PLA phase towards lower values appeared in DSC, confirming the enhanced compatibility of PLA and PBS. Also, the reinforcing ability of the POSS inorganic core structure impacted the thermal stability of the blends.     

抗氧剂1010对3D打印用聚乳酸氧化降解性能的影响

为研究抗氧剂1010(KY1010)对3D打印用聚乳酸(PLA)氧化降解性能的影响,以PLA和KY1010为原料,通过挤出成型工艺制得3D打印用PLA丝材,并采用FDM工艺制备复合材料,研究KY1010添加量对PLA丝材拉伸性能、动态热机械性能、氧化诱导期以及复合材料力学性能的影响.结果表明,KY1010可有效改善PL...     

Structural, morphological and mechanical characteristics of polyethylene, poly(lactic acid) and poly(ethylene-co-glycidyl methacrylate) blends

In this work, uncompatibilized and compatibilized blends of low density polyethylene (LDPE) and poly(lactic acid) (PLA) were subjected to several investigations: Fourier transform infrared (FTIR) spectroscopy, morphological analysis and mechanical testing (tensile, impact, microhardness). The copolymer (ethylene-co-glycidyl methacrylate) (EGMA) was used as compatibilizer. The percentages of PLA in LDPE/PLA samples ranged from 0 to 100 wt% while the EGMA was added to the blend 60/40 (LDPE/PLA) at concentrations of 2, 5, 7, 10, 15 and 20 parts per hundred (phr). FTIR analysis showed the absence of any interaction between LDPE and PLA, but after addition of compatibilizer, reactions between epoxy groups of EGMA and carboxylic or hydroxyl groups of PLA were confirmed. Tensile and impact tests revealed a loss of ductility of LDPE with the incorporation of PLA, except for the composition 80/20 (LDPE/PLA). However, the addition of 15 phr of EGMA led to the maximum increase in the elongation-at-break (about three times the value of uncompatibilized blend) and in the impact strength, but a marginal improvement was observed for tensile strength. SEM micrographs confirmed that the enhancement of mechanical properties is due to the improvement of the interfacial adhesion between different phases owing to the presence of EGMA. The microhardness values of the different blends (uncompatibilized or compatibilized) were in good agreement with the macroscopic mechanical properties (tensile and impact strengths).     

Effect of interface affinity on the performance of a composite of microcrystalline cellulose and polypropylene/polylactide blends

The effects of compatibilizer and fillers on the mechanical properties and dispersion state of droplets of polypropylene (PP)/polylactide (PLA) blends were investigated. Two blended composite systems, i.e. PP‐rich (80/20) containing microcrystalline cellulose (MCC) modified with silane (m‐MCC) and PLA‐rich (20/80) containing MCC were prepared by melt compounding using a twin‐screw extruder. The structural differences between MCC and m‐MCC were confirmed using Fourier transform infrared spectra. Universal testing machine results revealed that the tensile strength and Young's modulus increased with the addition of compatibilizer and filler, respectively. These results were supported by the reduction of domain size observed by scanning electron microscopy. Differential scanning calorimetric analysis showed a change of the melting and crystallization behavior of blends according to the presence of compatibilizer or filler. An increase of the dynamic storage modulus and a decrease in tan δ with addition of compatibilizer indicated that the interfacial adhesion between PP and PLA improved. © 2019 Society of Chemical Industry     

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。     

Effects of nanosilica filler surface modification and compatibilization on the mechanical,thermal and microstructure of PP/EPR blends

Polypropylene/ethylene-propylene rubber/nanosilica (PP/EPR/nano-SiO₂) composites were prepared by a melt blending masterbatch process using a Brabender mixer. In order to improve the interfacial adhesion and achieve diverse desired properties of the composites, nanosilica surface silylation by means of two silane coupling agents: N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (AEAPTMS) and 3-methacryloxypropyltrimethoxysilane (MPTMS) was explored. The composites were also compatibilized using three compatibilizers: methyl methacrylate grafted PP (MMA-g-PP), glycidylmethacrylate grafted PP (GMA-g-PP) and maleic anhydride grafted PP (MAH-g-PP). The properties of the blends and the composites were examined using tensile and Izod impact tests, differential scanning calorimetry (DSC), thermogravimetric analysis (ATG) and scanning electron microscopy (SEM). According to the mechanical property evaluations, the incorporation of nano-SiO₂ particles into PP/EPR blend improved the tensile strength and Young’s modulus of the composites. The elongation and Izod impact strength were adversely affected. A significant improvement in the mechanical properties was obtained for the composites with AEAPTMS-SiO₂ and MAH-g-PP. The DSC results indicated that the incorporation of the modified silica and MAH-g-PP increased the crystallinity of the composites. However, no significant variation in the crystallinity was observed as a result of the addition of MMA-g-PP and GMA-g-PP. The TGA results revealed that the composites exhibit a higher thermal stability than that of the neat matrix. SEM micrographs of the fractured surfaces revealed a two-phase morphology with EPR nodules being dispersed in the PP matrix. SEM also indicated that the incorporation of MAH-g-PP into PP/EPR composites contributes to a better dispersion of the EPR phase and nano-SiO₂ particles in the polymer matrix.     

Enhancing compatibility between poly(lactic acid) and thermoplastic starch using admicellar polymerization

An alternative method to improve the compatibility between poly(lactic acid) (PLA) and cassava starch (CS) is proposed and investigated. Admicellar polymerization is used to modify the surface of CS with poly(methyl methacrylate) (PMMA) in order to make it more hydrophobic and hence more compatible with PLA. The increased hydrophobicity of PMMA modified cassava starch (MS) is validated by contact angle measurement. Results from iodine test, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) confirm the formation of PMMA film on MS surface. Mechanical properties of PLA‐CS and PLA‐MS blends are investigated to compare their compatibility. Noticeable improvements in blend tensile strength and elongation at break evidently show that MS is more hydrophobic as well as more compatible with PLA than CS. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43755.     

Toughening of polylactic acid using styrene ethylene butylene styrene: Mechanical,thermal, and morphological studies

Polylactic acid, PLA, derived from renewable resources has gained great attention nowadays owing to their sustainability, biodegradability, superior property, and transparency. However, intrinsic brittleness and low toughness severely limits its variety of applications. Blending of PLA with other polymers is more economical and more flexible technique for the property improvement of PLA. In this study, Styrene Ethylene Butylene Styrene (SEBS) and Maleic Anhydride grafted SEBS (MA‐g‐SEBS) are used as toughening agents to study their effect for its toughness, high strength and heat resistance on PLA. PLA/SEBS and PLA/Maleic Anhydride grafted SEBS blends were prepared under four different compositions by melt mixing technique using a corotating twin–screw extruder after optimizing the mixing conditions. The mechanical properties of the blends such as tensile, flexural, and impact strengths were investigated using specimens prepared by injection molding process. The percentage elongation and impact strength of PLA/MA‐g‐SEBS blends were found to be increased significantly by 540 and 135%, respectively in comparison with virgin PLA and PLA/SEBS blends. However, tensile strength and modulus of PLA/SEBS and PLA/MA‐g‐SEBS blends decreased compared with pristine PLA. SEM behaviour supported the higher impact property of PLA with the incorporation of modified SEBS via multiple crazing and cavitation mechanisms. DSC study also supported greater compatibility between maleated SEBS and PLA. POLYM. ENG. SCI., 56:669–675, 2016. © 2016 Society of Plastics Engineers     

Highly toughened polylactide by renewable Eucommia ulmoides gum

Polylactide (PLA) derived from natural sources has attracted increasing interest and has provided a promising alternative to traditional plastics derived from petroleum sources. With no loss of environmental friendly features, PLA was highly toughened by Eucommia ulmoides gum (EUG) derived from Eucommia ulmoides oliv. The dynamic mechanical analysis, scanning electron microscopy (SEM), and differential scanning calorimetry results show that the PLA–EUG blends were immiscible systems. SEM micrographs revealed that EUG particles were well dispersed in the PLA matrix with number‐average particle diameters of 2–4 μm. The mechanical properties indicated that the tensile strength decreased with increasing EUG contents, but the elongation at break and the impact strength were enhanced. The notched impact strength of the blends improved by 5.9‐fold compared to that of neat PLA. The PLA–EUG blends exhibited distinct shear‐thinning behavior; this indicated good processability, and the storage modulus and loss modulus of the PLA–EUG blends increased with EUG content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46017.     

Mechanical Properties and Morphology of Nitrile Rubber Toughened Polystyrene

Mechanical properties and morphology of blends of polystyrene and finely powdered (uncrosslinked and crosslinked) nitrile rubber were studied with special reference to the effect of blend ratio. Blends were prepared by melt mixing polystyrene and nitrile rubber in an internal mixer at 180°C in the composition range of 0–20 wt% nitrile rubber. The tensile stress/strain properties and impact strength of the polystyrene/nitrile rubber blends were determined using injection molded test specimens. In comparison to the blends with uncrosslinked nitrile rubber, blends with crosslinked nitrile rubber showed higher tensile strength, elongation at break, Young's modulus, impact strength, flexural strength, and flexural modulus. The enhanced adhesion between the dispersed nitrile rubber phase and the polystyrene matrix results in an increase in mechanical properties. Scanning electron micrographs of the fractured surfaces confirm the enhancement in mechanical properties.     

Effect of acrylonitrile content of acrylonitrile butadiene rubber on mechanical and thermal properties of dynamically vulcanized poly(lactic acid) blends

We report here the morphology, thermal and tensile properties of poly(lactic acid) (PLA) blends composed of acrylonitrile butadiene rubber (NBR) with different acrylonitrile contents with/without dynamic vulcanization by dicumyl peroxide (DCP). The interfacial tension of PLA and NBR measured by contact angle measurement decreased as the acrylonitrile content of NBR decreased. Likewise, SEM images showed that the rubber particle size reduced with decreasing acrylonitrile content owing to the stronger interfacial adhesion between the PLA matrix and NBR domains. Incorporation of DCP at 1.0 phr for dynamic vulcanization led to higher crosslink density and, in turn, optimal tensile strength and tensile toughness as a result of the action of PLA‐NBR copolymer as a reactive compatibilizer. The dynamic vulcanization of the blends containing low acrylonitrile NBR gave the most improved tensile properties because the free radicals from DCP decomposition preferentially attacked the allylic hydrogen atoms or double bonds of the butadiene backbone. Accordingly, more NBR macroradicals were generated and probably more PLA‐NBR copolymers were produced. Moreover, further addition of DCP at 2.0 phr provided a large amount of crosslinked NBR gel, which significantly degraded the tensile properties. From the DSC results, dynamic vulcanization lowered the cold crystallization temperature, implying an improvement of cold crystallization. Finally, TGA results showed a higher degradation temperature as a function of DCP content, which suggested that thermal stability increased due to stronger interfacial adhesion as well as higher gel content. © 2019 Society of Chemical Industry     

PLA-g-GMA的制备及其对PLA/PPC共混体系性能的影响

采用双螺杆挤出机将甲基丙烯酸缩水甘油酯(GMA)接枝到聚乳酸(PLA)上,而后将接枝产物(PLA-g-GMA)与聚乳酸(PLA)、聚碳酸亚丙酯(PPC)反应性共混,考察了接枝物中GMA加入量变化对PLA/PPC/PLA-g-GMA共混体系的力学性能、热稳定性能的影响,并对共混体系的断裂机理进行了研究。结果表明,PLA-g-GMA的引入能够在一定程度上改善PLA与PPC的相容性。随着接枝物中GMA加入量的增加,共混物的冲击强度、断裂伸长率及拉伸强度均呈现出先升高后降低的趋势,并在接枝物中GMA加入量为3%时达到最大值。扫描电镜结果显示,PLA-g-GMA引入后共混物的韧性断裂特征越发显著,其冲击断裂方式由脆性断裂过渡为韧性断裂。热失重分析结果显示,加入PLA-g-GMA后共混物的起始分解温度和完全分解温度均有一定程度的提高。     

Melt blending of polylactide and poly(methyl methacrylate): Thermal and mechanical properties and phase morphology characterization

Blends of polylactide with poly(methyl methacrylate), PLA/PMMA, were prepared by a semi‐industrial twin screw extruder and afterwards were injection molded. Blends were studied using different techniques as Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and mechanical properties by means of tensile and impact tests, were also studied. This work helped better understanding of apparently contradictory results reported in the literature for PLA/PMMA blends prepared by melt compounding. DSC first heating scan and DMA results showed partially miscible blends, whereas the second DSC heating scan showed miscible blends. For miscible blends, T_g values were predicted using Gordon‐Taylor equation. On the other hand, Small and Van Krevelen approaches were used to estimate the solubility parameters of neat PLA and neat PMMA, and Flory‐Huggins interaction parameter was calculated from solubility parameters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42677.