聚己内酯/聚乳酸/竹纤维复合材料制备及性能

以聚己内酯（PCL）和聚乳酸（PLA）共混物为基材,竹纤维（BF）作为增强材料,硅烷偶联剂为改性剂,通过模压成型制备了PCL/PLA/BF复合材料。研究了PCL和PLA质量比、BF质量分数、硅烷偶联剂用量以及模压温度对复合材料性能影响。结果表明,适宜的PCL/PLA质量比为1∶1,BF质量分数为40 %时BF/PCL/PLA复合材料的冲击强度、拉伸强度和断裂伸长率分别达到最大值11.26 kJ/m2,12.68 MPa和5.2 %;硅烷偶联剂用量为1 %时复合材料的冲击强度、拉伸强度和断裂伸长率分别达到最大值15.11 kJ/m2、13.15 MPa和5.8 %;模压温度为150 ℃时,复合材料的冲击强度、拉伸强度和断裂伸长率分别达到最大值14.51 kJ/m2、13.75 MPa和5.8 %。     

Mechanical and thermal properties of bamboo fiber reinforced polypropylene/polylactic acid composites for 3D printing

In this article, a kind of degradable composite was prepared from bamboo fiber (BF), poly lactic acid (PLA), and polypropylene (PP). The mechanical and thermal properties were characterized by the universal testing machine, thermogravimetric analysis, differential scanning calorimetry. In order to improve the compability between BF and polymer matrix several modification on the surface of BF were explored and compared. Moreover, a compatibilizer (maleated PP) was applied to further increase compatibility between the fiber and matrix. It is found that the thermal stability of BF/PP/PLA composites decreased with the increase of maleated polypropylene (MAPP) content. When 5% MAPP was used the tensile strength, flexural strength, and impact strength of composites reached 33.73, 47.18 MPa, and 3.15 KJ/m², with an increase by 13, 11.7, and 23.5%, respectively, compared with the composites without MAPP. The improvement of mechanical properties is attributed to the fact that irregular grooves and cracks induced by the modification of BF facilitate the infiltration of polymer into fiber due to the strong capillary effect. Furthermore, BF/PP/PLA composites are potential to be used in 3D printing. POLYM. ENG. SCI., 59:E247–E260, 2019. © 2018 Society of Plastics Engineers     

Morphologies,crystallization, and mechanical properties of PLA-based nanocomposites: Synergistic effects of PEG/HNTs

In this study, the compounding modifier poly(ethylene glycol)/halloysite nanotubes (PEG/HNTs) was prepared by supersonic vibration and dynamic vacuuming. A series of poly(lactic acid) (PLA)/PEG and PLA/PEG/HNT composites were fabricated using a twin-screw extruder. Fourier transform infrared spectroscopy indicated that the hybrid between PEG and HNTs had no evident chemical interaction via supersonic vibration and dynamic vacuuming. The dispersed morphology of the compounding modifier in the PLA matrix was tested by high-resolution scanning electronic microscopy and transmission electron microscopy. The results showed that the low content of PEG/HNTs presented a good dispersion morphology. The binding energy of the PLA-based composites was studied through contact angle measurements. The results showed that PEG and PEG/HNTs can decrease the water contact angle of PLA, and that the binding energy between PEG and HNTs is higher than that of PLA/HNTs, which leads to more location of HNTs in the PEG phase. The crystallization behavior of PLA-based composites was examined by wide-angle X-ray diffraction and differential scanning calorimetry. The results suggested that the addition of PEG and PEG/HNTs effectively enhanced the crystallization of PLA and that the diffraction peak intensity of the PLA-based composites reached a maximum when the content of PEG/HNTs was 1.2 wt %. The spherulite morphology indicated that the addition of PEG resulted in perfect spherulites. The mechanical properties of PLA-based composites were analyzed with a universal testing machine and impact tester, which confirmed that the tensile strength and impact strength of the PLA-based composites increased slightly when the content of the PEG/HNT modifier was 1.2 wt %, while the tensile modulus of the PLA-based composites increased distinctly. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47385.     

废旧聚甲醛/改性竹纤维复合材料的力学性能研究

采用碱(NaOH)、硅烷偶联剂(KH560)、异氰酸酯(IPDI)等不同处理方法对废旧聚甲醛/竹纤维（POM/BF）复合材料的界面进行调控,研究了竹纤维改性方法和竹纤维含量对复合材料力学性能的影响。结果表明,NaOH+IPDI和NaOH+KH560能够实现对复合材料界面的调控,利用NaOH+2 %IPDI对BF进行处理后,POM/BF复合材料［BF为20 %（质量分数,下同）］的弯曲强度增加了13.38 %,拉伸强度为50.36 MPa;利用NaOH+5 %KH560对BF进行调控处理后,POM/BF复合材料的弯曲强度增加了12.61 %,拉伸强度为46.87 MPa;NaOH+2 %IPDI对BF的处理具有更好的效果,BF含量为20 %时复合材料的力学性能最佳。     

Preparation and thermomechanical properties of nanocrystalline cellulose reinforced poly(lactic acid) nanocomposites

A two‐step process was developed to prepare nanocrystalline cellulose (NCC) reinforced poly(lactic acid) (PLA) nanocomposites using polyethylene glycol (PEG) as a compatibilizer. It was composed of solvent mixing and melt blending. The NCC was well dispersed in the PLA matrix. A network was formed at high NCC‐to‐PEG ratio at which the amount of the PEG was not enough to cover all the surfaces of the NCC. The formation of the network was confirmed by the occurrence of a plateau for the storage modulus at low frequency. The incorporation of the PEG and NCC could improve the crystallinity of the PLA. The elongation at break increased from 11.0% for the neat PLA to 106.0% for the composites including 6 wt % NCC, impact strength was improved from 0.864 to 2.64 kJ m^?2 and tensile strength did not change significantly for the same 6 wt % NCC composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44683.     

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。     

Effects of mixing technique and filler content on physical properties of bovine bone‐based CHA/PLA composites

This study presented influence of mixing technique as well as filler content on physical and thermal properties of bovine bone‐based carbonated hydroxyapatite (CHA)/poly(lactic acid) (PLA) composites. CHA/PLA composites at various contents of CHA were prepared by either melt‐mixing or solution‐mixing techniques. Thermal properties, morphologies, and mechanical properties of the CHA/PLA composites including molecular weight deterioration of PLA matrices were investigated. Average molecular weights of PLA in the composites prepared by both techniques decreased with increasing CHA content, whereas their molecular weight distributions (MWDs) increased. Nonetheless, average molecular weights of PLA in melt‐mixed composites were lower than those of solution‐mixed composites. With increasing CHA content, elongation at break, tensile strength, and impact strength of the composites were decreased, whereas the tensile moduli of the composites were increased. In comparison between two mixing techniques, the melt‐mixing distributed and dispersed CHA into PLA matrix more effectively than the solution‐mixing did. Therefore, tensile moduli, tensile strength, and impact strength of the melt mixed composites were higher than those of the solution‐mixed composites of the corresponding CHA content. Moreover, decomposition temperatures and % crystallinity of the melt‐mixed composites were higher than those of the solution‐mixed composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

聚乙二醇对聚乳酸/淀粉纳米晶复合材料性能的影响

以聚乳酸（PLA）和淀粉纳米晶（SNC）为主要原料,聚乙二醇（PEG）为增塑剂,采用溶剂蒸发法制备PLA/SNC和PLA/SNC/PEG复合材料,通过差示扫描量热仪（DSC）、热台偏光显微镜（PLM）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）等研究了PEG对复合材料结晶行为、力学性能及界面相容性的影响。结果表明,PEG能够与SNC协同促进PLA结晶,使PLA/SNC/PEG复合材料的结晶速率明显提高;PEG的添加未改变PLA/SNC复合材料的结晶结构;随着PEG含量的增加,PLA/4%（质量分数,下同）SNC复合材料的拉伸强度先升高后下降,断裂伸长率不断提高;当PEG含量为2%时,PLA/4%SNC/2%PEG复合材料的力学性能最佳,拉伸强度为47.86 MPa,断裂伸长率为10.20%,PLA与SNC间界面相容性得到改善。     

Polylactic acid (PLA)/banana fiber (BF) biodegradable green composites

In this study, polylactic acid (PLA)/banana fiber (BF) composites were prepared by melt blending method. The BF was conjugated onto PLA chains through the use of a coupling agent and chemical modification. Consequently, the thermal stability and mechanical properties of the PLA were dramatically elevated through the incorporation of BF. Mechanical tests showed that the tensile and flexural strengths of the composites markedly increased with the fiber content, reaching 78.6 and 65.4 MPa when reinforced with 40 phr fiber, approximately 2 and 1.66 times higher, produced by pristine PLA. However, the impact strengths of composites are somewhat decreased with the increased content of fibers. The addition of 40 phr BF into the composite increased the HDT of pure PLA from 62 °C to 139 °C; an improvement of about 122%. Apart from enhancing the mechanical properties and thermal stability, the incorporation of BF can reduce the production cost of materials while meeting the demands of environmental protection agencies.     

二聚脂肪酸增韧改性聚乳酸/橡实淀粉共混体系的研究

通过熔融挤出法制备了二聚脂肪酸（DA）改性聚乳酸（PLA）/橡实淀粉（AS）共混体系,并在保持PLA和AS质量比不变（60/40）,仅DA含量变化的情况下,通过扫描电子显微镜、动态热机械分析仪和同步热分析仪等测试手段对共混体系的力学性能、疏水性能、热性能和熔体流动性进行了测试分析。结果表明,随着DA含量的增加,共混体系的疏水性和熔体流动性能逐渐增强,而共混体系的拉伸、弯曲强度则呈逐渐降低的趋势;DA的加入显著提高了PLA基体材料的韧性,并在一定程度上降低了共混体系的玻璃化转变温度和初始热稳定性。     

Plasticizing effect of coconut oil on morphological,mechanical, thermal,rheological, barrier,and optical properties of poly(lactic acid): A promising candidate for food packaging

This study explores the plasticizing effect of coconut oil (CO) on PLA for evaluating its suitability for flexible packaging. Changes in morphological, mechanical, thermal, rheological, barrier and optical properties of melt compounded Poly(lactic acid)–Coconut oil (PLA–CO) blend were investigated by varying the mixing ratio. Water vapor permeability of blends decreased by 58% at 7 wt % plasticizer content. The tensile strength showed a decreasing trend with increasing plasticizer percentage while the % elongation showed an increasing trend. At 7 wt % plasticizer content tensile strength decreased from 60 to 41 MPa and % elongation increased from 12% to 54%. Molecular weight (M_n) and onset of degradation (T_onset), upon 1 wt % plasticizer addition showed a reduction of 6% and 0.6%, respectively, which were well within permissible limits required for polymer processing. The melt flow properties of the blends were slightly improved (～16%) upon 5 wt % addition of CO. Transparency of the PLA films was improved by addition of plasticizer. FTIR spectra of PLA‐CO sample confirmed the interaction between PLA and coconut oil via hydrogen bonding. At higher loading, coconut oil shows very limited compatibility with PLA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45390.     

Toughening of polylactide via in situ formation of polyurethane crosslinked elastomer during reactive blending

Polylactide (PLA)/polyurethane (PU) composites were prepared by reactive blending method with in situ formation of PU particles via the reaction between polyester polyol (PPG) and toluene‐2,4‐diisocyanate (TDI). The interfacial compatibility and adhesion between the PLA and PU phases were greatly improved by the reaction of the terminal hydroxyl groups of PLA and N?C?O groups of TDI forming graft copolymer, as confirmed by FTIR spectroscopy. The elongation at break and notch impact strength of PLA/PU composites increased considerably with increasing PU content, and the tensile strength of PLA/PU composites decreased slightly compared with that of pure PLA. Upon addition of 12 wt % PU, the elongation at break and notch impact strength increased to 175.17% and 10.96 kJ/m², respectively, about 27 times and 5.4 times greater than the corresponding values for the pure PLA. The tensile strength decreased only slightly to 48.65 MPa. The excellent interfacial adhesion, the dispersed PU elastomeric particles acting as stress concentration areas, and the triggering of large matrix shear yield as well as many fibrils by internal cavitation were the main mechanical toughening mechanisms. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44383.     

Synergistic effects of polyethylene glycol and organic montmorillonite on the plasticization and enhancement of poly(lactic acid)

Poly(lactic acid) (PLA)/polyethylene glycol (PEG)/organic montmorillonite (OMMT) composites were prepared by melt blending, and their mechanical, rheological behavior, crystalline behavior, and thermal stability were investigated. Results showed that the elongation-at-break and notch-impact strength of PLA/15PEG/1.5OMMT were 466.45% and 4.34 kJ m⁻², respectively, which were nearly 42 and 2 times higher than those of PLA, respectively. The elongation-at-break of PLA/15PEG/1.5OMMT was also 33 times higher than that of PLA/15PEG and 30 times that of PLA/1.5OMMT. With addition of PEG, PLA chains could insert to OMMT effectively and increase the layer space of OMMT. The characteristics of dynamic behavior and fracture morphology showed that the plasticizer PEG could soften the PLA matrix, leading to easy plastic deformation. OMMT was well distributed in the PLA matrix and able to transfer the stress of external forces, thereby contributing to the matrix yielding initiation and expansion of polymer composites. The synergistic effect of OMMT and PEG was determined by studying the mechanical properties of PLA/PEG/OMMT composite. Differential scanning calorimetry and thermogravimetry studies revealed that OMMT as a nucleating agent improved crystallization and thermal stability. Thus, the synergistic effect of OMMT and PEG balanced the stiffness and toughness of PLA. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47576.     

An Innovative Approach to the Synthesis of PMMA/PEG/Nanobifiller Filled Nanocomposites with Enhanced Mechanical and Thermal Properties

A facile route was adopted to blend the matrix. The PMMA/PEG blend was reinforced with three types of nanofillers, i.e., pristine MWCNT (P-CNT), amine functionalized MWCNT (PDA-EA-CNT) and nanobifiller i.e. nanodiamond functional MWCNT (PDA-EA-CNT-ND) to yield three different types of nanocomposites i.e. PMMA/PEG/P-CNT, PMMA/PEG/PDA-EA-CNT and PMMA/PEG/PDA-EA-CNT-ND. These nanocomposites were reinforced with nanofiller loading (1 wt. %, 3 wt. %, 5 wt. %, 10 wt. %, 30 wt. % and 50 wt. %) by solution casting method. Structure of composite and nanofillers was confirmed by FTIR. FESEM imaging revealed that nanocomposites have micro porous morphology. At high magnification, distribution of functionalized CNT/ND appears to be protruding out of the polymeric matrix. The TGA result suggests that the thermal stability of the nanocomposites was enhanced in comparison to PMMA due to grafting of filler molecules with PMMA/PEG macromolecules. The DTG results showed that the bifiller nanocomposites (PMMA/PEG/PDA-EA-CNT-ND) exhibited improved thermal stability with T_max (431^°C) as compared to P-CNT and amine functionalized CNT (PMMA/PEG/PDA-EA-CNT) with T_max of 395^°C and 418^°C respectively. XRD results showed fine interaction between filler and the polymeric matrix. As the filler loading was increased the composites showed pronounced XRD peak at 25.9^°, corresponding to (002) reflection of nanotubes. Significant improvement in the mechanical properties of composites was recorded with the reinforcement of fillers as compared to the neat matrix. The most significant improvement in tensile strength and elastic modulus was observed for the bifiller nanocomposites with 5 wt. % PDA-EA-CNT-ND. They showed a tensile strength and elastic modulus of 29.9 MPa and 1474.31 MPa respectively as compared to amine functionalized CNT with tensile strength (25.7) and elastic modulus (1466.99 MPa)and P-CNT with tensile strength(25 MPa) and elastic modulus (1155.75 MPa).     

Poly(lactic acid) biocomposites reinforced with ultrafine bamboo‐char: Morphology,mechanical, thermal,and water absorption properties

In this study, ultrafine bamboo‐char (BC) was introduced into poly(lactic acid) (PLA) matrix to improve mechanical and thermal properties of PLA based biodegradable composites. PLA/BC biocomposites were fabricated with different BC contents by weight. Uniform dispersion of BC in the PLA matrix and good interaction via physical and chemical interfacial interlocks were achieved. The maximum tensile strength and tensile modulus values of 14.03 MPa and 557.74 MPa were obtained when 30% BC was used. Impact strength of the biocomposite with 30% BC was increased by 160%, compared to that of pure PLA. DSC analysis illustrated that PLA/BC biocomposites had a better thermal property. Crystallization temperature decreased and maximal crystallinity of 30.30% was observed with 30% BC load. We did not notice significant thermal degradation differences between biocomposites with different BC loadings from TGA. Better water resistance was obtained with the addition of BC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43425.     

机械力改性芦苇纤维及其对聚乳酸复合材料的阻燃性能研究

采用机械力化学法对芦苇纤维（RF）进行磷酰化改性,并将改性后的磷酰化芦苇纤维（MPRF）与聚乳酸（PLA）共混制备复合材料,研究了MPRF对复合材料热稳定性、阻燃性、燃烧性能以及力学性能的影响。结果表明,磷元素成功接枝到芦苇纤维表面,800 ℃时的残余质量增加;随着MPRF添加量的提高,PLA复合材料的阻燃性能随着MPRF的加入而逐渐增加,当MPRF添加量为40 %（质量分数,下同）时,其弯曲强度和拉伸强度可达266.9 MPa和44.7 MPa,极限氧指数为24.6 %;最大热释放峰值下降到366.9 kW/m²,与PLA相比下降了39.3 %,有效降低复合材料的火灾危险性。     

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.     

PLA/PCL/滑石粉复合材料的制备与性能

在聚乳酸(PLA)中添加不同含量的聚己内酯(PCL)和滑石粉,同时添加增容剂柠檬酸三丁酯(TBC),通过熔融共混制备一系列PLA/PCL/滑石粉复合材料。主要研究了PCL、滑石粉以及TBC对PLA力学性能和结晶性能的影响。结果表明,PCL提高了PLA的韧性,但降低了强度,滑石粉主要起到了增强作用,但降低了PLA韧性,而将两者共同添加到PLA中可以起到一定的增强增韧作用,其异相成核作用也提高了PLA的结晶度。增容剂TBC的加入,改善了PLA和PCL的相容性,提高PCL的增韧效果以及复合材料的结晶度,但略微降低了PLA的拉伸强度。当PCL和滑石粉质量分数均为10%且加入0.5份的TBC后,PLA/PCL/滑石粉复合材料的断裂伸长率、拉伸强度、结晶度分别为13.3%,61.6 MPa,43.0%,相比纯PLA分别提高了533%,2%,73.4%。     

Agricultural residue-derived lignin as the filler of polylactic acid composites and the effect of lignin purity on the composite performance

In this study, corn stover lignin with different purities was used as filler in polylactic acid (PLA) matrix. It was found that the impurity metals present in unpurified lignin can significantly affect the performance of the composites in terms of their thermal stability, rheological behavior, mechanical properties, and hydrophobicity. Among the PLA composites, the ones fabricated with the lignin containing 4% of impurities overall had the best thermal stability and tensile strength. From melt rheology analysis, it was also found that the presence of the impurity metals decreases the complex viscosity of the composites. It is suggested that the impurity metals acted as catalysts to promote the interaction between lignin and PLA, resulting in an improved compatibility between PLA and the filler. In the present study, mechanical properties and hydrophobicity of the composites were further improved by acetylating the lignin with the optimum content of impurities. Tensile strength of the composite with the acetylated lignin was comparable to that of pure PLA, whereas the modulus increased to as high as 2.75 GPa. Overall, the study showed that unpurified lignin could be used as filler to achieve similar or better performance than the composites made with highly purified lignin fillers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47915.     

表面改性核桃壳对聚乳酸/核桃壳粉体复合材料性能的影响

采用硅烷偶联剂（ＫＨ５５０）对核桃壳粉体（ＷＳＰ）进行表面处理,运用熔融共混法制备聚乳酸（ＰＬＡ）／ＷＳＰ复合材料,研究了填料对ＰＬＡ基复合材料力学性能和热稳定性的影响。结果表明,硅烷偶联剂ＫＨ５５０添加量为ＷＳＰ质量的６％ （质量分数,下同）时,ＰＬＡ／ＷＳＰ 复合材料的拉伸、弯曲和冲击强度分别为４２．０９、６３．８９ ＭＰａ和１．６９ｋＪ／ｍ２,比未处理的复合材料分别提高了１９．１ ％、２０．６ ％和１９．８ ％;用硅烷偶联剂ＫＨ５５０表面处理改善了ＷＳＰ与ＰＬＡ间的界面相容性;ＷＳＰ填料添加量为５％和４０％时,复合材料的热降解活化能（犈ａ）比ＰＬＡ分别降低了１３．１、２９．８ｋＪ／ｍｏｌ,硅烷偶联剂ＫＨ５５０处理使犈ａ 降低幅度较小。