Graphene‐reinforced biodegradable poly(ethylene succinate) nanocomposites prepared by in situ polymerization

In this study, poly(ethylene succinate)(PES)/graphene nanocomposites were facilely prepared by in situ melt polycondensation of succinic acid and ethylene glycol in which contained well dispersed graphene oxide (GO). Fourier transform infrared (FTIR), GPC, TGA, and XRD were used to characterize the composites. The FTIR spectra and TGA measurement confirmed that PES chains had been successfully grafted onto GO sheets along with the thermal reduction of GO to graphene during the polymerization. GPC results indicated that increasing amounts of graphene caused a slight decrease in number average molecular weight of PES matrix when polymerization time was kept constant. The content of grafted PES chains on graphene sheets was also determined by TGA and was to be about 60%, which made the graphene sheets homogeneously dispersed in the PES matrix, as demonstrated by SEM and XRD investigations. Furthermore, the incorporation of thermally reduced graphene improved the thermal stability and mechanical properties of the composites significantly. With the addition of 0.5 wt % graphene, onset decomposition temperature of the composite was increased by 12°C, and a 45% improvement in tensile strength and 60% in elongation at break were also achieved. The enhanced performance of the composites is mainly attributed to the uniform dispersion of graphene in the polymer matrix and the improved interfacial interactions between both components. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3212–3220, 2013     

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 %。     

Enhanced biodegradation and processability of biodegradable package from poly(lactic acid)/poly(butylene succinate)/rice-husk green composites

This work aims to study the possibility to process PLA/PBS/RH green composites into hexagonal plant-pots employing a large-scale industrial operation using injection molding. Green composites based on poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and rice husk (RH) with various RH contents (10–30%wt.) were produced successfully using a twin-screw extruder. The compatibility of RH-matrix was improved by chemical surface modifications using a coupling agent. RH was analyzed as an effective filler for PLA to develop green composites with low cost, high biodegradability, improved processability, and comparable mechanical properties as unfilled PLA. With increasing RH content, tensile modulus of the composites increased gradually. The addition of PBS, at PLA/PBS ratio of 60/40, improved the elongation at break and impact strength of PLARH30 by 55% and 7.1%, respectively. The suitable processing temperatures for PLA decreased from 220–230°C to 170–180°C when 30%wt. RH was composited into PLA matrix and were further reduced when PBS was applied. After biodegradation via either enzymatic degradation or hydrolysis, surface erosion with a large number of voids, mass loss, and the substantial decrease in tensile strength of all the composites were observed. In addition, the biodegradation of the composites has been improved by the addition of either RH or PBS.     

不同粒径氧化锌以及改性纳米氧化锌对多功能PBAT复合膜的影响

采用溶剂铸膜法制备了聚己二酸/对苯二甲酸丁二酯（PBAT）/聚乳酸（PLA）/对苯二甲酸二辛酯（DOTP）/氧化锌（ZnO）复合膜材料,并通过硬脂酸改性纳米ZnO,探讨了不同粒径ZnO以及改性纳米ZnO对复合薄膜力学性能、热性能、疏水性能、耐抽出性能以及抗菌性能的影响。结果表明,通过硬脂酸代替纳米ZnO表面的羟基极性基团,复合膜的耐抽出性能提高。硬脂酸的长链烷基与高分子链的链纠缠改善了改性纳米ZnO与PBAT的相容性。随着ZnO粒径的减小以及改性纳米ZnO含量的增大,复合薄膜的热性能有所下降,但耐抽出性能提高。拉伸强度提高,最高达到13.8 MPa。复合膜的疏水性能得到改善,接触角最高达到110°,复合膜材料的抑菌区域增大,抗菌性能有所增强。     

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。     

Preparation and characterization of amidated graphene oxide and its effect on the performance of poly(lactic acid)

An improved Hummers method was used to prepare graphene oxide (GO). Then, the orthogonal experiment design methods were used to select the optimum conditions of the preparation for amidated graphene oxide (AGO) via amidation. The optimum scheme was followed by: reaction temperature 70 °C, reaction time 5 h and GO: benzohydrazide of 1:3 (g:g). The structure of AGO was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscope (TEM) techniques, which demonstrated that the amidation of GO was successful. Furthermore, poly(lactic acid) (PLA)/AGO nanocomposites were prepared by melt blending to improve the comprehensive performance of PLA. Mechanical properties, thermal stabilities, crystallization properties, and rheological behavior of PLA/AGO nanocomposites were investigated, which showed that the addition of 0.3 wt % of AGO increased the tensile strength, elongation-at-break, and impact strength of PLA/AGO nanocomposites by 7.68, 47.32 and 41.27%, respectively, compared with neat PLA. Scanning electron microscopy analysis showed ductile fracture of the PLA/AGO nanocomposites. TEM analysis showed that nano-AGO single layers were evenly dispersed in the PLA matrix, confirming the formation of an exfoliated nanocomposite structure. Differential scanning calorimetry demonstrated that AGO eliminated the cold crystallization of PLA matrix and improved the crystallinity of PLA by 34.1%. In all, this study provided an effective and feasible method for improving the comprehensive performance of PLA.     

Graphene oxide/polybenzimidazole composites fabricated by a solvent-exchange method

Homogenous organic dispersion of graphene oxide (GO) sheets was prepared by a solvent-exchange method. This method enabled the simultaneous achievement of full exfoliation and high concentration of GO in several organic solvents such as dimethyl sulfoxide, which would facilitate the fabrication of individual graphene reinforced polymer composites through a solution-based process. To this end, poly [2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole] (OPBI)/GO composites were fabricated. X-ray diffraction characterization showed that the GO sheets were individually incorporated into the OPBI matrix. Scanning electron microscope images that taken of the fracture surface of the composites revealed that the GO sheets were spontaneous aligned parallel to the surface of the composite films as the content of GO exceeded 0.3 wt.%. The incorporation of GO also showed profound effects on the macroscopic properties of OPBI. Compared to pure OPBI, the composites showed a 17% increase in Young’s modulus, 33% increase in tensile strength and 88% improvement in toughness by the addition of only 0.3 wt.% of GO. Moreover, although the thermal stability of GO is far inferior to OPBI, it is found the thermal stability of OPBI is still improved by the addition of GO.     

Effects of stearic acid on the interface and performance of polypropylene/superfine down powder composites

To manufacture the hygroscopic sheets available for functional application, superfine down powder (SDP) and stearic acid modified superfine down powder (MSDP) were, respectively, blended and extruded with polypropylene (PP) to produce composite pellets, and the extruded pellets were hot‐pressed into composite sheets. The chemical reaction between SDP and stearic acid was characterized using the attenuated total reflection attachment on the Fourier transform infrared. PP/MSDP composites showed more uniform powder dispersion in PP matrix, higher compatibility, and better mechanical properties than that of PP/SDP composites, which showed an evident decrease in tensile strength and elongation at break compared with pure PP. It was worth noting that the Young's modulus of PP/SDP composites was higher than that of pure PP, but lower than that of PP/MSDP composites. The addition of SDP led to a large increase in water absorption of PP/SDP composites. However, the water absorption of PP/MSDP composites decreased slightly compared with that of PP/SDP composites. Furthermore, the effects of SDP and MSDP on the microstructural and thermal properties of different composites were also investigated, respectively. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

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.     

Morphology,thermal, mechanical,and barrier properties of graphene oxide/poly(lactic acid) nanocomposite films

To improve the physical and gas barrier properties of biodegradable poly(lactic acid) (PLA) film, two graphene nanosheets of highly functionalized graphene oxide (0.3 wt% to 0.7 wt%) and low-functionalized graphene oxide (0.5 wt%) were incorporated into PLA resin via solution blending method. Subsequently, we investigated the effects of material parameters such as loading level and degree of functionalization for the graphene nanosheets on the morphology and properties of the resultant nanocomposites. The highly functionalized graphene oxide (GO) caused more exfoliation and homogeneous dispersion in PLA matrix as well as more sustainable suspensions in THF, compared to low-functionalized graphene oxide (LFGO). When loaded with GO from 0.3 wt% to 0.7 wt%, the glass transition temperature, degree of crystallinity, tensile strength and modulus increased steadily. The GO gave rise to more pronounced effect in the thermal and mechanical reinforcement, relative to LFGO. In addition, the preparation of fairly transparent PLA-based nanocomposite film with noticeably improved barrier performance achieved only when incorporated with GO up to 0.7wt%. As a result, GO may be more compatible with hydrophilic PLA resin, compared to LFGO, resulting in more prominent enhancement of nanocomposites properties.     

几种加工助剂在聚丙烯基木塑复合材料中的应用对比

研究了3种加工助剂对聚丙烯(PP)基木塑复合材料物理力学性能和加工性能的影响,并利用扫描电子显微镜对复合材料的冲击断面进行了分析。结果表明,在一定用量范围内,芳香族碳氢化合物(S-105)和改性烷基酚醛树脂(TKM-M80)能够提高木粉在PP基体中的分散性,改善基体与木粉之间的相容性,从而提高PP基木塑复合材料的拉伸强度、冲击强度、弯曲强度、弯曲弹性模量和加工性能;脂肪醇和脂肪酸酯的混合物(Deoflow A)能够明显提高木粉在PP基体中的分散性和复合材料的加工性能,但用量较大时对复合材料的拉伸强度、弯曲强度和弯曲弹性模量有不利影响。     

Synthesis,Characterization of Fulvic Acid–Poly(Methylmethacrylate) Graft Copolymers Based on Surface-Initiated Atom Transfer Radical Polymerization and its Effect on Performance of Poly(Lactic Acid)

Fulvic acid–poly(methylmethacrylate) graft copolymers were synthesized by surface-initiated atom transfer radical polymerization with fulvic acid. The result demonstrated that the hydrophobicity of fulvic acid–poly(methylmethacrylate) was improved after modification by surface-initiated atom transfer radical polymerization. Furthermore, poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites were prepared to improve the performances of poly(lactic acid) by blend melting. Compared to poly(lactic acid) with X_c of 5.38%, the X_c of poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites was 19.94%. Moreover, the impact strength of poly(lactic acid)/fulvic acid–poly(methylmethacrylate) composites was increased by 5.19% compared to poly(lactic acid). In all, this study provided an effective and feasible method for optimizing interface performance and enhancing the thermal stability of poly(lactic acid).     

Graphene Nanoplatelets as Novel Reinforcement Filler in Poly(lactic acid)/Epoxidized Palm Oil Green Nanocomposites: Mechanical Properties

Graphene nanoplatelet (xGnP) was investigated as a novel reinforcement filler in mechanical properties for poly(lactic acid) (PLA)/epoxidized palm oil (EPO) blend. PLA/EPO/xGnP green nanocomposites were successfully prepared by melt blending method. PLA/EPO reinforced with xGnP resulted in an increase of up to 26.5% and 60.6% in the tensile strength and elongation at break of the nanocomposites respectively, compared to PLA/EPO blend. XRD pattern showed the presence of peak around 26.5° in PLA/EPO nanocomposites which corresponds to characteristic peak of graphene nanoplatelets. However, incorporation of xGnP has no effect on the flexural strength and modulus. Impact strength of PLA/5 wt% EPO improved by 73.6% with the presence of 0.5 wt% xGnP loading. Mechanical properties of PLA were greatly improved by the addition of a small amount of graphene nanoplatelets (<1 wt%).     

Properties of grafted wood flour filled poly (lactic acid) composites by reactive extrusion

Composites of poly(lactic acid) with wood flour which was grafted by melt extruding with methyl acrylate in the presence of benzoyl peroxide (BPO) were investigated. The modification of filler (WF-g-PMA) was carried out to enhance the filler-matrix interactions, while the treated component was characterized by infrared spectrum. Properties of binary (PLA/WF, PLA/WF-g-MA) composites were analyzed as a function of the grafting monomer amount by scanning electron microscopy, differential scanning calorimeter, thermogravimetric analysis, water absorption and mechanical tests. Compared with the untreated system (PLA/WF), all treated composites showed higher interfacial compatibility as a result of chemical bonding between WF and grated monomer. All composites showed higher tensile modulus and lower strength and elongation at break as compared to pure PLA; grafting modification with methyl acrylate led to an increased stiffness and decreased water absorption of the composites because of an enhanced filler-matrix interfacial compatibility.     

Biodegradable PLA-based composites modified by POSS particles

ABSTRACT

The poly(lactic acid)(PLA)/aliphatic poly(carbonate)(PPC)/polyethylene glycol-polyhedral oligomeric silsesquioxane (PEG-POSS) composites were prepared by reactive melting extrusion. The effect of various components on the mechanical, thermal, rheological, and hydrophilic properties of composites was systematically studied by means of various characterization methods. The results showed that, with the increase of PPC content, the toughness of composites improves significantly, while the strength decreases. Reactive extrusion and adding PEG-POSS could enhance the compatibility and adjust the crystallization of composites effectively. When the proportion of PPC and PEG-POSS in composites is 20-40wt% and 4wt%, respectively, the composites own the best comprehensive performance.     

Effects of Poly(ϵ-caprolactone) on Structure and Properties of Poly(lactic acid)/Poly(ϵ-caprolactone) Meltblown Nonwoven

To obtain flexile poly(lactic acid)-based melt-blown nonwoven filtration material, poly(lactic acid)/poly(?-caprolactone) melt-blown nonwoven with various components were melt-spun by melt-blown processing in the Melt-blown Experiment Line. The 3 wt.% tributyl citrate to poly(?-caprolactone) was added in the composites as compatibilizer. The effect of poly(?-caprolactone) on the structure, morphology, mechanical and filtration properties of poly(lactic acid)/poly(?-caprolactone) melt-blown nonwoven was reported. Scanning electron microscopy micrographs revealed good dispersion of the additive in the fiber webs. The crystallinity of melt-blown webs with poly(?-caprolactone) was more than that of poly(lactic acid) alone. The tensile strength, ductility and air permeability of poly(lactic acid) melt-blown nonwovens were enhanced significantly. The input of poly(?-caprolactone) increased the diameter of fibers and decreased the filtration efficiency of poly(lactic acid)/poly(?-caprolactone) melt-blown nonwoven.     

马来酸酐接枝细菌纤维素改性聚乳酸研究

制备了马来酸酐接枝细菌纤维素（BC-g-MAH）,然后采用溶液浇铸法将BC-g-MAH与聚乳酸（PLA）制备成复合材料,通过红外光谱、差示扫描量热分析、拉伸实验和热失重分析等测试手段,研究了由PLA与不同含量BC-g-MAH制备成的复合材料的结构和性能。结果表明,MAH对BC进行了成功的接枝,制得的BC-g-MAH与 PLA具有较好的界面相容性;随着BC-g-MAH含量的增加,改性后的复合材料的结晶度、拉伸强度和拉伸模量较纯PLA有较大提高;BC-g-MAH含量为 20 %（质量分数,下同）时,复合材料的结晶度、拉伸强度和拉伸模量较纯PLA分别提高了17.1 %、69.4 %和428.4 %,复合材料热稳定性能也有了显著增强。     

Mechanical,barrier, and thermal properties of poly(lactic acid)/poly(trimethylene carbonate)/talc composite films

Poly(l ‐lactic acid) (PLA) is now a very attractive polymer for food packaging applications. In this study, PLA/poly(trimethylene carbonate) (PTMC)/talc composite films were prepared by solvent casting. The influence of the talc loading (0, 1, 2, and 3 wt %) on the phase morphology of the PLA/PTMC/talc composites and the improvement in the resulting properties are reported in this article. The scanning electron microscopy images of the composite films demonstrated good compatibility between the PLA and PTMC, whereas talc was not thoroughly distributed in the PLA matrix at talc contents exceeding 3 wt %. The tensile strength and elongation at break of the composite films significantly improved (p < 0.05). On the contrary, the water vapor permeability and oxygen properties of the composite films decreased by 24.7 and 39.2%, respectively, at the 2 wt % talc loading. Differential scanning calorimetry showed that the crystallinity of the PLA phase increased with the presence of talc filler in the PLA/PTMC/talc composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40016.     

挤出-注塑制备黄麻增强PLA复合材料及其性能

通过挤出共混、造粒、注射成型的方式制备了黄麻纤维填充聚乳酸(PLA)复合材料,研究了复合材料的力学性能以及黄麻与PLA之间的微观界面形貌。结果表明:黄麻的加入,并没有很好地改善黄麻/PLA复合材料的拉伸强度和弯曲强度;碱处理后的黄麻与PLA之间的界面性能有所改善;碱处理黄麻的加入,改善了黄麻/PLA复合材料的断裂伸长率与冲击韧性。     

聚乳酸/木粉复合材料的制备与力学性能研究

以聚乳酸(PLA)为基体,木粉为填料,分别采用热压成型和注塑成型方法制备了PLA/木粉复合材料。实验研究结果表明:当木粉用量由20%增加到60%时,PLA/木粉复合材料的拉伸强度由41.83 MPa降至15.96MPa;弹性模量由1 035.96 MPa降至283.43 MPa,断裂伸长率由7.04%降至1.73%。