聚乳酸/纳米蒙脱土纳米复合材料的制备与挤出发泡研究

采用熔融插层法制备了聚乳酸/有机改性纳米蒙脱土（PLA/OMMT）复合材料,对其复合结构、力学性能、热性能、动态流变性能进行了测试和表征,并研究了复合材料的挤出发泡行为。结果表明,不同含量的OMMT与PLA进行熔融插层会形成不同的插层与剥离结构;3 %的OMMT可以提高PLA的力学性能、改善热性能;OMMT能够提升PLA的熔体强度,同时在挤出发泡过程中起到成核剂的作用,并且能够减弱发泡剂气体向PLA熔体外部的扩散,从而提高PLA挤出发泡的效果。     

Properties of mineral filled poly(lactic acid)/poly(methyl methacrylate) blend

This study examines the influence of three different minerals, that is, clay, calcium carbonate, and quartz on the physical, thermal, and mechanical properties of poly(lactic acid) (PLA)/poly(methyl methacrylate) blend. Rheological behavior and phase structure were initially studied by small-amplitude oscillatory shear rheology. Clay- and quartz-filled materials presented an increase in viscosity at low frequency associated with the presence of a yield stress. However, this behavior was not observed for calcium carbonate filled materials due to a matrix degradation effect. To elucidate this aspect, thermal stability and thermal properties were examined by thermogravimetric analysis and differential scanning calorimetry, showing that calcium carbonate promotes degradation of the PLA phase. No nucleating effect was observed in the presence of the minerals. Dynamical mechanical analysis and mechanical characterization revealed an increase of the overall softening temperature and, a reinforcing effect for clay- and quartz-based composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46927.     

Hydrolytic and thermal degradation of polyethylene glycol compatibilized poly(lactic acid)-nanocrystalline cellulose bionanocomposites

This study investigates the effect of nanocrystalline cellulose (NCC) and polyethylene glycol (PEG) on the hydrolytic degradation behavior of poly(lactic acid) (PLA) bio-nanocomposites compared with that of neat PLA, under specific environmental condition, namely at 37°C in a pH 7.4 phosphate buffer medium for a time period up to 60 days. The water absorption, mass loss, molecular weight, and the morphologies of nanocomposites before and after degradation were explored. Thermogravimetric analysis (TGA) was used to study the thermal decomposition of the PLA/NCC/PEG nanocomposites before and after degradation. The results showed that the presence of hydrophilic NCC and PEG significantly accelerated the hydrolytic degradation of PLA, which was related to the rapid dissolution of PEG causing easy access of water molecules to the composites and initiating fast hydrolytic chain scission of PLA. The thermal degradation temperatures of the nanocomposites slightly decreased due to the poor thermal stability of NCC in comparison with that of the neat PLA. After degradation, the thermal stability of the separated PLA from nanocomposites significantly decreased because the molecular decreased during the hydrolytic process. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46933.     

聚乙烯醇/聚乙二醇复合材料的热塑加工性能

通过热塑加工方法制备了增塑改性聚乙烯醇(mPVA)/聚乙二醇(PEG)复合材料,研究了PEG相对分子质量和含量对mPVA/PEG复合材料热性能、热塑加工性能,转矩流变性能和力学性能的影响.结果表明:加入适量PEG可降低mPVA的熔点,表明PEG对mPVA有一定的增塑作用;随着PEG用量的增加,mPVA的熔体流动速率增大...     

PLA/PBAT/OMMT纳米复合材料微观结构调控

利用环氧基化合物ADR在转矩流变仪中将PLA锚固到OMMT上,然后将所得PLA/OMMT/ADR体系与PBAT复配,制备（PLA/OMMT/ADR）/PBAT纳米复合材料。对不同体系的表面张力及相间的界面张力进行了测试,计算得到PLA和PBAT分别与OMMT间的浸润系数;借助TEM和SEM对相关体系的微观结构进行了观察和分析。结果表明,OMMT上锚固了PLA;随着ADR含量增加,浸润系数减小,使OMMT由倾向于分布在PLA与PBAT界面处逐渐转变为倾向于分布于PLA相的一侧;OMMT以剥离状态均匀分布于（PLA/OMMT/ADR）/PBAT体系中,这归因于ADR的加入改善了PLA与PBAT间的亲和性,促使OMMT向PLA与PBAT界面处及PBAT相中迁移;随着ADR用量的增加,PLA与PBAT相界面变得模糊,相容性改善。     

Morphology,mechanical properties,and thermal stability of rigid PVC/clay nanocomposites

PVC/Poly(ε‐caprolactone) (PCL)/organophilic‐montmorillonite (OMMT) and PVC/Polylactide (PLA)/OMMT nanocomposites were prepared by a two‐step process. PCL/OMMT and PLA/OMMT master batches were prepared by melt blending using a two‐roller mill first, and then they were blended with PVC via extrusion. PVC/OMMT nanocomposites were also prepared using a two‐roller mill. Morphology, mechanical properties, and thermal stability were investigated. The formation of exfoliated or intercalated nanocomposites was confirmed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Only the PVC/PCL/OMMT nanocomposite showed both higher tensile strength and stiffness than unfilled PVC. Atomic force microscopy (AFM) indicated dependency of this behavior not only on the clay dispersion, but also on the adhesion between the OMMT and the polymer matrix. Furthermore, scanning electron microscopy (SEM) showed that the large plastic deformation of the PVC/PCL matrix also contributed to the strength increase of the PVC nanocomposites. The effect of PCL/OMMT on the improvement of the thermal stability of PVC was remarkable while the effect of PLA/OMMT was moderate. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.     

Effects of two types of clay on physical and mechanical properties of poly(lactic acid)/wood flour composites at various wood flour contents

To investigate the effects of two types of clay, namely, Na‐montmorillonite (Na‐MMT) and organic‐montmorillonite (OMMT), on poly(lactic acid) (PLA)/wood flour (WF) composites, some physical and mechanical properties including the water sorption, thickness swelling, flexural modulus of rupture (MOR), and modulus of elasticity (MOE) of PLA/WF composites at different WF contents of 0, 20, 40, and 60 wt% were tested in this study. The results showed that: (1) the 24 h water uptake and thickness swelling increased and the flexural MOR and crystallinity decreased with the increasing WF content, whereas the flexural MOE of the composites increased with WF content up to 40 wt% but decreased sharply at WF content of 60 wt%; (2) the addition of Na‐MMT slightly increased the 24 h water uptake as well as the thickness swelling rate below 40 wt%, whereas OMMT reduced the thickness swelling at higher WF contents (40, 60 wt%) although it showed little effect on 24 h water uptake; (3) both Na‐MMT and OMMT could improve the flexural MOR and MOE of PLA/WF composite at WF contents below 40 wt%, and OMMT resulted in more obvious improvement than Na‐MMT. However, they both showed negative effect at WF content of 60 wt%; (4) XRD and FT‐Raman analysis suggested that clays would be attached more on the surface of the WF rather than diffused in the PLA matrix at a higher WF content (60 wt%); (5) SEM analysis proved that the interfacial adhesion of PLA and WF became poorer at WF content above 40 wt%, whereas it could be improved by OMMT modified. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of an alkalized‐modified halloysite on PLA crystallization,morphology, mechanical,and thermal properties of PLA/halloysite nanocomposites

Poly(lactic acid) (PLA)/alkalized halloysite nanotube (HNTa) nanocomposites were prepared by melt mixing. The morphology, crystallization behavior, mechanical properties, and thermal stability of the nanocomposites were investigated in comparison with those of the pristine PLA. HNTa can nucleate PLA, leading to a lower recrystallization temperature and higher crystallinity. Infrared spectra revealed that the hydroxyl groups of the PLA interacted with the external hydroxyl groups of HNTa nanofillers via hydrogen bonding. The thermal stability of the nanocomposites was improved with the addition of HNTa. The PLA/HNTa nanocomposites exhibited higher modulus and tensile strength than those of the PLA composites containing unmodified halloysite nanotubes (HNTs). The improvement in properties was probably due to a better dispersion of the HNTa in the PLA matrix compared to that of the unmodified HNTs. Therefore, the facile alkali treatment of HNTs offers a low cost nanofiller for the preparation of PLA based nanocomposites with high tensile modulus and tensile strength. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44272.     

茶粉/聚乳酸复合材料的增韧改性

为高值化利用茶产业剩余物资源,以茶粉（TD）为生物质填料,聚乳酸（PLA）为基体,以甘油（GL）、聚乙二醇400（PEG400）、环氧大豆油（ESO）和乙酰柠檬酸丁酯（ATBC）为增塑剂,制备了可降解TD/PLA增韧复合材料,并采用红外吸收光谱、热重分析、转矩流变仪、扫描电镜及力学性能测试等考察了增塑剂对TD/PLA复合材料结构与性能的影响。结果表明：4种增塑剂都可改善TD/PLA复合材料的加工流变性,GL的添加不利于复合材料韧性,PEG、ATBC及ESO的添加提高了复合材料韧性,其中ESO增韧效果最佳,其添加制备的复合材料断裂伸长率及缺口冲击强度分别提高了154.23%和65.53%,GL增韧效果最差,ATBC增韧后复合材料力学强度和模量最高。FTIR分析表明,ATBC和ESO可与PLA发生一定相互作用,使C-O键红外吸收峰位增大,其增韧后复合材料吸水率下降。ESO添加提高了TD/PLA复合材料的维卡软化点和热稳定性。SEM图片显示,TD/PLA/ESO复合材料断面粗糙,ESO分散较均匀,与PLA部分相容,而TD/PLA/GL复合材料断面出现严重相分离结构。该研究结果可为进一步探索聚乳酸基茶塑复合材料制备及应用提供试验数据和理论参考。     

Effects of thermoplastic polyurethane on the properties of poly(lactic acid)/organo‐montmorillonite nanocomposites based on novel vane extruder

Polylactic acid (PLA)/organo‐montmorillonite (OMMT) nanocomposites toughened with thermoplastic polyurethane (TPU) were prepared by melt‐compounding on a novel vane extruder (VE), which generates global dynamic elongational flow. In this work, the mechanical properties of the PLA/TPU/OMMT nanocomposites were evaluated by tensile, flexural, and tensile tests. The wide‐angle X‐ray diffraction and transmission electron microscopy results show that PLA/TPU/OMMT nanocomposites had clear intercalation and/or exfoliation structures. Moreover, the particles morphology of nanocomposites with the addition of TPU was investigated using high‐resolution scanning electronic microscopy. The results indicate that the spherical TPU particles dispersed in the PLA matrix, and the uniformity decreased with increasing TPU content (≤30%). Interestingly, there existed abundant filaments among amount of TPU droplets in composites with 30 and 40 wt% TPU. Furthermore, the thermal properties of the nanocomposites were examined with differential scanning calorimeter and dynamic mechanical analysis. The elongation at break and impact strength of the PLA/OMMT nanocomposites were increased significantly after addition of TPU. Specially, Elongation at break increased by 30 times, and notched impact strength improved 15 times when TPU loading was 40 wt%, compared with the neat PLA. Overall, the modified PLA nanocomposites can have greater application as a biodegradable material with enhanced mechanical properties. POLYM. ENG. SCI., 54:2292–2300, 2014. © 2013 Society of Plastics Engineers     

Investigation on the environmental-friendly poly(lactic acid) composites based on precipitated barium sulfate: Mechanical,thermal properties,and kinetic study of thermal degradation

A novel environmental-friendly poly(lactic acid) (PLA) composites based on precipitated barium sulfate (BaSO₄) were prepared via melt-compounding. The mechanical properties and thermal stability of PLA/BaSO₄ composites were investigated. To dig the decomposition mechanism, kinetic analysis of thermal degradation was emphasized systematically based on nonisothermal thermograms. Results showed that the mechanical responses were improved remarkably both under the quasi-static condition and subjected to high-speed shock due to the well-bonded interfaces between PLA and BaSO₄. Meanwhile, the added BaSO₄ suppressed the mass conversion rate of PLA phase and improved the thermal stability at high temperature. Due to the inhibition of BaSO₄, the calculated activation energy was enhanced obviously according to model-free isoconversional approaches. Finally, the apparent kinetic mechanism and reaction order for the over-all thermal degradation were determined by the combination of model-fitting approaches and Carrasco method. From this study, we hope to provide a facile method to prepare environmental-friendly PLA composites with excellent mechanical properties and thermal stability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47995.     

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.     

Composites of poly(lactic acid)/poly(butylene adipate-co-terephthalate) blend with wood fiber and wollastonite: Physical properties,morphology, and biodegradability

Poly(lactic acid) (PLA) was first melt blended with five weight percentages (10–50 wt %) of poly(butylene adipate-co-terephthalate) (PBAT) on a twin-screw extruder and then injection molded. The blend at 30 wt % PBAT exhibited the highest impact strength and elongation-at-break without phase inversion. The 70/30 (w/w) PLA/PBAT blend with high toughness improvement was selected for preparing both single and hybrid composites using an organic filler, wood fiber (WF) and inorganic filler, wollastonite (WT) with a fix total loading at 30 parts per hundred of resin (phr) throughout the experiment. Five WF/WT (phr/phr) ratios for the composites were 30/0, 10/20, 15/15, 20/10, and 0/30. The prepared composites were investigated for the mechanical and thermal properties, melt flow index (MFI), morphology, flammability, water uptake, and biodegradability as a function of composition. All the composites showed a filler-dose-dependent decrease in the impact strength, elongation-at-break, MFI, and thermal stability, but an increase in the tensile and flexural modulus, tensile and flexural strength, antidripping ability, and water uptake compared with the neat blend. The addition of WF and WT was also found to promote the biodegradability of the PLA/PBAT blend. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47543.     

PHBH/PLA共混物相容性研究

采用双螺杆挤出机熔融共混制备聚(3羟基丁酸酯3羟基己酸酯) （PHBH)/聚乳酸（PLA）共混物。通过电子万能试验机、差示扫描量热仪、热重分析及扫描电子显微镜等测定共混物的力学性能、热性能和热稳定性并观察其微观结构,研究了PHBH与PLA间的相容性。结果表明,PHBH与PLA共混后,综合力学性能得到改善,与PHBH相比,PHBH/PLA（80/20）共混物的断裂伸长率提高了38 %,冲击强度提高了15.7 %;PHBH和PLA的玻璃化转变温度呈现出相互靠近的趋势,两者表现出一定程度的相容性。     

Kinetics of water absorption and thermal properties of poly(lactic acid)/organomontmorillonite/poly(ethylene glycol) nanocomposites

Poly(lactic acid) (PLA)/organomontmorillonite (OMMT) nanocomposites were prepared by a melt intercalation technique. The effects of OMMT and poly(ethylene glycol) (PEG) on the thermal properties and water absorption behavior of PLA were investigated. The melting temperature and degree of crystallinity were comparable for the PLA and its nanocomposites. The glass transition temperature and crystallization temperature of PLA were decreased by the addition of PEG. X‐ray diffraction results revealed the formation of PLA nanocomposites, as the OMMT was partly intercalated and partly exfoliated. The maximum moisture absorption of PLA was increased in the presence of PEG and the diffusivity of the PLA nanocomposites decreased with increasing concentrations of PEG. However, the activation energy of the nanocomposites increased as the loading of PEG increased. These results indicated that the incorporation of OMMT and PEG enhanced the water‐barrier properties of the PLA. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Processing thermal stability and degradation kinetics of poly(vinyl chloride)/montmorillonite composites

Thermal stability of polyvinyl chloride (PVC) based montmorillonite composites with either sodium montmorillonite (MMT) or alkyl ammonium ion modified montmorillonite (OMMT) were investigated by thermogravimetric analysis. The apparent activation energies associated with the first thermal degradation stage were calculated by the methods of Flynn–Wall–Ozawa and Kissinger in nitrogen atmosphere at several different heating rates. The processing thermal stability of PVC and PVC/MMT(OMMT) composites was also discussed. Increase of mixing torque did not result in a larger intercalation extent of PVC on MMT; instead, it unexpectedly induced discoloration of PVC and then deteriorated the processing stability, especially in the presence of OMMT. The apparent activation energies in the first thermal degradation stage exhibited little difference among PVC, PVC/MMT, and PVC/OMMT composites, and the kinetic compensation effect of S_p^* kept a constant value, indicating that the thermal stability and thermal degradation mechanism of PVC were not affected by the presence of either MMT or OMMT, although the processing discoloration of PVC is observed for PVC/OMMT composite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1521–1526, 2004     

Enhancing the durability of poly(lactic acid) composites by nucleated modification

Biodegradable poly(lactic acid) (PLA) composites were prepared using an innovative combination of wood fiber (WF) and 1,3,2,4‐bis(3,4‐dimethylobenzylideno)sorbitol (DMDBS). DMDBS acted as an effective nucleating agent, which improved the mechanical properties and slowed down the degradation of the WF/PLA composites. The enzymatic degradation of the composites was examined by immersing in proteinase K or cellulase buffer. The presence of DMDBS resulted in a 26.7% increase of the crystallinity compared to the WF/PLA composites. The increase in crystallinity enhanced the thermal stability and tensile strength of the WF/DMDBS/PLA composites by 8.5%. The durability of the WF/DMDBS/PLA composites after nucleated modification was enhanced after enzymolysis. After nucleated modification, the surface of the WF/PLA composites showed clear cracks due to degradation, while these appeared about 2 weeks later in the case of the WF/DMDBS/PLA composites. The results revealed that the introduction of cellulase degraded WF in the composites, which increased hydrolysis or enzymolysis sites. The combination of nucleated modification and enzyme buffer gave an expanded downstream application of WF/PLA composites in packaging and agricultural materials. © 2019 Society of Chemical Industry     

Effect of OMMTs on flame retardancy and thermal stability of poly(ethylene‐co‐vinyl acetate)/LDPE/magnesium hydroxide composites

The aim of this study was to prepare poly (ethylene‐co‐vinyl acetate) (EVA)/ low density polyethylene (LDPE)/magnesium hydroxide (MH) composites applicable in cable industry with required flame retardancy. For this reason, two types of organo‐modified montmorillonites (OMMT) with different surface polarites (Cloisite 15A and Cloisite 30B) at various concentrations, and also combination of these two OMMTs with overall loadings of 2 wt % and 5 wt % were used. The samples were compounded using a twin screw extruder with total (MH + OMMT) feeding of 55 wt % and 60 wt %. Limiting oxygen index (LOI) of the samples containing 2 wt % of OMMTs increased about 16% and dripping was suppressed according to vertical burning test (UL‐94V). Thermogravimetric results of EVA/LDPE/MH samples containing OMMT showed that the beginning of second step degradation was shifted about 50°C to higher temperatures. The composite tensile strength results showed enhancement by incorporating some amount of nanoclays with EVA/LDPE/MH composites. Scanning electron microscopy images confirmed that MH particles had better wetting by EVA matrix in presence of nanoclays. Oxidative induction time of the EVA/LDPE/MH/OMMT nanocomposites was 140 min, which was more than that of the samples without OMMT (20 min). Employing the equal weight ratios of the two OMMTs demonstrated a synergistic effect on flame retardancy of the samples according to the both tests results (LOI, UL‐94V). X‐ray diffraction analysis of the samples confirmed the intercalation/semiexfoliation structure of nanosilicate layers in the bulk of EVA/LDPE matrix. This led to longer elongation at break and thermal stability of Cloisite 15A based nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40452.     

聚乳酸/蒙脱石复合材料的溶液插层法制备及其性能表征

的界面相容性良好.聚乳酸/蒙脱石复合材料的热失重曲线移向高温端,其热分解温度提高,表明其热稳定性比PLA基材提高.聚乳酸及聚乳酸/蒙脱石复合材料在不同环境中的初步降解实验结果表明该复合材料具有较好的生物可降解性.     

纳米氧化锌填充PBS复合材料性能的研究

采用硅烷偶联剂(KH-550)对纳米氧化锌进行了表面改性,通过熔融共混法制备了聚丁二酸丁二醇酯(PBS)/纳米氧化锌复合材料,利用扫描电子显微镜、热重分析仪、差示扫描量热仪等对复合材料的力学性能、热性能和非等温结晶性能进行了研究分析,并通过Ozawa-Flynn-Wall方法分析了复合材料的热降解行为。结果表明,纳米氧化锌能提高PBS的拉伸强度和弯曲强度,但降低了其冲击强度;改性后的纳米氧化锌可以提高其与PBS的界面相容性,并提高其在PBS基体中的分散性能,不同程度地提高了复合材料的力学性能;纳米氧化锌提高了PBS的结晶速率,降低了其热解反应活化能。