MAH/GMA共接枝聚乳酸对木粉/PLA复合材料性能的影响

采用熔融接枝法分别制备马来酸酐接枝聚乳酸、甲基丙烯酸缩水甘油酯接枝聚乳酸和马来酸酐/甲基丙烯酸缩水甘油酯共接枝聚乳酸,并利用红外光谱对接枝共聚物进行结构表征。分别以三种接枝共聚物为相容剂,采用注塑成型制备了木粉/PLA复合材料。利用扫描电子显微镜(SEM)对复合材料的断面形貌进行微观分析,结果表明,加入不同接枝共聚物后木粉/PLA复合材料两相看不出明显相界面,界面相容性得到改善。对不同接枝共聚物制备的复合材料的力学性能、加工流动性能和动态流变性能测定的结果显示,加入MAH/GMA共接枝聚乳酸后的木粉/PLA复合材料和未添加相容剂的复合材料相比,拉伸强度和冲击强度分别提高了9.54%和7.23%,复合体系的平衡扭矩和剪切热提高,储能模量及复数黏度均增大。     

硅烷偶联剂改性的木粉/P34HB复合包装材料的制备

目的研究硅烷偶联剂KH550含量对木粉/P34HB复合包装材料性能的影响。采用KH550改性木粉,提高与聚(3-羟基丁酸酯-4-羟基丁酸酯)(P34HB)的结合强度,改善复合材料的力学性能和界面相容性。方法以KH550为改性剂,木粉和P34HB为原料,利用共混热压工艺制备改性木粉/P34HB复合材料;通过对复合材料的形貌进行观察,以及傅里叶变换红外光谱(FTIR)、热重分析(TGA)和力学性能分析,研究KH550质量分数不同时对复合材料界面相容性、力学性能和热性能的影响。结果添加KH550后,复合材料的的界面相容性得到改善;FTIR分析表明,KH550已经成功接枝到木粉中;适量的KH550提高了复合材料的热稳定性;复合材料的储能模量增加;复合材料的力学性能也有所提高。此外还得到了最佳的KH550添加量,即质量分数为0.5%。结论 KH550不仅使得木粉与P34HB的相容性得到改善,同时也增强了复合包装材料的力学性能和热性能。     

木粉含量对木粉-淀粉/聚乳酸复合材料性能的影响

以杨木粉、玉米淀粉和聚乳酸(PLA)为原料,甘油为相容剂,利用熔融挤出法制备了木粉-淀粉/PLA复合材料。研究了木粉含量对复合材料界面相容性、热性能、力学性能、流变性能以及吸水率的影响。结果表明:随着木粉含量的增加,PLA与木粉之间的界面相容性下降,木粉-淀粉/PLA复合材料的热稳定性下降,储能模量、损耗模量和复数黏度逐渐增加;随着木粉含量的增加,木粉-淀粉/PLA复合材料的拉伸强度和弯曲强度呈现先增大后减小的趋势,当木粉含量为18wt%时,复合材料的拉伸强度和弯曲强度均达到最大值,最大值分别为40.65 MPa和60.91 MPa;随木粉含量的增加,复合材料的断裂伸长率由9.64%减小到5.97%,而吸水率由5.38%增大到13.43%。     

改性剂对纳米片状羟基磷灰石/聚乳酸复合材料性能的影响

分别采用硅烷偶联剂(SC)和硬脂酸(SA)对纳米层片状羟基磷灰石(LHAp)进行表面改性,并通过挤塑工艺制备未改性和两种改性纳米片状羟基磷灰石(np-HAp)增强聚乳酸(PLA) (np-HAp/PLA、SC-np-HAp/PLA和SA-np-HAp/PLA)复合材料。比较了三种复合材料的微观结构、力学性能、热稳定性、结晶性及润湿性。利用XRD、FTIR、XPS、SEM、TGA、DSC、力学性能测试和接触角测试对复合材料的理化性能进行表征。研究发现,np-HAp、SA-np-HAp与PLA界面处存在相分离,而SC-np-HA与PLA两相界面结合紧密;与np-HAp/PLA复合材料相比,SC-np-HAp/PLA复合材料的压缩屈服强度和拉伸强度分别提高了9.4%和6.6%,而SA-np-HAp/PLA复合材料的压缩屈服强度和拉伸强度则出现减小;此外,与np-HAp/PLA复合材料相比,SC-np-HAp/PLA和SA-np-HAp/PLA复合材料的初始分解温度分别提高了7.4%和5.6%,SC-np-HAp/PLA复合材料的结晶度提高了6.7%,SA-np-HAp/PLA复合材料的结晶度则减小了3.5%。水接触角测试结果表明,与np-HAp/PLA复合材料和SA-np-HAp/PLA复合材料相比,SC-np-HAp/PLA复合材料具有更为优异的亲水性。上述结果表明,经SC改性后的np-HAp具有与PLA基体更好的界面结合能力,为制备性能优异的骨植入复合材料提供借鉴。      

Polystyrene/wood composites and hydrophobic wood coatings from water-based hydrophilic-hydrophobic block copolymers

 The combination of synthetic thermoplastic polymers and wood is normally problematic because wood surfaces are hydrophilic while typical thermoplastic polymers are hydrophobic. A possible solution is to use block copolymer coupling agents. In this work we show the use of a potentially useful synthetic method of producing hydrophilic-hydrophobic block copolymers as hydrophobic coatings and coupling agents in polystyrene/wood flour composites. In particular, wood veneers are coated with water-based emulsions of hydrophilic-hydrophobic block copolymers from styrene and methacrylic acid. Dried coated surfaces are shown to become hydrophobic through dynamic contact angle measurements. When wood flour is coated with the hydrophilic-hydrophobic block copolymer based on styrene and acrylic acid, significant improvement in the ultimate tensile properties of composites formed from coated wood flour/polystyrene mixtures is realized. Since no volatile organic compounds (VOCs) are used in coating wood surfaces and subsequent composite production, improvement in mechanical properties of thermoplastic/wood flour composites are shown to occur in environmentally responsible formulations. Received: 13 May 1999 / Accepted: 5 February 2000     

水热处理对可逆热致变色竹粉/塑料复合材料性能的影响

探讨了水热处理对可逆热致变色竹粉/塑料复合材料的材色和力学性能的影响。通过ESEM观察竹粉/塑料试样表面的微观结构;分别利用FTIR和DSC方法表征试样表面化学成分的变化以及试样的结晶度。研究结果表明：水热处理对可逆热致变色竹粉/塑料复合材料各性能具有较大的影响,其影响程度为：水热80 ℃处理>常温水浴处理>干热80 ℃处理,水热处理使试样表面产生较大裂纹,接触角和力学性能明显降低,材色变化非常显著;常温水浴处理使得试样表面产生微裂纹,接触角略有降低,其力学性能呈现先升后降再升高的趋势,材色变化较明显;干热处理之后的试样表面光滑、平整,接触角反而增大,其力学性能变化不一致,材色变化不明显。红外光谱和差示扫描量热法分析表明,干热80 ℃、常温水浴和水热80 ℃处理使竹粉和高密度聚乙烯发生一定程度的降解,且高密度聚乙烯会发生再结晶现象。     

Using mechanical technique for preparing antibacterial offset lithography ink with ZnO nanoparticles

This paper presents a study on antibacterial performance of an offset lithography/ZnO nanocomposite ink prepared using a mechanical mixing technique. The hybrid ink exhibited very good antibacterial activity against Gram-negative Escherichia coli and Gram-positive Bacillus Staphylococcus aureus bacteria. The thermal properties of the pure and nanoparticle loaded ink films were evaluated using TGA and DSC techniques. Moreover, the quality of dispersion of ZnO nanoparticles within the ink matrix was characterized by means of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR).     

抗氧剂/光稳定剂对3D打印光致变色木塑复合材料性能的影响

功能性光致变色木塑复合材料(PWPC)使用寿命通常较短,因此本研究将抗氧剂1010和光稳定剂770引入到PWPC中,以改善复合材料的力学和耐光疲劳等性能。采用熔融共混法制得杨木粉/聚乳酸(WF/PLA)基光致变色复合材料,通过熔融沉积技术(FDM)打印成型,对制备的WF/PLA复合材料力学、界面相容性、热稳定性和耐光疲劳性能进行分析表征。与WF/PLA复合材料相比,当只添加抗氧剂1010时,WF/PLA复合材料拉伸、弯曲和冲击强度分别提高了42.58%、23.25%、6.52%;只添加光稳定剂770时,WF/PLA复合材料拉伸强度提高,弯曲强度和冲击强度均下降。当抗氧剂1010与光稳定剂770以质量比为1∶1添加到WF/PLA复合材料中时,在这两种助剂的协同作用下,WF/PLA复合材料的拉伸强度提高了1.8%,弯曲和冲击强度分别减小了9.3%和22.1%,相比于其他复配体系样品,力学性能降低幅度最低。此外,与WF/PLA复合材料相比,抗氧剂1010与光稳定剂770质量比为1∶1的WF/PLA复合材料的热降解性能和耐光变疲劳性能得到改善,质量损失为5%时的温度为219.84℃。老化第10天,其表面颜色变化值ΔE由5.3增至6.7,增加了26.7%。      

Surface modification of wood flour and its effect on the properties of PP/wood composites

The surface of wood flour used as reinforcement in PP/wood composites was successfully modified by benzylation in NaOH solution of 20 wt% concentration at 105 °C. The time of the reaction was changed between 5 and 360 min in several steps. The progress of modification was followed by the measurement of weight increase and by diffuse reflectance infrared spectroscopy (DRIFT). The structure of the wood was characterized by X-ray diffraction (XRD) and its surface tension was determined by inverse gas chromatography (IGC). PP composites containing 20 wt% filler were prepared from a PP block copolymer and the modified wood flour. The mechanical behavior of the composites was characterized by tensile testing. The majority of the active hydroxyl groups at the surface were replaced by benzyl groups in about 2 h under the conditions used. Further increase in reaction time did not influence the properties of the filler. Both the structure of the wood flour and its surface tension changed as an effect of modification. The reduction of surface tension led to significant changes in all interactions between the wood flour and other substances resulting in a considerable decrease of water absorption, which is the major benefit of this modification. All measured mechanical properties of the composites decreased slightly with increasing degree of modification. A detailed analysis of the results proved that the dominating micromechanical deformation process of these PP/wood composites is debonding, which is further facilitated by the decrease in the surface tension of the filler. Chemical modification of wood flour slightly improved processability and the surface appearance of the composites prepared with them and considerably decreased the water absorption of these latter.     

Creep behavior and manufacturing parameters of wood flour filled polypropylene composites

The influence of wood flour content, coupling agent and stress loading level on the creep behavior of wood flour–polypropylene composites was investigated. Maleated polypropylene (MAPP; Epolene G-3003™) was used as the coupling agent to treat the wood flour used as reinforcing filler for polypropylene composite. The tensile strength and modulus of various wood flour–polypropylene composites (WPCs), manufactured using the melt blending, extrusion, and palletizing methods, were measured before performing the creep test. The residual tensile strength, creep strain, and fractional deflection of the resultant wood flour–polypropylene composites were measured by means of the creep test. It was shown that the tensile strength decreased with increasing wood flour level in the composites. The creep strain also decreased as the wood flour level increased. The presence of the coupling agent increased the tensile strength of the wood flour–polypropylene composites, compared with the specimens made of pure polypropylene. For those composites containing the coupling agent, the creep deflection was significantly lower than those made without any coupling agent. The creep strains of the WPC specimens observed during the creep test fitted perfectly with the four-element burger creep model. Further investigation is required of the effects of combined mechanical and environmental loading in varying proportions.     

木粉对聚乳酸流变、结晶及发泡行为的影响

以超临界CO_2为发泡剂,设计高温保压、低温快速泄压发泡的工艺,制备微孔发泡木粉/聚乳酸复合材料。利用X射线衍射仪、差示扫描量热仪、旋转流变仪对复合体系结晶及流变性能进行分析。采用排水法及扫描电镜研究了木粉含量对发泡材料表观密度、发泡倍率,泡孔密度及泡孔形貌的影响。结果表明,木粉的加入提高了木粉/聚乳酸复合材料熔体的复数黏度和储能模量,降低了聚乳酸的结晶度,提高了泡孔密度,减小了泡孔尺寸。当木粉含量为20%时,木粉/聚乳酸发泡材料表观密度为0.19g/cm~3,发泡倍率达到7倍,泡孔密度为7.23×10~8 cm~(-3),平均泡孔直径为20μm。     

Agro-residue reinforced high-density polyethylene composites: Fiber characterization and analysis of composite properties

The main objective of this research was to study the potential of agro-residues such as wheat straw, cornstalk and corncob as reinforcements for thermoplastics as an alternative to wood fibers. High-density polyethylene (HDPE) composites were prepared with a high content of agro-residues (65 wt.%). Surface chemistry of agro-residues was studied in comparison with wood flour with a view to evaluate its importance in determining the end-use properties of the composites. Surface chemistry showed a more carbon rich surface for wheat straw compared to cornstalk, corncob and wood flour. Thermal degradation characteristics of the fibers were studied to investigate the feasibility of these fibers to the processing point of view. The results showed that the agro-residues starts decomposition as low as 200 °C indicating that they can be processed with thermoplastics having a melt temperature less than 200 °C. Mechanical properties and water absorption properties of the composites were studied to evaluate the viability of these fibers as reinforcements in HDPE. Wheat straw filled HDPE composites exhibited superior mechanical properties compared to cornstalk, corncob and even wood flour filled HDPE, where as cornstalk showed comparable mechanical properties to that of wood flour–HDPE composite. All the composites exhibited a high uptake of water due to the high amount of filler present and incorporation of compatibilizer decreased the water uptake of the composites. It was observed that irrespective of the presence of compatibilizers, flexural properties of the composites were decreased considerably after water absorption.     

PLA/木质纤维复合材料的制备及性能

目的研究PLA/木质纤维复合材料的制备工艺过程,分析PLA纤维含量对复合材料力学性能的影响,确定最优配比,以获得一种可应用于包装中的新型环保复合材料。方法将不同质量配比的PLA纤维及木质纤维按照造纸的工艺进行抄造,获得湿纸胚后再进行热压处理,获得需要的复合材料。对PLA纤维在复合材料中的分散性以及复合材料的力学性能进行表征与测试。结果分散性试验表明,PLA纤维能够与木质纤维均匀混合;当PLA纤维的质量分数为10%时,复合材料的性能较好。力学测试表明,复合材料的拉伸强度最大可达到42.79 MPa,耐折次数可达到1015次。结论 PLA/木质纤维复合材料可采用造纸的方法进行制备,且力学性能较好,能在包装领域内有较为广泛的应用,同时也为可降解纤维的研究应用提供了一种新思路。     

Preparation,characterization and mechanical properties of the polylactide/perlite and the polylactide/montmorillonite composites

In this study polylactide (PLA)/perlite and PLA/montmorillonite (MMT) composites were prepared by melt extrusion and solvent dissolution methods. The effects of organic/inorganic ratios and the kind of inorganic compounds on the characterization of the composite materials were investigated. The thermal stability of the organic–inorganic composite materials was evaluated by TGA and DSC, and the morphology of these composites was measured as SEM images. The modulus of elasticity was evaluated by Dynamic mechanical analysis (DMA). The PLA/inorganic composites exhibited remarkable improvement of mechanical and thermal properties when compared with those of the pure PLA.     

An experimental method for measurement of strain distribution between wood the flour particles and polymer matrix on micro-mechanical level

Wood plastic composites (WPCs) are comprised of wood flour and thermoplastic polymer. The matrix is typically high-density polyethylene, poly (vinyl chloride), or polypropylene. The effect of morphology and micromechanics of wood flour particles on the mechanical performance of the bulk composite is a relatively unexplored area. The knowledge about the in situ properties of wood particles and the interfacial properties between the wood particles and the polymer matrix in the bio-composites is very limited. The objective of this work is to characterize the full-field deformation and strain distribution in and around wood particles embedded in polymer matrix. The mechanical tests are performed in small-scale tensile loading stage on thin composite samples containing 1-3 wood particles orientated at various angles. The deformations and strains is measured using optical measurement system based on Digital Image Correlation (DIC) principle.     

竹炭和壳聚糖对聚氯乙烯基木塑复合材料界面性能的影响

以杨木粉为填充材料,聚氯乙烯（PVC）为基体材料,添加竹炭和壳聚糖,采用挤出成型制备竹炭和壳聚糖改性木粉/PVC木塑复合材料,采用SEM观察复合材料表面微观形貌,采用综合热分析仪分析复合材料的热稳定性,采用FTIR分析其官能团变化,测试了木粉/PVC木塑复合材料的力学性能。结果表明:复合添加竹炭和壳聚糖可较好地改善木粉和PVC的界面作用力和界面相容性,提高复合材料的力学性能,其拉伸强度、冲击强度、弯曲强度和弯曲模量分别比未添加增加14.6%、28.8%、11.1%和4.85%,且复合材料的微观界面缺陷较少;竹炭可提高复合材料的热稳定性,复合添加竹炭和壳聚糖可增加复合材料中羟基、氨基和亚甲基的数量,减弱碳氯键的结合强度,从而增强复合材料中木粉和PVC的界面结合力。      

不同改性剂对PP/木粉复合材料性能的影响

研究了苯甲酸(BA)、硬脂酸(SA)、甲苯-2,4-二异氰酸酯(TDI)对聚丙烯/木粉复合材料的改性效果。结果表明,木粉经改性剂处理后,表面极性减弱,与聚丙烯的界面张力降低,相容性提高;所有改性剂均可提高复合材料的拉伸强度、冲击强度以及熔体流动性能,但对弯曲强度影响不大。用TDI/SA复合处理木粉,复合材料的综合性能最好。扫描电镜(SEM)分析表明,木粉经过处理后,木粉与聚丙烯间界面较模糊。     

废旧聚乙烯/木粉复合发泡材料的研究

介绍采用ACY-2发泡剂对废旧聚乙烯/木粉复合材料进行改性,可以使复合材料密度降低30%以上.并研究木粉含量对复合材料力学性能的影响,得到木粉含量的最佳值.     

滑石粉对微孔发泡木粉/聚丙烯复合材料结晶行为及泡孔结构的影响

以滑石粉为成核剂,超临界CO_2为发泡剂,采用间歇釜式方法制备微孔发泡木粉/聚丙烯复合材料。采用DSC、XRD和SEM对微孔发泡木粉/聚丙烯复合材料的结晶行为与泡孔结构进行了测定与分析。结果表明:滑石粉的添加能够提高微孔发泡木粉/聚丙烯复合材料的结晶温度,诱导产生不完善的α晶型;能够提高聚合物基体的熔体黏度,减小泡孔尺寸,增加泡孔密度,促使泡孔尺寸分布更均匀,最终能够形成泡孔密度为1.0×10~9个/cm~3、平均泡孔半径为16.4μm、发泡倍率为18倍、表观密度约为0.055g/cm~3的微孔发泡木粉/聚丙烯复合材料。     

The influence of wood flour particle size and content on the rheological,physical, mechanical and morphological properties of EVA/wood cellular composites

Cellular composites reinforced with vegetal fibers are an emerging class of materials combining good mechanical properties with reduced density and superior impact energy absorption, as well as thermal and acoustic isolation compared to other composites. This research aims to investigate the effects of different particle sizes and contents of wood flour (WF) on the properties of cellular poly(ethylene-co-vinyl acetate) (EVA)/WF composites. The cellular composites were foamed in a heat press using azodicarbonamide as blowing agent. The results indicate that decreasing the particle size of WF increases the viscosity of the composite, which restricts the expandability of the composite. The presence of WF in the cellular composite increases the nucleation of cells, providing a larger number of smaller cells with increased filler content. Optimal homogeneity was observed with WF B (100–150 mesh), but the highest mechanical properties of tear strength were observed with WF C (150–270 mesh).