The effect of hybridization on mechanical properties of woven kenaf fiber reinforced polyoxymethylene composite

The challenges of using natural fibers in polymer composites include high moisture uptake and poor interfacial bonding with thermoplastic matrix. In this study, the effect of hybridization was investigated to address the challenges of high moisture uptake and balanced mechanical properties in natural fiber reinforced polymer composites. Polyethylene terephthalate fiber (PET) was used in woven kenaf reinforced POM due to its hydrophobic characteristics. The results of tensile test showed that the tensile strength of the interwoven POM/kenaf/PET hybrid composite when tested along kenaf fiber direction, increased from 72 to 85 MPa due to increase in fiber content. Similarly, the tensile strength of the interwoven POM/kenaf/PET hybrid composite increased from 67 to 75 MPa. However, the flexural strength of the interwoven POM/kenaf/PET hybrid composite dropped from 160.1 to 104.9 MPa while that of woven POM/kenaf composite dropped from 191.4 to 90.3 MPa. The interwoven hybrid composite also showed significant improvement in impact strength compared to the woven POM/kenaf composite. The water absorption of the woven POM/kenaf composite dropped by approximately 30% due to hybridization with PET fiber. The results confirmed that hybridization with PET fiber significantly improved the tensile and impact properties of the woven composite and increased its resistance to moisture uptake. POLYM. COMPOS., 35:1900–1910, 2014. © 2014 Society of Plastics Engineers     

后处理对PLLA/PDLA共混纤维结构和性能的影响

采用聚L-乳酸(PLLA)与聚D-乳酸(PDLA)共混熔融纺丝,初步研究了后处理条件对纤维结构与性能的影响。结果表明:通过PDLA与PLLA的共混熔融纺丝,形成了立体复合型PLA晶体(sc-PLA);随着热处理温度的提高,纤维中sc-PLA晶体的含量增加,纤维力学性能下降;拉伸温度为75℃时所得纤维的力学性能最好,随着拉伸倍数的增加,纤维力学性能提高,纤维中sc-PLA晶体的含量变化不大。     

无机复合涂层对碳纤维性能的影响

采用溶胶-浸渍法在碳纤维表面制备了二氧化钛-二氧化硅复合涂层。考察了钛溶胶与硅溶胶体积比、浸渍方式、浸渍次数对涂层的影响。利用X射线衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）分析了涂层的相组成及形貌。通过静态等温氧化实验考察了复合涂层碳纤维的抗氧化性能。结果表明：钛溶胶与硅溶胶体积比为15∶1条件下采用真空超声浸渍3次,制备的复合涂层均匀、完整、致密,与碳纤维表面结合良好,涂层抗氧化性能好,涂层二氧化钛为锐钛矿型、二氧化硅为无定型。将复合涂层碳纤维在400 ℃连续氧化15 h,其质量损失率仅为5.91%。     

改性剂对胶原蛋白复合纤维结构性能的影响

在胶原蛋白和聚乙烯醇共混溶液中,添加不同量改性剂制得纺丝原液,经湿法纺丝得到初生纤维,初生纤维再经过热拉伸、热定型和缩醛化处理得到胶原蛋白复合纤维。由该方法制得的复合纤维中胶原蛋白存留率达到91.6%,结晶度为57.8%。由扫描电镜观察纤维横截面为肾形,纤维内部致密、无相分离。纤维断裂强度为4.1 cN/dtex,初始模量为147.5 cN/dtex,断裂伸长为26.9%,纤维水中软化点为104℃。     

碳纤维粉对电铸镍–碳纤维粉复合材料组织与性能的影响

在硫酸镍溶液体系中,采用复合电铸工艺在金属镍基体上制备了镍–碳纤维粉复合材料。通过红外碳硫分析仪、扫描电子显微镜(SEM)和电子万能试验机研究了电铸液中碳纤维粉添加量对复合电铸层内碳纤维粉含量、表面微观形貌以及拉伸性能的影响。复合电铸层内的碳纤维粉含量、抗拉强度和屈服强度均随电铸液内碳纤维粉添加量的增加而先增大后减小,并在电铸液中碳纤维粉为6 g/L时达到最大值,抗拉强度为636.6 MPa、屈服强度为500.1 MPa,而延伸率降至最小。复合电铸层内碳纤维粉的存在明显改变电铸层的表面微观形貌。随着复合电铸层内碳纤维粉含量的增大,复合电铸层致密性下降。     

Effect of different fiber loadings and sizes on pultruded kenaf fiber reinforced unsaturated polyester composites

Application of the available natural resources became crucial for developing sustainability recently. The use of natural fiber as reinforced materials in polymer composite materials is gaining new interest from within industry. In this research, the effect of different fiber loadings and different types of kenaf yarns, used on the properties of Pultruded Kenaf Fiber Reinforced Composites (PKFRC), was studied. The pultruded composite samples were prepared with different fiber loadings and sizes (tex) of kenaf fiber. Three different fiber loadings, i.e., 60, 65, and 70% were used during the preparation of the PKFRC samples. Flexural and compression testing was performed, to study the effect of different fiber loadings and different kenaf fiber yarns, on the mechanical properties of kenaf fiber pultruded composites. The results show that the highest fiber loading of 70% gave more desirable flexural and compression properties to the PKFRC. The use of twist kenaf yarn fiber showed lower mechanical properties of PKFRC as compared to the single kenaf yarn. Damage configurations and accumulations for each loading case were examined. A morphological study, using optical microscopy (OM) revealed the type of fracture that occurred in the pultruded samples after mechanical testing. POLYM. COMPOS., 36:1224–1229, 2015. © 2014 Society of Plastics Engineers     

Effect of (3-aminopropyl)trimethoxysilane on mechanical properties of PLA/PBAT blend reinforced kenaf fiber

The composite-based poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT)/kenaf fiber has been prepared using melt blending method. A PLA/PBAT blend with the ratio of 90:10 wt%, and the same blend ratio reinforced with various amounts of kenaf fiber have been prepared and characterized. However, the addition of kenaf fiber has reduced the mechanical properties sharply due to the poor interaction between the fiber and polymer matrix. Modification of the composite by (3-aminopropyl)trimethoxysilane (APTMS) showed improvements in mechanical properties, increasing up to 42.46, 62.71 and 22.00 % for tensile strength, flexural strength and impact strength, respectively. The composite treated with 2 % APTMS successfully exhibited optimum tensile strength (52.27 MPa), flexural strength (64.27 MPa) and impact strength (234.21 J/m). Morphological interpretation through scanning electron microscopy (SEM) reveals improved interaction and interfacial adhesion between PLA/PBAT blend and kenaf fiber. The fiber was well distributed and remained in the PLA/PBAT blend evenly. DMA results showed lower storage modulus (E′) for PLA/PBAT/kenaf fiber blend and an increase after modification by 2 wt% APTMS. Conversely, the relative damping properties decreased. Based on overall results, APTMS can be used as coupling agent for the composite since APTMS can improve the interaction between hydrophilic natural fibers and non-polar polymers.     

Tensile properties of wood flour/kenaf fiber polypropylene hybrid composites

Hybrid composites of wood flour/kenaf fiber and polypropylene were prepared at a fixed fiber to plastic ratio of 40 : 60 and variable ratios of the two reinforcements namely 40 : 0, 30 : 10, 20 : 20, 10 : 30, and 0 : 40 by weight. Polypropylene was used as the polymer matrix, and 40–80 mesh kenaf fiber and 60–100 mesh wood flour were used as the fiber and the particulate reinforcement, respectively. Maleic anhydride and dicumyl peroxide were also used as the coupling agent and initiator, respectively. Mixing process was carried out in an internal mixer at 180°C at 60 rpm. ASTM D 638 Type I tensile specimens of the composites were produced by injection molding. Static tensile tests were performed to study the mechanical behavior of the hybrid composites. The hybrid effect on the elastic modulus of the composites was also investigated using the rule of hybrid mixtures and Halpin–Tsai equations. The relationship between experimental and predicted values was evaluated and accuracy estimation of the models was performed. The results indicated that while nonhybrid composites of kenaf fiber and wood flour exhibited the highest and lowest modulus values respectively, the moduli of hybrid composites were closely related to the fiber to particle ratio of the reinforcements. Rule of hybrid mixtures equation was able to predict the elastic modulus of the composites better than Halpin–Tsai equation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Mechanical properties of recycled kenaf/polyethylene terephthalate (PET) fiber reinforced polyoxymethylene (POM) hybrid composite

Environmental concerns have attracted researchers to study the recycling of composite materials and thermoplastics due to the desire not to waste materials and reduce disposal of scraps that may eventually pollute the environment. The main objective of this article is to study the effect of recycling on the mechanical properties of kenaf fiber/PET reinforced POM hybrid composite. The virgin hybrid composite was produced by compression molding and later subjected to mechanical testing. The scraps obtained after the mechanical testing were shredded, granulated and subjected to compression molding to produce samples for mechanical testing. Tensile strength of 27 MPa was obtained and (after second recycling process) which is lower compared to 73.8 MPa obtained for the virgin hybrid composite. There was a significant increase in flexural modulus (4.7 GPa) compared to the virgin hybrid composite. The impact strength dropped to 4.3 J cm^?1 as against 10.5 J cm^?1 for the virgin hybrid composite. The results of thermal degradation showed about 80% weight loss for kenaf fiber between 300 and 350°C. The weight loss may be due to the degradation of cellulose and hemicellulose content of the fiber. The percentage water absorption of the recycled composite dropped by about 80% compared to the virgin hybrid composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39831.     

拉伸工艺对PET/PTT复合纤维性能的影响

以310 dtex/48 f聚对苯二甲酸乙二醇酯(PET)/聚对苯二甲酸丙二醇酯(PTT)复合预向丝为原料,经拉伸后得到PET/PTT复合纤维,探讨了拉伸工艺对PET/PTT复合纤维力学性能和卷曲性能的影响。结果表明:在卷绕速度为500 m/min,拉伸温度160℃,热定型温度150℃的条件下,随着拉伸倍数的增加,PET/PTT复合纤维的断裂强度、沸水收缩率、卷曲收缩率明显提高,断裂伸长率呈下降趋势,卷曲稳定度变化不明显;拉伸温度和热定型温度对PET/PTT复合纤维力学性能和卷曲性能的影响相对较小;拉伸过程中,控制拉伸倍数为1.95～2.00,拉伸温度为140～160℃,热定型温度为130～170℃,PET/PTT复合纤维性能较好。     

纺丝工艺对PET/PTT复合纤维性能的影响

将不同黏度的聚对苯二甲酸乙二醇酯(PET)与聚对苯二甲酸丙二醇酯(PTT)按质量比40∶60进行混合,通过熔融复合纺丝、拉伸制得PET/PTT复合纤维,研究了纺丝工艺对纤维力学性能以及卷曲弹性的影响。结果表明:随着PET与PTT的特性黏数差由0.12 d L/g增加至0.54 d L/g,PET/PTT复合纤维的断裂强度和初始模量下降,断裂伸长率增加;随着拉伸比由2.5增加至4.5以及拉伸辊温度由120℃升高至150℃,PET/PTT复合纤维的断裂强度增加,断裂伸长率降低,卷曲性能增加,弹性增大。     

热处理工艺对石英纤维复合材料介电性能的影响

通过热处理温度、热处理气氛和防潮涂层对石英纤维增强复合材料介电性能影响的研究,结果表明:在800℃或500℃通氧条件下进行热处理,才可以较彻底的排除石英纤维增强复合材料中残余的游离碳。经高温处理后介电性能较好,进行防潮处理后能达到更好的效果,更好的应用于航天领域。     

PANI/PP复合纤维对沥青混凝土力学性能的影响

以聚苯胺/聚丙烯(PANI/PP)复合纤维为导电相材料,采用非连续密级配制备了PANI/PP复合导电纤维沥青混凝土,采用马歇尔试验法对沥青混凝土的力学性能进行了测试。结果表明:随着PANI/PP复合纤维掺量的增加,PANI/PP复合导电纤维沥青混凝土的稳定度、流值、空隙率均有增大趋势,复合纤维的质量掺量为0.8%时,沥青混凝土稳定度可增加近50%,流值增加100%。复合纤维的质量掺量为0.2%~0.8%时,纤维在沥青混凝土中分散均匀性好。     

热处理对PET/PTT复合纤维力学性能的影响

对不同线密度的聚对苯二甲酸乙二醇酯/聚对苯二甲酸丙二醇酯(PET/PTT)复合纤维分别进行干热处理,常压沸水处理,120℃及0.2MPa的高压沸水处理,研究了其热处理前后的力学性能。结果表明:PET/PTT复合纤维经常压沸水处理后,初始模量下降,断裂伸长率及断裂功增大,断裂强度略有减小;复合纤维经高压沸水处理后,其力学性能明显提高,常压沸水处理其次,干热处理则变化不大;复合纤维经干热处理后,其初始模量、断裂强度、断裂伸长率及断裂功随温度的升高均先升高后降低,150℃时达到最大。     

混杂纤维对脱硫石膏基复合胶凝材料性能影响

掺加聚乙烯醇（PVA）纤维、玄武岩纤维（BF）及混杂纤维（PVA纤维与BF）对脱硫石膏基复合胶凝材料性能进行改性,研究纤维复合材料的力学性能、耐水性能及耐干湿性能;应用电镜扫描技术对复合材料的微观形貌进行观察,探讨纤维对脱硫石膏基复合胶凝材料的影响机制。结果表明：PVA纤维掺量为1.5%时复合材料力学性能较好,试样的绝干抗折强度和绝干抗压强度较空白组分别提升了92.55%和32.62%;混杂纤维掺量为0.9%时耐水性能较好,试样的抗折软化系数较空白组提升了46.60%、吸水率低至13.87%;混杂纤维掺量为0.6%时耐干湿性能较优,干湿强度系数较空白组提升了50.74%。     

静电纺PLLA/PCL有序纤维的制备及性能研究

以三氯甲烷为溶剂,按聚乳酸(PLLA)/聚己内酯(PCL)质量比70/30配制质量分数3%的溶液进行静电纺丝,接收装置为转筒,电压为10 kV,接收距离为25 cm,推进速度为1.0 mL/h,制备PLLA/PCL有序纤维膜。通过对有序纤维膜进行扫描电镜、X射线衍射、动态力学性能以及力学性能测试,讨论了转筒的表面线速度对PLLA/PCL有序纤维膜性能的影响。结果表明:随着转筒表面线速度的增加,收集的有序纤维接近于平行排列,纤维的排列有序度提高;转筒表面线速度为3.75 m/s时,收集的有序纤维膜的晶粒尺寸及结晶度达到最大值,拉伸强度也达到最大值;转筒表面线速度大于3.75 m/s,收集的有序纤维膜的结晶度和晶粒尺寸减小,拉伸强度降低;转筒表面线速度为3.75 m/s时,得到的PLLA/PCL有序纤维膜的综合性能最好。     

Effect of screw design on fiber damage in extrusion compounding and composite properties

The mechanism of fiber length degradation during twin screw extrusion compounding and methods to reduce it through process and machine design are extremely important in discontinuous fiber reinforced composites. Fiber damage along the screw and the extruder die are determined for three screw designs with different mixing sections. The pellet quality, wet-out, and fiber dispersion in the extruded strands are compared. The fiber orientation distributions in the screw are determined to identify regions of higher fiber interaction. The fiber damage during subsequent injection molding has also been determined. The tensile, flexural, and impact properties of the tensile bars are compared. It is found that the residence time, fill-up, and the intesity of mixing during extrusion compounding have a predominant effect on fiber length degradation. The screw designs were seen to have a greater effect on the fiber damage in the 40 wt% glass-filled polymer than the 30 wt% glass-filled polymer. However, the mechanical properties of the 30 wt% glass-filled polymer showed an increasing trend compared to the 40 wt% glass filled polymer. A screw design that provides a balance of the fiber length, wet-out, and fiber dispersion was noted to give consistent mechanical properties.     

PHB/PLLA/PEO共混纤维的晶态结构与拉伸性能研究

采用溶液干纺法制备了聚β-羟基丁酸酯/聚乳酸/聚氧乙烯(PHB/PLLA/PEO)共混纤维,研究了PHB/PLLA/PEO初生纤维的晶态结构、在50℃和110℃下拉伸后共混纤维的力学性能及表面形态。结果表明:PHB与PLLA在PHB/PLLA/PEO共混纤维中的晶型均为α晶型;初生纤维经50℃和110℃拉伸2倍后,纤维的断裂强度均有所增加,断裂伸长率减小,50℃拉伸的纤维断裂强度高于110℃拉伸,其断裂方式均为韧性断裂;w(PEO)为5%,PHB/PLLA质量比为1:1,50℃拉伸2倍的PHB/PLLA/PEO共混纤维断裂强度为0.471 cN/dtex,断裂伸长率为34.05%     

后处理对胶原蛋白/PVA复合纤维结构与性能的影响

研究了环氧氯丙烷(ECH)处理和缩醛化反应对胶原蛋白/聚乙烯醇(PVA)初生复合纤维中蛋白质存留率、水中软化点的影响。结果表明:当ECH浴处理温度50℃,处理时间2 h,pH值11;缩醛化浴温度50℃,处理时间40 min,缩醛化浴中硫酸质量浓度180 g/L,甲醛质量浓度45 g/L时,复合纤维水中软化点为101℃,胶原蛋白存留率为90.33%。