超高分子质量聚酯(UHMW-PET)纤维牵伸工艺及结构性能研究(Ⅰ)

研究了超高分子质量聚酯 (UHMW PET)纤维的一级牵伸工艺条件对纤维结构性能的影响。结果表明 :在两级牵伸工艺条件下 ,采用较低的一级牵伸温度和牵伸速率 ,有利于得到结晶度较低 ,双折射、强度及牵伸倍率较高的纤维 ,从而保证能够制取高强度纤维     

棉皮纤维增强聚丁二酸丁二醇酯复合材料的热性能及力学性能研究

采用连续式蒸汽爆破法对棉皮纤维进行预处理,将其与聚丁二酸丁二醇酯(PBS)进行共混,制备了PBS/棉皮纤维复合材料。利用扫描电镜对棉皮纤维及PBS/棉皮纤维复合材料的微观形貌进行了分析,并研究了棉皮纤维含量对PBS/棉皮纤维复合材料熔融及结晶行为、热降解性能、热变形温度以及力学性能的影响。结果表明:经蒸汽爆破处理后,棉皮纤维直径变小,比表面积变大,在PBS基体中分散均匀;棉皮纤维的存在改变了PBS的熔融峰值温度,提高了其结晶度;与纯PBS相比,PBS/棉皮纤维复合材料在高温条件下的热稳定性得到改善维,卡软化温度和弯曲强度提高。     

PET/PTT并列复合纤维制备工艺对其结构与性能的影响

以PET和PTT为原料通过熔融纺丝制备了具有自卷曲性能的并列复合纤维,研究了复合纤维制备工艺,探索并明确了两组分配比、牵伸倍率、热定形温度等参数对纤维断面形貌、力学性能、卷曲回弹性能的影响。试验结果表明:随着复合纤维中PTT组分从40%逐渐增加至60%,纤维断面保持8字形,且两相界面的熔接痕始终保持PTT相凸向PET相的形貌,同时纤维的弹性模量逐渐降低;牵伸倍率的增大能够显著提升纤维的强度、模量以及卷曲收缩率,但纤维的断裂伸长率及卷曲稳定度变差;在144~168℃范围内,热定形温度为156℃时,纤维的弹性模量、强度及卷曲收缩率较高,这主要是结晶度提高导致的。     

222 dtex/150f超高分子量聚乙烯纤维后牵伸工艺研究

为改进222 dtex/150f超高分子量聚乙烯纤维均匀性、可加工性能和力学性能,在现有的2 000吨/年超高分子量聚乙烯干法纺丝后牵伸线上进行研究。通过电镜测试、条干不匀率测试、差热分析以及强力仪测试等方法,初步验证了牵伸方法、热浴温度、牵伸倍率分配对纤维均匀性、可加工性能和力学性能的影响。结果表明:相比一、二道牵伸法,三道牵伸法制备的纤维条干不匀率低且截面更加规整,纤维整体均匀性较好;用三道牵伸法进行试加工,当热浴温度在142～144℃范围内时万米接头数只有0.08,可加工性能较好,当热浴温度在低于138℃或高于148℃时无法进行牵伸;三道牵伸法的倍率分配中一道牵伸倍率(DR1)、二道牵伸倍率(DR2)设定为3.38、1.37(三道牵伸倍率(DR3)固定为1.05)时,纤维的力学性能较好。     

管式保压蒸汽牵伸对高性能碳纤维用聚丙烯腈原丝性能的影响

采用管式保压蒸汽牵箱伸制备了高性能碳纤维用聚丙烯腈(PAN)基原丝。通过蒸汽压力和温度匹配实验,找到最佳蒸汽牵伸工艺和设备保压极限值。即蒸汽压力0.20MPa,蒸汽牵伸温度133℃,蒸汽牵伸倍率2.0为最佳蒸汽牵伸工艺,管式保压蒸汽牵伸箱保压极限值为0.38MPa。利用XRD广角衍射仪考察了不同压力、不同牵伸倍率条件下原丝结晶取向度,结果得出蒸汽压力为0.38MPa,蒸汽牵伸温度为150℃,蒸汽牵伸倍率为2.0时结晶度、取向度最大,分别为54.2%和89.9%。利用X射线小角散射(SAXS)对比了两种不同蒸汽牵伸工艺下原丝的孔径尺寸及分布。实验结果表明,管式保压蒸汽牵伸制备原丝与过热蒸汽牵伸制备原丝相比,最小微孔比例增大3%,分形维数减小0.20。最佳工艺条件下管式保压蒸汽牵伸制备原丝对应的碳丝强度比过热蒸汽牵伸制备原丝对应的碳丝强度高0.50GPa。     

纤维素纳米晶增强海藻酸复合纤维的制备及性能

采用微晶纤维素(MCC)通过酸解法制备纤维素纳米晶(CNC),将CNC均匀分散在水中,与海藻酸钠水溶液混合搅拌均匀,制得海藻酸钠/CNC混合纺丝原液,通过湿法纺丝制备海藻酸/CNC复合纤维,研究了CNC含量对海藻酸纤维结构及性能的影响。研究结果表明:CNC的添加有效改善了海藻酸纤维的脆性断裂;CNC的添加量在8%(wt)之内,有效改善了海藻酸纤维的力学性能;少量CNC的加入可以提高海藻酸纤维的吸水性。     

POM/PBS共混纤维的结构与性能研究

采用聚丁二酸丁二醇酯(PBS)对聚甲醛(POM)进行改性,经共混纺丝制得POM/PBS共混纤维,研究了POM/PBS共混体系的流变行为以及共混纤维的热稳定性、结晶结构和力学性能。结果表明:PBS对POM有一定的增塑作用,可以降低POM的黏度和剪切敏感性;添加PBS可降低共混体系的熔点、结晶温度和结晶度,POM的熔点为168.6℃,结晶温度为145.6℃,结晶度为78.6%,而加入PBS质量分数20%的POM/PBS共混体系的熔点为165.7℃,结晶温度为139.7℃,结晶度为68.9%;PBS增大了POM的球晶尺寸,但PBS质量分数超过15%时,由于发生相分离而产生PBS的环带球晶;当PBS质量分数为10%时,POM/PBS共混纤维力学性能最好,拉伸强度和弹性模量分别达到1 264 MPa,9.5 GPa,相比纯POM纤维分别增加了25.8%和15.9%。     

干法工艺制备PE–UHMW纤维

采用干法纺丝工艺,以超高分子量聚乙烯(PE–UHMW)纤维专用树脂为原料,制备高性能PE–UHMW纤维,通过电子拉力机、扫描电子显微镜、差示扫描量热仪对不同后拉伸倍率的纤维进行力学性能和微观结构分析。结果表明,随着拉伸倍率的增加,纤维初生丝结晶度由49.57%逐渐提高至72.17%,拉伸倍率50倍以后,结晶度逐渐趋于平稳;随着拉伸倍率的增加,纤维的力学性能逐渐增强,在拉伸倍率达到83.3倍时,纤维的力学性能达到最佳,纤维断裂强度为31.53 c N/dtex,断裂伸长率为2.69%,断裂模量为1 054.78 c N/dtex;纤维微观表面结构也发生有规律的变化。     

低熔点皮芯复合聚酯纤维干热收缩研究

为了降低低熔点皮芯复合聚酯纤维的干热收缩,提高尺寸稳定性,采用干热收缩测试仪和声速取向测量仪研究了低熔点皮芯复合聚酯纤维的收缩机理以及纺丝成形和牵伸工艺对干热收缩率的影响规律。结果表明降低纺丝速度、升高牵伸温度、降低二牵倍率分配比例,有利于降低纤维干热收缩率。通过工艺调整,降低了低熔点复合纤维干热收缩率。     

PTT/ECDP并列复合纤维的制备及性能研究

采用聚对苯二甲酸丙二醇酯(PTT)和低温易染阳离子聚酯(ECDP)为原料,通过熔融纺丝制备了PTT/ECDP并列复合纤维,研究了牵伸倍数、热定形温度、热处理温度对复合纤维力学性能和卷曲性能的影响。结果表明：随牵伸倍数的增大,复合纤维的卷曲性能提高;随热定形温度的升高,复合纤维的力学性能下降,卷曲性能提高;随热处理温度的降低,复合纤维的卷曲性能提高。最后,复合纤维经圆机织造后,进行阳离子染色处理,织物在98℃染色就可以达到良好的染色效果。     

PBS/蔗渣复合材料的制备与性能

用蒸汽爆破后的甘蔗渣纤维(BF)与聚丁二酸丁二醇酯(PBS)制备复合材料,研究温度以及蒸汽爆破预处理对复合材料力学性能的影响,并通过红外光谱和电子扫描电镜分析其作用机理.结果表明:随着温度的升高,纤维的分散性、BF与PBS的界面粘结性能及复合材料力学性能提高,温度为200℃时复合材料的拉伸性能最佳,在温度为230℃时弯曲性能和冲击性能达到最佳;而蒸汽爆破预处理可提高纤维素的含量,增大纤维比表面积,使复合材料的力学性能得到改善.     

碳纳米纤维增强聚甲醛复合材料制备及性能

通过纳米碳纤维(CNFs)在聚甲醛(POM)基体中的均匀分散以及取向,制备了具有优异力学性能和热性能的POM/CNFs复合材料。利用扫描电子显微镜、透射电子显微镜、拉伸性能测试、热重分析、动态热机械分析测试表征了POM/CNFs复合材料的结构和力学、热学性能。结果表明,CNFs与POM分子链形成氢键相互作用,促进了CNFs在POM基体内分散,同时使POM/CNFs复合材料的结晶度显著提高。随着CNFs含量增加,POM/CNFs复合材料的拉伸强度、储能模量和损耗模量均得到提高。当添加0.5%的CNFs时,拉伸强度、储能模量及损耗模量分别提高了20.5%,127%和58%。进一步研究了高温拉伸对POM/CNFs复合材料性能的影响。结果表明,CNFs沿拉伸方向定向排列,同时复合材料拉伸后结晶度提高,拉伸强度显著增加。     

Pineapple leaf fiber reinforced thermoplastic composites: Effects of fiber length and fiber content on their characteristics

Pineapple leaf fiber (PALF) was used as a reinforcement in polyolefins. Polypropylene (PP) and low‐density polyethylene (LDPE) composites with different fiber lengths (long and short fibers) and fiber contents (0–25%) were prepared and characterized. The results showed that the tensile strength of the composites increased when the PALF contents were increased. It was observed that the composites containing long fiber PALF were stronger than the short fiber composites as determined by greater tensile strength. An SEM study on the tensile fractured surface confirmed the homogeneous dispersion of the long fibers in the polymer matrixes better than dispersion of the short fibers. The unidirectional arrangement of the long fibers provided good interfacial bonding between the PALF and polymer which was a crucial factor in achieving high strength composites. Reduction in crystallinity of the composites, as evident from XRD and DSC studies suggested that the reinforcing effect of PALF played an important role in enhancing their mechanical strength. From the rule of mixtures, the stress efficiency factors of the composite strength could be calculated. The stress efficiency factors of LDPE were greater than those of PP. This would possibly explain why the high modulus fiber (PALF) had better load transfers to the ductile matrix of LDPE than the brittle matrix of PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

聚乳酸/纤维素纳米晶复合材料的制备与性能研究

研究了添加表面活性剂十二烷基三甲基氯化铵(DTAC)前后,纤维素纳米晶(CNC)在水体系中的分散,并采用溶液浇注法制备了聚乳酸(PLA)/CNC纳米复合材料。结果表明,有效减少了DTAC处理后的CNC(mCNC) 的团聚现象,PLA与mCNC间的相容性增强,并通过氢键产生较强的界面相互作用;mCNC能促进PLA的异相成核,提高复合材料的结晶度;mCNC的含量为2 %（质量分数,下同）时,PLA的拉伸强度提高了70.7 %,但断裂伸长率有所下降。     

Conjugate electrospinning of continuous nanofiber yarn of poly(L‐lactide)/nanotricalcium phosphate nanocomposite

The continuous nanofiber yarns of poly(L ‐lactide) (PLLA)/nano‐β‐tricalcium phosphate (n‐TCP) composite are prepared from oppositely charged electrospun nanofibers by conjugate electrospinning with coupled spinnerets. The morphology and mechanical properties of PLLA/n‐TCP nanofiber yarns are characterized by scanning electron microscope, transmission electron microscope, and electronic fiber strength tester. The results show that PLLA/n‐TCP nanofibers are aligned well along the longitudinal axis of the yarn, and the concentration of PLLA plays a significant role on the diameter of the nanofibers. The thicker yarn of PLLA/n‐TCP composite with the weight ratio of 10/1 has been produced by multiple conjugate electrospinning using three pairs of spinnerets, and the yarn has tensile strength of 0.31cN/dtex. A preliminary study of cell biocompatibility suggests that PLLA/n‐TCP nanofiber yarns may be useable scaffold materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Preparation and characterization of bamboo fibers coated with urushiol-ferric and its composite with polypropylene

To improve the interfacial adhesion of bamboo powder/plastic composites by using natural coupling agents, bamboo fibers (BFs) coated with urushiol-ferric (BCFeU) were obtained via in situ polymerization and BCFeU/ polypropylene (PP) composites were prepared. Direct correlations were found between coating ratio of BCFeU and activation time, concentration of urushiol, reaction time and concentration of ferric chloride. Five methods consisting of polarizing microscope, scanning electron microscope, X-ray photoelectron spectroscope, thermo gravimetric analysis, and differential scanning calorimetry were used to characterize the BCFeU. The results show that BCFeU was obtained successfully. Urushiol-ferric compounds were coated on the BFs by hydrogen bonding. Tensile test results and scanning electron microscope analysis of tensile fracture surfaces showed that urushiol-ferric acted as a coupling agent in BCFeU/PP composite. This results in 56% increase in elongation at break and 46% increase in maximum deflection of BCFeU/PP composite (compared with that of BF/PP composite) while there was no evident of variation in tensile strength and bending strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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     

Effects of rice straw fiber morphology and content on the mechanical and thermal properties of rice straw fiber‐high density polyethylene composites

Rice straw fiber‐high density polyethylene (HDPE) composites were prepared to investigate the effects of rice straw fiber morphology (rice straw refined fiber, rice straw pellet, rice straw strand), fiber content (20 and 40 wt %), and maleic anhydride polyethylene (MAPE) concentration (5 wt %) on the mechanical and thermal properties of the rice straw fiber‐HDPE composites in this study. Rice straw refined fiber exhibited more variability in length and width, and have a higher aspect ratio of 16.3. Compared to the composites filled of rice straw pellet, the composites made of the refined fiber and strand had a slightly higher tensile strength and lower tensile elongation at break. The tensile and flexural strength of the composites increased slightly with increasing rice straw fiber content up to 40 wt %, while the tensile elongation at break decreased. With addition MAPE, the composites filled with 20 wt % rice straw fiber showed an increase in tensile, flexural and impact strength and a decrease in tensile elongation at break. Differential scanning calorimetry showed that the fiber addition and morphology had no appreciable effect on the crystallization temperature of the composites but decreased the crystallinity. The scanning electron microscopy observation on the fracture surface of the composites indicated that introduction of MAPE to the system resulted in promotion in fiber dispersion, and an increase in interfacial bonding strength. Fiber breakage occurred significantly in the composites filled with refined fiber and strand after extruding and injection processing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Modified ethylene/α-octene co-polymer elastomer composites with sacrificial bonds crosslinking networks and their reinforced mechanical performance

The low tensile strength of ethylene/α-octene co-polymer (POE) limits its application as high-strength materials. In this study, 3-amino-1,2,4-triazole (ATA) was grafted onto maleic anhydride functionalized POE (PM) by melt reaction to obtain side chains capable of forming hydrogen bonding and metal coordination bonding, and then ferric chloride hexahydrate and POE are blended with them to obtain composite materials with high strength and fracture energy. The introduction of iron-based coordination bonding and hydrogen bonding double dynamic crosslinking network endow thermoplastic elastomers with excellent mechanical strength and high toughness. Fourier transform infrared spectroscopy, rheological tests, and X-ray photoelectron spectroscopy reveal the existence of non-covalent crosslinking networks. Based on the strengthening and toughening of non-covalent dynamic crosslinking network, the tensile strength of the modified POE elastomer composites achieves 12.5 MPa along with the elongation at break of 3540%. In addition, the modified POE elastomer composites exhibit improved melt elasticity and thermal stability.     

纳米ZnO改性PLA/PBS及其发泡体系的性能

采用熔融共混法制备了纳米氧化锌(ZnO)填充聚乳酸/聚丁二酸丁二酯(PLA/PBS)复合材料。研究了ZnO质量分数对复合材料的力学性能、结晶性能以及动态流变性能的影响。结果表明,随着ZnO含量的增加,复合材料的力学性能和结晶度先升高后降低,当ZnO质量分数为0.5%时,复合材料的拉伸强度和冲击强度分别达到最大值40.99 MPa和8.82 k J/m~2,比未添加ZnO时分别提高了6.3%和28.2%,同时结晶度达到24.4%。动态流变性能测试表明,ZnO的质量分数为0.5%时,复合材料的损耗模量和储能模量均为最大值,反映出此时复合材料内部氢键和交联网络最完善,协同作用效果达到最佳状态,因此力学性能也最优。在ZnO质量分数为0.5%的基础上,采用超临界二氧化碳发泡法对复合材料进行间歇发泡,结果显示添加ZnO的发泡材料泡孔密度比未添加的高出一个数量级,泡孔尺寸分布更加集中,体积膨胀率更高。