预炭化过程中升温速率对碳纤维结构与性能的影响

借助13C核磁共振波谱（13C-NMR）,X射线衍射（XRD）,拉曼光谱（Raman）等表征手段,研究了预炭化过程中聚丙烯腈基热氧稳定化纤维的热化学反应以及微观结构的变化,且重点研究了预炭化过程（400~800 ℃）升温速率对纤维热应力、结构、力学性能的影响。结果表明：随着预炭化升温速率的提高,纤维类石墨层间距 d₀₀₂ 呈现出先减小后增大,晶区堆叠厚度 L_c 呈现出先增大后减小的的趋势;与之相对应的纤维拉伸强度和拉伸模量则呈现出先增大后减小的变化;当升温速率达到132 ℃/min时, d₀₀₂ 和 L_c 分别出现最小值和最大值,此时所得碳纤维的力学性能最高。     

原位转化碳纤维增韧氧化铝复合材料的制备工艺

以聚丙烯腈预氧化纤维为先驱纤维,使其在真空烧结过程中原位转化生成碳纤维来增韧氧化铝陶瓷材料.利用热重–差热分析和X射线衍射研究了聚丙烯腈预氧化纤维的相结构和化学结构以确定制备复合材料的升温烧结工艺,并探讨了加压方式和聚丙烯腈预氧化纤维含量对复合材料组织结构和性能的影响.研究发现聚丙烯腈预氧化纤维在差热曲线上444℃左右的放热峰和X射线衍射图谱中17左右的衍射峰是由预氧化阶段残留的未充分氧化的聚丙烯腈分子引起的;而1073℃左右的吸热峰和25.5左右的衍射峰说明预氧化纤维在加热烧结过程中已开始向碳纤维转变.热压烧结制备的复合材料的力学性能明显优于无压烧结.随着聚丙烯腈预氧化纤维含量的增加,复合材料的密度和显微硬度降低,而断裂韧性则先升高后降低,当聚丙烯腈预氧化纤维体积分数为20%时,复合材料的断裂韧性最大,达9.39MPa.m1/2,说明原位碳纤维的生成提高了复合材料的断裂韧性,其增韧机制主要为纤维拔出和脱黏.     

一步活化法制备过程中H2O蒸气对聚丙烯腈基活性碳纤维(PAN-ACFs)结构性能的影响

以Courtaulds纤维为原料,采用连续化碳纤维生产线制备出稳定的预氧纤维,通过连续化活化炉进行预碳化和水蒸气物理一步活化,制备出具有高吸附性能和高拉伸强度的聚丙烯腈基活性碳纤维（PAN-ACFs）丝束。借助比表面积（BET）、广角X射线衍射（WAXD）、力学性能和碘吸附等表征测试手段研究了水蒸气量对PAN-ACFs孔结构及力学性能的影响。结果表明：在适当的活化时间、活化温度下,逐步增加水蒸气的流量,活性碳纤维的吸附能力先快速增大,而后稳定,最后再缓慢地增加;纤维的拉伸强度呈现出先增大后减小的变化趋势;当水蒸气流量为1g/min,起始的温度为650℃,高温区为850℃,活化时间为20min时,所制备的PAN-ACFs具有相对较高的吸附性能、力学性能和碳化收率。     

聚丙烯腈预氧纤维致密结构的温度时间效应

研究了聚丙烯腈(PAN)纤维在预氧化过程中致密结构的温度时间效应,通过体密度表征纤维的致密结构,并结合其他预氧参数如环化指数、环化度、氧含量及相对环化率的变化,全面分析研究了致密结构的形成演变特征及其梯度预氧化的温度效应和时间效应。结果表明：PAN预氧纤维环化程度的增高有利于致密结构形成,且碳纤维的力学性能与致密结构相关;PAN预氧纤维致密结构的温度效应体现在促进交联芳构化反应上,生成交联环化致密结构;时间效应表现为提高纤维的氧化能力,生成含氧环化梯形的致密结构。     

铜盐在聚丙烯腈(PAN)纤维热稳定化过程中的作用

本文采用动态力学粘弹法(DDV)、红外光谱法(IR)、差示扫描量热法(DSC)、X 光电子能谱分析(XPS)等实验方法研究了铜盐对聚丙烯腈(PAN)纤维热稳定化过程的作用。研究结果表明,经铜盐处理后的 PAN 纤维,其玻璃化温度(Tg)升高了45.6℃,在热稳定化过程中模量损失小,同时,模量回升的温度,即开始环化的温度明显降低。IR 分析显示,经铜盐处理的 PAN 纤维热稳定化时,脱氢和形成芳化结构的速度加快,从而证实了铜盐对 PAN 纤维的环化和氧化有催化作用。     

丙烯酸甲酯在聚丙烯腈原丝热稳定化中的作用

研究了丙烯酸甲酯在丙烯腈共聚纤维热稳定化过程中的作用。实验结果表明,丙烯酸甲酯作为丙烯腈的共聚组分,主要起着延缓氰基环化反应的作用。同时,丙烯酸甲酯的存在对提高聚丙烯腈预氧丝的皮层含量是有益的。     

化学改性聚丙烯腈原丝热应力的研究

采用对比的方法,研究了在热氧稳定化过程中,经高锰酸钾（ＫＭｎＯ４）改性的纤维与未改性纤维的热应力变化。实验表明,两咎纤维在稳定化过程听热应力变化可分为物理和化学变化两个阶段。在相同热氧稳定化条件下,要使两种纤维在物理变化范围内得到相同内和,改性纤维所需负荷较小;在化学变化区,改性纤维所对应的热应力峰值温度较低,表明改性对热氧稳定化反应具有一定的催化作用。     

预氧结构对聚丙烯腈基碳纤维致密结构的影响

利用TG,Raman,EA,XRD,NMR等分析手段,研究了预氧纤维在碳化过程中的结构转变。研究结果表明：碳纤维体密度随预氧纤维体密度的升高呈下降趋势;预氧纤维中的含氧量会影响碳纤维的致密结构,氧元素的脱除影响碳纤维非晶区结构的交缠程度进而影响碳纤维体密度,碳纤维体密度随预氧纤维的含氧量增加而降低。通过碳纤维致密结构与预氧纤维结构的相关性分析,初步建立了两者之间的关联关系。     

预炭化温度对聚丙烯腈基活性碳纤维结构与力学性能影响初探

采用连续化碳纤维实验装置制备活性碳纤维,借助广角X射线衍射(WAXD)、元素分析(EA)、比表面积(BET)、力学性能及碘吸附等表征测试手段研究了预炭化温度对聚丙烯腈基活性碳纤维(PAN-ACFs)结构与力学性能的影响。结果表明:PAN-ACFs的N元素质量分数、孔结构、晶粒尺寸是影响PAN-ACFs力学性能的重要因素,且随着预炭化温度的升高均呈现先减小后增大的趋势;当预炭化温度为680℃时,所制备的PAN-ACFs吸附性能较好,力学性能较佳,此时晶粒尺寸La为1.08nm,N元素质量分数5.7%,平均孔径0.81nm。     

用DSC法研究聚丙烯腈纤维的热性能及其预氧化过程

本文用差示扫描量热法(DSC法)测定了各种聚丙烯腈纤维的热性能.研究表明:纤维的组成、结构、使用的溶剂、成形方法对纤维的热性质都有影响.本文还用DSC法测定聚丙烯腈预氧化纤维的环化度、用DTA法测定预氧化纤维的含湿量,以了解聚丙烯腈纤维预氧化反应的程度,所有这些结果对于预氧化过程的工艺控制及预氧化过程终点的确定都有参考意义.     

Synthesis and Preparation of Polysulfone Hollow Fiber Chelating Membrane Modified with Thiourea

Several kinds of chloromethyl polysulfones （CMPF） with different chlorinity and reactive groups were synthesized by Friedel.crafts reaction, which could be utilized as reactively matrix membrane materials. The CMPF hollow matrix membranes were prepared with phase inversion by utilization of CMPF/additive/DMAC casting solution and CMPF as membrane materials. It was found that the effects of additive content, bore liquid and dry spinning distance on the structure of CMPF hollow fiber matrix membrane were different. A high qualified palysulfone hollow fiber chelating membrane modified with thiourea as chelating groups was prepared using CMPF as membrane matrix materials, through the reaction between thiourea and CMPF hollow fiber matrix membrane to afford the methyl iso-thiourium polysulfone. The experimental results showed that thermal drawing could increase the mechanical properties of matrix membrane, and the thermal treatment could increase the homogeneity and stability of the structure of polysulfoue hollow fiber chelating membrane modified with thiourea.     

Stress and Strain During the Process of Thermal Stabilization of Modified Pan Precursors

Thermal mechanical analysis, FT- IR, WAXD and some conventional measurements, such as densities and mechanical properties, were used to characterize the effect of the modification using KMnO4 and SnCl4 on the thermal mechanical behaviors and structural changes dining the process of thermal stabilization of modified PAN precursors. to the unmodified original PAN precursors, some conclusions were drawn that the thermal stabilization starts at a lower temperature for modified PAN fibers, for example, the peak of thermal stress changes for modified PAN precursors using KMnO4 displays a decrease of 20℃ and a increase of 30% in the ultimate thermal stress, that chemical modification makes structural transformation perfect and increases by 25% of the thermal stress at the temperature range of 230℃- 300℃, that the modified PAN fibers display an increase of 100% in the thermal strain, once after pre-oxidized, show an increase of 7.8% in orientation index, and a decrease of 9.9% in crystal size for identical preload in the region of 13.1 - 14.5 MPa. It was also concluded that the modification using SnCl4 would alleviate the changes in physical and chemical stress regimes and result in improvement in structure and decrease in defects.     

PVC复合稀土热稳定体系加工与应用性能

研究不同稳定体系对聚氯乙烯(PVC)的加工流变行为、力学性能和维卡软化点的影响,通过对比,评价复合稀土稳定剂的综合性能结果表明,复合稀土稳定体系具有良好的综合加工性能,大大改善PVC材料的力学性能.扫描电镜及红外光谱分析证实,稀土热稳定剂具有偶联增韧作用;热分析结果表明,PVC-HREC(稀土稳定剂)体系在氮气中的热降解反应较为简单,为一步反应,通过外推得到其起始降解温度和终止降解温度分别为264.82,325.47 ℃.     

竹束精细疏解与炭化处理对重组竹性能的影响

以去青留黄的竹片为原料,利用纤维原位可控分离技术,对竹片进行精细化疏解处理,再经浸胶、干燥后,采用热压法制备重组竹,并与普通的本色重组竹、低温炭化重组竹、高温炭化重组竹以及竹基纤维复合材料进行对比。结果表明:高温热处理是提高重组竹的耐水性能和尺寸稳定性的有效方法之一,其缺点是力学性能损失严重,静曲强度损失率达到45%; 与高温炭化处理相比,精细疏解加工工艺简单,加工的重组竹力学性能基本不损失,且能更有效地改善重组竹的耐水性能和尺寸稳定性; 与普通本色重组竹相比,采用精细化疏解竹束制备的重组竹,其吸水率降低75%,吸水厚度膨胀率降低67%,耐水性能和尺寸稳定性接近竹基纤维复合材料。     

纤维织物和耐烧蚀填料对硅橡胶涂覆织物性能的影响

为研制防隔热效率更高的耐烧蚀硅橡胶涂覆织物,采用不同种类的纤维织物和耐烧蚀填料制备出多种新型硅橡胶涂覆织物,并分别研究了纤维织物种类、耐烧蚀填料种类和用量对硅橡胶涂覆织物力学性能和烧蚀性能的影响。实验结果表明:当选用碳纤维布(T300)作为增强骨架材料时,硅橡胶涂覆织物的烧蚀性能最优;随着耐烧蚀填料添加量的增大,硅橡胶涂覆织物的邵氏A硬度逐渐增大,其拉伸强度和断裂延伸率均呈现出先升高后降低的趋势;综合考虑力学性能,耐烧蚀填料的最佳用量为2 g/100 g;耐烧蚀填料能有效提高硅橡胶涂覆织物的烧蚀性能,其中酚醛纤维和黏胶基碳纤维的增强效果更好。     

高石粉含量下C80混凝土力学性能数值模拟研究

为研究石粉含量和纤维掺量对C80混凝土基本力学性能（包括立方体抗压强度、轴心抗压强度、抗折强度、劈裂抗拉强度和弹性模量）的影响,本文结合Digimat和Abaqus建立2D随机骨料模型、3D纤维混凝土细观模型。将不同石粉含量、纤维掺量下混凝土的数值模拟与同等条件下基本力学试验结果进行对比分析：2D随机骨料模型中过高（石粉含量大于5%时称为高石粉含量）的石粉含量会降低混凝土的整体力学性能,石粉含量越低模拟值与试验值越接近,当石粉含量为5%时混凝土的整体力学性能达到最佳。3D纤维混凝土细观模型中不同纤维类型对高石粉含量混凝土的强度有不同影响,与玄武岩纤维相比,铜镀纤维的掺入对高石粉含量下混凝土力学性能的增幅更明显。铜镀纤维体积分数为4%和6%时均能提高混凝土力学性能,当体积分数为6%时,混凝土数值模拟与试验结果误差小于7.1%且力学性能达到最优;玄武岩纤维混凝土的抗压性能随纤维体积率的增加而降低,当纤维体积率为1 kg/m3时数值模拟结果与试验结果误差范围在0.4%-8.7%,但对混凝土整体力学性能的提升较小。     

活性碳纤维静电植绒制品及其空气净化性能研究

介绍了利用静电技术将活性碳纤维短绒栽植在普通织物和聚丙烯筛网上的技术与工艺，测试了其吸附与脱附性能，结果表明活性碳纤维静电植绒制品具有优良的吸附、脱附性能，有效地解决了活性碳纤维加工性能差的问题。     

加捻对热致液晶聚芳酯初生纤维拉伸性能的影响

热致液晶聚芳酯(TLCP)的特殊化学结构使其具有高强度、高模量、低粘度、易加工等诸多优良特性,且TLCP纤维力学性能对其应用于纺织业具有举足轻重的作用。本论文主要研究加捻对TLCP纤维力学性能的影响,探究其影响机理。研究结果表明:加捻对其力学性能影响很大,TLCP纤维束的强力随着捻度的增加呈先增大后减小趋势。当TLCP纤维束的线密度为52.50 tex,捻度为130Tm时,最大强度为9.14 cN/dtex。未加捻TLCP单纤维的线密度为1.394 tex时,最大强度为11.3cN/dtex。     

Influence of Thermal Treatment on the Structure and Thermal Properties of Kaolin Modified Polyester Fibers

Modified polyester fibers were obtained using 2% and 6% of kaolin blends through melt spinning.The influences of two thermal treatments maintaining the original tension(180 ℃×2 min and 200 ℃×1 min)on the structure and properties of fiber were compared.The changes of grain size and crystallinity of fiber were investigated by X-ray diffraction(XRD).The changes of thermal properties of fibers were analyzed using dynamic mechanical analyzer(DMA).The results show that the crystalline structure of kaolin modified polyester fiber doesn't change with the thermal treatment.With the kaolin content increasing,the grain size of fiber changed.The higher the thermal treatment temperature is,the higher the crystallinity of fiber is.There are two glass-transition temperatures for kaolin modified:the lower one is the glass-transition temperature of polyester fiber matrix,and the higher one is derived from the heterogeneous blend of polyester matrix and nano kaolin.The higher the kaolin content is,the higher the glass-transition temperature is.Thermal treatment could increase the compatibility of polyester matrix and nano kaolin.There was only one glass-transition temperature for the thermal treatment fiber,and the heat resistance of fiber was improved.Thermogravimetric analysis-differential scanning calorimetry(TGA-DSC)results of kaolin modified polyethylene terephthalate(PET)matrix indicate that the decomposition temperature of PET fibers,kaolin modified PET fibers,and thermal treated fibers were little different within 40%-60% of weight loss rate range.     

Mechanical and Thermal Properties of Apocynum and Ramie Fiber Mat Reinforced Polylactic Acid Composites

With the increasing awareness of environmental protection and rational utilization of resources, natural fiber reinforced composites have shown broad development prospects. Apocynum fiber, known as the "king of wild fiber", not only has moisture absorption, air permeability, and good mechanical properties but also has many health-related advantages such as antibacterial properties. In this study, four types of needle-punched Apocynum fiber and ramie fiber mat reinforced polylactic acid(PLA) composites were fabricated. Mechanical and thermal properties of the composites were tested and analyzed. The results showed that compared with those of the ramie fiber finish needle-punched mat reinforced composites, the tensile strength and the tensile modulus of Apocynum fiber finish needle-punched mat reinforced composites had increased by 15.3% and 60.1%, respectively. In comparison, the bending strength and the bending modulus were decreased by 21.8% and 7.6%, respectively. Moreover, compared with the Apocynum fiber finish needled-punched mat reinforced composites and the ramie fiber finish needle-punched mat reinforced composites, the Apocynum 50/ramie 50 finish needle-punched mat reinforced composites had the best tensile and bending properties. The after-fracture morphology was detected by a scanning electron microscope(SEM). The thermal properties of the composites were also characterized. It was found that the thermal properties of the four types of composites showed very similar behaviors.