芳纶浆粕纤维的辐照改性研究

将芳纶浆粕纤维经NaOH溶液处理后再在氧气和空气两种不同的氛围中用60Co-γ进行辐照改性,研究辐照后芳纶浆粕纤维的吸收剂量和气体氛围对芳纶浆粕纤维的影响.结果表明,经NaOH溶液处理的芳纶浆粕纤维表面发生了变化,接触角降低;经γ射线辐射改性后,纤维表面粗糙度增大,产生了一定的横断纹;芳纶浆粕纤维在氧气氛围中经辐射改性,当其吸收剂量为50～300 kGy时,纤维表面的接触角增大,亲水性提高.     

芳纶短纤维/芳纶浆粕增强制备高性能氯丁橡胶复合材料

对芳纶短纤维和芳纶浆粕进行微观结构表征和热失重分析,系统地研究了芳纶短纤维和芳纶浆粕对橡胶复合材料基本物理性能、动态力学性能和动刚度的影响。结果表明,芳纶短纤维为巨原纤模型;芳纶浆粕为微纤模型,呈羽绒状。芳纶短纤维在500 ℃降解,650 ℃左右降解基本完全;芳纶浆粕在350 ℃左右开始降解,500 ℃左右迅速降解,直到650 ℃左右降解基本完全。芳纶短纤维/芳纶浆粕增强制备的氯丁橡胶复合材料的撕裂强度、拉断伸长率、屈挠性能随着芳纶短纤维/芳纶浆粕并用比值减小而提高,但其动刚度减小。动态力学性能表明芳纶短纤维与芳纶浆粕并用比为10:10时,有相对较高的储能模量,较低的损耗模量和损耗因子,动态疲劳性能较好。     

提高芳纶原纸强度的工艺研究

通过实验研究了芳纶浆粕的性质、芳纶浆粕与芳纶短切纤维配比、分散剂的用量及成形方法对芳纶原纸强度的影响,从而确定较为合适的芳纶原纸抄造工艺。结果显示:高打浆度、表面起毛程度较好的浆粕有利于提高芳纶浆粕与纤维之间的结合力,从而提高芳纶原纸的强度;浆粕与纤维质量比为1.5∶1时芳纶原纸强度最好;抄纸时适量加入PEO分散剂可提高芳纶原纸的匀度和强度,最佳PEO质量分数为0.15%;分层成形比一次成形所得芳纶原纸强度更高。     

一种通过打浆度预测对位芳纶浆粕性能的新方法

对位芳纶浆粕是高性能纤维对位芳纶纤维的差别化产品,广泛应用于复合材料、航空航天、汽车工业等领域.本文以对位芳纶短切纤维为原料用实验室小型瓦利打浆机制备了一系列不同打浆度的对位芳纶浆粕,对浆料的打浆度(Bd)、保水值(Wrv)、帚化率(Rf)及细小纤维含量(Fc)进行测定.并根据试验数据对对位芳纶浆粕的打浆度与保水值、帚化率及细小纤维含量之间的关系进行了深入分析.研究发现,对位芳纶浆粕的打浆度与保水值、帚化率及细小纤维含量有良好的线性关系,三者之间量化关系的方程分别为:Wrv=1.09×Bd+40.81;Rf=0.037×Bd+1.49;Fc=0.69×Bd+43.77,相关系数分别为0.9894、0.9915、0.9803,据此可通过打浆度的测定由这些经验公式对对位芳纶浆粕的保水值、帚化率及细小纤维含量进行预测.进一步的验证试验表明,该预测方法有很高的准确率,预测的保水值、帚化率及细小纤维含量的平均误差率均较小,分别为1.08%、3.29%、2.02%.该研究成果对于对位芳纶浆粕的生产和质量控制具有非常重要的参考价值.     

芳纶浆粕增强制动摩擦材料摩擦性能的可拓评价

研究了芳纶浆粕含量和摩擦温度对制动摩擦材料摩擦性能的影响,并应用可拓评价方法对芳纶浆粕增强制动摩擦材料的摩擦系数和磨损率进行了可拓评价。结果表明,5种制动摩擦材料都具有较好耐磨性,且芳纶的加入进一步改善了摩擦材料的耐磨性;5个试样按照计算所得综合关联度的优劣排序为:T-3.4,T-0,T-14.6,T-5.6,和T-9.0(数字代表芳纶浆粕在配方中的体积分数),且芳纶浆粕体积分数为3.4%时该摩擦材料的摩擦系数和磨损率的综合效果最好。     

剪切速率对直接法制备芳纶浆粕缩聚反应影响的研究

研究了剪切速率对低温溶液直接缩聚法制备聚对苯二甲酰对苯二胺浆粕(芳纶浆粕，PPTAPulp)缩聚反应过程的影响。利用PPTA刚性分子发生逐步缩聚反应的缩聚模型，解释了在缩聚反应过程中，分子链的取向是提高PPTA相对分子质量的必要条件。实验结果表明，提高剪切速率有利于PPTA分子沿流动方向取向，从而提高缩聚反应速率以及芳纶浆粕的相对分子质量，同时还有利于提高浆粕的长径比(L／D)。     

改性尼龙6复合材料的力学性能研究

采用经化学改性的芳纶纤维增强尼龙6,并通过红外光谱和环境扫描电镜分析其界面层.结果表明,芳纶纤维经异氰酸酯化及封端稳定处理后,其表面所接枝的不稳定基团-NCO转化成稳定的-NHCO-,封端结果较为明显;改性后纤维表面附有接枝物,从而使表面粗糙程度大大增加.力学性能测试结果显示改性尼龙6复合材料的拉伸和弯曲强度得到了改善,但冲击性能略为下降.     

芳纶短纤维对丁腈橡胶的增强作用

未经粘合处理的芳纶短纤维对丁腈橡胶也有明显的增强作用．通过对芳纶、尼龙及腈纶短纤维增强橡胶复合材料的性能研究,发现芳纶纤维在开炼机上混炼过程中,出现纤维劈裂和原纤化,既增大了纤维的表面积,又使主纤维通过原纤维相互缠结．结果表明：纤维与基体拔脱力的增加,是芳纶短纤维增强丁腈橡胶复合材料拉伸强度和溶胀性能提高的主要因素．     

耐磨高强度工程塑料的研究

该产品主要应用于煤矿工业洗煤厂振动筛所用的脱水筛板,替代使用寿命不到6个月的不锈钢脱水筛板.该研究采用复合耐磨剂-纤维-尼龙6多元复合技术,使尼龙6的综合力学性能、摩擦、磨损性能有很大提高,使改性尼龙6材料性能满足脱水筛板的使用要求.     

尼龙-6的准韧性特征分析

通过缺口冲击、无缺口冲击及缺口拉伸实验研究了尼龙-6的准韧性特征。尼龙-6的缺口冲击表现为脆性,而无缺口冲击则表现为韧性。在尼龙-6的无缺口冲击实验中,拉伸响应区横截面因拉伸塑性变形而收缩,压缩响应区的横截面则因压缩而挤压膨胀。在尼龙-6单边缺口拉伸实验中,随着拉伸速度增加,缺口拉伸断裂发生韧脆转变,同时伴随着裂纹扩展功的急剧降低。尼龙-6准韧性特征可能主要与材料的局部应变响应速率有关。当局部应变响应速率较低时,尼龙-6的断裂表现为韧性;当局部应变响应速率较高时,尼龙-6的断裂表现为脆性。     

A STUDY OF THE MORPHOLOGY OF POLY(1,4 PHENYLEN TEREPHATHALAMIDE) (PPTA) PULP

The morphology of PPTA pulp is investigated by means of optical microscope and scanningelectron microscope (SEM). It shows that PPTA pulp has feather-like branch, needle point-likeend, and irregular cross-section, which are very important for PPTA pulp as a reinforcer. Theseparation limitation of PPTA pulp is also investigated from both torn and brittle break cross-sec-tion. A packing mechanism is proposed to illustrate the microfibril packing in the gel system.     

新型对位芳香族聚酰胺PPTA浆粕制备的综述

本文是一篇关于PPTA(聚对苯二甲酰对苯二胺)浆粕的制备,成型机理及应用的综述。它汇集了近几年来国内外对PPTA浆粕纤维在制备工艺,成型机理以及应用等方面的研究成果,并对目前国内外主要采用的纺丝法,非纺直接法工艺分别进行了讨论。特别是对于八十年代中期刚刚兴起的非纺直接法,由于其生产成本低,工艺简单,很有发展前途,本文对此作了较为详细的介绍。     

低温溶液缩聚法直接制备PPTA浆粕基本规律的研究

对聚对苯二甲酰对苯二胺浆粕在N-甲基吡咯烷酮-氯化钙溶剂体系中低温溶液缩聚反应及熟化成纤过程的基本规律进行了研究，通过优化聚合工艺条件得到相对分子质量较高的PPTA浆粕，为采用双螺杆挤出机作为主反应器低温溶液缩聚法直接制备PPTA浆粕奠定基础。     

Surface Modification of Poly-(p-Phenylene Terephthalamide) Pulp with a Silane Containing Isocyanate Group for Silicone Composites Reinforcement

A silane containing isocynate groups(3-(trimethoxysilyl) propyl cyanic acid ester,NCO) associated with hexamethyldisilazane(HDMS) is used to modify the surface of poly-(p-phenylene terephthalamide)(PPTA) pulps. As concerns surface chemistry,Attenuated Total Reflection Flourier Transformed Infrared Spectroscopy(ATR FT-IR) and X-ray photoelectron spectroscopy(XPS) confirm that NCO associated with HDMS silylated PPTA pulp surface successfully. While the modified PPTA pulps are used as reinforcing fillers for silicone composites,the dispersibility and storage stability of the composites are improved as Mooney testing indicated. The silicone composites filled with modified PPTA pulps present a higher tensile strength and much higher broken elongation(3.30 MPa and 166.54%) than that with unmodified pulps(3.08 MPa and 68.47%),respectively.     

Surface modification of poly-(<Emphasis Type="Italic">p</Emphasis>-phenylene terephthalamide) pulp with a silane containing isocyanate group for silicone composites reinforcement

A silane containing isocynate groups (3-(trimethoxysilyl) propyl cyanic acid ester, NCO) associated with hexamethyldisilazane (HDMS) is used to modify the surface of poly-(p-phenylene terephthalamide) (PPTA) pulps. As concerns surface chemistry, Attenuated Total Reflection Flourier Transformed Infrared Spectroscopy (ATR FT-IR) and X-ray photoelectron spectroscopy (XPS) confirm that NCO associated with HDMS silylated PPTA pulp surface successfully. While the modified PPTA pulps are used as reinforcing fillers for silicone composites, the dispersibility and storage stability of the composites are improved as Mooney testing indicated. The silicone composites filled with modified PPTA pulps present a higher tensile strength and much higher broken elongation (3.30 MPa and 166.54%) than that with unmodified pulps (3.08 MPa and 68.47%), respectively.     

PPTA/尼龙1010分子复合材料的结晶与熔化行为

研究了PPTA/尼龙1010分子复合材料的等温结晶与熔化行为,发现PPTA对尼龙1010有强的成核作用,使尼龙1010的T_c,k值,T_m提高,n值减小,这是由于PPTA作为晶核其表面与尼龙1010分子链的相互作用所致。PPTA还可减弱尼龙1010自身形成氢健的温度依赖性而有利于改善尼龙1010在等温结晶时的晶格畸变。     

Effect of Added Poly （vinyl pyrrolidone） during Condensation on Properties of Poly（p-phenylene terephthalamide）Pulp

Poly (p-phenylene terephthalamide) (PPTA) pulp was prepared by polycondensation of the p-phenylene diamine (PPDA) with terephthaloyl chloride (TPC) in the completely anhydrous solvent system of N-methyl pyrrolidone (NMP) having calcium chloride, in the presence of poly (vinyl pyrrolidone) (PVP) having a viscosity average molecular weight lower than 40 000. It was confirmed that the polycondensation could be accelerated, the inherent viscosity of the polymer could be increased, and the polymers could be fibrillated more easily by the addition of the PVP. FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps. The morphology of the resultant pulps, the effect of viscosity average molecular weight, amount and adding mode of PVP on inherent viscosity, specific surface area,and mean length of the resultant pulps were discussed in detail. And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.     

PPTA/尼龙-1010分子复合材料热行为与力学性能的研究

采用共沉淀法制得了 Ｐ Ｐ Ｔ Ａ／ 尼龙－ １０１０ 分子复合材料,并对其熔融特性、拉伸性能作了测试。结果发现由于 Ｐ Ｐ Ｔ Ａ 的加入,可以提高尼龙－ １０１０ 熔点和结晶温度,提高尼龙－ １０１０ 的拉伸强度和模量,并对 Ｐ Ｐ Ｔ Ａ 增强尼龙－ １０１０ 的机理进行了初探。     

AN INVESTIGATION OF THE BENDING FATIGUE OF MODIFIED PPTA FIBRE

PPTA fibres have high axial tensile strength,but the transverse links at the macromolecularlevel of the fibres are low.The high orientation and crystallization of the PPTA fibres leads to alow resistance to bending fatigue.A comparative study on fatigue behaviour of PPTA fibres and modified PPTA fibres weremade by rotating fibre over a pin.The resistant properties of the PPTA fibre to the bending fa-tigue are low,but can be improved by modification.The morphological differences of the deformation processes of the PPTA fibres and modi-fied PPTA fibres as they are tensioned in a monofilament from after being knotted are shown.The properties of resistance to bending fatigue of the different PPTA fibres can be evaluatedby comparing the morphologies of the tensile broken ends of these fibres after knotting.