PA6/POE-g-MAH共混物缺口冲击的裂纹萌生韧性及裂纹扩展韧性

研究了PA6/POE-g-MAH共混物缺口冲击的裂纹萌生韧性及裂纹扩展韧性.结果显示:质量分数为5%和10%的POE-g-MAH对PA6/POE-g-MAH共混物缺口冲击裂纹萌生阶段增韧效果十分明显,裂纹源为锥窝韧性断裂形貌,但对裂纹扩展阶段的影响不大,其裂纹扩展断面为补丁状脆性断裂特征;15%质量分数以上的POE-g-MAH对PA6/POE-g-MAH共混物缺口冲击裂纹萌生及扩展阶段的增韧效果均十分明显.裂纹扩展断面具有抛物线韧性断裂形貌.锥窝形貌是裂纹源区多核心生长伴随基体塑性变形的结果.裂纹扩展断面的抛物线形貌则是主裂纹扩展面与次级断裂源相交的结果.     

用仪器化冲击实验研究尼龙6的缺口冲击断裂行为

用仪器化冲击实验研究了尼龙6在23、-10、-50℃时的缺口冲击断裂行为。结果显示:温度对尼龙6塑性变形能力的影响导致其裂纹萌生功随温度的降低而减小。冲击曲线的惯性峰值和最大力值受材料硬度和拉伸强度的影响。在23℃时,缺口根部外表层的塑性变形导致最大应力由外表层向内部移动,所以裂纹源在次表层形成。在-10℃和-50℃时,尼龙6的塑性变形能力降低,导致裂纹源在缺口根部的外表层形成。断面形貌显示裂纹源区束状带的断裂可能是尼龙6缺口冲击时裂纹萌生的重要方式。随着温度的降低,束状带的数量减少,尺寸变大。     

PA6/CaCO3复合材料的单边缺口拉伸断裂研究

研究了尼龙6(PA6)/CaCO3复合材料的单边缺口拉伸断裂。结果表明,PA6/CaCO3复合材料在拉伸速率为0.1～300 mm/min的缺口拉伸实验中,裂纹扩展均为脆性断裂。断口主要分为塑性屈服变形区和弹性变形区两部分。塑性屈服变形区形貌是以缺口根部为底边的圆弧型,弹性变形区将塑性屈服变形区包围在里面。塑性屈服变形区面积到达临界尺寸后,材料瞬间断裂。断裂后观察到的塑性屈服变形区面积即为在该实验条件下的裂纹源面积。随着拉伸速率增加,其裂纹源面积减小,而弹性变形区域增加,弹性储存能的储存速度增加,在其裂纹源面积较小的情况下即可发生瞬间脆断。     

用仪表示波系统研究聚丙烯材料的冲击断裂行为

研究了加入一定量成核剂的聚丙烯材料的冲击断裂行为,通过在一般Charpy冲击实验采用仪表示波系统测定了材料的载荷－时间曲线,通过该曲线将冲击断裂过程分为裂纹萌生和裂纹扩展两阶段,并计算出了裂纹萌生功和裂纹扩展功。结果显示,冲击功在成核剂加入量为0．4％处出现极大值,而裂纹萌生功和裂纹扩展功在成核剂加放量为0．4％处出现转折变化,而且裂纹扩展阶段的功耗居于主导地位。     

“沙袋结构”增韧PA6/EPDM-M/nano-CaCO_3复合材料的断裂行为研究

采用二步法工艺制备了含有独特"沙袋结构"的超韧尼龙6/三元乙丙橡胶-马来酸酐接枝三元乙丙橡胶/纳米碳酸钙(PA6/EPDM-M/nano-CaCO3)(两步法)三元复合材料,并通过缺口拉伸和缺口冲击试验研究了其断裂行为,用扫描电镜观察了断面形态。研究结果表明,在材料破坏过程中,纯PA6的裂纹扩展能几乎为零,属典型的脆性断裂,PA6/EPDM-M和PA6/EPDM-M/nano-CaCO3(一步法)有一定的裂纹扩展能,表现出一定的韧性特征。含有"沙袋结构"粒子的PA6/EPDM-M/nano-CaCO3(两步法)复合材料的裂纹引发能与PA6/EPDM-M、PA6/EPDMM/nano-CaCO3(一步法)体系相差不多,但是裂纹扩展能最高,所以断裂总能量最高。断面研究可得,PA6/EPDMM/nano-CaCO3(两步法)通过形成微纤、空穴而消耗大量能量,因此具备极高韧性。     

韧性聚合物材料的基本断裂功和变形行为研究

用双边缺口拉伸试样研究了几种聚烯烃塑料薄片在平面应力条件下的破坏行为。从断裂功 -韧带长度关系得到反映断裂韧性的材料常数比基本断裂功和反映材料塑性变形行为的比非基本断裂功 ,藉此分析和解释了这些材料的韧性和塑性特征 ;同时验算处理表明这些材料的试样断裂伸长与韧带长度均呈直线关系 ,线性回归相关系数达到 0 97～ 0 99,由此求得了反映临界裂纹张开位移的材料参数等。这些参数可用于研究材料的变形能力和断裂行为 ,解释材料的破坏机理     

韧性聚合物材料的基本断裂裂功和变形行为研究

用双边缺口拉伸试样研究了几种聚烯烃塑料薄片在平面应力条件下的破坏行为，从断裂功－韧带长度关系得到反映断裂韧性的材料常数比基本断裂功和反映材料塑性变形行为的比非基本断裂功，藉此分析和解释了这些材料的韧性和塑性特征，同时验算处理表明这些材料的试样断裂伸长与韧带长度均呈直线关系，线性回归相关系数达到0．97－0．99，由此求得了反映临界裂纹张开位移的材料参数等，这砦参数可用于研究材料的变形能力和断裂行为，解释材料的破坏机理。     

长玻璃纤维增强热塑性复合材料研究

分别制备了长玻璃纤维(LGF)、短玻璃纤维(SGF)增强聚苯硫醚(PPS)、聚酰胺(PA)6复合材料,研究了基体树脂粘度、口模类型、GF类型及喂料速度对复合材料力学性能、热性能的影响,利用扫描电子显微镜观察了注塑试样断面形貌及LGF在树脂基体中的分布状态.结果表明,基体树脂的粘度越大,对复合材料的力学性能影响越大;在相同GF含量下,LGF增强PPS、PA6复合材料的热变形温度普遍高于SGF增强PPS、PA6复合材料;LGF增强复合材料抵御裂纹开裂的能力提高.     

PA6相对黏度对PA6/POE-g-MAH共混物缺口冲击性能的影响

研究了尼龙(PA)6相时黏度对PA6/马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)共混物缺口冲击性能的影响.结果表明,PA6的相对黏度对PA6/POE-g-MAH共混物的缺口冲击断裂韧性有明显影响;低黏度PA6/POE-g-MAH共混物冲击断裂过程中的裂纹扩展功明显高于中、高黏度PA6/POE-g-MAH共混物;...     

PC/ABS共混物的仪表冲击试验研究

介绍系列PC／ABS共混物的仪表冲击试验。结果表明，不同温度和不同缺口形式下PC/ABS共混物冲击断裂过程中的裂纹萌生功和扩展功随共混物组成的变化趋势基本一致，但萌生功的变化比扩展功的变化更趋平缓；裂纹萌生功在冲击功中所占比例受温度影响较大，较高温度(19℃)下萌生功所占比例比较低温度(2℃)下小；不同温度下所到得的系列PC/ABS共混物的临界裂纹扩展力GIC值随共混物组成变化均有一极大值，但不同温度下GIC值的极大值点所对应的共混比不同。     

Melt processing,mechanical, and fatigue crack propagation properties of reactively compatibilized blends of polyamide 6 and acrylonitrile–butadiene–styrene copolymer

Within a IUPAC study, melt processing, mechanical, and fatigue crack growth properties of blends of polyamide 6 (PA 6) and poly(acrylonitrile–butadiene–styrene) (ABS) were investigated. We focused on the influence of reactive compatibilization on blend properties using a styrene–acrylonitrile–maleic anhydride random terpolymer (SANMA). Two series of PA 6/ABS blends with 30 wt % PA 6 and 70 wt % PA 6, respectively, were prepared with varying amounts of SANMA. Our experiments revealed that the morphology of the matrix (PA 6 or ABS) strongly affects the blend properties. The viscosity of PA 6/ABS blends monotonically increases with SANMA concentration because of the formation of high‐molecular weight graft copolymers. The extrudate swell of the blends was much larger than that of neat PA 6 and ABS and decreased with increasing SANMA concentrations at a constant extrusion pressure. This observation can be explained by the effect of the capillary number. The fracture resistance of these blends, including specific work to break and impact strength, is lower than that of PA 6 or ABS alone, but increases with SANMA concentration. This effect is most strongly pronounced for blends with 70 wt % PA 6. Fatigue crack growth experiments showed that the addition of 1–2 wt % SANMA enhances the resistance against crack propagation for ABS‐based blends. The correlation between blend composition, morphology and processing/end‐use properties of reactively compatibilized PA 6/ABS blends is discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Short glass fiber reinforced ABS and ABS/PA6 composites: Processing and characterization

In this study acrylonitrile‐butadiene‐styrene (ABS) terpolymer was reinforced with 3‐aminopropyltrimethoxysilane (APS)‐treated short glass fibers (SGFs). The effects of SGF concentration and extrusion process conditions, such as the screw speed and barrel temperature profile, on the mechanical properties of the composites were examined. Increasing the SGF concentration in the ABS matrix from 10 wt% to 30 wt% resulted in improved tensile strength, tensile modulus and flexural modulus, but drastically lowered the strain‐at‐break and the impact strength. The average fiber length decreased when the concentration of glass fibers increased. The increase in screw speed decreased the average fiber length, and therefore the tensile strength, tensile modulus, flexural modulus, and impact strength were affected negatively and the strain‐at‐break was affected positively. The increase in extrusion temperature decreased the fiber length degradation, and therefore the tensile strength, tensile modulus, flexural modulus, and impact strength increased. At higher temperatures the ABS matrix degraded and the mechanical strength of the composites decreased. To obtain a strong interaction at the interface, polyamide‐6 (PA6) at varying concentrations was introduced into the ABS/30 wt% SGF composite. The incorporation and increasing amount of PA6 in the composites broadened the fiber length distribution (FLD) owing to the low melt viscosity of PA6. Tensile strength, tensile modulus, flexural modulus, and impact strength values increased with an increase in the PA6 content of the ABS/PA6/SGF systems due to the improved adhesion at the interface, which was confirmed by the ratio of tensile strength to flexural strength as an adhesion parameter. These results were also supported by scanning electron micrographs of the ABS/PA6/SGF composites, which exhibited an improved adhesion between the SGFs and the ABS/PA6 matrix. POLYM. COMPOS. 26:745–755, 2005. © 2005 Society of Plastics Engineers     

超细旦PA6 FDY的开发

采用稀土化合物与PA6切片共混制备稀土化合物母粒,再与PA6切片共混纺丝,开发了超细旦PA6 FDY,探讨了其生产工艺。结果表明:选择纤维中稀土化合物质量分数0.04%,喷丝板孔径0.25 mm,长径比3.0,纺丝温度270℃,纺丝速度4 200 m/min,侧吹风温度30～40℃,湿度40%～60%,生产40 dtex/72 f超细旦PA6 FDY,生产过程稳定,满卷率达90%,纤维断裂强度4.5 cN/dtex,断裂伸长率30%。     

煤矸石填充聚酰胺6复合材料的结构与性能研究

采用熔融共混法制备了聚酰胺6／煤矸石复合材料，研究了复合材料的力学性能、微观结构、结晶行为和流变性能。结果表明：煤矸石的加入使聚酰胺6的的拉伸强度、弹性模量、弯曲强度和弯曲模量分别增加了约53．8％、66．1％、37．1％和63．4％，而冲击韧性基本保持，煤矸石最佳填充量为25％；煤矸石在聚酰胺6基体中分散均匀，复合材料具有韧性断裂特征；煤矸石使聚酰胺6的结晶温度由187．0℃升高到191．3℃，过冷度由33．6℃降至18．9℃，结晶温度范围变窄，即煤矸石提高了聚酰胺6的结晶速率，对聚酰胺6具有异相成核作用；在所研究的剪切速率范围内，聚酰胺6及其复合材料的流变行为表现为假塑性，煤矸石的加入使非牛顿指数减小，聚酰胺6对剪切敏感性下降。     

Investigation of wicking phenomenon and tensile properties in three-layer composite nanofibrous PA/PLLA yarn

One critical property of a nanofibrous structure is the wicking behavior in contact with liquids. This work's purpose is fabrication and investigation of tensile and wicking properties of a newly designed three-layer nanofibrous yarn consisting of polyamide 6/poly(L-lactic acid) (PA/PLLA) with a similar idea to Bobtex spun yarn structure in which adhesion between core (PA) and sheath (PLLA) is provided with a thin layer of polymeric thin film. The tensile strength and strain decreased 32 and 46%, respectively, in a three-layer yarn compared with two-layer, that is, yarn without the adhesion film. In addition, the ultimate strength of the three-layer yarn was higher than a PLLA yarn. The vertical wicking test for three-layer nanofibrous yarn reveals that at short times, capillary rise kinetics follow the Lucas–Washburn law while increasing the take-up velocity of the take-up roller in yarn fabrication leads to increasing the maximum height of water in yarn.     

熔融反应扩链制备高黏度PA6及其力学性能研究

采用熔融反应挤出作为聚酰胺6(PA6)的扩链方法,以不同马来酸酐含量的苯乙烯-马来酸酐共聚物(SMA)为扩链剂,对PA6进行了扩链研究。对扩链后产物的特性黏度、熔体质量流动速率、氨基含量、凝胶含量及力学性能进行了表征。结果表明,马来酸酐摩尔分数为50%的SMA对PA6扩链效果较好,可使其特性黏度由2.0dL/g增大至4.2 dL/g,熔体质量流动速率则从115 g/10min减小至0.5 g/10min;通过扩链后的PA6氨基滴定测试表明,SMA在熔融挤出过程中与PA6末端氨基官能团进行反应从而引发PA6扩链。经扩链改性,PA6的力学性能得到明显改善,拉伸强度由62 MPa提高至85 MPa,缺口冲击强度则从3.8 kJ/m2提高至7.5 kJ/m2。     

PA6/稀土复合材料的结构和性能研究

通过熔融共混法制备了聚酰胺6(PA6)/稀土复合材料,采用红外光谱测试仪、差示扫描量热仪、X射线衍射仪等对其结构和性能进行了研究。结果表明,PA6与稀土没有发生化学相互作用,稀土对PA6起到异相成核作用,促进γ晶型的生成,但阻碍了α晶型的完美排列;复合材料的结晶度和结晶温度均高于纯PA6;随着稀土含量的增加,复合材料的拉伸强度略有降低,而断裂伸长率先增加后降低;稀土含量为6 %（质量分数,下同）时,断裂伸长率达到328.25 %;PA6/稀土复合材料的初始亮度随着稀土含量的增加而逐渐增强,而亮度呈指数规律衰减。     

熔融挤出温度对PA6/CaCl2复合材料结构与性能的影响

采用熔融挤出的方法,制备了PA6/CaCl2复合材料,研究了熔融挤出温度对PA6/CaCl2复合材料的结晶行为和性能的影响。实验结果表明：随熔融挤出温度的提高,CaCl2与PA6的络合反应程度越大,PA6/CaCl2复合材料的结晶度越小,结晶不完善程度越大,复合材料的粘度越大,熔体流动速率越小。随熔融挤出温度的提高,复合材料的拉伸强度先增大后减小,最后近似趋于定值,冲击强度、弯曲强度随熔融挤出温度的提高总体呈增加趋势。     

耐油性PA6/NBR共混物的制备与性能研究

采用不同种类的丁腈橡胶(NBR)与聚酰胺6(PA6)熔融共混制备了聚酰胺6/丁腈橡胶混合物(PA6/NBR),考察了共混过程中转矩值的变化,并研究了不同腈基含量共混物的拉伸性能及耐溶剂性能。结果表明,随着橡胶相含量的增加,共混物的熔体黏度、体积溶胀率与质量溶胀率均显著提高,但拉伸强度下降。红外光谱分析表面NBR与PA6在高温高剪切作用下存在微化学反应,并且随腈基含量的增加,PA6/NBR共混物的平衡转矩值增大,拉伸强度明显提高,耐溶剂性下降。