碳纤维-Ni/尼龙66复合材料的制备与性能表征

为制备低电阻率的尼龙66基复合材料,以碳纤维和镍粉(Ni)填充尼龙66制备碳纤维-Ni/尼龙66高导电复合材料。研究填料表面改性和含量对碳纤维-Ni/尼龙66复合材料导电性能和力学性能的影响。结果表明:KH550改性碳纤维和Ni有助于降低碳纤维-Ni/尼龙66复合材料的电阻率。碳纤维-Ni/尼龙66复合材料的电阻率随着碳纤维和Ni含量的增加而减小,且碳纤维和Ni填充尼龙66的导电逾渗阈值均为20wt%,此时制备的碳纤维-Ni/尼龙66复合材料的电阻率为455Ω·cm,熔融温度为202.2℃。碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度随着碳纤维或Ni含量的增加而先增大后减小。当Ni含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度在碳纤维含量分别为20wt%和10wt%时达到最大值,分别为98MPa和70 MPa;当碳纤维含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度则在Ni含量为30wt%和20wt%时达到最大值,分别为120 MPa和67 MPa。     

酰胺链硅烷界面结合剂对尼龙66/玻纤复合材料性能的影响

采用熔融挤出共混制备了尼龙66(PA66)/玻璃纤维(GF)复合材料,比较了常用硅烷偶联剂KH550与不同有机酸封端的酰胺链硅烷界面结合剂(ASI)对复合材料的力学性能、动态力学性能及界面层结构的影响,探究了复合材料中界面层形成的机理。结果表明,ASI与玻纤表面反应发生了化学反应,ASI添加量为1.5%时,对PA66/GF复合材料的力学性能改善效果最明显,其中,以对苯二甲酸封端,相对分子质量为2000左右的PTA-ASI使PA66/GF复合材料的界面能力提升最高,拉伸强度提高了54.8%,复合材料的综合性能提高最为显著。     

有机化蒙脱石填充尼龙66复合物的结晶与热力学行为研究

通过熔融共混法制备了有机化蒙脱石填充的尼龙66复合材料,通过示差扫描量热分析（DSC）,偏光显微镜照片（POM）和动态力学分析（DMA）等手段研究了复合材料的非等温结晶过程,结晶形态和球晶尺寸,动态力学行为等,并与普通尼龙66进行了比较,发现经过有机化蒙脱石填充的尼龙66的结晶速率比较快,球晶尺寸较小,弹性模量较大。     

多孔n-HA/CS/PA66三元复合支架材料的制备及性能

采用常压共混复合法制备了纳米羟基磷灰石/壳聚糖/聚酰胺66(n-HA/CS/PA 66)三元复合材料,并以乙醇为溶剂,聚乙烯吡咯烷酮和氯化钠混合物为致孔剂的粒子沥滤法制备了n-HA/CS/PA 66三元复合多孔支架材料,用燃烧试验、IR、XRD、SEM、孔隙率及力学性能测试等手段对其进行了表征。结果表明,n-HA在复合材料中分布均匀且呈弱结晶状态,复合前后三组分的化学组成未发生显著变化,但三相间两两均发生了相互作用。在制备n-HA/CS/PA 66多孔材料时,加入少量的聚乙烯吡咯烷酮可使该多孔材料孔隙率更高,孔的贯通性更好。     

金属基复合材料减磨抗冲击性能试验研究

阐述了50#钢的优点与不足,提出了一种主要成分为50#钢及尼龙66(聚己二酸已二胺)的金属塑料复合材料.论述了这种金属塑料复合材料的制备过程,进行了摩擦、摩损及冲击试验,并分别用相同尺寸的50#钢及表面附着普通涂料的50#钢作对比试验.摩擦、磨损试验结果表明,复合材料的摩擦系数高于50#钢的摩擦系数,稳定摩擦出现较早;相同时间内,复合材料的磨损体积远低于50#钢.冲击试验结果表明,相同条件下,复合材料的抗冲击性能比对比材料高18%～27%.试验结果表明复合材料的综合性能明显提高.     

On the sliding wear of nanoparticle filled polyamide 66 composites

The tribological properties of polyamide 66 (PA66) composites, filled with TiO₂ nanoparticles, short carbon fibres, and graphite flakes, were investigated. Sliding tests were performed on a pin-on-disk apparatus under different contact pressures, p, and sliding velocities, v. It was found that nano-TiO₂ could effectively reduce the frictional coefficient and wear rate, especially under higher pv (the product of p and v) conditions. In order to further understand the wear mechanisms, the worn surfaces were examined by scanning electron microscopy and atomic force microscopy. A positive rolling effect of the nanoparticles between the material pairs was proposed which contributes to the remarkable improvement of the load carrying capacity of polymer nanocomposites.     

Embrittlement Mechanisms of Nylon 66/Organoclay Nanocomposites Prepared by Melt-Compounding Process

Nylon 66 nanocomposites with different smectite clay loadings were prepared by conventional melt compounding process. The fracture toughness decreases with increasing clay content, which is a direct result of reduced plastic zone size at the crack tip region. The fracture mechanisms were studied using double-notched four-point-bending (DN-4PB) technique. A constraining effect from nanoclay fillers on plastic deformation of matrix is revealed by transmission electron microscopy (TEM). Micron-sized and submicron voids could be observed around the clay platelets. The voids coalesce and form premature cracks that promote crack propagation, thus reducing toughness.     

聚酰胺/聚苯硫醚共混物摩擦学性能研究--(Ⅱ)水润滑

研究了PA66／PPS共混物在水润滑条件下的摩擦磨损性能。结果表明，共混物显著降低了PA66和PPS的摩擦系数，并远远低于干摩擦条件下的摩擦系数。其中，70％φ(PA)／30％φ（PPS)共混物在水润滑条件下的摩擦磨损性能最好。扫描电子显微镜(SEM)分析表明，水的存在抑制了聚合物在对偶钢环上形成转移膜的能力，材料的摩擦磨损主要是由对偶面上的微突起在样品表面的犁耕作用造成的。同时，水也起到了冷却剂的作用。     

n-HA晶体及n-HA/PA66复合材料与人皮质骨的定性和定量对比研究

用TEM、XRD、FT-IR、TG-DTA等测试手段对成熟的人股骨皮质骨、纳米羟基磷灰石n-HA及n-HA／聚酰胺66(PA66)复合材料的形貌、相组成、晶胞参数、微晶尺寸分布、微观应变、特征基团和离子以及组成等进行了定性和定量表征。提出了一种简单易行的制样方法以获得较为清晰的人骨磷灰石照片。定量比较了人骨与两种材料中磷灰石晶体的结构差异。结果表明，n-HA和n-HA／PA66均具有较高的仿生性能。n-HA和n—HA／PA66中磷灰石的结晶度高于人骨磷灰石，晶格较人骨磷灰石完善，晶格畸变程度较人骨磷灰石小，并且两者中水分含量和CO3^2-含量均低于人骨。本文的研究对于进一步优化现有的骨修复替代材料和进一步开发更接近于人骨的骨修复替代材料具有重要意义。     

The prevalence of keratoconus in northern Poland: A cross-sectional study of patients from a primary healthcare practice

IntroductionKeratoconus is defined as central and/or paracentral corneal thinning and steepening with consequent irregular astigmatism. To date, no prospective study has reported its prevalence in Central Europe. This study aimed to evaluate the prevalence of keratoconus assessed with Scheimpflug imaging in a profile of general medicine practice in Poland.MethodsThis cross-sectional study collected data by inviting all patients aged 10–80 years subscribed to a single general practitioner in the Elbląg area, Poland. Corneal measurements were performed using a rotating Scheimpflug corneal tomography system. Three masked examiners established the diagnosis of keratoconus in the right or left eye. Fleiss’ kappa coefficient (κ) was used to qualitatively analyze the interexaminer agreement.ResultsOf 1,705 patients invited to the study, 771 agreed to participate (45.2%). The mean age of the 728 patients (60.6% female and 39.4% male) with gradable images in at least one eye was 53.6 ± 16.5 years. All of the examiners classified the same four cases as keratoconus (0.549%, 549 per 100,000, 95% confidence interval 150 to 1,400 per 100,000), of which two were bilateral. Fleiss’ kappa showed almost perfect agreement among the three examiners regarding the diagnostic decision (κ = 0.784, 95% confidence interval 0.750 to 0.817, p < 0.001). The keratoconus cases were all women (p = 0.106), aged 48, 69, 70, and 71 years old.ConclusionThe prevalence of keratoconus in this area was higher than that previously demonstrated in many European countries. Underestimation of the prevalence has been postulated but never demonstrated.