Effect of different types and loadings of modified nanoclay on mechanical properties and adhesion strength of EPDM-g-MAH/nylon 66 systems

In this study, the effect of different levels and loadings of modified nanoclay (NC), nanoclay 1 CEC, 2 CEC and 4 CEC, cation exchange capacity on mechanical properties and adhesion strength of maleic anhydride grafted ethylene-propylene-diene terpolymer (EPDM-g-MAH)/nylon 66 systems were investigated. Fourier transform infrared (FTIR) data confirmed the reaction mechanism between maleic anhydride in the polymer backbone and the organomodifier of the nanoclay. Dynamic mechanical analysis (DMA) results showed that on increasing the levels of nanoclay modification, the storage modulus (Eʹ) increased as well as the glass transition temperature (T_g) was slightly shifted to lower temperature and the height of the damping property (tan δ) peaks decreased. The results revealed that the use of the three levels of modified clay with EPDM-g-MAH had significant effects on the tensile strength and elongation at break, especially at 5 parts per hundred rubber by weight (phr) filler content. Whereas in the case of lower nanoclay filler contents (i.e. 1 and 3 phr) the results clarified that they had little effect on tensile and elongation at break values. Pull-out adhesion tests showed that the adhesion force of NC 2 CEC nanocomposite was approximately twice that of the virgin polymer while the nanocomposite NC 4 CEC showed inferior adhesion values, especially at 5 phr filler content. Scanning electron microscopy (SEM) clarified that good wettability of elastomer took place, especially in case of NC 2 CEC which in turn led to an enhancement of the adhesion force between the elastomer and the nylon 66 cord.     

直接电导法测定水溶液中尼龙-66盐的含量

目前 ,测定Nylon -66盐 (以下简称N -66)水溶液中N -66的方法有化学法、折光率法。化学法测量误差大 ,折光率法用眼睛观察刻度尺确定测量数据 ,人为因素较大 ,需要试样量多 ,设备较贵。采用直接电导法测定N -66盐水溶液中N -66含量 ,根据N -66盐在稀溶液中电导率与浓度成线性关系 ,通过测N -66浓度和相应电导率值作工作曲线 ,然后测试样电导率值 ,在工作曲线上求出N -66的浓度、计算出N -66的含量。温度对电导率测定结果有影响 ,可以测温度系数校正 ,也可在恒温水溶中测定以消除温度影响。直接电导法测N -66回收率为 99.88%～ 10 0 .44% ,干扰离子实验绝对误差为 0 .0 1～ 0 .0 4mmol·L- 1 。与化学法、折光率法进行对照实验 ,电导法绝对误差小于 0 .0 1mmol·L- 1 ,相对标准偏差为 0 .0 5 %。比化学法、折光率法都小。直接电导法设备简单、操作方便 ,快速 ,精密度等 ,准确度好。适合于化工实验生产监控     

锦纶—66帘子线耐热油剂的研究

根据锦纶—６６帘子线对油剂的要求进行了该油剂的配方设计，调整了平滑剂与乳化剂的比例，合成了理想的耐热油剂，用于原丝和帘子布生产，各项物理性能指标合格，效果良好．     

基于新UNIFAC基团的尼龙66盐溶解度的计算方法

尼龙66(PA66)盐在水中溶解度的准确计算是尼龙66 聚合过程模型化基础。选择UNIFAC 活度系数方法,针对PA66 聚合体系对组分进行基团划分,定义的新基团为羧基和氨基形成的缔合基团(-CH₂COO^-·⁺H₃NCH₂-)、羧基与其相邻的亚甲基(-CH₂COOH)。利用PA66 盐-水的固液平衡实验数据以及PA66 盐的熔点和熔化焓,回归得到UNIFAC 模型的基团交互作用参数。基于构建的UNIFAC 物性模型预测了0~100℃范围内PA66 盐在水中的溶解度,与实验数据的平均相对误差为2.1%;采用该模型进一步计算工业操作条件(120℃)下的盐浓度,与Aspen 自带参数的UNIFAC 模型比较,其误差从20%左右降到5%以下。     

Quantifying requirements volatility effects

In an organization operating in the bancassurance sector we identified a low-risk IT subportfolio of 84 IT projects comprising together 16,500 function points, each project varying in size and duration, for which we were able to quantify its requirements volatility. This representative portfolio stems from a much larger portfolio of IT projects. We calculated the volatility from the function point countings that were available to us. These figures were aggregated into a requirements volatility benchmark. We found that maximum requirements volatility rates depend on size and duration, which refutes currently known industrial averages. For instance, a monthly growth rate of 5% is considered a critical failure factor, but in our low-risk portfolio we found more than 21% of successful projects with a volatility larger than 5%. We proposed a mathematical model taking size and duration into account that provides a maximum healthy volatility rate that is more in line with the reality of low-risk IT portfolios. Based on the model, we proposed a tolerance factor expressing the maximal volatility tolerance for a project or portfolio. For a low-risk portfolio its empirically found tolerance is apparently acceptable, and values exceeding this tolerance are used to trigger IT decision makers. We derived two volatility ratios from this model, the π-ratio and the ρ-ratio. These ratios express how close the volatility of a project has approached the danger zone when requirements volatility reaches a critical failure rate. The volatility data of a governmental IT portfolio were juxtaposed to our bancassurance benchmark, immediately exposing a problematic project, which was corroborated by its actual failure. When function points are less common, e.g. in the embedded industry, we used daily source code size measures and illustrated how to govern the volatility of a software product line of a hardware manufacturer. With the three real-world portfolios we illustrated that our results serve the purpose of an early warning system for projects that are bound to fail due to excessive volatility. Moreover, we developed essential requirements volatility metrics that belong on an IT governance dashboard and presented such a volatility dashboard.     

Design of experiments for bivariate binary responses modelled by Copula functions

Optimal design for generalized linear models has primarily focused on univariate data. Often experiments are performed that have multiple dependent responses described by regression type models, and it is of interest and of value to design the experiment for all these responses. This requires a multivariate distribution underlying a pre-chosen model for the data. Here, we consider the design of experiments for bivariate binary data which are dependent. We explore Copula functions which provide a rich and flexible class of structures to derive joint distributions for bivariate binary data. We present methods for deriving optimal experimental designs for dependent bivariate binary data using Copulas, and demonstrate that, by including the dependence between responses in the design process, more efficient parameter estimates are obtained than by the usual practice of simply designing for a single variable only. Further, we investigate the robustness of designs with respect to initial parameter estimates and Copula function, and also show the performance of compound criteria within this bivariate binary setting.     

增强增韧尼龙66工程塑料结晶行为的研究

采用ＤＳＣ技术,对增强增韧尼龙６６进行了结晶行为的研究。实验结果表明,在合金化改性ＰＡ６６结晶过程中,所填充的玻纤增强剂成核剂作用,而共混低密度聚乙烯、聚丙烯及其马来酸酐接枝物等增韧剂,使成核作用下降,总的成核作用顺序是：ＰＡ／ＧＦ〉ＰＡ／ＧＦ／ＬＤＰＥ－ｇ－ＭＡＨ〉ＰＡ／ＧＦ／ＰＰ〉ＰＡ／ＧＦ／ＰＰｇ－ＭＡＨ。     

Structure characterization of heat set and drawn polyamide 66 fibers by FTIR spectroscopy

Structural changes that occur during thermally induced and strain induced crystallization of polyamide 66 fibers were studied by infrared spectroscopy, density measurement and optical microscopy. Two bands at 924 and 1136 cm^–1 were shown to arise from the amorphous phase and assignment of the bands at 936 and 1200 cm^–1 to the crystalline phase were confirmed. We demonstrated that two different infrared spectroscopic methods could be used to determine the total crystallinity of polyamide 66 fibers. One is a calibration method in which the band ratio of 1200 and 1630 cm^–1 is plotted against the crystallinity measured by density measurements. The other one is an independent infrared method. Crystallinity obtained by the independent infrared spectroscopic method showed good agreement with crystallinity observed by density measurement. Infrared dichroism was used to obtain the crystalline orientation using the band at 936 cm^–1. The transition moment angle of 48° was found for the band at 936 cm^–1 with respect to chain axis. Amorphous orientation was obtained using Stein’s equation. Received: 18 September 2000 / Reviewed and accepted: 20 September 2000     

碳纤维增强尼龙66的研究

利用HAAKE流变仪研究了碳纤维增强尼龙66的流变特性,以及温度对碳纤维增强尼龙66流变性能的影响,并测试了碳纤维增强尼龙66的力学性能。结果表明,碳纤维增强尼龙66在一定剪切速率下,剪切应力下降,表观粘度降低,并且随着剪切速率增加,表观粘度提高;当挤出机头温度升高时,在一定剪切速率下,其剪切应力和表观粘度都降低。而制品的硬度、冲击强度和拉伸强度等力学性能均比纯尼龙66有明显的提高。     

PA66/UHMWPE合金的力学性能和微观结构研究

制备了PA66／uHMwPE／HDPE-g-MAH共混合金,并对其力学性能和微观结构进行了研究。结果表明,随着UHMWPE质量分数的增加,共混合金常温和低温下的缺口冲击强度都显著提高,拉伸强度和拉伸模量下降,但仍能保持较高的力学性能;添加了UHMWPE的PA66合金的断裂面有大量的空穴产生和应力发白现象。