热塑弹性体SBS气候老化行为规律

SBS是苯乙烯-丁二烯的嵌段共聚物，具有弹性和可塑性双重性能，是一种用途非常广泛的高分子材料，可是由于分子链结构中存在二烯结构，其耐候性极差，在广州户外暴露试验仅只能维持半个月时间，如果掺入适量的稳定剂可以适当延长其户外寿命。户内暴露试验却完全不同，尤其生胶，试验5年或更长时间，还可以再使用。在气候试验的基础上，研讨了二种SBS(线型和星型)的凝胶含量与拉伸性能表征行为的相关性，看来用凝胶含量来衡量SBS户内外老化程度是可行的，可作为力学性能的补充。     

Evaluation of biocides for treatment of polyvinyl chloride film

The results of a study to determine the biological stability of clear, colorless, biocide-treated PVC film are presented. With the exception of a resistant control, all the PVC film samples tested contained a plasticizer susceptible to biological deterioration. Biocide-treated and control PVC film samples were subjected to biological attack in soil burial. Portions of each sample were exposed to leaching and to weathering in a weatherometer followed by soil burial to test the stability of each biocide to loss by water and weathering exposure. Of the 32 biocide preparations tested only 2, N-(trichloromethylthio) phthalimide and copper 8-quinolinolate, a known effective reference compound, were found to provide good protection for treated film in direct soil burial and in soil burial following leaching and weatherometer exposure. Natural weathering outdoors confirmed the results found with weatherometer exposed samples. The N-(trichloromethylthio) phthalimide was less effective than the reference compound in suppressing surface growth. In addition, N-(trichloromethylthio) phthalimide may not be compatible with all PVC formulations.     

底面合一阴极电泳漆的研究

采用丙烯酸树脂与环氧树脂冷拼工艺制备的阴极电泳漆解决了环氧类阴极电泳漆作为底面合一涂层时老化性能差的问题，针对乳液在施工应用中的稳定性，探讨了亲水性溶剂、酸值对乳液及电泳漆漆膜的影响，通过液相色谱仪分析槽液中树脂比例变化，并用人工加速老化实验验证了涂膜的老化水平，结果表明，底面合一型电泳漆在老化、盐雾等方面达到了和谐统一，可满足有关汽车底盘及零部件的综合要求。     

UPVC门窗型材用复合稳定剂的对比研究

选择未增塑聚氯乙烯（UPVC）门窗型材市场上常用的铅盐复合稳定剂、稀土复合稳定剂和新近推出的钙锌复合稳定剂，在配方相同或相近的条件下，采用刚果红试验、吉尔加速热老化试验、转矩流变试验、耐候性试验比较加入不同复合稳定剂的未增塑聚氯乙烯材料的热稳定性、流变性和耐候性，反推其对应复合稳定剂的热稳定剂、内外润滑匹配和光稳定剂的差异。结果显示：传统的铅盐类复合稳定剂在UPVC材料的热稳定性上占优势，新推出的钙锌类复合稳定剂在UPVC材料的耐候性上占优势，而不同复合稳定剂的内外润滑匹配的差异性导致UPVC材料的流变行为不一致。     

Reststabilität von verarbeitetem Polyvinylchlorid

The residual stability of a PVC-compound, stabilized by a solid stabilizing agent, was measured by degradation experiments in bulk under pure nitrogen at 180°C. Several samples of different processing times were prepared by thermomechanical treatment on an extruder. Investigations of the residual stability showed an increasing tendency after the first runs, and then a decrease in stability. The same experiments were performed with a plasticized PVC-compound. Instead of an increase of the residual stability in the beginning of the thermomechanical treatment, a continuous decrease was observed. The same result was found by application of a liquid stabilizing agent to unplasticized PVC. Thus, maximum initial stability is found in the case of plasticized PVC and with liquid stabilizers in unplasticized PVC. In contrast to this result maximum initial stability of PVC, stabilized by a solid stabilizer, was obtained only after several runs on the extruder. This phenomenon can be attributed to a better homogeneity of the stabilizer and the polymer, which is effected by gelation of the PVC by the thermomechanical treatment on the extruder. If the investigation of the residual stability is measured after each run by degradation in a solution of ethylbenzoate the nonplasticized PVC-compound shows maximum stability at the beginning of the experiment. This result leads to the conclusion that the stability of a PVC-compound does not only depend either on the kind or on the amount of the applied stabilizer. To ensure the optimal efficiency of the utilized amount of stabilizer it is necessary to secure a maximum of homogeneity between stabilizer and polymer from the very beginning. Therefore it is of great importance t o the estimation of the residual stability of a PVC-compound after processing to make sure of maximum homogeneity between stabilizer and polymer.     

Effect of expandable graphite and ammonium polyphosphate on the thermal degradation and weathering of intumescent fire-retardant coating

This research aims to study the effect of ammonium polyphosphate and expandable graphite on the intumescent coating formulations (ICF). The coating presented in this research article is based on carbon source expandable graphite (EG), blowing agent melamine, acid source ammonium polyphosphate (APP), epoxy resin as a binder with polyamide amine. The stability of the developed coating was verified at 950°C for 1-hour fire test. The results showed that the coating is stable and well bond with the steel substrate. The char was characterized by using FESEM, XRD, FTIR, DTA, TGA, XPS, Py-GCMS and Weathering Test. The morphology of the char was studied by SEM of the coating after furnace fire test. XRD and FTIR show the presence of graphite, borophosphate; boron oxide and sassolite in the residual char. TGA and DTG disclosed that EG improved the residual mass of coating. XPS analysis showed the char residue of IF5-APP-EG contains carbon and oxygen contents 47.50 and 40.70, respectively. Py-GCMS analysis described that the IF5-APP-EG released less gaseous compounds. The weathering test illustrated that's the char expansion of coatings samples was decreased due to the presence of a humid environment and UV light. The IF5-APP-EG showed the maximum char expansion, lower substrate temperature and high residual weight among the studied formulations.     

Effect of artificial weathering and temperature cycling on the performance of coating systems used for wooden windows

The effects of ultraviolet light irradiation and water spray and temperature cycling on the color stability of waterborne coating systems on spruce were investigated. The test samples were treated with three coating systems (white and brown pigmented acrylate waterborne coatings systems with different layering) from six producers. The artificial weathering was carried out based on standardized (504 h) and increased weathering parameters (504 h). Thirty cycles of temperature changes were performed. Discoloration suggesting the rate of degradation process and color stability was measured by a spectrophotometer in L*a*b* color space. The results showed greater color stability of white coating systems during both experiments. The producer of acrylate coatings with iodopropynyl butyl carbamate and permethrin as biocides and benzotriazole, silicon dioxide and methylsiloxane as additives was characterized by the best coatings performance. The most sensitive color parameter to describe the surface quality as a result of irradiation and water spray has proven to be a change of lightness. A tendency towards degradation with increasing lightness was observed during weathering. The effect of temperature itself on color change was minimal. Scanning electron microscopy and energy dispersive spectroscopy revealed microscopic changes of coatings caused by artificial weathering.     

Thermal residual stresses in bilayered,trilayered and graded dental ceramics

Layered ceramic systems are usually hit by residual thermal stresses created during cooling from high processing temperature. The purpose of this study was to determine the thermal residual stresses at different ceramic multi-layered systems and evaluate their influence on the bending stress distribution. Finite elements method was used to evaluate the residual stresses in zirconia-porcelain and alumina-porcelain multi-layered discs and to simulate the ‘piston-on-ring’ test. Temperature-dependent material properties were used. Three different multi-layered designs were simulated: a conventional bilayered design; a trilayered design, with an intermediate composite layer with constant composition; and a graded design, with an intermediate layer with gradation of properties. Parameters such as the interlayer thickness and composition profiles were varied in the study. Alumina-porcelain discs present smaller residual stress than the zirconia-porcelain discs, regardless of the type of design. The homogeneous interlayer can yield a reduction of ~40% in thermal stress relative to bilayered systems. Thinner interlayers favoured the formation of lower thermal stresses. The graded discs showed the lowest thermal stresses for a gradation profile given by power law function with p=2. The bending stresses were significantly affected by the thermal stresses in the discs. The risk of failure for all-ceramic dental restorative systems can be significantly reduced by using trilayered systems (homogenous or graded interlayer) with the proper design.     

Improvement of optical quality and vibration characteristics of injection molded disk with processing condition control

Increased application of optical disks has required a rotating disk with more dynamic stability and better optical quality. A new concept of controlling the processing condition of injection molded disks is developed to improve their optical quality and vibration characteristics. To assess the effect of process conditions on residual stresses, birefringence, and critical speed, an orthogonal array for design of experiments is used. Melt temperature, filling speed, and packing pressure were effective parameters, but mold temperature and interactions among process conditions were not. The birefringence and critical speed were affected by the residual stress distribution, which varied according to the distance from the gate and processing condition. Considering the effect of the processing conditions and distance from the gate, we calculated the weight factors on residual stresses along the radial direction. Choosing weighted stress to be the target value for optimization of residual stresses, processing conditions control was accomplished. Under the newly proposed conditions, optical quality and stability of injection molded disk were simultaneously improved. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3275–3285, 2006     

Effects of expandable graphite on char morphology and pyrolysis of epoxy based intumescent fire-retardant coating

The current study was designed to investigate the effects of expandable graphite (EG) on fire protection properties of intumescent fire-retardant coating for steel structures. Several formulations of intumescent coating were prepared and tested according to ISO 834 for char expansion. The chars were found without cracks and bonded with the steel substrate. The results showed that the coating slowly degraded during the test and char remained in contact with vertically tested coated substrate. The coated substrates were also tested for weather resistance using humid and ultraviolet environment. The char was characterized by using FESEM, XRD, FTIR, TGA, and XPS analysis. FESEM examined char morphology of the coatings after furnace fire test. XRD and FTIR showed the presence of graphite, borophosphate; boron oxide and sassolite in the char. TGA and DTGA results disclosed that EG improved the residual mass of coating. XPS analysis showed the percentages of carbon and oxygen are 48.50 and 43.45 in char of formulation with 12.8% EG. The results of weathering test coatings showed decreased in char expansion because of a humidity and UV light. The formulation with 9.8% EG showed the maximum char expansion and high residual mass among the formulations investigated in this study. The weathering tested coated samples showed their capability of fire protection.     

抗氧剂2246在BR生产中的应用

分析了抗氧剂２２４６对ＢＲ的稳定化作用，并与抗氧剂２６４的稳定效能进行了比较。结果表明，抗氧剂２２４６和抗氧剂２６４用量相同时，前者使ＢＲ的氧化诱导期延长，氧化温度提高，热氧老化性能改善，且耐候性，加工稳定性都明显变好。采用０．６％抗氧剂２２４６，即可达到或超过１．１％抗剂２６４的效能，并能满足ＢＲ贮存３ａ及在运输，加工过程中性能稳定不变的要求。     

Structure and properties of polypivalolactone

Pivalolactone (α,α-dimethyl-β-propiolactone) can be polymerized to linear polyesters with widely different molecular weights. The polymer has a high degree of crystallinity and a high crystalline melting point. Several other basic properties of the polymer have been determined, such as molecular weight, glass-transition temperature, rheological characteristics, etc., and its possible use in the fibre and plastics field has been extensively investigated. It was found that the polymer, when adequately stabilized, has a high thermal stability and shows hardly any discoloration upon processing.Ultimate products such as fibres and injection-moulded articles based on polypivalolactone have a high resistance to hydrolysis, heat and chemicals, and exhibit excellent weathering properties. A remarkable characteristic of the products is their high elastic recovery, in particular after annealing at high temperatures. Many of the observed properties can be explained by means of the molecular and crystalline structure of the polymer.     

渣油胶体稳定性研究进展

由于环境、物质变化常破坏渣油原有的稳定状态,在不同阶段对渣油的高效加工利用带来不利影响。本文综述了近年来渣油稳定性现有研究进展,介绍了国内外学者对渣油胶体理论和胶体模型的认识。简述了结合渣油胶体稳定性理论而提出的CI、CⅡ、S、NCSI等稳定性预测参数,并对稳定性分析方法进行了归纳和总结,包括直接观察法、基于溶剂滴定的参数法、指数评价方法等,做了详细的阐述和说明,并就各个方法的优缺点进行了讨论。就渣油胶体体系稳定性研究来说,经典的四组分理论模型和基于溶剂效应来表征稳定性的分析方法在今后一段时间将会一直是研究重点,然而展望渣油稳定性研究,基于分子水平理论研究以及更便捷准确快速的稳定性分析方法会是今后研究的重点。     

钢渣沥青混合料水稳定性研究

为研究不同浸水时间钢渣沥青混合料体积稳定性和路用性能特征,对热闷钢渣沥青混合料、冷弃陈渣沥青混合料和石灰岩沥青混合料分别进行车辙试验、低温弯曲试验、冻融劈裂试验、浸水马歇尔试验、疲劳试验和膨胀性试验,并通过原子力显微镜分析水对钢渣沥青混合料路用性能影响机理.结果表明:膨胀量合格的钢渣沥青混合料高温稳定性、水稳定性、低温...     

汽车前保险杠支架断裂缺陷分析及残余应力优化

建立某大型汽车注塑件模型并进行断裂缺陷分析,确定易断裂位置,综合利用正交实验法、计算机辅助设计（CAE）分析和数据处理技术,以易断裂处的残余应力为优化目标,对汽车大型注塑件成型工艺进行优化研究,得到各成型工艺因素对制品易断裂处残余应力影响程度及最佳工艺因素组合。     

Effect of weathering on oil sands processability

Effect of weathering on oil sand processability was studied using a good processing ore, a laboratory weathered ore and a naturally weathered ore. The laboratory weathered ore was prepared by weathering the good processing ore in an oven under controlled conditions to study the nature of ore weathering. It was found that the bitumen recovery, bitumen flotation rate, and bitumen froth quality were greatly reduced due to ore weathering. It was also observed that the fresh bitumen coating on a silicon surface could recede and liberate from the silicon surface easily even in a warm water of 35°C. However, after weathering of the bitumen coating, its liberation became more difficult and effective liberation of bitumen from the silicon surface could only occur at higher temperature of 65°C. The current study further confirms that weathering enhanced adhesion of bitumen with solids, causing difficulties for bitumen liberation from sand grains and hence poor processability of weathered ores.     

不同条件下尼龙材料光老化行为的研究

目前,氙灯加速老化试验是评估材料耐候效果最常用的一种方法.但是,关于该测试方法是否能客观反应材料实际使用过程中的颜色、力学变化规律的相关数据积累非常少.详细对比了两种测试条件对材料耐候效果的影响,结果表明,在定性评估方面,不同耐候剂组合在两种老化试验中的优劣顺序基本上保持一致,说明氙灯加速老化试验可以比较客观地反映材料...     

干、湿热气候环境塑料自然老化试验与研究

通过几种塑料制品在干、湿热气候环境老化试验,指出了试件在严酷干热与湿热气候环境的老化速度与高分子聚合物材料自身结构、添加剂配方等密切相关;同时指出在严酷干热环境中试件的老化速率比其他气候区域高。     

ABS材料人工加速老化与户外自然老化的相关性

通过红外光谱、色差和力学性能等研究了丙烯腈–丁二烯–苯乙烯塑料(ABS)在人工加速老化试验(UVA,UVB和氙灯)及户外自然老化试验过程中老化行为的相关性。红外分析结果表明,不同ABS材料在人工加速老化和自然老化过程中遵循相同的光氧老化动力学,但不同光源对ABS材料的加速老化作用有明显差别;色差分析结果表明,人工加速老化试验对色差变化的加速倍率由大到小顺序为:UVBUVA氙灯。通过分析ABS材料的色差及力学性能在人工加速老化与户外自然老化过程中变化的相关性,拟合了人工加速老化与户外自然老化的时间换算方程。     

聚丙烯树脂稳定性的研究

比较了４种不同催化剂制备的聚丙烯（ＰＰ）树脂在粉料稳定性、熔融加工稳定性、热老化稳定性和辐照稳定性等方面的差异,发现４种ＰＰ树脂稳定性的差异很大,其中,用Ｎ型催化剂制备的ＰＰ稳定性最好。研究结果表明,引起ＰＰ稳定性差异的基本原因为：各种ＰＰ中存在的催化剂残留种类和数量不同,其结晶度和微观结构也不同。