木塑原材料摩擦系数的测定及其对挤出加工的影响

测定了高密度聚乙烯(HDPE)、木粉及HDPE/木粉混合物与钢板在20℃下的摩擦系数,并测定了HDPE/木粉混合物在不同温度下与钢板的摩擦系数,分析了摩擦系数对木塑复合材料挤出加工的影响,为深入开展木塑复合材料的挤出加工研究提供了实际可靠数据.     

CPE对PVC/木粉复合材料动态力学性能及耐热性能的影响

为了增强聚氯乙烯(PVC)基木塑复合材料的动态力学性能,加入氯化聚乙烯(CPE)对复合材料进行改性,并探究CPE对PVC基木塑复合材料性能的影响。采用动态力学分析仪(DMA)和维卡软化温度测试仪,对加入CPE的PVC/木粉复合材料进行测试,分析CPE对PVC/木粉复合材料动态力学性能及耐热性能的影响。结果表明:CPE的加入会对PVC/木粉复合材料的动态力学性能产生重要的影响,且CPE含量约为5份时,复合材料的动态力学性能最佳;但维卡软化温度、热变形温度测试结果显示,CPE的加入降低了PVC/木粉复合材料的耐热性,且随着CPE含量的增加,复合材料的耐热性逐渐减弱。     

扭矩流变测定法研究硬质PVC/木粉熔融性能

研究了扭矩流变仪中木粉含量、木材种类(软木和硬木)及粒度对硬质PVC/木粉复合材料熔融性能(熔融时间、熔融温度、熔融扭矩和熔融能)的影响。纯硬质PVC只有1个熔融峰,而PVC母体材料中加入木粉后会产生2个熔融峰。结果表明,增加木粉含量会使基本粒子间开始熔融时间、温度和能量明显增加,从而引起熔融扭矩的增加,与木粉种类无关;用木粉填充的硬质PVC应该在比纯树脂高的温度下加工;木材种类会影响复合材料的熔融性能,但软木和硬木之间确定不出一个明显的趋势;精细粒子的熔融速度比粗粒子快,需要的能量也较少。     

PP/木粉复合材料的蠕变特性研究

研究了木粉含量和木粉类型对PP/木粉复合材料物理机械性能和蠕变特性的影响规律.结果表明:当木粉含量增大时,PP木塑复合材料的拉伸强度、弯曲强度、冲击强度等性能指标明显下降,而弯曲模量、热变形温度则有所提高.添加木粉后,材料的蠕变特性明显改善;当许用弯曲极限(即规定蠕变极限)较小(如为制品厚度的1.5倍)且材料中木粉质量含量为50%时,其耐弯曲蠕变特性最佳.采用的木粉类型不同时,PP木塑复合材料的性能有较大差异,采用松木粉和水曲柳木粉制备的PP木塑复合材料的综合性能最好,而采用黄麻纤维制备的PP木塑复合材料的冲击韧性最好.     

稀土偶联剂在再生PP/木粉复合材料中的应用研究

用稀土偶联剂(WOT)处理木粉,对改性木粉进行了红外光谱分析;将改性木粉、再生聚丙烯(PP)及其它助剂用双螺杆造粒机组挤出造粒制备PP/木粉复合材料,研究了WOT用量、木粉用量对复合材料性能的影响,并采用扫描电子显微镜进行了材料断面的形态分析。结果表明,WOT与木粉之间的化学结合作用可以增强木粉与PP的界面结合,提高了塑木复合材料的性能,合适的WOT用量为4～6份(每100份木粉)。木粉用量在20～60份时,复合材料的拉伸弹性模量、弯曲弹性模量和热变形温度随木粉用量的增加而提高。     

新型多单体接枝物增容PP/PVC共混体系的研究

自制了多单体接枝物PP g (St co MMA) ,并利用其增容PP/PVC共混体系。讨论了共混物组成、相容剂用量在不同温度、不同压力下对其流变行为的影响。实验结果表明 ,在所研究的温度和压力范围内 ,加入PP g (St co MMA)增容PP/PVC共混体系后 ,共混物熔体呈典型的假塑性流体特性 ,粘流活化能增加 ,非牛顿性有增大的趋势。共混体系的力学性能提高 ,SEM照片证明了多单体接枝物对PP/PVC的增容作用     

加工参数对PP／木粉复合材料结构和性能的影响

将聚丙烯(PP)与处理木粉混合,经双螺秆挤出机适粒后·混入微扎发泡母粒,经单螺杆挤出机塑化和片材口模成型PP/木粉复合微孔片材试样.通过改变挤出温度、螺杆转速、口模压力降以及冷却定型条件,测定试样拉伸性能、密度、孔隙率,扫描电镜(SEM)观察试样断面形貌,研究加工参数与PP/木粉复合微孔片材结构和性能的关系.结果发现,在挤出温度180℃,螺杆转速50 r/min,高的挤出压力时,泡孔尺寸小而均匀.对片材坯料给予的冷却定型可以固定泡孔结构防止泡孔合并和过度生长及塌陷.     

PVC/木粉复合材料的挤出研究

采用聚氯乙烯(PVC)与木粉制得PVC／木粉复合材料。研究了木粉的含量、偶联剂的类型和含量、邻苯二甲酸二辛酯(DOP)和抗冲改性剂氯化聚乙烯(CPE)的用量对复合材料性能的影响以及润滑剂含量对加工性能的影响。结果表明,当PVC与木粉用量比为7.0:3.0、偶联剂为木粉用量1.5％、DOP用量为PVC用量20.0％、CPE用量为PVC用量10.0％、润滑剂用量为PVC用量1.2％时,所得复合材料的综合性能较好。     

CaCO3在PVC电缆粒料中的应用

在PVC(聚氯乙烯)电缆粒料的生产与开发中,通过对填充不同CaCO_3(碳酸钙)的对比试验,验证分析了填充料CaCO_3在PVC电缆粒料中所起的作用和经济效益。     

异氰酸酯处理木粉对PVC/木粉性能的影响

采用木粉填充聚氯乙烯(PVC)基木塑复合材料,研究异氰酸酯处理木粉对PVC/木粉性能的影响.红外光谱、DMA和sEM较好地证明异氰酸酯和木粉之间的作用,结果表明:用异氰酸酯处理的木粉填充PVC,能够改善木粉与PVC之间的界面粘结作用,提高PVC/木塑复合材料的力学性能.     

载荷、速度及环境温度对聚醚砜酮摩擦磨损性能的影响

利用MM—2000型和THT07—135型摩擦磨损试验机系统考察了载荷、滑动速度和环境温度对含二氮杂萘联苯型聚醚砜酮(PPESUK)摩擦磨损性能的影响，并利用扫描电子显微镜(SEM)观察分析了其磨损表面形貌及磨损机理。研究表明，干摩擦条件下，随载荷增加PPESUK的摩擦系数降低、磨损率增加；在高的滑动速度下，摩擦系数和磨损率都降低；环境温度对PPESUK的摩擦系数影响不大，并且粘着磨损是其主要磨损机理。     

塑料摩擦试验方法的研究

以尼龙和超高分子量聚乙烯为研究对象,寻求一种理想的摩擦试验用试样预处理方法;并研究塑料在钢上滑动和钢在塑料上滑动的两种摩擦类型的摩擦系数区别及关系。通过反复性试验发现,采用砂纸预处理螺纹状试样,并与螺纹状摩擦副配套使用,摩擦面积和稳定性都大幅度增加;两种不同的滑动方式所得到的摩擦系数相差很大,具有不可比性。     

Friction properties of new porous carbon materials: Woodceramics

Woodceramics are new porous carbon materials obtained from wood or woody materials impregnated with phenol resin, and carbonized in a vacuum furnace at high temperature. Woodceramics have several superior characteristics from the viewpoints of engineering materials and ecological materials: they are hard and strong, have porous structure and low density, are made from natural resources, do not cause environmental pollution, and are cheap to manufacture. This paper describes the fundamental friction properties of Woodceramics in sliding contact with several materials. Woodceramics made of medium density fiberboard (MDF) and beech impregnated with phenol resin and carbonized in a vacuum furnace at 800°C and 2000°C were rubbed against alumina, silicon nitride, bearing steel and diamond by using a reciprocating friction apparatus. Experiments were carried out unlubricated in air, impregnated with base oil and in water, at several normal loads and sliding velocities. The following principal results were obtained: (1) The friction coefficient is around 0.15, under all three lubrication conditions; (2) The friction coefficient slightly decreases and then stays constant with increasing normal load; (3) The friction coefficient is not affected by sliding velocity; (4) Woodceramics have a good self-lubricity.     

Friction coefficient and wear resistance of a modified polypropylene impregnated with different oils

The aim of the study was to determine the changes in the sliding friction coefficient and wear mechanism of PP impregnated by oils with respect to the unmodified PP under dry sliding conditions. The study showed that the impregnation of the PP clearly influenced the wear rate of PP and its friction coefficient. During the test, the wear behavior of the unmodified and impregnated polypropylenes was investigated using ASTM G77-98 standard wear test equipment in which the specimens were worn by counter sample made by steel 100Cr6. The recording program of the test system enabled the visualization and registration of the following parameters: specimen rotation and load value, linear wear of specimen, friction coefficient, and temperature of specimen and environment. The wear of the specimens was evaluated by weight loss and their wear mechanisms were investigated using scanning electron microscopy. The predominant wear mechanism between a polymer and steel was adhesion. However, at the high sliding velocity, when a higher temperature was generated, the predominant mechanism of wear was thermal wear. Impregnation of PPs moved the thermal wear into the higher sliding velocity values and caused better resistance of the PPs to melting and plastic flow. The most important finding of this investigation was that impregnation of PPs improved their tribological properties at a low value of load represented by the sliding velocity.     

煤仓漏斗的焊接工艺

针对Q235-B钢板制成的原煤仓漏斗锈蚀、磨损严重的问题,更换采用了内层为4Cr13马氏体不锈钢,外层为Q235-B钢板的双层结构漏斗,并通过焊接工艺试验为煤仓漏斗的制造工艺确定了正确的焊材和焊接方法,取得了良好的效果。     

The determination of the coefficient of dynamic friction of organic powder compacts on steel

A practical experimental model system has been successfully used to study the frictional response of organic powder compacts sliding across a polished steel plate, representative of the die bore of a production compaction system. This system offers a controlled approach to the study of frictional phenomena occurring during compaction and facilitates a more detailed investigation into the fundamental mechanisms of friction than a simple resolution of forces within a punch and die apparatus.For acetylsalicyclic acid sliding on steel, the dynamic friction coefficient was found to be dependent on the displacement and, to a lesser extent, the initial normal load, whereas for PTFE on steel, the dynamic friction coefficient was independent of displacement and load and estimated at 0.09. Thus, soft organic materials exhibit very different frictional characteristics to those of brittle materials. These differences reflect the differing importance and magnitude of the three frictional components, adhesion, shear and ploughing.     

Q235钢热浸渗铝层的组织分析和性能

分析了Q2 35钢热浸渗铝层的组织 ,并对其抗高温氧化和耐高温腐蚀性能进行了研究。显微硬度试验结果表明渗层硬度可达 10 0 0HV ,并具有较大的脆性。经扩散退火后 ,渗层组织和显微硬度都发生了明显的变化。高温氧化和热腐蚀试验结果表明 ,渗铝Q2 35钢的抗高温氧化性能和 1Cr18Ni9Ti奥氏体不锈钢相当 ,而耐热腐蚀性能明显优于后者     

Accelerated ultraviolet weathering of PVC/wood‐flour composites

Ultraviolet weathering performance of polyvinyl chloride (PVC) filled with different concentrations of wood flour was studied. Extruded PVC/wood‐flour composite samples were subjected to cyclic ultraviolet lamps/condensation exposures and assessed over a total of 400 and 2600 hours. Each assessment consisted of DRIFTFTIR and XPS collections, contact angle measurement, color measurement, and tensile property testing. The experimental results indicated that wood flours are effective chromophore materials since their incorporation into a rigid PVC matrix accelerated the degradation of the polymeric matrix. Photodegradation converted unfilled PVC samples to a colored material of lower extensibility. Although composite samples exhibited greater discoloration than unfilled PVC samples, they retained all their original strength and stiffness properties even after 2600 hours of cyclic UV irradiation/condensation exposures.     

加工时间对木粉/PP复合材料结构与性能的影响

以硅烷接枝乙烯-辛烯共聚物(POE-g-Si)为增容剂,通过X射线衍射(XRD)、电子扫描显微镜(SEM)、动态力学分析(DMA)研究了加工时间对木粉/POE-g-Si/PP复合材料晶态结构、动态力学性能及界面形态的影响。结果表明,随着加工时间的延长,由于剪切作用,处于界面处的相容剂POE-g-Si向PP基体树脂渗透,界面层厚度变小,且POE-g-Si粒径也随之变小,分布也更加均匀;而木粉/POE-g-Si/PP复合材料的晶态结构却无变化;同时,木粉/POE-g-Si/PP复合材料的阻尼性能也随之增强,这主要取决于木粉与聚合物基体间的界面作用力的提高。     

木塑复合材料的成型加工及影响因素

以废旧塑料和木粉为原料,采用4份的硅烷偶联剂对木粉进行预处理,通过单螺杆挤出机造粒,模压成型方法制备木塑复合材料(WPC).研究了模压成型工艺参数对WPC抗弯强度的影响,分析了WPC的表面形貌.结果表明,塑料与木粉质量比为1:1时,成型工艺因素对WPC抗弯强度影响程度的排序为:成型温度>成型时间>成型压力;在170℃、5 MPa条件下热压60 min,所得WPC的抗弯强度为31.16 MPa.