PVC-O管材双轴取向工艺PLC控制系统的设计

简述了PVC-O管材的生产方法.结合PVC-O管材一步加工法的生产特点,开发了PVC-O管材双轴取向工艺的PLC控制系统.阐述了该控制系统的设计方案及控制方法.     

西班牙Molecor新设PVC-O管材生产线进军马来西亚

<正>西班牙塑料管材生产巨头Molecor集团宣布已在马来西亚投资8 000万林吉特(1 800万欧元),用于其PVC-O管材生产线第一阶段工程项目支出。该新建生产基地坐落于马来西亚关东县,内设3条PVC-O管材生产线。待正式投产运营后,其最初产能预计将达11 000 t/a,随后几年会翻倍。     

西班牙Molecor新设PVC-O管材生产线进军马来西亚

<正>西班牙塑料管材生产巨头Molecor集团宣布,公司已在马来西亚投资8000万林吉特(1800万欧元),用以其PVC-O管材生产线第一阶段工程项目支出。该新建生产基地坐落于马来西亚关东县,内设3条PVC-O管材生产线。待正式投产运营后,其最初产能预计将达11 000 t/a,然随后几年会翻倍。Molecor表示,公司拟将用三年半的时间完成该新建工厂的扩能计划,并彻底实现本土化生产。此     

热介质老化对HNBR力学性能的影响

采用加速老化实验方法研究了热介质对氢化丁腈橡胶（HNBR）材料力学性能的影响,获得了热空气、ASTM 1#标准油和ASTM 3#标准油中老化温度及老化时间对HNBR材料力学性能的影响规律。结果表明,HNBR材料具有良好的力学性能和耐油性能。     

双轴取向聚氯乙烯(PVC-O)管材的专用配方

研究了PVC-O专用配方及加工工艺.通过双辊筒开炼机对PVC-O配方进行初试并确定增韧剂的用量;通过正交试验确定了主要助剂对材料性能的影响程度,复合润滑剂的用量过多会导致材料的性能显著下降,PVC(SG-3)树脂的加入明显提高了PVC-O材料的冲击强度,但是使PVC-O配方最为关心的断裂伸长率明显下降,从而给出了主要助剂的最佳用量.布拉本德流变测试表明:PVC( SG-3)树脂的加入使材料的平衡转矩呈上升趋势,增加挤出机的能耗并造成加工困难.     

热老化对聚砜改性酚醛树脂力学性能的影响

研究了聚砜改性酚醛树脂玻纤维强模塑料在200℃、230℃，时间为500h的热老化过程中所发生的力学性能变化情况。结果表明，在200℃老化时，经过500h后，材料的力学性能仍很高，其弯曲强度可达1058．35MPa，冲击强度为242．73kJ/m^2，拉伸强度为389．9MPa,压缩强度（平行于纤维方向）为160．33MPa。老化后，虽然力学性能（除弯曲强度外）会有所下降，但仍能满足材料的使用要求。说明此种模塑料能在200℃以下长期使用，是一种有发展前途的耐热塑料。     

热空气老化对丁基橡胶交联密度和力学性能的影响

采用热空气老化试验机研究了丁基橡胶（IIR）的老化行为,获得了不同老化温度和老化时间对IIR交联密度和力学性能的影响规律。结果表明,随着老化时间的延长,IIR硫化胶的交联密度先增大后减小,并随老化温度的升高变化幅度较为明显。拉伸强度、定伸应力和硬度均出现类似变化规律,而拉断伸长率先迅速下降后逐渐趋于平缓。     

加速紫外老化对聚乙烯薄膜力学性能的影响

介绍了聚乙烯(PE)薄膜老化机理,并对PE薄膜进行了人工加速紫外光老化试验。分析了老化时间对PE薄膜力学性能的影响。结果表明:紫外光的照射使PE的化学键发生交联和断裂反应,其中断裂反应占主导,使聚合物分子量减小,物理性能下降;PE薄膜的拉伸强度、断裂伸长率和弹性模量随老化时间的延长而降低;PE薄膜抵抗破坏的能力在老化60 h以上会急剧下降,而此时弹性模量的变化趋势变得平缓,断裂伸长率与老化时间近似成线性关系递减。     

增塑剂对聚氯乙烯紫外光老化性能影响的研究

采用力学性能测试、扫描电镜（SEM）、红外光谱（FT-IR）等方法研究了增塑剂邻苯二甲酸二辛酯（DOP）对聚氯乙烯（PVC）紫外光老化性能的影响。结果表明：随着紫外光照射时间的延长，试样表面颜色逐渐变深并产生裂纹，硬质PVC试样的断裂伸长率显著减小，拉伸强度变化不大；而软质PVC试样的断裂伸长率和拉伸强度均降低；在老化过程中，出现了C—Cl键的断裂、羰基的形成及其红外吸收峰的逐步增大等过程。     

高密度聚乙烯管材光氧老化性能及寿命预测

采用荧光紫外灯人工加速老化方法模拟自然太阳光对高密度聚乙烯(PE-HD)管材和热熔接头的光氧老化,在不同温度下(50、60、70℃),使用UVA-340型标准荧光紫外灯管在光照和冷凝2种循环模式下模拟老化,并利用傅里叶变换红外光谱仪(FTIR)对老化后的管材和接头试样进行了分析表征,通过差示扫描量热仪(DSC)测量了管...     

取向聚氯乙烯(PVC-O)管的发展

取向聚氯乙烯(PVC-O)管是于1974年首次出现的管道品种。本文介绍取向聚氯乙烯管的卓越性能、制造技术的分类和创新突破,并提出开发建议。     

Effects of physical aging on dynamic mechanical and transient properties of polyetheretherketone

The effects of physical aging on dynamic mechanical and transient stress-relaxation properties of a high performance thermoplastic, polyetheretherketone (PEEK), are reported in this study. The aging effects are shown to be physical effects (and not chemical degradation) by establishing thermoreversibility of the aging process. The unique aspect of the present study is the simultaneous investigation of both dynamic and transient properties in the same mode of loading, namely, in shear. The influence of continuous dynamic deformation on the aging process is also reported. The results for the aging rate, obtained from dynamic and transient testing under shear load, agree with one another and verify the equivalence of dynamic and transient viscoelastic properties. However, these results differ significantly from the aging rate results reported in an earlier study for tensile loading. A possible explanation for the difference has been proposed in terms of the volume change that accompanies tensile creep deformation.     

Thermal aging on mechanical properties and crosslinked network of natural rubber/zinc Dimethacrylate composites

This article dealt with the relationship between mechanical properties and crosslinked networks of natural rubber (NR) reinforced by zinc dimethacrylate (ZDMA) after thermal aging. After thermal aging at the present experimental conditions, the covalent crosslink density showed a decrease all the time, whereas the ionic crosslink density was stable at 80°C but decreased at a higher temperature. The decrease in the total crosslink density after aging indicates the degradation of the crosslinked network. However, an experimental phenomenon observed was that the tensile strength and tear strength increased in a certain degree after aging at 80°C or at a 100°C for a short time. In addition, the thermal stability of the NR/ZDMA composite was evaluated by thermal gravimetric analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of crosslink structures on dynamic mechanical properties of natural rubber vulcanizates under different aging conditions

The effects of crosslink structures on the dynamic mechanical properties (DMPs) of unfilled and carbon black N330‐filled natural rubber (NR) vulcanizates cured with conventional (CV), semiefficient (SEV), and efficient (EV) cure systems and having about the same total crosslink densities were investigated before and after aerobic and anaerobic aging at 100°C. The three unfilled NR vulcanizates cured with the CV, SEV, and EV systems had about the same mechanical loss factor (tan δ) values at about 0°C but showed some apparent differences in the tan δ values in the order EV > SEV > CV at relatively high temperatures of 40–80°C before aging. However, N330‐filled NR vulcanizates gave higher tan δ values than the unfilled vulcanizates and showed little effect of the crosslink types on the tan δ at different temperatures over the glass‐transition temperature (T_g) before aging. Aerobic heat aging increased the T_g and tan δ values of the vulcanizates over a wide range of temperatures from ?80 to 90°C that was mainly due to the changes in the total density and types of crosslinks. The unfilled vulcanizates cured with the CV system showed the greatest change in DMP because of their poor resistance to heat aging. Aerobic heat aging of NR vulcanizates caused a more significant change in the DMP than anaerobic heat aging because of the dominant effect of the oxidative degradation during aerobic heat aging on the main‐chain structure, crosslink structures, and DMPs of the vulcanizates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 710–718, 2001     

The effect of shear on fusion and mechanical properties of rigid PVC pipes

The shear level was increased during twin screw extrusion of PVC at different melt temperatures by inserting a hole plate in front of the screw tips. The variation of shear level did not significantly affect the capillary pressure in capillary viscometry at 135°C. However, the falling weight impact strength was markedly influenced. In internal water pressure tests at 60°C premature failure was obtained for pipes extruded at 198°C at the highest shear level.     

Effect of annular expansion pipe extruder head on mechanical properties of pipes

With polymer pipes being used more commonly, performance requirements are increasing. Studies on the enhancement of mechanical properties of polymer pipes are particularly important. In this study, a self-designed annular expansion pipe extruder head was used to enhance the mechanical properties of HDPE pipes. Different morphologies of the HDPE pipes were produced under different processing conditions. When the extrusion angle was 30° (P30), the best mechanical properties were obtained. The hoop tensile strength and axial tensile strength were 14.5% and 41.0% higher, respectively, compared with the specimen without expansion (P0). This improvement of mechanical properties can be attributed to several reasons. First, the processing parameters of P30 reached the threshold shear rate and strain for shish-kebab formation, as shown by scanning electron microscopy. Second, P30 has the highest orientation parameter and crystallinity of 0.679 and 67.27%, respectively, from 2D wide-angle diffraction (WAXD). Polarized FTIR shows the same trend as 2D-WAXD. Third, the outer bamboo-like self-reinforced structure is formed inside the pipe at 30° expansion angle while the core layer has a well-formed crystal structure; the special structure improves the overall performance of HDPE pipe. This method can be utilized in large-scale industrial production.     

Effects of weathering aging on mechanical and thermal properties of injection molded glass fiber reinforced polypropylene composites

The effect of weathering aging on the degradation behavior of injection molded short glass fiber reinforced polypropylene composites (GFPP) is studied. First, the effect of outdoor weathering on mechanical properties of GFPP composite was investigated by tensile, flexural, and impact tests. Furthermore, to clarify the degradation behavior under natural weathering environments, differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) measurements were carried out to analyze the structural and molecular changes during weathering aging. The results show that weathering aging has a significant influence on changes in mechanical properties, melting temperature and the degree of crystallinity of PG6N1 without added carbon black and UV absorbing agent. Those degradations not only occurred on the surface of GFPP but also proceeded to the inner matrix and interface. However, GFPP GWH42 with added carbon black and UV absorbing agent shows excellent weathering stability.     

Effects of Sm3+/PMAA on mechanical and thermal properties of natural rubber latex film

Samarium carbonate [Sm₂(CO₃)₃] was taken as the source of Sm³⁺, and methyl acrylic acid (MAA) was employed as the precursor to prepare polymethacrylic acid (PMAA). The mixture of Sm₂(CO₃)₃ and PMAA was marked as “SmP.” The SmP prepared under different conditions was added to natural rubber (NR) latex to prepare NR/SmP films. The influence of the polymerization temperature of MAA and the amount of SmP on the mechanical properties and structure of NR/SmP films were analyzed. The results show that polymerization temperature has significant effect on the mechanical properties of NR/SmP film; lower temperature is benefit to improve modulus and rigidity, whereas higher temperature helps maintain good elasticity. Compared with neat NR, addition of 5-phr Sm₂(CO₃)₃ results in a 30%–37% increase of tensile strength. Furthermore, the glass transition temperature (T_g) can also be increased by the addition of SmP; and the tan δ curves of all samples exhibit only one transition peak and indicate no phase separation between SmP and NR matrix. The influence of SmP on the structure and morphology of NR was explored by Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy analysis; and the results show that SmP can be dispersed uniformly in the NR latex when loading of Sm₂(CO₃)₃ is lower than 20 phr.     

Effects of crosslinking densities on mechanical properties of nitrile rubber composites in thermal oxidative aging environment

The effects of crosslinking densities on mechanical properties of nitrile rubber (NBR) composites before and after thermal oxidative aging are investigated. Tensile strengths of NBR composites are enhanced slightly at the initial aging stage, attributing to moderate increment of crosslinking densities. Continuous decrease with further aging is followed, resulting from over-crosslinking and uneven distribution of crosslinking densities. The digital image correlation method is explored for large-strain deformation measurement by displacement accumulation and establishing strain model, being promising in practical age detection and measurement of mechanical properties in complex environments. Compression sets are gradually increased with aging because of the destruction of the original crosslinking structures. The molecular chains fracture inhibits elastic recoveries of compressive NBR composites and results in residual deformation in thermo-oxidative and compressive environment after unloading. This study provides new ideas for exploring mechanical properties of rubber-based composites before and after thermal oxidative aging.