注射工艺条件对抗冲共聚聚丙烯力学性能的影响

用注塑成型方法制备了抗冲嵌段共聚聚丙(烯PP-B)试样,研究了工艺条件的改变对PP-B力学性能的影响。结果表明:注射速率和模具温度与PP-B弯曲强度、弯曲模量成正相关,而与冲击强度、拉伸强度的关系较为复杂;模具温度的升高有利于结晶度的提高,PP-B刚性上升,韧性下降;注射速率改变引起的剪切、拉伸流动使熔体发生取向流动,从而使沿取向方向上的强度升高,垂直取向方向上的强度降低;保压压力对PP-B性能的影响主要是通过熔体非晶部分在保压阶段的分子定向作用来实现的,随着保压时间的延长,PP-B塑件密度提高缺,陷减少拉,伸强度弯、曲模量呈增大趋势。     

共聚聚丙烯注射成型工艺分析

采用差示扫描量热法、热失重及转矩流变仪等分析了共聚聚丙烯(PP)的性能,讨论了注射成型工艺 (如熔体温度、注射压力、注射速率和模具温度等)对共聚PP加工性能及产品性能的影响。结果表明,共聚PP的加工温度在175～325℃,模具温度30～110℃为宜。     

注射工艺对不同熔体流动速率共聚聚丙烯力学性能的影响

在聚丙烯(PP)M20V中添加不同用量的过氧化物,并研究了注射工艺参数对不同熔体流动速率共聚PP力学性能的影响。结果表明:熔体温度、注射速度和保压时间都会影响最终制品的性能。其中,熔体温度对PP的性能影响很大,降低熔体温度,材料的冲击强度大幅提高,拉伸强度增大;提高注射速度,试样的弯曲强度和模量增大;延长保压时间会严重影响产品抗冲击性能。     

汽车保险杠用抗冲共聚PP结构性能分析

采用红外光谱仪、核磁共振谱仪、凝胶渗透色谱仪、差示扫描量热仪、扫描电子显微镜及动态流变仪研究汽车保险杠用抗冲共聚聚丙烯的结构与性能。结果表明,国产料与进口料的结构基本相同,性能已达到甚至超过进口料,可代替进口料使用。     

溶剂刻蚀对抗冲共聚聚丙烯微观形态的影响

利用扫描电子显微镜(SEM),研究了溶剂刻蚀时间、刻蚀溶剂种类(正庚烷、正辛烷、邻二甲苯)、外力作用(超声与不超声)对所观察到的抗冲共聚聚丙烯(IPC)相形貌的影响。研究结果表明:对具有不同相对分子质量的乙烯-丙烯无规共聚物(EPR)的IPC,溶剂刻蚀时间会对观察到的相形貌产生较大影响;利用正庚烷、正辛烷作为刻蚀溶剂,均仅观察到1种相态结构,而以邻二甲苯作为刻蚀溶剂,可以观察到4种核壳分散相态结构。     

过氧化物对抗冲共聚聚丙烯结构与性能影响的研究

通过凝胶渗透色谱(GPC)、二甲苯溶出、多次挤出等方法研究过氧化物对抗冲共聚聚丙烯结构与性能的影响,获得结构与性能均可控的高熔指抗冲共聚聚丙烯产品。结果表明:随着过氧化物量的增加,材料摩尔质量变低,分布变窄,且橡胶相较非橡胶相分子链断裂更为严重;经过多次挤出发现,材料的加工稳定性好,过氧化物残留低。     

聚丙烯高抗冲共聚产品SP179开发与生产

介绍了兰州石化聚丙烯装置,开发与生产高抗冲共聚产品SP179的主要工艺参数、产品结构和性能。同时确定了聚丙烯环管工艺生产超高抗冲产品的技术指标,最后对SP179产品做出了全面的性能测试。     

可控流变共聚PP的制备工艺及力学性能

用可控流变法降解共聚聚丙烯(PP)获得可控流变共聚PP。考察了基础树脂、过氧化物加入量、工艺参数对最终产品力学性能的影响。研究发现:在QP73N加入少量过氧化物便能显著改善流动性;根据基础树脂和最终产品的熔体流动指数可确定过氧化物的加入量;各种工艺参数对流变性能的影响由大到小依次为:温度、喂料转速、主机转速;喂料转速与主机转速之比越小,熔体流动指数越高;对降解产品力学性能的各项指标影响最大的因素都是挤出温度,其次是喂料转速和主机转速。     

热处理对抗冲共聚聚丙烯结晶行为和力学性能的影响

通过WXRD和SEM研究了抗冲共聚聚丙烯(HIPC)在热处理过程中的结晶行为变化,结果表明,随着热处理的进行,HIPC中所有β晶型都转化为更为稳定α晶型,结晶度和球晶尺寸最初随着热处理时间延长而增大,经过一段时间后不再变化,橡胶相含量有所减少,但分布更均匀,且橡胶网络逐步形成。研究还发现,热处理对HIPC力学性能和热性能都有不同程度的影响。     

不同工艺嵌段共聚PP结构与性能研究

采用核磁共振碳谱、凝胶渗透色谱和动态力学等多种分析手段对北京燕化石油化工股份有限公司3种不同聚合工艺生产的嵌段共聚聚丙烯产品进行结构与性能研究,分析出不同聚合工艺生产的产品结构、性能的特点及差异,结构对性能的影响,为今后的生产及应用提供参考。     

注塑成型工艺对透明PP光学性能的影响

采用不同的工艺条件注塑成型无规共聚透明聚丙烯(PP),测试透光率、雾度和表面光泽度,分析了成型工艺参数对制品光学性能的影响。所选透明PP的最佳注塑工艺为:加工温度220～230℃,模具温度40～60℃。在保证制品顺利成型的情况下应尽量采用较小的注塑压力。注塑速率和注塑时间对制品的光学性能影响较小。     

基于Unipol工艺的流延膜专用二元无规共聚聚丙烯的开发

对流延膜专用二元无规共聚聚丙烯的性能指标进行了深入研究和分析,确定了其技术攻关指标,开展了添加剂配方选择、装置试生产及试用工作.根据添加剂选择、催化剂选择、装置试生产、下游客户试用情况,对流延膜专用二元无规共聚聚丙烯进行持续优化,适当提高了二甲苯可溶物含量,将其调整为6.7％±0.5％(w).     

Effect of vibration parameters of electromagnetic dynamic plastics injection molding machine on mechanical properties of polypropylene samples

Dynamic injection processing experiments have been carried out on polypropylene using the self‐made electromagnetic dynamic plastics injection molding machine, and the effects of the vibration force field on mechanical properties of molding samples are studied, namely, the influence of vibration frequency and vibration amplitude on the mechanical properties of samples are researched by using tensile testing, impact testing, differential scanning calorimeter (DSC) and scanning electronic micrograph (SEM) techniques. The results show that the tensile strength and impact strength are both enhanced and the melting point shifts toward the higher temperature, which facilitates the perfection of crystal. The best vibration parameters for processing polypropylene using electromagnetic dynamic plastics injection molding machine are that frequency is from 3 to 9 Hz and amplitude is from 0.1 to 0.4 mm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 972–976, 2006     

聚丙烯/超临界氮气微孔注塑充模过程工艺参数研究

以聚丙烯(PP)为原料,超临界氮气(N2)为发泡剂,通过自行设计的一种扁平螺旋线形流道模具探究了注塑制品充模长度与减重比、泡孔结构之间的关系,并设计正交试验研究了注气压差、注气时间、注射压力和注射速率对制品充模长度的影响.结果表明,在一定范围内,熔体背压越高,制品充模长度越长,且随着充模长度增加,制品的减重比呈先缓慢增...     

无规共聚透明聚丙烯的研制

用添加透明剂的方法研制了无规共聚透明聚丙烯,通过与无规共聚聚丙烯、均聚透明聚丙烯等的性能比较发现,无规共聚透明聚丙烯的透明性、光泽度好、物理机械性能改善,且缩短了成型周期。     

Influence of pre-shearing on the crystallization of an impact-resistant polypropylene copolymer

Impact-resistant polypropylene copolymer (IPC) samples with various pre-shear histories were prepared by a Brabender Rheometer. The influence of pre-shearing on crystallization of IPC, including isothermal and nonisothermal crystallization behaviors was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results of nonisothermal crystallization showed that compared with as-received IPC, the temperatures referred to the peak of crystallization exotherm, T_p, were prominently elevated for pre-sheared IPC. In isothermal crystallization experiment, combining Avrami Method and Hoffman-Lauritzen Model, it was found that the half-time of crystallization (t_1/2) of pre-sheared IPC was greatly shortened and the calculated fold surface free energy (σ_e) within the isothermal temperatures investigated showed a large reduction. Morphological development during isothermal crystallization observed by POM clearly confirmed that the enhancement in crystallization is mainly due to the fast formation of nuclei during crystallization. Besides, using successive self-nucleation and annealing (SSA) thermal fractionation technique, changes in chain structures induced by pre-shearing were obtained. The relaxation behavior of pre-sheared IPC was also evaluated and it was found that the shear-induced enhancement in crystallization could be relaxed to various extents under annealing conditions.     

液压脉振塑化过程振动参数对LDPE性能的影响

采用新型液压脉振式注塑机成型低密度聚乙烯(LDPE)标准试样,测试成型过程整机能耗及试样的拉伸强度、密度等,探讨塑化过程中振动频率和振幅对制品性能的影响.实验发现,保持其他工艺参数不变,施加振动后,试样拉伸强度最大提高6.1%,密度增大3.3%,熔点向高温移动1.7℃,整机的加工能耗约降低6.8%,且呈现一定的变化规律.     

Effect of process parameters and composition on mechanical,thermal, and morphological properties of polypropylene/sawdust composites

Polypropylene/sawdust composites have been prepared according to a statistical experimental design, with varying sawdust and compatibilizer (maleic anhydride grafted PP) concentrations. To investigate process conditions, composites were first extruded in a twin screw extruder coupled to a Haake torque rheometer, without degassing, and then reextruded in a Werner Pfleiderer twin screw extruder, with two degassing zones. Process conditions were analyzed according to statistical techniques. Effect of the variables on mechanical properties was assessed through flexural modulus, tensile strength, and percent elongation at break and morphology was assessed by scanning electron microscopy. Comparison between the extruded and reextruded compounds indicated the need to reduce moisture, prior to and during processing, as well as the need of effective mixing of the compounds. Sawdust concentration showed to be the variable which affected most all properties assessed. Increase in sawdust concentration resulted in increased composite stiffness. The presence of the compatibilizer caused a slight increase in tensile strength and reduction in percent elongation at break, indicating improved adhesion at the PP/sawdust interface. The reprocessed compounds were also analyzed by differential scanning calorimetry. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Investigation of grafted impact-resistant polypropylene by temperature rising elution fractionation

The goal of the present work is the examination of maleic anhydride (MAn) grafted impact-resistant polypropylene (I-PP), consisting of amorphous rubber and semicrystalline matrix. A special instrument to separate the rubber from the matrix is preparative temperature rising elution fractionation (TREF). Investigations of the isolated fractions permit conclusions on the course of the grafting reaction and side reactions during the modification. The present work has shown that the fractionation is just as possible in the modified products as in the raw material. It has also shown that a grafting reaction occurs mainly in the rubber phase of this two-phase polypropylene. During the grafting reaction, only small degrees of radical degradation of the homopolymeric polypropylene matrix could be detected. © 1997 John Wiley & Sons, Inc.