耐热聚乙烯管材料的稳定性

研究了3种耐热聚乙烯(PE-RT)管材料的氧化诱导期、加工稳定性、长期热稳定性等。结果表明:3种管材料的氧化诱导期(210℃)均在60 min以上,其中,PE-RT QHM22F的加工稳定性和长期热稳定性最优,5次造粒后熔体质量流动速率变化率小于3%,4 800 h热水老化后断裂标称应变大于700%。     

辛烯共聚地暖管专用料抗氧体系优化研究

介绍了耐热聚乙烯管材PE-RT树脂抗氧剂筛选,在溶剂中溶解度,借助DSC分析仪器,对国内外PE-RT树脂进行氧化诱导期测试,对比分析这些树脂的抗氧化性能,提出地暖管产品优化方案,生产结果表明,抚顺石化辛烯共聚耐热聚乙烯管材树脂氧化稳定性较好。     

转矩流变仪在管材专用PE-RTⅠ型料加工性能研究中的应用

采用转矩流变仪评价管材专用耐热聚乙烯(PE-RT)Ⅰ型料的加工热稳定性,表征了树脂的剪切黏度随加工温度、螺杆转速的变化趋势,评价了树脂的加工性能。结果表明:4种管材专用PE-RT加工性能优异;DGDZ3606在强剪切时黏度最低,DNGCL-2黏度最高,DNGCL-3和DNGCL-1基本相当,处于中间水平;DGDZ3606离模膨胀最明显,但高速挤出过程的稳定性更优。     

抗氧剂对聚苯乙烯树脂加工稳定性的影响

通过测定聚苯乙烯(PS)树脂的氧化诱导时间、黄色指数及多次挤出前后的熔体流动速率(MFR)、热空气老化前后的力学性能,研究了抗氧剂1010及其与抗氧剂168复配对PS树脂加工稳定性的影响。结果表明:受阻酚类抗氧剂1010和亚磷酸酯类抗氧剂168能够产生很好的协同作用,在多项指标上要远优于只添加抗氧剂1010的体系;在抗氧剂1010/168复配体系中,抗氧剂168用量2倍于抗氧剂1010时,PS的综合性能较佳;当抗氧剂总用量超过1%时,反而会使PS树脂的加工稳定性和力学性能有所下降。     

管材专用耐热聚乙烯的等温结晶行为

研究了两种管材专用耐热聚乙烯(PE-RT)的氧化诱导时间、抗冲击性能、等温结晶行为、相对分子质量及其分布等。结果表明:210℃时,两种PE-RT的氧化诱导时间均在70 min以上;其中一种PE-RT的结晶温度较高(119.0℃),结晶速率较快,更有利于满足快速成型加工的需要,其相对分子质量分布较宽、重均分子量较高,有利于提高管材的静液压强度。     

抗氧剂对ABS树脂加工稳定性的影响

通过测定ABS树脂的氧化诱导时间和氧化诱导温度及其在多次挤出前后熔融指数、黄色指数及微观结构的变化,研究了不同加工抗氧剂168、618、1076/168、1076/618对ABS树脂加工稳定性的影响.结果表明:四种抗氧体系均能使ABS树脂在多次挤出加工中保持良好的熔体稳定性,当抗氧剂168和618单独使用时,加入抗氧剂168和618的ABS树脂的热稳定性相当,但抗氧剂168能够更有效地抑制ABS树脂在加工过程中的黄变.当引入受阻酚类主抗氧剂1076后,其与亚磷酸酯类抗氧剂并用时的效果好于亚磷酸酯类抗氧剂单独使用时的效果.与其他抗氧剂相比,复合抗氧剂1076/168能够更好地保持ABS树脂在多次挤出加工中的各项性能.     

抗氧剂对ABS树脂加工稳定性的影响

通过测定ABS树脂的氧化诱导时间和氧化诱导温度及其在多次挤出前后熔融指数、黄色指数及微观结构的变化,研究了不同加工抗氧剂168、618、1076／168、1076／618对ABS树脂加工稳定性的影响。结果表明：四种抗氧体系均能使ABS树脂在多次挤出加工中保持良好的熔体稳定性,当抗氧剂168和618单独使用时,加入抗氧剂168和618的ABS树脂的热稳定性相当,但抗氧剂168能够更有效地抑制ABS树脂在加工过程中的黄变。当引入受阻酚类主抗氧剂1076后,其与亚磷酸酯类抗氧剂并用时的效果好于亚磷酸酯类抗氧剂单独使用时的效果。与其他抗氧剂相比,复合抗氧剂1076／168能够更好地保持ABS树脂在多次挤出加工中的各项性能。     

N2保护对加工PP和HDPE的影响

探讨了在N2保护和无N2保护下不同抗氧剂体系对聚丙烯(PP)、高密度聚乙烯(HDPE)性能的影响.结果表明,造粒加工过程中,在N2保护下加入抗氧剂,PP的熔体流动速率变化率最高可下降46.1%,氧化诱导期最大可延长3.3 min;HDPE的氧化诱导期最大可延长19.3 min,提高了合成树脂的加工稳定性和抗氧化效果.     

耐热聚乙烯管材专用树脂QHM22F的性能及加工应用

研究了工业化生产的耐热聚乙烯(PE-RT)管材专用树脂QHM22F的常规物性、加工稳定性、加工性能等,并在不同管材生产线上进行了加工应用试验。结果表明:QHM22F的简支梁缺口冲击强度在70 k J/m2以上;200℃氧化诱导期大于120 min;耐压等级达到PE-RTⅡ型;QHM22F的加工性能良好,可满足高速牵引(36.1 m/min)的加工需要;采用QHM22F生产的管材内外表面光滑、壁厚均匀,性能满足用户要求。     

PE100级管材专用树脂的结构与性能

通过熔体流动速率、差示扫描量热法分析、力学性能以及管材静液压试验等研究了3种PE100级管材专用树脂的结构与性能。结果表明:3种树脂在200℃条件下的氧化诱导时间均大于120 min,耐热氧老化性能良好;GC100S的熔流比为26.3,结晶度为60.1%,冲击强度为58.49 kJ/m~2,在80℃,5.4 MPa条件下的短期静液压测试耐压时间为348 h,均较其他两个试样好,为管材专用树脂的质量提升提供了技术支持。     

Effect of combining boron nitride with fluoroelastomer on the melt fracture of HDPE in extrusion blow molding

Boron nitride (BN) is a new polymer processing aid which not only eliminates surface melt fracture in the extrusion of molten polymers, but also postpones the critical shear rate for the onset of gross melt fracture to significantly higher values that depend on resin type and additive concentration. In this work, the influence of BN as a polymer processing additive is first examined in the extrusion blow molding of high‐density polyethylene (HDPE) resins in order to evaluate its usefulness and performance in operations other than continuous extrusion. The equipment used includes both a Battenfeld/Fisher 50‐mm extrusion blow molding machine and a parallel‐plate rheometer. Two types of HDPE, which are blended with boron nitride at various concentration levels, are tested accordingly. It is found that the degree of BN dispersion, characteristics of the HDPE resins, extrusion temperature, and induction time play an important role in eliminating melt fracture. Finally, the influence of combining BN with fluoroelastomer, as an enhanced and potentially better processing aid on the melt fracture of a third HDPE is examined. It is found that such a combination is a superior processing aid that allows extrusion blow molding at very high shear rates.     

高流动性聚丙烯的制备及其热稳定性能研究

采用过氧化物作为聚丙烯(PP)的分子量调节剂,高分子量受阻胺作为PP的热稳定剂,制备了高流动性PP(HFRPP)。研究了过氧化物含量对HFRPP流动性能和冲击性能的影响,并通过氧化诱导期试验、热氧老化试验及流变性能测试研究了高分子量受阻胺热稳定剂对HFRPP性能的影响。结果表明,添加质量分数为0.04%的过氧化物,经过一次和二次双螺杆挤出后,能够实现PP优异的流动性能并保持其适当的缺口冲击强度。高分子量受阻胺能够有效稳定过氧化物催化降解PP体系后所残留的活性中心,提高HFRPP热老化寿命且不影响其流动性能。     

Effect of additive interactions on the thermo‐oxidative stabilization of a film grade metallocene LLDPE

The simultaneous effects of a range of additives and associated interactions on melt processing stability, processing discoloration, and long‐term stability of a blown film‐grade metallocene LLDPE (mLLDPE) were investigated by using a two‐level factorial experimental design. The additives investigated were a phenolic antioxidant, a phosphite processing stabilizer, a calcium stearate antacid, a synthetic silica antiblocking agent, and an erucamide slip additive. A multiple extrusion experiment was carried out to assess processing stability. Melt stabilization performance was monitored by melt flow rate (MFR) measurements, and color development was determined using yellowness index (YI) measurements. Long‐term thermal stability was assessed by monitoring the rate of formation of the non‐volatile carbonyl oxidation products using FTIR. Results were quite consistent with the literature. Therefore, the two‐level factorial experimental design proved to be a very useful tool for screening the simultaneous effects of each additive and the possible interactions between additives present in the stabilizer system investigated. J. Vinyl Addit. Technol. 10:149–156, 2004. © 2004 Society of Plastics Engineers.     

Use of regrind in the PVC extrusion process

Extrusion products that to not meet specification are generally reground for extrusion reprocessing. This paper describes the effect of heat history of regrind materials on extrusion quality, including surface appearance (melt fracture), toughness, edge tear, and heat stability. It is hoped that the information presented in this paper will help processors optimize use of regrind for best performance.     

Evaluation of the oxidative stability of multiextruded polypropylene as assessed by physicomechanical testing and simultaneous differential scanning calorimetry–chemiluminescence

Common physicomechanical tests comprising impact strength, the melt flow index (MFI), and the yellowness index (YI) were used to study the thermooxidative stability of polypropylene (PP) following multipass extrusion. Differential scanning calorimetry (DSC) coupled with chemiluminescence (CL) monitoring was also used to assess the stability. Three PP formulations were studied: (i) PP‐1 containing 0.050% w/w of the phenolic antioxidant Irganox 1010^™, (ii) PP‐2 containing 0.028% w/w Irganox 1010, 0.056% w/w of the phosphite costabilizer Irgafos 168^™ and 0.014% w/w of the lactone processing stabilizer HP 136^™, and (iii) PP‐3 containing 0.050% w/w Irganox 1010 and 0.100% w/w of the phosphite Ultranox 641^™. All formulations contained 0.045% w/w of the hydrotalcite acid scavenger DHT‐4A^™. The results suggest that physicomechanical tests cannot reliably detect the small difference in the stability between PP‐2 and PP‐3 but can detect the larger difference between these and the less stable PP‐1. The oxidative induction time (OIT) determined by CL monitoring (i.e., CL– OIT) is consistent with the OIT determined by DSC but has better reliability. The CL–OIT data suggest that PP‐3 has superior oxidative stability to PP‐2 in the early stages of multipass extrusion. However, PP‐2 exhibits a better resistance to yellowing. A correlation between the CL–OIT data and each of the MFI and YI data was found. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 733–741, 2001     

Die design for rigid PVC—the effect of die land length on extrudate swell

PVC profile extrusion compounds have a unique morphology. While other polymers gradually decrease in extrusion die swell with increasing length/thickness (L/D) ratio, PVC profile extrusion compounds have a low die swell, quite independent of the die's L/D ratio in the range of 5 to 20. The fact that the die land length can be changed without changing the extrudate swell is an important consideration, which makes die design and balancing dies simpler and easier for PVC profile extrusion compounds. While other polymers substantially increase extrudate swell with increased shear rate, the swell of the PVC profile compounds is not much affected by shear or extrusion rate. This unique behavior allows wider processing latitude in profile extrusion and faster extrusion rates than with other polymers. Another unique factor in the rheology of PVC profile extrusion compounds is that extrusion die swell increases with increasing melt temperature, while other polymers have decreasing die swell with increasing melt temperature. The unusual rheology of PVC profile extrusion compounds is attributed to its unique melt morphology, where the melt flow units are 1 um bundles and molecules that have low surface to surface interaction and entanglement at low processing temperatures but increased melting and increased entanglement at higher processing temperatures. Other polymers, unlike PVC, have melt flow at the molecular level.     

增强热塑性塑料管材高温水浴老化性能研究

老化易使高分子链断裂,使材料变脆、脱层、变色,严重制约了塑料管材在高温、高湿工况下的应用.以交联聚乙烯PEX、耐热聚乙烯PE-RT和高密度聚乙烯PE100为研究对象,进行90 ℃水浴老化.采用万能力学试验机、差示扫描量热仪、维卡软化温度测定仪研究了三种材料老化前后力学性能变化和耐热行为.结果表明,在90 ℃热水浴老化9...     

POLYFLOW在高分子成型加工中的应用研究进展

在聚合物制品外形控制和性能调控过程中,高分子熔体的流动分析对于研究高分子成型工艺至关重要.POLYFLOW软件在高分子成型加工中的应用日渐广泛.本文深入分析了POLYFLOW在挤出、吹塑和热成型等方面的应用,重点介绍了挤出过程中的正向流动仿真和逆向口模设计,最后对POLYFLOW在高分子成型加工中的应用研究方向进行展望...     

Shrinkage in rigid PVC profile extrusions

Shrinkage in PVC profile extrusions may have an effect on the end use performance (dimensional stability, mechanical properties) of the building products such as house siding and windows when they are heated by the sun. This paper examines the heat shrinkage tests being used in the industry, and most importantly, describes effects of the extrusion conditions such as melt temperature, shear rate, percent drawdown, and other variables on shrinkage in PVC profiles.     

苯并呋喃酮在抑制聚丙烯降解过程中的作用

采用多次挤出的方法对三种不同结构苯并呋喃酮与受阻酚及亚磷酸酯的三元复配稳定体系在等规聚丙烯 (PP)中的稳定化作用进行了研究。结果表明:含5,7-二叔丁基-3-(3,4-二甲基苯基)-3氢-苯并呋喃-2-酮 (OXBF1)的复配体系3#配方5次挤出之后的熔体流动速率相对于其同分异构体5,7-二叔丁基-3-(2,5-二甲基苯基)-3氢-苯并呋喃-2-酮(PXBF1)、5,7-二叔丁基-3-(2,4-二甲基苯基)-3氢-苯并呋喃-2-酮 (MXBF1)复配体系的5#配方和6#配方分别下降了24．8％和26％;并且,其抑制所稳定PP加工发黄的作用优于其他两种结构,使得3#配方5次挤出之后的黄度指数(YI)相对于5#配方和6#配方分别下降了9．3％和11．9％;此外,亚磷酸酯对氢过氧化物的还原作用同样提高了苯并呋喃酮高温含氧条件下在PP中的热氧稳定化作用。