共查询到20条相似文献,搜索用时 78 毫秒
1.
聚合物原位复合纳米碳酸钙增韧PP研究 总被引:6,自引:0,他引:6
通过有机单体原位聚合包覆的CaCO3与PP熔融混合制备了PP/CaCO3纳米复合材料,经过正交实验研究了填料饱覆聚合物比、接枝聚丙烯以及复合填料含量对PP缺口冲击强度的影响,结果表明:复合纳米CaCO3只需填加5%就可以将缺口冲击强度提高为原树脂的2倍左右。 相似文献
2.
采用广角X射线衍射仪、差示扫描量热仪等测定了β成核剂改性聚丙烯(PP)(β-PP)中β晶含量,研究了β晶含量与PP悬臂梁缺口冲击强度的关系、β成核剂的成核热稳定性及β成核剂对PP结晶速率的影响。结果表明:随着β成核剂用量的增加,PP的抗冲击性能提高,但其冲击强度与β晶含量不成正比;β晶含量与β-PP的结晶度达到平衡时,PP冲击强度最佳,当β成核剂质量分数为0.05%时,β-PP的冲击强度最高,达82.4 k J/m2,此时β晶含量为75.78%,β-PP结晶度为77.3%;加入β成核剂使PP的结晶速率降低,较快的降温速率会减少β晶的形成。 相似文献
3.
4.
PP塑料工程化应用改性研究 总被引:3,自引:0,他引:3
采用熔融共混法,在对化学交联、结晶成核剂、纳米SiO2、纳米CaCO3改性聚丙烯等进行了系统研究的基础上,讨论了各因素对复合体系力学性能的影响规律,进一步研究了纳米填料、交联剂、β晶型成核剂3,3,5,5-四甲基联苯胺(TMB)、热塑性弹性体(TPE)共用时对聚丙烯的增强、增韧规律。结果表明,聚丙烯被同时增强、增韧的条件分别是体系中加入质量分数O.5%β晶型成核剂TMB和质量分数0.5%交联剂A;质量分数2%纳米SiO2与适量TPE质量分数5%~10%纳米CaCO3与质量分数O.5%β晶型成核剂TMB。 相似文献
5.
6.
7.
聚丙烯的高性能化研究 总被引:5,自引:0,他引:5
在小型反应器内合成了不含及含有成核剂的聚丙烯(PP)、双峰聚丙烯(BMPP)和聚丙烯共聚物(PPc),并用纳米CaCO3改性PPc。研究结果表明:釜内成核的PP和BMPP的弯曲模量和热变形温度显著增加,结晶温度和结晶速率明显提高,BMPP的拉伸强度也较PP大幅增加;但成核剂对PPc的性能影响不大,而加入纳米CaCO3后则使PPc的力学性能和结晶温度同步显著增加。 相似文献
8.
利用乙烯基聚二甲基硅氧烷/苯乙烯接枝型长支链聚丙烯(PP-g-VS/St)在剪切和快速降温过程中可以诱导形成β晶聚丙烯这一优势,研究了PP-g-VS/St在注塑加工过程中作为高分子β晶成核剂对等规聚丙烯(iPP)结晶温度、晶体结构及力学性能的影响。结果表明改性聚丙烯的结晶温度、β晶相对含量和力学性能随着PP-g-VS/St添加量的增加而增加。当PP-g-VS/St的添加量为50%(质量分数)时,改性聚丙烯的结晶温度相对于纯iPP提高约10℃,β晶相对含量达32.8%,冲击强度、弯曲模量和拉伸强度分别相对于纯iPP提高了355.3%、53.8%和15.9%。这些结果为聚丙烯高分子β晶型成核剂的设计提供了新思路。 相似文献
9.
采用熔融挤出法制备了β成核剂改性聚丙烯(PP)。研究了成核剂含量和退火处理对β成核剂改性聚丙烯(β-PP)力学性能的影响,采用广角X射线衍射仪、扫描电子显微镜对β-PP的微观结构进行表征和分析。结果表明,β成核剂含量为0.05 %(质量分数,下同)时β-PP力学性能最佳,110 ℃下退火处理1 h能够进一步提高β-PP的改性效果;适宜的成核剂含量和退火处理对诱导PP基体β晶生成及结晶完整有利;退火处理的β-PP冲击断面存在明显塑性变形现象,呈韧性断裂特征。 相似文献
10.
采用NT-A和NT-D成核剂制备了β晶型聚丙烯(β-PP),研究其熔融及结晶特性、结晶形态和力学性能.结果发现,NT-A和NT-D成核剂均使聚丙烯(PP)球晶细化,提高PP的拉伸强度、拉伸断裂应变和悬臂梁缺口冲击强度,但NT-D的β成核效果更好,其改性PP的β晶型质量分数可达80%~90%,悬臂梁缺口冲击强度是纯PP的3倍多.注射成型PP样条具有明显的皮芯层结构,纯PP样条的皮层和芯层仅含有α晶型.且结晶度差异不大;β-PP样条的皮层仅有α晶型,而芯层除α晶型外还有β晶型. 相似文献
11.
12.
采用物理共混与化学反应(歧化)并用的方式制备新型PP韧性材料,在增容剂(SB)含量m2%,化学反应物(NX)含量为n2%的情况下,研制的80PP/20PE合金韧性材料的冲击强度和断裂伸长率比原PP分别提高9倍和3倍以上,而拉伸强度仅降低约10%,合金力学性能基本满足汽车行业的需要。 相似文献
13.
概述了以聚丙烯粉料部分代替传统的聚丙烯粒料来生产塑料编织袋扁丝的新工艺,分析了捏合速度、挤出温度、弓板加热温度等因素对扁丝性能的影响。 相似文献
14.
聚丙烯粉料生产中的质量控制 总被引:2,自引:0,他引:2
尚广龙 《现代塑料加工应用》2000,12(2):27-29
分析了间歇液相本体法聚丙烯生产中的质量问题 ,重点讨论了聚丙烯粉料生产中块料、黑料及降解料产生的原因 ,并提出预防措施 相似文献
15.
分析了间歇液相本体法聚丙烯生产中的质量问题,重点讨论了聚丙烯粉料生产中块料、黑料及降解料产生的原因,并提出预防措施。 相似文献
16.
17.
The FTIR quantitative evaluation of grafting succinic anhydride onto polypropylenes is presented. It was done by correlating relative absorbance values obtained from IR spectra with grafting levels of the sample as determined by an improved traditional hot titration method. The results obtained seem to be valid for either atactic or isotactic modified polypropylenes and suggest a careful review about how this technique is usually used in the quantification of polar groups grafted onto polyolefins. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2837–2847, 1999 相似文献
18.
The quiescent isothermal crystallization kinetics of polypropylene was studied as a function of molecular weight (Mw), amount of ethene, and amount of maleic anhydride and acrylic acid grafting. Differential scanning calorimetry and polarized light optical microscopy were used to follow this kinetics. It was observed that the linear growth rate, G, decreased with the increase of Mw, but increased with the amount of ethene. In the grafted polymers, as the amount of grafting increased, G decreased. The fold surface free energy, σe, was found to increase with the increase in Mw. The heterophasic and grafted polymers had σe values higher than the homopolymers. All samples showed spherulitic morphology, except the acrylic acid-grafted polypropylene that showed axialitic morphology. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1159–1176, 1998 相似文献
19.
20.
Issues in blends of polymers of the same chemical repeat unit but with different tacticities were addressed by investigating on the phase behavior and interaction strength of binary blends of three polypropylenes of different tacticities, i.e., isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), and atactic polypropylene (aPP) using polarized optical microscopy (POM) and differential scanning calorimetry (DSC). Although blends of polypropylenes have been widely studied in the past, there are still on-going debates on true phase behavior (miscibility vs. upper critical solution temperature (UCST) or immiscibility). Except for several earlier theoretical predictions based on the Flory-Huggins mean field theories, UCST behavior had not been experimentally proven for blends of sPP/iPP or aPP/sPP, owing to interference from PP crystallinity. In addition, interaction strength of the blends of different tactic polypropylenes is yet to be established. Using the method of equilibrium melting points, the Flory-Huggins interaction parameter of the aPP/iPP blend was shown to possess a significantly negative value (χ12 = −0.21), which proves that the blend is indeed miscible in the melted amorphous as well as semicrystalline states as previously reported in the literature. However, the interaction parameters for the sPP/iPP and aPP/sPP blends were found to be nearly zero (χ12 = −0.02 and −0.0071, respectively, at T = 150-180 °C), indicating that the interactions in two blends are weak and that the corresponding phase behavior for them borders on immiscibility at ambient temperature. This study also utilized novel approaches in constructing UCST phase diagrams by separating the amorphous phase domains from the crystalline spherulites, yielding data plausible for experimentally determining the UCST in iPP/sPP blend vs. aPP/sPP blend. 相似文献