不同晶须改性聚丙烯的性能研究

研究了碱式硫酸镁(M-HOS)和钛酸钾(K2Ti6O13)晶须填充改性PP热变形温度、流动性能和力学性能等。结果表明,这两种晶须均能有效地提高PP热变形温度,同时也能改善其力学性能。镁盐和钛酸钾晶须的最佳含量均为30%,此时PP热变形温度分别提高到151.8℃和146.5℃。     

晶须镁盐/POE/聚丙烯共混体系力学性能的研究

采用晶须镁盐、POE、聚丙烯（PP）研制改性PP复合材料；讨论了晶须镁盐和增韧剂POE改性PP的机理；对改性PP进行了力学性能测试；分析了改性PP的微观结构。实验结果表明，晶须镁盐和POE并用能对PP产生良好的增韧增强作用。     

β成核剂和碱式硫酸镁晶须改性聚丙烯

研究了β成核剂和碱式硫酸镁(M-HOS)晶须对聚丙烯(PP)热变形温度及力学性能的影响,并用DSC和广角X射线衍射仪对其进行了表征。结果表明,单独使用0.6%β成核剂和30%M-HOS晶须改性PP,PP热变形温度从129.4℃分别提高到155.2℃和151.8℃。此外,β成核剂在PP增韧方面效果显著,改性后PP缺口冲击强度和断裂伸长率分别为纯PP的4倍和5倍;M-HOS晶须能提高PP的拉伸强度、弹性模量和弯曲强度、弯曲模量;两者同时改性PP,PP热变形温度提高了24℃,缺口冲击强度是单独使用晶须时的3倍。     

镁盐晶须/聚丙烯复合材料的研究

研究了镁盐晶须／聚丙烯复合材料的力学性能和耐热性能。结果表明：随着镁盐晶须用量的增加，复合材料的拉伸强度、弯曲强度、弯曲模量及热变形温度显著提高，而简支梁缺口冲击强度基本保持不变。利用马来酸酐接枝聚丙烯作为相容剂，可以改善基体树脂与镁盐晶须的界面结合性，有助于提高力学性能。     

PP/EPDM-g-MAH/CaCO_3晶须复合材料的性能研究

采用高剪切应力和添加引发剂的复合引发方法制备了EPDM-g-MAH,将其单独或与CaCO_3晶须协同改性PP。通过滴定分析、红外表征和熔体流动速率测定方法研究了175℃条件下螺杆转速对EPDM-g-MAH的熔体流动速率、接枝率的影响。探讨了EPDM-g-MAH和碳酸钙晶须用量对PP力学性能、热变形温度的影响。结果表明:二元共混材料PP/EPDM-g-MAH在弹性体用量为30phr时缺口冲击强度为9.85k J/m2,是纯PP的1.97倍,热变形温度呈下降趋势;三元共混材料PP/EPDM-g-MAH/CaCO_3晶须比二元共混材料具有更好的力学性能,在碳酸钙晶须用量为20phr时缺口冲击强度达到最大值12.94k J/m2,是纯PP的2.59倍,此时共混体系的热变形温度最佳。     

高性能无机阻燃、增强纤维——镁盐晶须在塑料改性和涂料工业中的应用

晶须(新型纤维)和纳米材料是二十一世纪材料科学和材料产业最重要的二大类尖端产品。镁盐晶须是继钛酸钾晶须后的第二代晶须产品，在世界上也只有少数国家可以生产。镁盐晶须以其晶体结构无缺陷的纤维增强效果、耐老化性能、耐温性能和优越的无机阻燃效果，对提高塑料高分子材料和复合材料的综合性能有显著影响。中国生产镁盐晶须仅仅不到一年，但已经得到国内几家著名生产改性塑料的大公司的认可和使用。本文着重介绍新型高性能补强材料——镁盐晶须在塑料改性和涂料等行为中的应用。     

剑麻纤维与晶须混杂增强聚丙烯复合材料

采用熔融共混和注塑成型方法制得了剑麻短纤维(SF)和CaSO4晶须混杂增强聚丙烯(PP)复合材料，研究了复合材料的热性能、微观结构和力学性能。结果表明，晶须提高了复合材料的热稳定性，阻碍了PP的结晶，降低了复合材料中PP相的结晶度和结晶速率；SF和晶须提高了复合材料的模量和韧性，但由于混杂增强复合材料弱界面键合的制约，晶须的高强性能并没有在复合材料中充分表现出来。     

PP与镁盐晶须复合材料性能的研究

以镁盐晶须增强聚丙烯(PP)复合材料为研究对象，添加马来酸酐接枝聚丙烯(PP-g-MAH)1与PP-g-MAH2界面改性剂来改善两者界面粘合强度及提高复合材料的力学性能；探讨了不同加工工艺流程对复合材料性能的影响。结果显示：采用PP-g-MAH1作界面处理剂的复合物体系其增强效果较好；当PP／PP-g-MAH 1／镁盐晶须的质量比为97／3／30时，复合材料的综合性能最佳。应用扫描电子显微镜(SEM)，分别对不同复合材料进行了界面形态的观察，证明与试验结果一致。     

硅灰石粉填充改性聚丙烯复合材料性能研究

采用熔融共混的方法制备了硅灰石粉填充改性聚丙烯(PP)复合材料。通过力学性能、溶体流动速率(MFR)及DSC等测定,考察了硅灰石粉对PP力学性能、热性能及加工性能的影响。结果表明:用硅灰石粉填充改性PP,大大提高了PP/硅灰石粉复合材料的模量,缺口冲击强度的敏感性得到明显改善;改性PP的耐热温度、硬度及加工性能得到一定提高,但其强度有所降低。     

尼龙6/硼酸镁晶须复合材料的制备与研究

使用自制的硼酸酯偶联剂BE-1和BE-2在硼酸镁晶须表面引发聚合形成有机涂层,用改性后的硼酸镁晶须制备尼龙6/硼酸镁晶须复合材料并对其性能进行了研究。结果表明:随着硼酸镁晶须含量的增加,复合材料的拉伸强度、弯曲强度及热变形温度出现了先增加后降低的趋势,当硼酸镁晶须在复合材料基体中的含量为30%时,复合材料的力学性能最佳,BE-1改性的尼龙6/硼酸镁晶须复合材料拉伸强度、弯曲强度、冲击强度、热变形温度分别比未改性的尼龙6/硼酸镁晶须复合材料提高了14.47%、13.72%、29.73%和7.19%;BE-2改性的尼龙6/硼酸镁晶须复合材料的拉伸强度、弯曲强度、冲击强度、热变形温度分别比未改性的尼龙6/硼酸镁晶须复合材料提高了23.37%、22.54%、37.84%和10.78%。     

退火处理对成核聚丙烯性能的影响

采用退火处理对磷酸酯钠盐成核的聚丙烯（PP）体系进行了性能调控,研究了退火时间和退火温度对成核PP力学性能、耐热性能和结晶性能的影响。结果表明,随着退火温度的提高和退火时间的延长,PP的力学性能、耐热性能和结晶能力均得到了明显提升,特别是在120 ℃下,退火0.5 h,PP的拉伸强度从38.0 MPa提高到39.4 MPa,弯曲模量从1227 MPa提高到1882 MPa,热变形温度从112.2 ℃提高到122.7 ℃,结晶度从36 %提高到44 %。     

Effect of Modified Abietate Nucleating Agents on the Properties of Polypropylene

Two kinds of modified abietates, cocrystals of dehydroabietic acid with sodium dehydroabietate and tetrahydroabietic acid with sodium tetrahydroabietate, were prepared, respectively. The properties and crystallization behavior of polypropylene (PP) with the modified abietate cocrystals as nucleating agents were investigated by the measurement of mechanical properties and heat distortion temperature (HDT), testing of differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarizing light microscopy (PLM) observation. The results show that the heat distortion temperature (HDT), transmittance, crystallizing point, the degree of crystallinity, and mechanical properties, especially the flexural strength and modulus of PP are enhanced obviously, but the size of spherulites measured by polarizing optical microscopy decrease, by adding modified abietate cocrystals. By adding the modified abietates, the typical α-form monoclinic structure of PP was formed, which was proved by the results of X-ray diffraction. It is concluded that the modified abietates can be used as effective nucleating agents for PP.     

晶须改性二苯甲烷型双马来酰亚胺树脂体系的研究

以硼酸铝晶须、钛酸钾晶须为增强剂，以N，N′-二胺基二苯甲烷型双马来酰亚胺(BMI)／O，O′-二烯丙基双酚A(BA)体系作为基体，采用浇注成型工艺制备了晶须增强二苯甲烷型双马来酰亚胺树脂基复合材料。研究了晶须对树脂体系凝胶特性的影响，晶须对体系固化反应性的影响；晶须的种类、表面处理方法、含量对树脂体系力学性能和热性能的影响；树脂体系的固化工艺材料对性能的影响。结果表明，晶须对树脂体系固化工艺影响不大；硼酸铝晶须增强效果优于钛酸钾晶须；偶联剂以丙酮作溶剂处理的效果优于乙醇水溶液，酸化溶剂的效果更好；晶须可明显改善体系的力学性能和耐热性，在晶须添加量为15％左右时，所得体系的综合性能较好；改进的固化工艺有助于树脂体系性能的改善。在本研究中，弯曲强度最大提高了约18％，热变形温度最大提高了12％。     

增塑聚丙烯结晶行为和力学性能的研究

以液体石蜡（LP）为增塑剂，采用双螺杆挤出机对无规共聚聚丙烯（PP）进行了增塑，研究了LP用量对PP力学性能和结晶性能的影响。研究结果表明：PP经过增塑后，冲击强度可提高150％，拉伸强度提高80％，断裂伸长率提高110％；增塑PP的结晶度和热变形温度也有所提高。     

Comparison of structure and properties of conventional and “high‐crystallinity” isotactic polypropylenes and their blends with metallocene‐catalyzed linear low‐density polyethylene. I. Relationships between rheological behavior and thermal and physical properties

The present study was conducted to compare the structure and properties of conventional and so‐called “high‐crystallinity” (hcr) polypropylene (PP) and to establish characteristic features of the latter that are responsible for its superior thermal and mechanical performance. Moreover, structure–properties relationships of hcr PP blends with metallocene‐catalyzed, linear low‐density polyethylene (mLLDPE) were compared with those of conventional PP/mLLDPE blends. In Part 1, relationships between rheological behavior (viscosity and melt density) and thermal (transition temperatures and level of crystallinity) and mechanical properties (impact strength and Young's modulus) were analyzed with reference to composition. The rheological and MDSC tests showed that both types of the blends were miscible at the processing temperatures, whereas immiscible in the solid state and in vicinity of the PP melting point. It was found that the improved mechanical properties and the extraordinary high crystallization temperature of hcr PP (and, correspondingly, hcr PP/mLLDPE blends) are not due to the assumed high level of crystallinity but due to alteration of internal structure of this polypropylene. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1591–1599, 2000     

Ram extrusion of high-density polyethylene and polypropylene in solid state: Process conditions and properties

Highly oriented high-density polyethylene (HDPE) and polypropylene (PP) were obtained by solid state extrusion near, but below, the melting temperature. Draw ratios of 6 and 11 were obtained using properly designed dies, preformed billets and lubrication for different extrusion temperatures. Orientation induced significant changes in properties and morphology that are related to the final draw ratio. The draw ratio was observed to decrease with an increase in extrusion speed due to the molecular relaxation occurring because of local heating during deformation. An increase in the degree of crystallinity was observed for the oriented polymers as well as a large improvement in the tensile modulus. Significant molecular relaxation and elastic recoil were observed during processing. Extrusion speed strongly increases the extent of relaxation, and, consequently, reduces many of the mechanical properties.     

Thermal and mechanical properties of polypropylene nanocomposite materials reinforced with cellulose nano whiskers

We use polypropylene (PP, an apolar polymer) and cellulose nano whiskers (CNW, a polar material) to produce nano polymer composites with enhanced mechanical and thermal properties. To improve compatibility, maleic anhydride grafted PP has also been used as a coupling agent. To enhance the uniform distribution of CNW in the composite, the matrix polymer is dissolved in toluene, and sonification and magnetic stirring are applied. Good film transparency indicates uniform CNW dispersion, but CNW domains in the composite film observed under an scanning electron microscope may indicate slight agglomeration of CNW in the composite film. The tensile strength of the composite compared with neat PP improves by 70–80% with the addition of CNW. The crystallinity has also been improved by about 50% in the CNW reinforced samples. As the content of CNW increases, the composite exhibits higher thermal degradation temperature, higher hydrophilicity, and higher thermal conductivity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Shear‐induced crystallization of injection molded vetiver grass‐polypropylene composites

Vetiver grass was used as an alternative filler in polypropylene (PP) composites in this study. Chemical treatment of vetiver grass by alkalization was carried out to obtain alkali‐treated vetiver grass. It was shown that alkali‐treated vetiver grass exhibited higher thermal stability than untreated vetiver grass. Injection molding was used to prepare the composites. The microstructure of injection molded samples showed a distinct skin layer due to shear‐induced crystallization. It was found that normalized thickness of shear‐induced crystallization layer of the composite was lower than that of neat PP. The effect of vetiver particle sizes on shear‐induced crystallization and physical properties of the composites were elucidated. Furthermore, the effect of processing conditions on shear‐induced crystallization, degree of crystallinity, gapwise crystallinity distribution, and mechanical properties of the composite were investigated. It was shown that injection speed and mold temperature affected the normalized thickness of shear‐induced crystallization layer and degree of crystallinity of the composites. However, processing conditions showed insignificant effect on the mechanical properties of vetiver fiber‐PP composites. The degree of crystallinity showed no distribution throughout the thickness direction of the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

聚丙烯/改性长石复合材料的制备、性能及结构表征

以新疆地产哈密长石为原料,对长石进行湿法表面改性。以改性长石作为填料,制备了聚丙烯(PP)/改性长石复合材料,对其性能及微观结构进行了测试和表征。结果表明,改性长石的界面接触角明显增大;与PP基体相比,PP/5%改性长石复合材料的拉伸强度提高了3.78%,冲击强度提高了3.40%,热分解温度提高了6.47℃;改性长石填料起到了部分β-PP晶成核剂的作用,PP/改性长石复合材料的结晶度比纯PP有了不同程度的提高。     

碳酸钙晶须的制备及其对PP增强特性的研究

通过改进的碳酸化方法合成了文石型碳酸钙晶须,并对晶须的开貌牲以及与ＰＰ进行复合的增强特性进行了研究。结果表明：晶须充体系的力学性能明显高于粒状填充由于碳酸钙晶须的均匀性较好,其对ＰＰ的增强改性效果略好于钛酸钾晶须填充体系。