交联剂DB对丁腈橡胶/聚氯乙烯共混物性能的影响

研究交联剂DB对丁腈橡胶/聚氯乙烯共混物性能的影响。结果表明,交联剂DB的加入,使NBR/PVC共混物的正硫化时间、最低扭矩和最高扭矩增大,时缩短焦烧时间。当交联剂DB用量为2.0份时,共混物具有较好的力学性能。适当增加交联剂DB用量,可以提高NBR/PVC共混物的耐热老化性能的耐油性能。     

R-PET/LLDPE/SEBS-g-MA共混物的动态力学分析

通过红外光谱证明在加工过程中,SEBS-g-MA的酸酐基团与PET的端羟基发生反应生成了共聚物,研究了SEBS-g-MA用量对共混物的流动性和动态力学性质的影响,MFR分析结果表明,随着SEBS-g-MA用量增加,共混物的流动性呈现先升高后降低趋势,DMA分析结果表明,SEBS-g-MA用量为10%(质量分数)时,共混物的储能模量和损耗模量与未添加SEBS-g-MA的共混物的结果接近,且SEBS-g-MA用量对共混物的tanδ无影响。     

AIM中橡胶相交联密度对AIM/PMMA共混物性能的影响

采用乳液聚合方法制备了四种不同交联密度且粒径及折光指数可控的丙烯酸酯类冲击改性剂(AIMs),考察了AIMs中橡胶相的交联密度变化对AIM/PMMA共混物力学性能及光学性能的影响。结果表明,AIM/PMMA共混物的冲击强度随AIM中交联剂用量的提高呈先上升后下降趋势,当AIM的橡胶相交联剂含量为2%(质量分数,下同)时,AIM/PMMA共混物的最大裂纹引发能(Kmax)、裂纹增长能(Uprop)及冲击强度均达到最大值,与纯聚甲基丙烯酸甲酯(PMMA)相比较,其冲击强度提高了5倍,且光学性能没有明显下降。结合共混物的冲击强度与形变区的扫描电镜(SEM)观察,可见断裂过程中此种AIM橡胶粒子的空洞化能够有效地促进基体树脂的能量吸收。     

PPS/PA-66共混物结构与性能的研究

用Ｘ射线衍射、ＳＥＭ和ＦＴ－ＩＲ研究了ＰＰＳ／ＰＡ－６６共混物的聚集态结构、相形态和共混体系分子间的相互作用。结果表明，随着ＰＡ－６６含量增大，共混物的结晶性更好；ＰＰＳ／ＰＡ－６６共混体系属于多相体系，含微量支化或交联键的ＰＰＳ占５０％时，为分散相，ＰＡ－６６占７５％时，ＰＰＳ成为连续相；随着ＰＡ－６６含量增加，ＰＰＳ的苯环Ｃ－Ｈ振动７０５ｃｍ－１峰位向低波数移动，随ＰＰＳ含量增加，ＰＡ－６６中酰胺的Ｃ＝Ｏ１６３９ｃｍ－１峰位向低波数移动，酰胺基团与苯环上的Ｃ－Ｈ存在氢键相互作用。熔融流动性、流变性和冲击性能试验证明，共混物有良好的熔融流动性和韧性。     

DCP用量对PP／EPDM共混物力学性能及形态的影响

过氧化二异丙苯（DCP）能有效降解PP;当DCP用量为2‰（质量分数）时,PP／EPDM共混物的冲击强度较高。共混物的相形态结构表明,EPDM橡胶粒子均匀地分散在基体中。     

多单体熔融接枝PP增容PP/PVC共混体系的力学和流变性能研究

合成了一种新型的多单体接枝物PP－g-(St-co-MMA),研究了其对PP／PVC共混体系的增容作用。讨论了接枝物用量对共混物力学性能和流变行为的影响，并通过扫描电镜（SEM）对共混物的亚微观相结构进行了分析。结果表明，该接枝物对PP／PVC共混体系有较好的增容效果，材料的力学性能在接枝物用量为6份时出现峰值；加入接枝物能使体系的熔体粘度增加，并且在所研究的温度和压力范围内共混物熔体呈典型的假设性流体特性。     

酚醛树脂增容聚甲醛／丁腈橡胶共混物的亚微相态与增韧机理研究

采用扫描电子显微镜（SEM）和透射电子显微镜（TEM）考察了热塑性酚醛树脂（Novolak）增容聚甲醛（POM）/丁腈橡胶（NBR）共混物的亚微相态。通过对共混物的TEM及经刻蚀后脆性断裂面的SEM观察发现,对于POM/NBR共混物,NBR在基体中呈现不规则的“海-岛”结构,由于两相不相容导致分散相NBR在基体中的分散性很差。对于POM/NBR/Novolak共混物,在NBR含量为30%时,共混物仍然呈现“海-岛”结构,但NBR在基体中的分散性有所提高;当NBR含量为40%时,NBR在基体中呈现带状网络结构相态,文中提出了Novolak增容POM/NBR共混物的增韧机制,即高含量的NBR通过Novolak的增容作用,在POM中基体形成互锁的带状网络结构;当材料受到外力冲击时,这种橡胶网络带给够终止受到外力作用而在基体中产生的银纹和剪切屈服,增加了共混物的破裂能,从而使共混物的韧性得到显著提高。     

苯乙烯-甲基丙烯酸甲酯共聚物与酚醛树脂共混体系相形态控制研究

用溶液浇铸膜法制备一系列不同比例的苯乙烯-甲基丙烯酸甲酯共聚物，酚醛树脂共混物，并利用原子力显微镜和扫描电镜观察其表面形态。材料的微观结构分析表明：苯乙烯-甲基丙烯酸甲酯共聚物和酚醛树脂共混体系由于氢键作用存在相容窗口，在其相容窗口内可以通过改变共聚物的共聚比或共混比来控制相形态结构，获得预期的纳米形态结构；在相容窗口中，共混物存在分散的颗粒，它源于聚合物分子链间的分凝结构，共混物中PS含量的增加会增加分子链间的分凝结构，致使分散颗粒出现，当分凝程度越来越大时，最终会导致共混体系进入相分离状态。     

动态硫化聚氯乙烯／橡胶共混型热塑性弹性体的研究

本文选用硫磺、二硫化四甲基秋兰姆和2,4,6-三巯基-1,3,5-三嗪三种硫化体系及聚氯乙烯与丁腈橡胶和丁苯橡胶的共混物,用动态硫化法制备了一类性能优异的材料——聚氯乙烯/橡胶共混型热塑性弹性体,具有强度高、永久变形小、可重复加工等特点。考查了共混比、交联荆含量和品种、聚氯乙烯树脂品种、以及相容性等因素对此材料力学性能的影响。实验结果表明:交联剂品种和用量对力学性能有重要影响;聚氟乙烯与橡胶分子之间的相互作用力越大,则此共混型热塑性弹性体的力学性能越好。     

HPVC/PP共混改性研究Ⅳ共混物的流变特性

研究了ＨＰＶＣ／ＰＰ共混物的流变性能，结果表明，ＣＰＥ、ＡＢＳ对ＨＰＶＣ／ＰＰ有增粘作用。随着ＣＰＥ用量增加，共混物熔体粘度（ηａ）增加。ＣＰＥ或ＡＢＳ先与ＨＰＶＣ共混后再与ＰＰ共混的共混物的ηａ高于ＣＰＥ或ＡＢＳ先与ＰＰ共混后再与ＨＰＶＣ共混的共混物的ηａ。ＨＰＶＣ／ＰＰ、ＨＰＶＣ／ＰＰ／ＭＡＨ２．５、ＨＰＶＣ／ＰＰ／ＣＰＥ１０、ＨＰＶＣ／ＰＰ／ＡＢＳ１０共混物的ηａ～组成（Ｃ）的关系均属于正－负偏离共混物（Ｐ－ＮＤＢ）体系，即在特定共混比下发生相转变。     

Highly toughened polypropylene/ethylene–propylene-diene monomer/zinc dimethacrylate ternary blends prepared via peroxide-induced dynamic vulcanization

Polypropylene (PP)/ethylene–propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blends with remarkable toughness and extensibility were successfully prepared via peroxide dynamical vulcanization. A unique structure with the EPDM particles surrounded by a transition zone containing numerous polymerized ZDMA (PZDMA) nano-particles was observed for the first time by using transmission electron microscopy (TEM) examination, which contributed to the dramatically increase of Izod impact strength. Dynamic mechanical analysis (DMA) confirmed that the possible PZDMA graft products resulted from peroxide dynamical vulcanization improved the compatibility between EPDM and PP phases. The specific morphology of the PP/EPDM/ZDMA blends indicated that ZDMA can lead to size reduction and good distribution uniformity of the crosslinked rubber particles and the increase of adhesion between PP matrix and EPDM phases during deformation. The synergic effect of the increase in the effective volume of the EPDM phase, the improved compatibility and adhesion between EPDM and PP phases and the deformation of those fine rubber particles is believed to result in the remarkable high toughness and extensibility of the PP/EPDM/ZDMA blends. Particularly for the PP/EPDM ratio of 70/30, the PP/EPDM/ZDMA (70/30/9, w/w/w) ternary blends with the Izod impact strength nearly 2 times higher than PP/EPDM (70/30, w/w) binary blends and 15–20 times higher than PP are achieved; besides, the elongation at break of PP/EPDM/ZDMA ternary blends is 4–5 times higher than that of PP/EPDM binary blends.     

顺酐改性乙丙三元胶／尼龙的共混研究

对极性差别较大的乙丙三元橡胶和尼龙1010体系,首次通过官能化反应及动态全硫化共混方法制得了一种耐温性较高的热塑性弹性体,并对相容性的表征及分散相粒径问题进行了研究。实验表明,上述共混体系仍是非均相的不相容体系,尼龙相的玻璃化转变温度向低温移动的程度可以作为相容程度的判断。此时,在两相界面间是橡胶向尼龙基质的渗透,渗透方向应该也对改性作用有其特有的贡献。同时分散相的最大填充体积φ_(max)可以用来表征相容性的优劣。     

Improvement of impact property of natural fiber–polypropylene composite by using natural rubber and EPDM rubber

In this research, vetiver grass was used as a filler in polypropylene (PP) composite. Chemical treatment was done to modify fiber surface. Natural rubber (NR) and Ethylene Propylene Diene Monomer (EPDM) rubber at various contents were used as an impact modifier for the composites. The composites were prepared by using an injection molding. Rheological, morphological and mechanical properties of PP and PP composites with and without NR or EPDM were studied. Adding NR or EPDM to PP composites, a significant increase in the impact strength and elongation at break is observed in the PP composite with rubber content more than 20% by weight. However, the tensile strength and Young’s modulus of the PP composites decrease with increasing rubber contents. Nevertheless, the tensile strength and Young’s modulus of the composites with rubber contents up to 10% are still higher than those of PP. Moreover, comparisons between NR and EPDM rubber on the mechanical properties of the PP composites were elucidated. The PP composites with EPDM rubber show slightly higher tensile strength and impact strength than the PP composites with NR.     

Electrical properties and morphology of carbon black filled PP/EPDM blends: effect of selective distribution of fillers induced by dynamic vulcanization

The roles of dynamic vulcanization process in the electrical properties, morphology, and rheology of carbon black (CB)-filled polypropylene (PP)/ethylene–propylene-diene rubber (EPDM) blends have been investigated. With the addition of CB, the uncross-linked (TPE) and dynamically vulcanized (TPV) composites showed a notable difference in the electrical properties, which is mainly caused by different distributions of CB particles resulting from the dynamic vulcanization process. Particularly, it was found that the CB particles in the TPE composites tended to distribute in EPDM phase, whereas the CB particles in the TPV composites were almost located in the PP matrix. The rheological behavior of the TPE and TPV composites was significantly changed with the incorporation of CB particles. Due to the selective distribution caused by the dynamic vulcanization process, the formation of the conductive network for the TPE composites is caused by the double percolation effect, while for the TPV composite, the formation of the conductive network is caused by the excluded volume effect.     

DCP用量对PP／EPDM共混物性能和形态的影响

用动态硫化法制备的PP／EPDM共混型热塑性弹性体的性能明显优于直接共混型PP／EPDM热塑性弹性体,这是由于模量低的EPDM柔性长链经化学交联后,强化对PP的增韧效果,而交联后又被扯断细化的EPDM的颗粒,改变了因EPDM相互缠结所导致的熔融粘度大,加工性能差的缺陷。制备PP／EPDM热塑性弹性体的关键是动态硫化,由于PP／EPDM共混物的动态硫化是一个融物理共混、化学引发交联和剪切细化分散为一体的复杂过程,材料的性能除决定于组成、组分性能和化学交联体系外,还强烈依赖于所采用的共混工艺方式及其条件。本章采用过氧化二异丙苯（DCP）作为硫化剂,研究了过氧化物用量对动态硫化PP（K8303）／EPDM共混物性能和形态的影响。     

动态硫化EPDM／PP热塑性弹性体动态力学性能的研究

应用动态热力学分析仪测定了动态硫化EPDM／PP共混物的动态力不宪为,Tg峰的变化,表明P的非晶部分与EPDM具有部分互溶性,同时讨论了共混物动态模量的特点,研究了不同橡塑比,硫化剂和软化剂用量对动态硫化EPDM／PP共混物动态力学性能的影响。     

动态全硫化热塑性弹性体EPDM／PP拉伸蠕变行为的研究

Santoprene是当前颇具代表性的动态全硫化共混型热塑性弹性体EPDM/PP品种,其EPDM形成分散相,PP形成连续相。本文依据它的这种结构特征,引用高柳素夫模型,计算出模型中各单元的重量比、体积比和拉伸蠕变柔量,由此推论它的蠕变行为。     

Effect of crosslinking on morphology and phase inversion of EPDM/PP blends

This study investigates the effect of cross-linking on morphology and phase inversion of EPDM/PP blends. Several EPDM/PP blends without and with cross-linking agent were prepared in a Haake batch mixer under constant conditions. The morphology was studied by electronic microscopy (SEM and TEM), and cross-linking was followed by EPDM gel content and swelling. The results showed that the position of the phase inversion region is essentially governed by composition, being independent of the viscosity ratio of the EPDM/PP blend. The TPVs’ morphology of the EPDM/PP blend, with 70 and 50 wt% of PP, consists of EPDM cross-linked particles dispersed in the PP matrix. For EPDM-rich composition (30 wt% of PP), the TPVs’ morphology appears to be co-continuous. Even though dynamic vulcanisation of the rubber phase always improves the dispersion of the EPDM phase, complete phase inversion (from fully dispersed PP in the EPDM matrix to EPDM fully dispersed in the PP matrix) was achieved only with low viscosity EPDM.     

部分动态预硫化对EPDM发泡行为的影响

采用部分动态预硫化工艺制备三元乙丙橡胶(EPDM)发泡材料,即通过在哈克中动态预硫化来控制橡胶预交联,然后混入相同的硫化和发泡剂体系并制得发泡材料。研究了部分动态预硫化对EPDM凝胶含量及发泡行为的影响。结果表明,动态预硫化过程中,随硫磺用量增加,其最终平衡扭矩升高,预硫化混炼胶的凝胶含量增加;硫化和发泡行为测量表明,动态预硫化并未影响EPDM混炼胶二次硫化速度以及发泡剂分解速度;扫描电镜(SEM)显示,预硫化阶段硫磺用量为0.0125phr时的试样,能获得较好的泡孔结构和较低的密度,表明适量的预硫化能明显改善EPDM混炼胶的发泡行为。     

SC–CO<Subscript>2</Subscript>-assisted rubber dispersion and dynamic vulcanization in blending of PP/EPDM thermoplastic olefin

Supercritical CO₂ (SC–CO₂), as a green medium, was induced in the traditional way of preparing polypropylene/ethylene–propylene–diene terpolymer (EPDM) thermoplastic olefin (TPO) by dynamic vulcanization using a twin-screw extruder. The morphology observation suggested that the SC–CO₂ not only promoted the rubber dispersion, but also facilitated the rubber dynamic vulcanization; therefore, the crosslinked EPDM particles were more densely distributed in the TPOs prepared with SC–CO₂, and existed as a stronger viscoelastic phase restricting the mobility of polymer chains, increasing the complex viscosity and storage modulus and promoting the mechanical properties.