对浇铸型有机玻璃增韧改性的实验研究

通过试验研究了溶液和乳液聚合法制备聚丙烯酸丁酯（PBA）对浇铸型有机玻璃（PMMA）的增韧改性。研究表明,当PBA以粒子形式分散于PMMA基体中时,对浇铸型PMMA有较好的增韧改性效果。     

浅析浇铸型有机玻璃的增韧改性

通过试验研究了溶液和乳液聚合法制备聚丙烯酸丁酯(PBA)对浇铸型有机玻璃(PMMA)的增韧改性。实验表明,当PBA以粒子形式分散于PMMA基体中时,对浇铸型PMMA增韧改性效果良好。     

浇铸型有机玻璃增韧改性研究

通过试验研究了溶液和乳液聚合法制备聚丙烯酸丁酯(PBA)对浇铸型有机玻璃(PMMA)的增韧改性。研究表明,当PBA以粒子形式分散于PMMA基体中时,对浇铸型PMMA有较好的增韧改性效果。     

纳米CaCO_3的接枝改性及其填充PVC复合材料的性能

采用表面原位接枝聚合在纳米CaCO3颗粒表面引入聚甲基丙烯酸甲酯(PMMA)或聚丙烯酸丁酯(PBA),用共混法制备了纳米CaC03/PVC复合材料,研究了不同界面特性时纳米CaCO,/PVC复合材料的力学性能.研究结果表明:通过表面原位接枝聚合反应可以在纳米CaCO3颗粒表面接枝PMMA和PBA;表面接枝聚合改性大大促进了纳米CaCO3粒子在PVC基体中的分散行为,增加了复合材料的拉伸强度以及与聚合物的界面粘接强度,但复合材料的冲击强度有所下降.     

PMMA接枝纳米ZnO复合粒子改性PVC塑料性能研究

通过原位聚合将甲基丙烯酸甲酯（MMA）接枝于纳米ZnO表面,制备了PMMA接枝纳米ZnO复合粒子,将其加入聚氯乙烯（PVC） 基体中进行改性。研究了纳米ZnO粒子在PVC基体中的分散性和PVC复合材料的力学性能,探讨了改性纳米ZnO粒子填充PVC材料的抗紫外线性能。结果表明,改性后的纳米ZnO粒子在PVC基体中分散均匀, 提高了纳米ZnO粒子与PVC基体之间的相容性,使改性PVC材料的拉伸强度达到78 MPa,比纯纳米ZnO粒子改性PVC提高了35 %;冲击强度提高了近1倍,达到13.6 kJ/m2;加入改性纳米ZnO粒子的PVC还具有明显的吸收紫外线功能。     

改性纳米CaCO3/PVC复合材料的力学性能

采用钛酸酯偶联剂和PMMA接枝方法改性纳米碳酸钙,并采用熔融共混法制备了改性纳米CaCO3增韧PVC（CaCO3／PVC）复合材料,研究了复合材料的力学性能。对比于未处理纳米CaCO,和钛酸酯偶联剂处理纳米CaCO3,PMMA接枝聚合改性纳米CaCO3与基体的相容性最好,增韧PVC复合材料的拉伸强度得到较大幅度提高。     

有机刚性粒子增韧聚苯硫醚的研究

采用有机刚性粒子聚甲基丙烯酸甲酯(PMMA)增韧改性聚苯硫醚(PPS)。考察了加工温度及PMMA用量对聚苯硫醚复合材料微观形态结构和力学性能的影响。结果表明,复合材料的力学性能随着加工温度的升高而下降。PMMA与PPS基体以“海岛”状的形式存在;少量PMMA加入时,PMMA同PPS结合较好,冲击强度显著提高;当增加PMMA的用量时,PMMA在PPS基体中的相区尺寸增大,界面变得明显,各项力学性能有小幅下降。     

聚甲基丙烯酸甲酯／纳米SiO2复合粒子的制备与表征

采用甲基丙烯酸-3-甲氧基硅丙酯（MPs）对分散于甲基丙烯酸甲酯（MMA）中的纳米SiO2粒子进行偶联改性，得到了表面改性的纳米SiO2单体分散液，用原位悬浮聚合方法制备了不同SiO2含量的PMMA／纳米SiO2复合粒子。通过红外光谱、透射电镜、差示扫描量热分析和热重分析等方法对制备的纳米复合粒子进行了表征，结果表明，纳米SiO2粒子在PMMA中分散良好；MMA可通过与MPS的共聚而有效地接枝到SiO2粒子表面，当SiO2含量为6．6％（质量分数，下同）、MPS用量为0．06g／gSiO2时，其接枝率可达73．8％；同时，纳米SiO2的引入可提高PMMA的耐热性能，当Si02含量为14.7％时，其玻璃化转变温度和最大热分解速率时的温度分别提高了11．8℃和18．8℃。     

聚甲基丙烯酸甲酯包覆纳米CaCO3改性聚氯乙烯研究

研究了聚甲基丙烯酸甲酯(PMMA)包覆纳米CaCO3复合粒子填充聚氯乙烯(PVC)复合材料的加工塑化和力学性能，并与未改性纳米CaCO3的改性效果进行比较。结果发现，填充纳米CaCO3使PVC平衡扭矩和平衡熔融温度均会有所提高，填充未改性碳酸钙增加更大，填充PMMA包覆CaCO3使材料冲击性能提高的幅度大于填充未改性纳米CaCO3，而拉伸强度下降幅度较小。当PMMA包覆CaCO3填充量为8％时缺口冲击强度增加到未改性PVC的194％。冲击缺口断面形态分析表明，采用PMMA包覆CaCO3时，纳米CaCO3在PVC基体中分散均匀、团聚少。     

高韧性PMMA共混物的制备与性能研究

采用乳液聚合方法合成了核-壳粒子聚甲基丙烯酸甲酯-聚丁二烯接枝共聚物(PB-g-PMMA)作为聚甲基丙烯酸甲酯(PMMA)的增韧剂,同时加入聚偏氟乙烯(PVDF)进行协同增韧,研究共混物的增韧行为。结果表明,PVDF加入导致PMMA玻璃化转变温度向低温移动,二者具有热力学相容性;PB-g-PMMA粒子在PMMA中分散均匀,PVDF不改变PB-g-PMMA在基体树脂中的均匀分散状态;PMMA/PB-g-PMMA共混物的缺口冲击强度为30 J/m,加入PVDF质量分数为40%时,共混物的缺口冲击强度高达305 J/m,PB-g-PMMA的增韧效率显著提高;断裂机理表明,当共混体系中PVDF质量分数高于20%后,共混物的断裂过程以剪切屈服为主,导致材料韧性显著提高。     

抗冲改性剂ACR的组成与粒径对R—PVC应用性能的影响

本文中对ACR的组成及粒径对R—PVC抗冲性能的影响,用简单模型进行了理论分析和验证。发现内核粒径(D_W)为115.8nm的ACR的较佳组成为PBA/PMMA(wt%)=55/45,组成相同的ACR,当交联PBA核粒径(D_W)在85～115.8nm范围内变化时,抗冲改性效果随粒径的增加而增加;PBA平均粒径(D_W)相同时,内核PBA的分散度越小,对R—PVC的抗冲改性效果越好。DSC研究表明:有两个明显的玻璃化转变温度,R—PVC中加入6phr的ACR,能使其加工性能得到改善,提高材料的缺口冲击强度。     

Blends containing core–shell impact modifiers. Part 3 – Effects of temperature on tensile impact behaviour

Abstract

The performances of two contrasting core–shell impact modifiers, in blends with polycarbonate (PC), poly (methyl methacrylate) (PMMA), and poly (styrene-co-acrylonitrile) (PSAN), have been evaluated using tensile impact tests at temperatures between -80 and +50°C. In both modifiers, each individual particle has a 10 nm thick outer shell of PMMA, which is grafted to the rubber phase. In the case of modifier PB, the core of the particle is a 200 nm diameter homogeneous sphere of polybutadiene, with a T _g of -86°C. Modifier PBA has a 260 nm core of PMMA, surrounded by a 20 nm inner shell of poly (butyl acrylate-co-styrene), which has a T _g of -17°C. Tensile impact tests show that the T _g of the rubber does not necessarily control the brittle–ductile transition temperature T _BD. Both the PC–PB and PC–PBA blends exhibit some ductility at -80°C, although neither blend is as tough as plain PC at any temperature. The blend of PB with PMMA shows a modest increase in toughness above -40°C and there is a similar but rather larger increase in the toughness of the PMMA–PBA above -20°C. In PSAN blends, the PBA modifier is the more effective toughening agent ahove 0°C. It is concluded that these differences originate from differences in the balance between shear yielding and crazing in the matrix polymer, and in the ability of cavitated rubber particles to prevent crazes from turning into cracks. In PMMA and PSAN blends, the PBA modifier is the more effective toughening agent at 23°C because of its rigid core, which enables stable rubber fibrils both to form and to contribute to local strain hardening, thereby stabilising the yield zone.     

粒径可控的聚丙烯酸丁酯/聚甲基丙烯酸甲酯核壳乳液的制备及表征

采用种子乳液聚合法制备了聚丙烯酸丁酯(PBA)乳液,然后通过第二单体甲基丙烯酸甲酯的预溶胀法聚合制备了PBA/聚甲基丙烯酸甲酯(PMMA)乳液,用激光散射粒度仪和透射电子显微镜对乳液粒径和结构进行了表征.结果表明,当乳化剂十二烷基硫酸钠质量分数为丙烯酸丁酯的1.5%时,可制备粒径为53.6 nm且分布窄的PBA种子乳液;通过调整补加乳化剂、单体与种子乳液的用量,可制得粒径为53.6～443.8 nm的一系列单分散PBA乳液;PBA/PMMA乳液具有完善的核壳结构,且在核壳两相间存在着一个过渡层.     

以PVC为外壳层的ACR抗冲改性剂的合成及其对PVC的增韧作用

以聚丙烯酸丁酯(PBA)为内核,通过种子乳液聚合制备了分别以聚甲基丙烯酸甲酯(PMMA)、聚氯乙烯(PVC)、PMMA/PVC为壳层的纯丙烯酸酯(ACR)和PVC改性ACR乳液.扫描电镜观察发现,纯ACR乳胶粒子具有明显的核-壳结构,进一步包覆PVC后形成疏松外层.考察了不同结构ACR与PVC共混物的相态结构、抗冲性能和断面形貌,发现用PVC部分或完全替代PMMA壳层的改性ACR在PVC基体分散良好,具有与纯ACR相当的增韧PVC作用,冲击断面呈现典型的韧性断裂特征.     

Synthesis and characterization of poly(butyl acrylate)/silica and poly(butyl acrylate)/silica/poly(methyl methacrylate) composite particles

Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006     

Synthesis of poly(butyl acrylate)—laponite nanocomposite nanoparticles for improving the impact strength of poly(lactic acid)

This work aims at preparing and characterizing poly(butyl acrylate) (PBA)—laponite (LRD) nanocomposite nanoparticles and nanocomposite core (PBA‐LRD)‐shell poly(methyl methacrylate) (PMMA) nanoparticles, on the one hand, and the morphology and properties of poly(lactic acid) (PLA)‐based blends containing PBA‐LRD nanocomposite nanoparticles or (PBA‐LRD)/PMMA core–shell nanoparticles as the dispersed phase, on the other hand. The PBA and (PBA‐LRD)/PMMA nanoparticles were synthesized by miniemulsion or emulsion polymerization using LRD platelets modified by 3‐methacryloxypropyltrimethoxysilane (MPTMS). The grafting of MPTMS onto the LRD surfaces was characterized qualitatively using FTIR and quantitatively using thermogravimetric analysis (TGA). The amounts of LRD in the PBA‐LRD nanocomposites were characterized by TGA. The PBA/PMMA core–shell particles were analyzed by ¹H‐NMR. Their morphology was confirmed by SEM and TEM. Mechanical properties of (PBA‐LRD)/PLA blends and (PBA‐LRD)/PMMA/PLA ones were tested and compared with those of the pure PLA, showing that core–shell particles allowed increasing impact strength of the PLA while minimizing loss in Young modulus and tensile strength. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

丙烯酸酯接枝改性天然橡胶增韧聚乳酸

通过在天然橡胶(NR)分子链上接枝甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA),制备了三种丙烯酸酯接枝改性NR:NR-g-PMMA,NR-g-PBA和NR-g-(PMMA,PBA)。采用核磁共振氢谱对三种接枝物进行了化学结构鉴定。将接枝改性后的NR和未改性的NR与PLA采用哈克密炼机熔融共混,分别制备了PLA/NR,PLA/NR-gPMMA,PLA/NR-g-PBA和PLA/NR-g-(PMMA,PBA)共混物,研究了接枝改性NR和未改性NR含量对共混物力学性能和热性能的影响。各共混物的拉伸弹性模量和拉伸强度均随接枝改性NR和未改性NR含量的增加而降低,断裂伸长率和缺口冲击强度随接枝改性NR和未改性NR含量的增加而提高。其中,PLA/NR-g-PBA共混物的断裂伸长率和缺口冲击强度比其它共混物提高的幅度大,当NR-g-PBA的质量分数为5%时,PLA/NR-g-PBA共混物的断裂伸长率达到78%,缺口冲击强度为5.2 k J/m2,而纯PLA的断裂伸长率仅为7.7%,缺口冲击强度为2.5 k J/m2,说明NR接枝分子柔顺性较高的BA更有利于促进其与PLA共混物的韧性提高。热分析结果表明,PLA/NR-gPBA共混物的热稳定性相比于纯PLA也有所提高。     

Toughening of polylactide with natural rubber grafted with poly(butyl acrylate)

Natural rubber grafted with poly(butyl acrylate) (NR‐g‐PBA) in an attempt to toughen polylactide (PLA) was prepared by grafting butyl acrylate onto natural rubber (NR) through emulsion polymerization. The purified NR‐g‐PBA was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. NR‐g‐PBA/PLA blend and NR/PLA blend were prepared with a Haake internal melt mixer. The morphology and mechanical properties of the blends were investigated as a function of rubber content. Observations by scanning electron microscopy showed that the spherical‐particle‐dispersed phase appearing in the NR/PLA blend was not found in the NR‐g‐PBA/PLA blend, which showed that NR grafted with PBA is compatible with PLA, and accounted for the efficient toughening effect on PLA. The elongation at break and the impact strength were significantly improved with an increase in NR‐g‐PBA content. The thermal stability of PLA decreased when blended with NR but was retained with NR‐g‐PBA. Copyright © 2011 Society of Chemical Industry