PVC/N-AIM共混物的力学性能及形态结构研究

采用乳液聚合法制备了粒径为200 nm的新型丙烯酸酯类核-壳改性剂(N-AIM),并与聚氯乙烯树脂(PVC)进行熔融共混,制备PVC/N-AIM共混物,对PVC/N-AIM共混物的力学性能及形态结构进行了系统的研究。结果表明,当丙烯酸丁酯/丁二烯/苯乙烯的质量比为70/25/5,改性剂用量为5.71 phr时,共混物的冲击强度达到最大值(1 280 J/m),并在此时发生了脆韧转变,且增韧效果明显优于丙烯酸酯类抗冲改性剂(KM355);橡胶粒子在PVC基体中分散良好,共混物的断裂方式为韧性断裂。     

MBS粒子尺寸对PVC／MBS共混物性能及形变机理的影响

通过乳液聚合方法制备了两种不同粒径（分别为270nm和80nm）的甲基丙烯酸甲酯/丁二烯/苯乙烯（MBS）核壳改性剂，与聚氯乙烯（PVC）进行熔融共混，得到了PVC／MBS共混物。对PVC／MBS共混物力学、光学等方面的性能及其形变机理分别进行了考察。结果表明：PVC／MBS共混物的脆-韧转变温度（BDT）和拉伸性能均随着MBS粉料粒径的增加而增加；但是光学测试则表明MBS粒子对改善PVC基体的光学性能的效果却随MBS粉料粒径的增加而降低；透射电镜（TEM）的分析表明大粒径的MBS粉料能促使橡胶粒子产生空洞化，而由小粒径的MBS粉料制备的PVC／MBS共混物没有观察到橡胶粒子空洞化的产生。     

基体组成对橡胶改性的PVC／PMMA共混物断裂行为的影响

通过种子乳液聚合方法合成聚丁二烯接枝甲基丙烯酸甲酯（PB-g-MMA）核-壳改性剂。将PB-g-MMA、聚氯乙烯（PVC）和聚甲基丙烯酸甲酯（PMMA）在160℃下熔融共混，制得橡胶含量为16％（质量含量）的一系列的橡胶改性PVC／PMMA共混物。研究了基体组成对共混物力学性能和形态结构的影响。结果表明在宽组成范围内PVC和PMMA是相容的，并且当PVC含量较少时，共混物以脆性方式断裂，银纹是其主要的形变机理；当PVC含量较多时，共混物以韧性方式断裂，此时主要的形变机理是橡胶粒子的空洞化和基体的剪切屈服。在橡胶改性PVC／PMMA共混物中，随着基体组成的改变形变，机理存在着从银纹到剪切屈服的转变。     

核壳改性剂增韧聚苯醚/聚苯乙烯共混物的形态结构及性能

采用乳液聚合方法合成了核壳比为50/50(聚丁二烯/聚苯乙烯,PB/PS),粒径分别为120 nm和350 nm的PB-g-PS接枝共聚物,而后将PB-g-PS弹性体与高抗冲聚苯乙烯(HIPS)同时作为改性剂增韧聚苯醚(PPO)/聚苯乙烯(PS)共混物,考察了基体组成(PPO/PS)和橡胶粒子尺寸对HIPS/PPO/PS/PB-g-PS共混物的力学性能及形态结构的影响。结果表明,随着基体中PPO含量的增加,共混物的冲击强度和拉伸屈服强度显著提高。HIPS中Salami结构橡胶粒子和亚微米尺寸橡胶粒子在PPO/PS基体中分散状态较好,协同增强了共混物的韧性;随着PB-gPS橡胶粒子尺寸的增加,共混物的冲击强度逐渐增加而拉伸屈服强度无明显变化,同时共混物的冲击断裂方式逐渐由脆性断裂向韧性断裂发生转变。     

PB橡胶粒径对CPVC/PVC/ABS共混体系结构与性能的影响

采用乳液聚合技术合成了一系列不同PB橡胶粒径的ABS核壳改性剂,将其与CPVC、PVC共混,考察了CPVC/PVC/ABS共混物的结构与性能。动态力学分析表明：CPVC与PVC比例为90/10时,CPVC/PVC共混物部分相容,CPVC/PVC/ABS共混物也是部分相容;扫描电子显微镜分析其形态结构表明：共混物中ABS分散受PB橡胶粒径影响,PB橡胶粒径为113 nm的ABS在CPVC中分散最均匀。力学性能测试表明：随着PB橡胶粒径的增加,共混物的冲击强度先增大后减小,拉伸强度并无明显变化。     

PMMA/SAN/ABS共混物的结构与性能研究

采用乳液聚合技术合成丙烯腈-丁二烯-苯乙烯(ABS)接枝粉料,将制得的ABS接枝粉料与聚甲基丙烯酸甲酯(PMMA)/苯乙烯-丙烯腈共聚物(SAN)熔融共混,制备透明ABS树脂。研究了体系橡胶含量,接枝粉料壳层组成,基体组成对透明ABS树脂结构与性能的影响。结果表明,随着体系橡胶含量的增加,共混物的冲击强度增大,透光率略有降低;壳层组成为75/25的共混物具有较高的韧性和透明性;随着基体PMMA/SAN组成的增加,共混物的冲击强度基本不变,而透光率先增大后减小。透射电子显微镜(TEM)研究表明,壳层组成为75/25的橡胶粒子能均匀地分散在基体中。     

基体组成及橡胶含量对PPO/PS共混物性能的影响

采用种子乳液聚合法合成了核壳比(PB与PS的质量比)为70/30、粒径为332 nm的PB-g-PS接枝共聚物,然后,将其引入聚苯醚/聚苯乙烯(PPO/PS)共混体系中,研究了基体组成(PPO/PS)及橡胶含量对PPO/PS/PB-g-PS共混物的力学性能、形态结构及断裂机理的影响。研究结果表明,引入PB-g-PS能够显著提高PPO/PS共混物的冲击韧性。随着基体中PPO含量的增加,共混物的冲击强度与屈服强度不断提高,基体发生脆-韧转变所需的橡胶含量逐渐减少,橡胶粒子在基体中的分散状态得到明显改善。随着共混物中橡胶含量的增加,共混物的冲击强度逐渐提高,冲击断面上的韧性断裂特征越发显著,共混物的冲击断裂方式逐渐由脆性断裂转变为韧性断裂。当PPO∶PS=75∶25,且基体中PB的含量为15%时,PPO/PS/PB-g-PS共混物达到了最佳的刚韧平衡,此时,冲击强度增大到610 J/m,而屈服强度仍保持在61 MPa。     

核壳结构改性剂对PBT／PC共混物冲击强度的影响

采用乳液聚合技术合成了以聚丁二烯（PB）为核、以聚甲基丙烯酸甲酯（PMMA）为壳的及壳上接枝甲基丙烯酸环氧丙酯（GMA）的两种核壳结构改性剂MB、MB—g—GMA，分别用于聚对苯二甲酸丁二醇酯（PBT）／聚碳酸酯（PC）共混物的增韧改性。力学性能结果表明，改性剂质量分数为20％，PBT／PC用量比为50／50时，共混物冲击性能最佳。固定PBT,／PC用量比为50／50，MB质量分数为10％时，共混体系实现了脆韧转变，缺口冲击强度可达到1016．9J／m，实现了超韧，而MB-g-GMA质量分数为15％时，共混体系才发生脆韧转变；动态力学分析仪分析结果显示，PC与改性剂壳层PMMA相容性好，GMA的加入提高了PBT与改性剂的相容性；扫描电镜分析表明，两种粒子都能均匀分散在基体中；基体的剪切屈服和橡胶粒子的空洞化是PBT／PC共混体系主要的形变机理。     

马来酸酐官能化ASA对PA6的增韧研究

采用乳液聚合法制备了一系列马来酸酐（MAH）官能化的丙烯酸丁酯橡胶（PBA）与苯乙烯（St）及丙烯腈（AN）的接枝共聚物（PBA-g-SAN）核壳结构改性剂（ASA-g-MAH）,用于聚酰胺6(PA6)的增韧。Molau实验证实了PA6/ASA-g-MAH共混体系中存在化学反应,考察了MAH含量对共混体系结构和性能的影响。结果表明,随着MAH含量的增加,PA6/ ASA-g-MAH共混物的冲击强度逐渐增大,当MAH含量为4 %（质量分数,下同）时材料冲击强度达到1008 J/m;与PA6/ASA共混物相比,PA6/ASA-g-MAH共混物具有较高的拉伸强度和断裂伸长率;随着MAH含量的增加,ASA- g-MAH在PA6基体中的分散程度越来越好,当MAH含量达到4 %以上时,无聚集现象发生;ASA-g-MAH中橡胶粒子的空洞化和PA6基体的剪切屈服是主要的增韧机理。     

核壳结构微纳橡胶粒子的可控合成及对PPO/PS共混体系的增韧

采用乳液聚合方法在粒径为100 nm的聚丁二烯(PB)胶乳上接枝聚合苯乙烯(St),合成了核壳比为70/30(PB/PS)的PB-g-PS接枝共聚物,将其与聚苯醚(PPO)、聚苯乙烯(PS)树脂熔融共混,制备出一系列橡胶含量、基体组成不同的PPO/PS/PB-g-PS共混物,并考察了共混物的相容性、力学性能及形态结构。结果发现:PPO与PS为完全相容体系,且PB-g-PS在PPO/PS基体中的均匀分散程度随体系中PPO引入量的增大而明显改善,共混物的冲击强度及屈服强度也随之逐渐增大,进而促使共混物发生脆-韧转变所需的橡胶含量逐渐降低;随着共混体系中橡胶含量的增加,共混物的冲击强度逐渐提高,而屈服强度却逐渐降低,共混物的韧性断裂特征越发显著。     

Toughness enhancement of poly(lactic acid) by melt blending with natural rubber

Rubber toughened poly(lactic acid) (PLA) was prepared by blending with natural rubber (NR)‐based polymers. The blends contained 10 wt % of rubber and melt blended with a twin screw extruder. Enhancement of impact strength of PLA was primarily concernced. This study was focused on the effect of rubber polarity, rubber viscosity and molecular weight on mechanical properties of the blends. Three types of rubbers were used: NR, epoxidized natural rubber (ENR25 and ENR50), and natural rubber grafted with poly(methyl methacrylate) (NR‐g‐PMMA). Effect of viscosity and molecular weight of NR, rubber mastication with a two‐roll mill was investigated. It was found that all blends showed higher impact strength than PLA and NR became the best toughening agent. Viscosity and molecular weight of NR decreased with increasing number of mastication. Impact strength of PLA/NR blends increased after applying NR mastication due to appropriate particle size. DMTA and DSC characterization were determined as well. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of acrylic core–shell rubber particles on the particulate flow and toughening of PVC

Different types of acrylic core–shell rubber particles with a poly(butyl acrylate) (PBA) core and a grafted poly(methyl methacrylate) (PMMA) shell were synthesized. The average size of acrylic core–shell latex particles ranged from 100 to 170 nm in diameter, having the core gel content in the range of 35–80%. The melt blending behavior of the poly(vinyl chloride) (PVC) and the acrylic core–shell rubber materials having different average particle sizes and gel contents was investigated in a batch mixing process. Although the torque curves showed that the particulate flow of the PVC in the blends was dominant, some differences were observed when the size and gel content of the particles varied. This behavior can be attributed to differences in the plasticizing effect and dispersion state of various types of core–shell rubber particles, which can vary the gelatin process of the PVC in the mixing tool. On the other hand, the highest toughening efficiency was obtained using core–shell rubber particles with the smallest particle size (i.e., 100 nm). The results showed that increasing the gel content of the core–shell impact modifiers with the same particle size improved the particle dispersion state in the PVC matrix. The toughening efficiency decreased for the blends containing 100 and 170 nm rubber particles as the gel content increased. Nevertheless, unexpected behavior was observed for the blends containing 140 nm rubber particles. It was found that a high level of toughness could be achieved if the acrylic core–shell rubber particles as small as 100 nm had a lower gel content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of the rubber crosslinking density of a core–shell structure modifier on the properties of toughened poly(methyl methacrylate)

Four kinds of core–shell structure acrylic impact modifiers (AIMs) with different rubber crosslinking densities were synthesized. The effects of the rubber crosslinking density of the AIMs on the crack initiation and propagation resistance and the mechanical properties of the AIM/poly(methyl methacrylate) (PMMA) blends were investigated, and we found that the maximum stress intensity factor, crack propagation energy, and Izod impact strength reached maximums when the appropriate rubber crosslinking density of AIM, 2.51 × 10²⁵ crosslinks/m³, was adopted. Transmission electron microscopy photographs of the AIM/PMMA blends showed that the AIMs dispersed uniformly in the PMMA matrix. Meanwhile, through the analysis of optical photos and scanning electron microscopy of the impact fracture surface, we found that the deformation mechanism of the AIM/PMMA blends was local matrix shear yielding initiated by rubber particle cavitation of the AIM. The rubber of the AIM, whose crosslinking density was 2.51 × 10²⁵ crosslinks/m³, was beneficial to the formation of intensive voids and initiated the local shear yielding of nearby modifiers of the PMMA matrix effectively in impact tests, which led to higher Izod impact strengths. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of the composition of structured rubber particles on the toughness of poly(methylmethacrylate)

Composite natural rubber (NR) and monodisperse poly(n-butylacrylate) (PBuA) based latex particles were tested as possible impact modifiers for a poly(methylmethacrylate) (PMMA) matrix. A continuous extrusion process was used for the incorporation of wet latexes directly into a twin-screw extruder. All latexes had been coated by a PMMA shell. Furthermore, polystyrene (PS) subinclusions were introduced into the NR core. The impact resistance of the prepared PMMA blends can be most effectively improved by NR particles containing a large weight fraction of compatibilising PMMA in the shell. The degree of crosslinking of the shell polymer has to be restricted. PBuA based latex particles of 180 nm in size are ineffective to toughen the PMMA matrix. The degree of grafting of the NR phase in core–shell particles containing PS subinclusions is not crucial. Scanning electron microscopy was used to analyse the failure processes in composite rubber particle toughened PMMA blends at fast (impact conditions) and slow (tensile testing) deformation speeds.     

Rubber toughening of an amorphous polyamide by functionalized SEBS copolymers: morphology and Izod impact behavior

Rubber toughening of an amorphous polyamide (Zytel 330) using combinations of triblock copolymers of the type SEBS and a maleic anhydride functionalized version, SEBS-g-MA, was investigated and the results compared with those of nylon 6 and nylon 66. The effects of rubber content and the type of extruder on the morphology, Izod impact behavior and the ductile-brittle transition temperature were explored. The shape and sizes of the rubber particles in blends with this amorphous polyamide were found to be more similar to those in nylon 6 than in nylon 66 blends. The twin screw extruder produced smaller particles with a more narrow distribution of sizes than the single screw extruder. Higher rubber contents generally yielded tougher blends; there is a critical rubber particle size above which the ternary blends are brittle at 20 wt% total rubber. The ductile-to-brittle temperature was found to decrease with increased rubber content and decreased rubber particle size. In general, the trends for this amorphous polyamide are rather similar to those reported earlier for semi-crystalline nylon 6 and nylon 66.     

乙丙橡胶增韧聚丙烯共混物中橡胶相形态

通过电子扫描电镜(SEM),研究了乙丙橡胶增韧聚丙烯共混物中作为分散相的橡胶粒子的形态。结果表明,在交联剂等助剂的作用下进行过动态硫化的共混物中橡胶相的粒子形状、粒径、粒径分布以及橡胶粒子与连续相聚丙烯所形成的界面形态与单纯的橡塑共混物和PP/EPDM反应器共混物相比有着截然不同的区别。正是由于这些区别,提高了经过动态硫化的共混物的冲击性能。     

Effect of matrix composition on the fracture behavior of rubber-modified PMMA/PVC blends

Summary PB-g-MMA core-shell impact modifiers were synthesized by seed emulsion polymerization and impact-modified PMMA/PVC blends were prepared by melt blending PMMA, PVC and PB-g-MMA at 160 °C. The PB-g-MMA particles were dispersed uniformly in the PMMA/PVC matrix. PMMA/PVC blends were prepared in the blend ratio from 100/0 to 0/100 and the rubber content was kept 16% in all the compositions. The effects of matrix composition on the mechanical properties and morphology of the blends were studied. It was found that when the matrix was a PMMA-rich system, the sample broke in a brittle mode and crazing of the matrix was the main mechanisms of deformation. When the matrix was a PVC-rich system, the sample broke in a ductile mode and the main deformation mechanisms were cavitation of the particle and shear yielding of the matrix. There existed a transition from crazing to shear yielding in the rubber-modified PMMA/PVC blend as the matrix composition varied.     

橡胶相结构特征对ABS树脂力学性能的影响

采用乳液聚合法合成了具有橡胶结构特征的丙烯腈丁二烯苯乙烯共聚物（ABS）,将其与苯乙烯丙烯腈共聚物（SAN）共混,制备了ABS/SAN共混物,并系统地研究了橡胶相结构特征的影响因素及其对共混物力学性能及其形变机理的影响。结果表明,随着聚丁二烯（PB）橡胶粒子粒径的增大,共混物的冲击强度提高,拉伸强度降低;随着橡胶粒子粒径的增大,共混物形变机理从单一的银纹向橡胶粒子空洞化诱发基体剪切屈服转变。     

Effect of crosslinking on polyamide 11/butadiene-acrylonitrile copolymer blends

The effect of crosslinking of polyamide 11 and butadiene-acrylonitrile copolymer (nitrile rubber) was studied. The effect of static and dynamic crosslinking on blending are described. Static and dynamic crosslinking do not significantly improve impact strength of low-rubber-content PA11/NBR blends. For blends with dynamic crosslinking and high rubber contents, mechanical properties including impact strength improve. Thermal behavior of crosslinked PA11/NBR blends were studied by DSC and DMA. SEM was used for investigation of the effect of crosslinking on particle size and particle size distribution, phase morphology, and fracture surface morphology. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1605–1611, 1997