中国专利

橡胶改性的苯乙烯类树脂组合物 一种橡胶改性的苯乙烯类树脂组合物,它通过用溶解橡胶状聚合物的苯乙烯类单体进行接枝聚合得到。其中,(1)橡胶状聚合物以颗粒形式分散在苯乙烯类聚合物基体中,颗粒的体均粒径为0.5～1.6μm;(2)上述橡胶状聚合物分散粒子具有萨拉米香肠结构,其中数均粒径为0.13～0.20μm的一部分苯乙烯类聚合物分散并包埋于橡胶状聚合物粒子中;(3)上述橡胶状聚合物分散粒子在甲苯中的溶胀比为7～12。本发明的橡胶改     

PA6/ABS的结构与力学性能研究

采用熔融共混法制备了苯乙烯-马来酸酐共聚物(SMA)增容的聚酰胺6/丙烯腈-丁二烯-苯乙烯共聚物(PA6/ABS)共混物,用扫描电镜(SEM)对PA6/ABS共混物结构进行了表征.结果表明,随着SMA含量的增加,PA6/ABS共混体系的橡胶相粒径减小.橡胶颗粒的多分散系数保持不变,基体层厚度逐渐减小;PA6/ABS共混体系的脆韧转变温度随SMA含量的增加先减小后增加.     

两种不同橡胶粒径的ABS树脂协同作用研究

采用两种不同橡胶粒径的丙烯腈-丁二烯-苯乙烯共聚物(ABS)掺混制备橡胶粒子尺寸双峰分布的ABS树脂。恒定ABS树脂的橡胶含量,通过调节不同粒径橡胶的质量比,考察其对ABS树脂力学性能的影响,并利用扫描电子显微镜和透射电子显微镜观察了ABS树脂的微观结构,分析了协同作用的增韧机理。结果表明,ABS树脂的冲击强度和屈服强度都随着大粒径橡胶粒子比例的减少而增大;当L-PB/S-PB为1/9时,ABS树脂的冲击强度和屈服强度最高,两种橡胶粒子发生了明显的协同作用。     

橡胶粒子尺寸对ABS树脂性能的影响

通过乳液聚合制备了橡胶粒子尺寸为64～420 nm的丙烯腈-丁二烯-苯乙烯(ABS)共聚物.然后将其与SAN-T树脂熔融共混制备橡胶质量分数为15%的ABS树脂.研究了橡胶粒子尺寸对ABS树脂力学性能影响和材料内部形态结构.结果表明:随着橡胶粒子尺寸的增加ABS树脂的冲击韧性提高.当橡胶粒子尺寸在320 nm时,拉伸强度达到最大,ABS树脂的综合性能达到最好.粒子尺寸在64～110 nm时,橡胶粒子在基体内部发生团聚,材料发生脆性断裂.当橡胶粒子尺寸在216～420 nm时,材料主要以韧性断裂为主,发生脆韧转变.具有双峰分布ABS-110nm/ABS-275 nm共混物大、小橡胶粒子间发生明显的协同作用.     

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。     

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。     

影响ABS树脂韧性的因素

通过收集相关资料,整理影响ABS树脂韧性的因素,讨论了接枝聚合物的接枝结构、基体SAN树脂结构、温度、共混条件等因素对ABS冲击强度的影响。接枝后的聚丁二烯橡胶增韧效果明显,不同粒径的橡胶粒子的最佳接枝层厚度相同,接枝层SAN与基体SAN树脂的组成相似时增韧效果好。基体SAN树脂的分子量或丙烯腈含量增加有利于ABS树脂的冲击强度。低温条件下ABS增韧机理以银纹机理为主。双螺杆挤出机拥有良好的剪切作用,能够将橡胶相分散更均匀,有利于冲击强度的提高。     

ABS树脂的性能与形态结构设计 ⅠSAN在PB橡胶粒子上接枝率的控制及其对ABS树脂结构和性能的影响

采用种子乳液聚合技术在聚丁二烯乳胶粒上接枝共聚苯乙烯和丙烯腈 ,通过改变共聚单体和聚丁二烯的投料比合成了一系列PB g SAN共聚物 ,将这些共聚物与SAN树脂进行熔融共混制得了ABS树脂。研究了投料比对SAN在PB上的接枝率、SAN的分子量和ABS树脂的形态结构及性能的影响。结果发现 ,随着投料比的增加 ,SAN在PB上的接枝率及SAN的分子量提高 ,接枝率和SAN分子量共同作用影响着ABS树脂的冲击韧性和加工性能。形态结构研究结果表明 ,投料比不仅影响着橡胶粒子在SAN基体中的分散程度 ,而且影响着橡胶粒子的内部结构 ,随着投料比的增加 ,橡胶粒子在基体中的分散程度提高 ,其内部的包容结构增多并导致了橡胶粒子粒径的增大。     

ABS高胶粉增韧PA6的结构与性能研究

采用熔融共混法制备了苯乙烯-马来酸酐共聚物（SMA）增容的PA6/ABS共混物,用透射电子显微镜对PA6/ABS共混物结构进行了表征,研究了增容剂含量对PA6/ABS共混体系结构、性能以及脆-韧转变温度的影响。结果表明,随着SMA含量的增加,PA6/ABS共混体系的橡胶相粒径先逐渐减小,后趋于平缓;橡胶颗粒的多分散系数逐渐增加;基体层厚度不断减小;PA6/ABS共混体系的拉伸强度逐渐增加;PA6/ABS共混体系的脆-韧转变温度先减小,后上升。     

ABS树脂的性能与形态结构设计——I SAN在PB橡胶粒子上接枝率的控制及其对ABS树脂结构和性能的影响

采用种子乳液聚合技术在聚丁二烯乳胶粒上接枝共聚苯乙烯和丙烯腈,通过改变共聚单体和聚丁二烯的投料比合成了一系列PB－g-SAN共聚物,将这些共聚物与SAN树脂进行熔融共混制得了ABS树脂。研究了投料比对SAN在PB上的接枝率、SAN的分子量和ABS树脂的形态结构及性能的影响。结果发现,随着投料比的增加,SAN在PB上的接枝率及SAN的分子量提高,接枝率和SAN分子量共同作用影响着ABS树脂的冲击韧性和加工性能。形态结构研究结果表明,投料比不仅影响着橡胶粒子在SAN基体中的分散程度,而且影响着橡胶粒子的内部结构,随着投料比的增加,橡胶粒子在基体中的分散程度提高,其内部的包容结构增多并导致了橡胶粒径的增大。     

New toughening mechanisms in rubber modified polymers

Abstract

Rubber toughening usually involves the addition of rubber particles to a rigid polymer in order to promote energy absorption through the initiation of local yielding, which takes the form of multiple crazing and/or extensive shear yielding. In addition to these classic mechanisms, recent studies of deformation mechanisms in various rubber modified polymers, using a range of electron microscopy techniques, have revealed two new mechanisms of energy absorption. Direct observations of micromechanical processes in high impact polystyrene and copoly(styrene/acrylonitrile)–acrylate blends, carried out in situ on the stage of a transmission electron microscope have shown that the rigid, glassy subinclusions found in both ‘salami’ and hard–soft–hard ‘core–shell’ rubber particles respond to high tensile stresses by cold drawing. Fibrillation begins in the rubber phase and then draws fibrils of glassy polymer from the subinclusions, causing initially spherical inclusions to become flattened discs before finally disintegrating. In addition, when thin sections of rubber toughened polypropylene are stretched in situ on the stage of the transmission electron microscope, hard–soft core–shell particles consisting of a polyethylene core and an ethylene/propylene copolymer rubber shell are able to initiate crazing in the matrix at -100°C, well below the glass transition temperature of the ethylene/propylene copolymer rubber. Micrographs illustrating these mechanisms are presented and discussed.     

Morphological,mechanical properties,and fracture behavior of bulk‐made ABS resins toughened by high‐cis polybutadiene rubber

Acrylonitrile‐butadiene‐styrene (ABS) resins with various rubber contents were prepared by applying nickel catalyzed high‐cis polybutadiene rubber (BR9004) as toughening agent via bulk polymerization. The influence of rubber content and its characteristics on the morphology, mechanical properties, and fracture mechanisms of ABS resins were investigated. The relevant performance parameters were also evaluated and compared with a commercial injection grade resin (ABS‐8434). The results show that each synthesized resin generally contains some irregular microsized particles with a certain amount of subinclusions besides the analogous “sea‐island” morphology to ABS‐8434. The subinclusions considerably enhance the volume fraction of rubber phase; this leads to an increasing maximum loss tangent (tan δ) value, a decreasing storage modulus and glass transition temperature (T_g) of rubber phase. Besides, the higher grafting degree can not only produce a higher T_g of grafted copolymer but also improve the compatibility of rubber phase with matrix. Based on the performance measurements andfractography, the final product with a rubber content of 9.3% reveals ductile fracture behavior and excellent comprehensive properties far superior to ABS‐8434 due to combined shear yielding and massive crazing. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Morphology and mechanical properties of ABS blends prepared from emulsion‐polymerized PB‐g‐SAN impact modifier with AIBN as initiator

A series of PB‐g‐SAN impact modifiers (polybutadiene particles grafted by styrene and acrylonitrile) are synthesized by seed emulsion copolymerization initiated by oil‐soluble initiator, azobisiobutyronitrile (AIBN). The ABS blends are obtained by mixing SAN resin with PB‐g‐SAN impact modifiers. The mechanical behavior and the phase morphology of ABS blends are investigated. The graft degree (GD) and grafting efficiency (GE) are investigated, and the high GD shows that AIBN has a fine initiating ability in emulsion grafting of PB‐g‐SAN impact modifiers. The morphology of the rubber particles is observed by the transmission electron microscopy (TEM). The TEM photograph shows that the PB‐g‐SAN impact modifier initiated by AIBN is more likely to form subinclusion inside the rubber particles. The dynamic mechanical analysis on ABS blends shows that the subinclusion inside the rubber phase strongly influences the T_g, maximum tan δ, and the storage modulus of the rubber phase. The mechanical test indicates that the ABS blends, which have the small and uniform subinclusions dispersed in the rubber particles, have the maximum impact strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

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.     

The effects of particle bulk modulus on toughening mechanisms in rubber-modified polymers

The interaction of a blunting mode I plane-strain crack tip with a periodic array of initially spherical rubber particles directly ahead of and parallel to the crack front in the effective medium is studied by the crack tip-particle interaction model. The local stress concentrations responsible for rubber cavitation, matrix crazing and shear yielding are obtained by three-dimensional large deformation elastic-plastic finite element analysis with a sub-modeling technique to explore the relationship between these toughening mechanisms. It is shown that rubber particles can act as stress concentrators to initiate matrix crazing or shear yielding but they behave differently from voids at high triaxiality because of their high bulk modulus. Particle bulk modulus affects significantly the hydrostatic stress inside rubber particles as well as the plastic deformation in the ligament between the crack tip and particles. Rubber cavitation or interface debonding relieves the triaxial stress planestrain condition so that extensive plastic deformation can be developed in the toughening process.     

Development of AAS resin by the emulsion–suspension polymerization method

In order to improve the weatherability of acryonitrile—styrene—butadiene rubber graft polymer (ABS resin), an attempt was made to develop a resin (AAS resin) in which acrylic rubber of good weatherability was used instead of butadiene rubber. First, by copolymerizing dicyclopentenyl-methacrylate (DCP-MA,3%) with butyl acrylate, crosslinked acrylic rubber was obtained. This also introduced grafting sites into the rubber. Next, methods of graft copolymerizing styrene and acrylonitrile with this rubber were examined. An emulsion–suspension polymerization method was developed in which the initial stage of the polymerization, emulsion polymerization, changed into suspension polymerization during the process. By this method of polymerization, rubber particles were combined and enlarged, bringing about a graft-type resin with high impact resistance. This polymerization method is industrially useful because particle-shaped resins are obtained without the need of a salting-out process. The AAS resin, obtained in this way, has much improved weatherability over ABS resin and shows strength equal to that of ABS resin. © 1992 John Wiley & Sons, Inc.     

Mechanism of Toughening in Rubber Toughened Polyolefin—A Review

The recent advances and theories in the studies of the toughening mechanism have been reviewed to explain the effect of rubber particles in different rubber modified Polyolefin materials. To elucidate toughening effect, major theories e.g., critical particle distance, particle size, micro deformation by stress field of rubber, shear yielding and crazing phenomena has been reviewed. Based on these theories, variety of blends of rubber modified Polyolefin materials has been compared but no one of these provided adequate information to be considered as total theory of toughening. To achieve the objective of toughening, it is important to maintain critical particle size, uniform particle distribution and good interfacial adhesion by inclusion of suitable compatibilizer in the matrix. Particular attention has been paid to study the type of morphology and bimodal distribution of rubber particles to elucidated toughening effect. Rubber particle cavitation, which comes from micro-voids and rubber phase interface are then further discussed.     

Morphology and toughness characterization of epoxy resins modified with amine and carboxyl terminated rubbers

The morphology (dispersed phase composition, size distribution, and particle/matrix interface shapes) of epoxy resins modified with 5–15 parts by weight (pbw) of carboxyl (CTBN) and amine (ATBN) terminated butadiene acrylonitrile rubber have been characterized. The characterization techniques were transmission electron microscopy coupled with energy dispersive X-ray analysis, differential scanning calorimetry and proton and ¹³C nuclear magnetic resonance. ATBN modified epoxies have a diffuse-appearing interface between the dispersed rubber phase and the epoxy matrix, in contrast to the sharp boundaries of CTBN particle interfaces. Interface mixing of epoxy and rubber, hypothesized initially to explain the interface diffuseness in ATBN modified epoxy, was not found in either CTBN or ATBN modified epoxy. The difference in interface appearance is attributed to ATBN particles having highly irregular shapes compared to the nearly spherical CTBN particles. Bimodal particle size distributions are observed with both modifiers. Both rubber modifiers also produce essentially identical toughness values which do not increase with rubber content in the range 5–15 pbw despite a commensurate increase in the population of large particles.