ABS树脂形态结构及力学性能的研究

ABS树脂具有优良的抗冲击性、耐热性和耐化学药品性，还具有易加工性、制品尺寸稳定性等特点，广泛应用于工业领域。ABS树脂的制备方法有许多种，目前应用最为广泛的是乳液接枝ABS共聚物一本体SAN掺混法。首先采用乳液聚合方法合成聚丁二烯胶乳，然后将其作为种子进行苯乙烯和丙烯睛的接枝共聚反应生成ABS接枝共聚物；采用本体法制备SAN树脂；最后将ABS接枝共聚物（冲击改性剂）和SAN树脂共混制得ABS树脂。由此看来，ABS接枝共聚物的合成是控制ABS树脂性能的关键。目前国产ABS树脂普遍存在的问题是ABS接枝共聚物的增韧效率低。影响其增韧效率的因素包括共聚单体的组成、橡胶相的组成及结构、橡胶与树脂之间的界面结合力等。因此为提高ABS冲击改性剂的增韧效率，拓宽ABS树脂的应用领域，应合理地控制ABS冲击改性剂的合成参数。本论文采用种子乳液聚合方法在PB（聚丁二烯）橡胶粒子上接枝共聚苯乙烯和丙烯睛合成ABS接枝共聚物，将其作为冲击改性剂与SAN树脂共混制备ABS树脂，对ABS树脂形态结构及力学性能进行了研究。主要研究内容和结论如下：1、研究ABS接枝共聚物中PB／SAN组成、TDDM（叔十二碳硫醇）链转移剂和CHP（过氧化氢异丙苯）用量、单体加料方式及引发剂类型对SAN在PB橡胶粒子上接枝度的影响。sAN在PB橡胶粒子上的接枝度随PB和TDDM含量的增加而降低；随CHP用量的增加先增加后降低；随单体滴加时间的延长而增加，但过分延长时间则对接枝度影响很小；与AIBN（偶氮二异丁睛）和K25208（过硫酸钾）相比，采用氧化一还原引发体系得到的接枝度较高。2、研究ABS接枝共聚物的力学性能。DMA结果表明，随着PB含量的增加，ABS接枝共聚物的储能模量降低，橡胶相的玻璃化转变温度向低温移动，内耗峰值增加。拉伸试验结果表明，当体系中没有TDDM时，不同橡胶含量的ABS接枝共聚物均没有发生明显的应变软化；当加入适量的TDDM后，材料发生应变软化，且随着TDDM用量的增加，材料的屈服应力提高。3、研究ABS接枝共聚物对ABS树脂形态结构及力学性能的影响。ABS接枝共聚物中PB／SAN组成及TDDM链转移剂用量影响ABs树脂中橡胶粒子的内部形态及橡胶粒子在基体中的分散。在合成ABS接枝共聚物的过程中，应合理地调节PB／SAN组成及TDDM的用量以使ABS接枝共聚物达到最大的增韧效率。4、研究ABS树脂在不同应变速率下的断裂行为及形变机理。结果表明，橡胶含量及应变速率影响ABS树脂的力学性能，但没有改变ABS树脂的形变机理。ABS树脂的形变机理包括银纹、橡胶粒子的空洞化及基体的剪切屈服，其中占主导地位的是橡胶粒子的空洞化及基体的剪切屈服。

PVC/ABS共混系统力学性能的研究

用冲击试验机、材料试验机和另外一些相关的仪器对PVC/ABS共混体系的力学性能进行了测试、研究,结果发现,PVC/ABS共混体系的性能是组分的函数.ABS的加入改善了PVC/ABS共混体系的力学性能,随着ABS的增加,体系的冲击强度和断裂伸长率明显地提高,而体系的拉伸强度、拉伸模量几乎是随ABS含量的增加而单调地下降.

Transition from crazing to shear deformation in ABS/PVC blends

ABS/PVC blends were prepared over a range of compositions by mixing PVC, SAN, and PB-g-SAN. All samples were designed to have a constant rubber level of 12 wt % and the ratio of total-SAN to PVC in the matrix of the blends varied from 70.5/17.5 to 18/80. Transmission electron microscope and scanning electron microscope have been used to study deformation mechanisms in the ABS/PVC blends. Several different types of microscopic deformation mechanisms, depending on the composition of blends, were observed for the ABS/PVC blends. When the blend is a SAN-rich system, the main deformation mechanisms were crazing of the matrix. When the blend is a PVC-rich system, crazing could no longer be detected, while shear yielding of the matrix and cavitation of the rubber particles were the main mechanisms of deformation. When the composition of blend is in the intermediate state, both crazing and shear yielding of matrix were observed. This suggests that there is a transition of deformation mechanism in ABS/PVC blends with the change in composition, which is from crazing to shear deformation.

Influence of rubber content in ABS in wide range on the mechanical properties and morphology of PC/ABS blends with different composition

A series of acrylonitrile-butadiene-styrene (ABS) with different rubber content were prepared by diluting ABS grafting copolymer containing 60% rubber with a styrene-acrylonitrile copolymer. ABS prepared were blended with bisphenol-A-polycarbonate (PC) at the ratio of 70/30, 50/50, and 30/70 to prepare PC/ABS blends. Influence of rubber content in ABS on the properties of ABS and PC/ABS blends were investigated. PC/ABS blends with different compositions got good toughness when the rubber in ABS increased to the level that ABS itself got good toughness. The tensile properties and processability of PC/ABS blends decreased with the increase of the total rubber content introduced into the blends. ABS with the rubber content of 30 wt% is most suitable to be used to prepare PC/ABS blends. The rubber content in ABS affected the viscosity of ABS, and subsequently the viscosity ratio of PC to ABS. As a result, the morphology of PC/ABS blends varied. The increase of rubber content in ABS results in finer structure of PC/ABS blends.

Properties of compatibilized nylon 6/ABS polymer blends

Nylon 6/poly(acrylonitrile-butadiene-styrene)(ABS) blends were prepared in the molten state by a twin-screw extruder. Maleic anhydride-grafted polypropylene (MAP) and solid epoxy resin (bisphenol type-A) were used as compatibilizers for these blends. The effects of compatibilizer addition to the blends were studied via tensile, torque, impact properties and morphology tests. The results showed that the additions of epoxy and MA copolymer to nylon 6/ABS blends enhanced the compatibility between nylon 6 and ABS, and this lead to improvement of mechanical properties of their blends and in a size decrease of the ABS domains.

ABS树脂合成中影响PB-g-SAN接枝共聚物接枝率的因素

采用种子乳液聚合方式 ,以 K2 S2 O8为引发剂引发聚合 ,合成了一系列 PB- g- SAN接枝共聚物。考察了引发剂用量、分子量调节剂 (TDDM)用量和橡胶 (PB)含量对 PB- g- SAN接枝共聚物接枝率的影响。并将 K2 S2 O8引发剂与氧化 -还原引发体系做了比较。结果表明 ,随着引发剂 K2 S2 O8用量逐渐增加 ,PB- g- SAN接枝共聚物的接枝率逐渐降低。引发剂用量太少时 ,不能满足聚合要求 ,PB- g- SAN接枝共聚物的接枝率也会降低。随着分子量调节剂 (TDDM)用量的增加 ,PB- g- SAN接枝共聚物的接枝率逐渐降低。随胶含量的增加 ,PB- g- SAN接枝共聚物的接枝率逐渐降低。采用氧化 -还原引发体系引发聚合有利于接枝反应的进行 ,在 PB含量相同时 ,采用氧化 -还原引发体系合成的 PB- g- SAN接枝共聚物的接枝率比采用 K2 S2 O8合成的接枝共聚物接枝率高。

链转移剂用量对ABS树脂性能的影响

通过种子乳液聚合 ,合成了PB -g -SAN接枝共聚物 ,与SAN树脂共混后制得了ABS树脂。在PB -g -SAN接枝共聚物合成过程中 ,通过调节链转移剂的用量调整接枝SAN链在PB橡胶粒子上的分布状况 ,考察了接枝过程中链转移剂用量对PB -g -SAN接枝共聚物的接枝率及制得的ABS树脂性能的影响。结果表明 :随着链转移剂用量的增加 ,ABS树脂的拉伸强度有所降低 ,而伸长率有所增加。

Novel hydrogen-bonded three-dimensional networks encapsulating one-dimensional covalent chains: [M(4,4 '-bipy)(H2O)4](4-abs)2 center dot nH(2)O (4,4 '-bipy=4,4 '-Bipyridine; 4-abs=4-aminobenzenesulfonate) (M=Co, n=1; M=Mn, n=2)

Two novel compounds, [Co(4,4'-bipy)(H2O)(4)](4-abS)(2).H2O (1) and [Mn(4,4'-bipy)(H2O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H2O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H2O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C22H30CoN4O11S2, monoclinic P2(1), a = 11.380(2) Angstrom, b = 8.0274(16) Angstrom, c = 15.670(3) Angstrom, alpha = gamma = 90degrees, beta = 92.82(3)degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H2O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C22H32WN4O12S2, monoclinic P2(1)/c, a = 15.0833(14) Angstrom, b = 8.2887(4) Angstrom, c = 23.2228(15) Angstrom, alpha = gamma = 90degrees, beta = 95.186(3)degrees, Z = 4.

Effects of rubber content and temperature on dynamic fracture toughness of ABS materials

The effects of rubber content and temperature on dynamic fracture toughness of ABS materials have been investigated based on the J-integral and crack opening displacement (COD, delta) concepts by an instrumented Charpy impact test. A multiple specimens R-curve method and stop block technique are used. It is shown that the materials exhibit a different toughness behavior, depending on rubber content and temperature. The resistance against stable crack initiation (J(0.2) or delta(0.2)) increases with increasing rubber content. However, J(0.2) first increased with increasing temperature until reaching the maximum value; after that, it decreases with further increasing the temperature. (C) 2000 John Wiley & Sons, Inc.

Effects of rubber content and temperature on unstable fracture behavior in ABS materials with different particle sizes

The fracture behavior of ABS materials with a particle diameter of 110 nm and of 330 nm was studied using instrumented Charpy impact tests. The effects of rubber content and temperature on fracture behavior, deformation mode, stable crack extension, plastic zone size, J-integral value, and crack opening displacement were investigated. In the case of a particle size of 110 nm, the material was found to break in a brittle manner, and the dominant crack mechanism was unstable crack propagation. Fracture toughness increases with increasing rubber content. In the case of a particle size of 330 nm, brittle-to-tough transition was observed. The J-integral value first increases with rubber content, then levels off after the rubber content is greater than 16 wt %. The J-integral value of a particle diameter of 330 nm was found to be much greater than that of 110 nm. The J-integral value of both series first increased with increasing temperature until reaching the maximum value, after which it decreased with further increasing temperature. The conclusion is that a particle diameter of 330 nm is more efficient than that of 110 nm in toughening, but for both series the effectiveness of rubber modification decreases with increasing temperatures higher than 40 degreesC because of intrinsic craze formation in the SAN matrix at temperatures near the glass transition of SAN. (C) 2000 John Wiley & Sons, Inc.