Morphologies and physical properties of PA1010/HIPS/HIPS-g-MA ternary blends

The effect of the content of a copolymer consisting of high impact polystyrene grafted with maleic anhydride (HIPS-g-MA) on morphological and mechanical properties of PA1010/HIPS blends has been studied. Blend morphologies were controlled by adding HIPS-g-MA during melt processing, thus the dispersion of the HIPS phase and interfacial adhesion between the domains and matrices in these blends were changed obviously. The weight fractions of HIPS-g-MA in the blends increased from 2.5 to 20, then much finer dispersions of discrete HIPS phase with average domain sizes decreased from 6.1 to 0.1 mu m were obtained. It was found that a compatibilizer, a graft copolymer of HIPS-g-MA and PA1010 was synthesized in situ during the melt mixing of the blends. The mechanical properties of compatibilized blends were obviously better than those of uncompatibilized PA1010/HIPS blends. These behaviors could be attributed to the chemical interactions between the two components of PA1010 and HIPS-g-MA and good dispersion in PA1010/HIPS/HIPS-g-MA blends. Evidence of reactions in the blends was seen in the morphology and mechanical behaviour of the solid. The blend containing 5 wt % HIPS-g-MA component exhibited outstanding toughness. (C) 1999 Kluwer Academic Publishers.

Preparation of the HIPS/MA graft copolymer and its compatibilization in HIPS/PA1010 blends

The graft copolymer of high-impact polystyrene (HIPS) grafted with maleic anhydride (MA) (HIPS-g-MA) was prepared with melt mixing in the presence of a free-radical initiator. The grafting reaction was confirmed by infrared analyses, and the amount of MA grafted on HIPS was evaluated by a titration method. 1-5% of MA can be grafted on HIPS. HIPS-g-MA is miscible with HIPS. Its anhydride group can react with polyamide 1010 (PA1010) during melt mixing of the two components. The compatibility of HIPS-g-MA. in the HIPS/PA1010 blends was evident. Evidence of reactions in the blends was confirmed in the morphology and mechanical behavior of the blends. A significant reduction in domain size was observed because of the compatibilization of HIPS-g-MA in the blends of HIPS and PA1010. The tensile mechanical properties of the prepared blends were investigated, and the fracture surfaces of the blends were examined by means of the scanning electron microscope. The improved adhesion in a 15% HIPS/75% PA1010 blend with 10% HIPS-g-MA copolymer was detected. The morphology of fibrillar ligaments formed by PA1010 connecting HIPS particles was observed. (C) 1999 John Wiley & Sons, Inc.

HIPS/PP反应共混物的热性能研究

研究了高抗冲聚苯乙烯(HIPS)/聚丙烯(PP)在过氧化二异丙苯(DCP)存在下熔融反应共混物的热学性能。HIPS���DCP存在下以PS的降解为主，PS的Tg明显下降，PP在DCP存在下也以降解为主，PP的结晶完善性受到破坏，HIPS/PP共混物在DCP存在下以PP同HIPS���反应接枝为主，分子运动的特征及热性能较前两者发生明显变化，PS的Tg略有下降，PP分子链的规整性降低，结晶熔点降低，完善性变差。

用仪器化冲击仪研究HIPS/SBS共混物的冲击性能

用JJ-20型仪器化冲击仪研究了HIPS/SBS共混物在组成为100/0、100/5、100/10、100/15、100/20和100/25质量比下样品的Izod缺口冲击性能。结果表明，在组成范围内，随着SBS含量的增加，样品的Izod缺口冲击强度随之增加。质量比为100/25样品的Izod缺口冲击强度值(225.9J/m)比质量比为100/0的样品(108.7J/m)增加了1倍以上。通过对冲击断裂过程的分析表明，冲击强度的提高主要是由于缺口根部应力集中产生塑性区所消耗的裂纹引发能的提高引起的，而裂纹扩展能基本没有多大变化

HIPS���镍系顺丁橡胶的工业技术开发

采用镍催化体系，以抽余油为溶剂，研究了丁二烯溶液聚合的聚合条件。结果表明，在ＢＲ－９０００生产装置上通过增加镍催化体系用量，降低水用量和适当提高聚合温度，可以制备出ＨＩＰＳ生产所需要的顺丁橡胶。

HIPS/PP熔融反应共混及其动态力学性质

研究了高抗冲聚苯乙烯（HIPS���／聚丙烯（PP）共混物在过氧化二异丙苯（DCP）存在下的熔融反应过程及其动态力学性质．HIPS���DCP存在下以聚苯乙烯（PS）的降解为主，伴随着聚丁二烯（PB）的交联和接枝，PP在DCP存在下以降解为主，HIPS���PP在DCP存在下以PP同HIPS���反应接枝为主，这种原位生成的增容剂显著地改善了HIPS���PP两组份间的相容性，其分子运动特征较前两者发生明显变化，PS的Tg下降，PB和PP的Tg升高.

用SBS或SBR或BR改进HIPS���冲击性能

采用机械共混法，在弹性体用量为５％～２５％时，研究了ＳＢＳ，ＳＢＲ，ＢＲ分别对ＨＩＰＳ的增韧效果。ＳＢＳ可使ＨＩＰＳ的冲击韧性大幅度提高，并随ＳＢＳ含量增加显著上升。ＳＢＲ也能提高ＨＩＰＳ的冲击韧性，但幅度不大。ＢＲ的加入使ＨＩＰＳ的冲击韧性下降。前两者的冲击试样断面平整而光洁，有明显的应力发白现象，属韧性断裂，后者的断面粗糙不平，无应力发白现象，属脆性断裂。改性ＨＰＳ的形态随着弹性体的不同以及含量的变化均有不同特点，与冲击韧性的变化相对应。

γ－射线辐照对HIPS���SBS共混物结构与性能的影响

采用６０Ｃｏγ－射线对ＨＩＰＳ／ＳＢＳ共混物以不同剂量和时间进行辐照，适当条件下，可改善共混物的性能，其中的丁二烯橡胶相可产生不同程度的交联，使抗张强度、弹性模量增加，热变形温度及硬度明显提高。并观察了交联后形态结构的变化。

α－甲基苯乙烯对HIPS���SBS共混物流变行为及力学性能的影响

用锥板式流变仪研究了α－ＭＳ对ＨＩＰＳ／ＳＢＳ共混物流动行为的影响，结果表明：不同α－ＭＳ用量的共混物和如曲线相似．均随增加τ＿ｗ增大、η＿ａ下降。流动指数，ｎ均小于１为非牛顿假塑性流体。加入少量（约２．５％）α－ＭＳ使共混物熔融指数提高３倍，其总体力学性能变化不大。

HIPS/SBS共混物的形态结构和性能

通常,高抗冲聚苯乙烯(HIPS)为多相体系,由连续聚苯乙烯(PS)相和分散的聚丁二烯(PB)颗粒组成。PB含量一般为5～15%,粒径范围为0.5～10μm,PB颗粒是交联的,同时含有接枝的PS,其内部结构由制备工艺决定。HIPS���学性能与其制备工艺、PB含量、PB分子结构、相区尺寸及内部结构密切相关。PS和PB嵌段共聚物(SBS)通常为热塑弹性体,由于PS段和PB段的不相容性而呈现微相分离的结构特征。SBS常用于与其它聚合物共混以增加后者的韧性。本工作研究了HIPS/SBS共混物的形态结构和力学性能。

电冰箱专用HIPS���静电板材的研究

本文采用机械共混的方法,对国内外不同种类的抗静电剂进行了性能对比,筛选出了适用于HIPS���冰箱板材的抗静电剂,板材的各种性能满足厂家的使用要求。

HIPS/TiO_2复合材料的电子显微学研究

高抗冲聚苯乙烯树脂(HIPS)在实际应用中,往往要加入着色剂进行着色,钛白粉(TiO_2)是一种通用的白色着色剂。然而着色剂的加入对材料的力学性能有较大影响。本文对着色后的HIPS/TiO_2复合材料进行了电子显微学研究,明确了TiO_2影响HIPS���学性能的原因。 HIPS/TiO_2复合材料超薄切片的透射电子显微镜结果表明,TiO_2在样品中的分布很不均匀,局部区域TiO_2严重堆积(图1a)。扫描电子显微镜对HIPS/TiO_2冲击断面的组成观察得到了同样的结果(图1b。TiO_2在材料内部的堆积区域形成材料力学性能的弱点,材料受外力作用时首先从这些弱点处断裂,

TiO_2分布对HIPS/TiO_2性能的影响

本文利用电子显微镜对HIPS/TiO_2复合材料的组成和形貌进行了研究。结果表明,TiO_2在HIPS/TiO_2中分布的均匀程度与材料的力学性能密切相关。采用适当的分散剂对TiO_2进行包封,减少了TiO_2颗粒间的粒子间力,阻止了TiO_2的聚集,有利于TiO_2在HIPS���的均匀分散。TiO_2的均匀分布消除了材料内部力学性能的弱点,使材料的力学性能大幅度提高。

Studies on the fracture behaviour of polymer blends with special reference to PP/HDPE and PS/HIPS blends

Investigations on the fracture behaviour of polymer blends is the topic of this thesis. The blends selected are PP/HDPE and PS/HIPS. PP/HDPE blend is chosen due to its commercial importance and PS/HIPS blend is selected to study the transition from brittle fracture to ductile fracture.PP/HDPE blends were prepared at different compositions by melt blending at 180°C and fracture failure process was investigated by conducting notch sensitivity test and tensile test at different strain rates. The effects of two types of modifiers (particulate and elastomer) on the fracture behaviour and notch sensitivity of PP/HDPE blends were studied. The modifiers used are calcium carbonate, a hard particulate filler commonly used in plastics and Ethylene Propylene Diene Monomer (EPDM). They were added in 2%, 4% and 6% by weight of the blends.The study shows that the mechanical properties of PP/HDPE blends can be optimized by selecting proper blend compositions. The selected modifiers are found to alter and improve the fracture behaviour and notch sensitivity of the blends. Particulate fillers like calcium carbonate can be used for making the mechanical behaviour more stable at the various blend compositions. The resistance to notch sensitivity of the blends is found to be marginally lower in the presence of calcium carbonate. The elastomeric modifier EPDM produces a better stability of the mechanical behaviour. A low concentration of EPDM is sufficient to effect such a change. EPDM significantly improves the resistance to notch sensitivity of the blends. The study shows that judicious selection of modifiers can improve the fracture behaviour and notch sensitivity of PP/HDPE blends and help these materials to be used for critical applications.For investigating the transition in fracture behaviour and failure modes, PS/HIPS blends were selected. The blends were prepared by melt mixing followed by injection moulding to prepare the specimens for conducting tensile, impact and flexure tests. These tests were used to simulate the various conditions which promote failure.The tensile behaviour of unnotched and notched PS/HIPS blend samples were evaluated at slow speeds. Tensile strengths and moduli were found to increase at the higher testing speed for all the blend combinations whereas maximum strain at break was found to decrease. For a particular speed of testing, the tensile strength and modulus show only a very slight decrease as HIPS content is increased up to about 40%. However, there is a drastic decrease on increasing the HIPS content thereafter.The maximum strain at break shows only a very slight change up to about 40% HIPS content and thereafter shows a remarkable increase. The notched specimens also follow a comparable trend even though the notch sensitivity is seen high for PS rich blends containing up to 40% HIPS. The notch sensitivity marginally decreases with increase in HIPS content. At the same time, it is found to increase with the increase in strain rate. It is observed that blends containing more than 40% HIPS fail in ductile mode.The impact characteristics of PSIHIPS blends studied were impact strength, the energy absorbed by the test specimen and impact toughness. Remarkable increase in impact strength is observed as HIPS content in the blend exceeds 40%. The energy absorbed by the test specimens and the impact toughness also show a comparable trend.Flexural testing which helps to characterize the load bearing capacity was conducted on PS/HIPS blend samples at the two different testing speeds of 5mmlmin and 10 mm/min. The flexural strength increases with increase in testing speed for all the blend compositions. At both the speeds, remarkable reduction in flexural strength is observed as HIPS content in the blend exceeds 40%. The flexural strain and flexural energy absorbed by the specimens are found to increase with increase in HIPS content. At both the testing speeds, brittle fracture is observed for PS rich blends whereas HIPS rich blends show ductile mode of failure.Photoelastic investigations were conducted on PS/HIPS blend samples to analyze their failure modes. A plane polariscope with a broad source of light was utilized for the study. The coloured isochromatic fringes formed indicate the presence of residual stress concentration in the blend samples. The coverage made by the fringes on the test specimens varies with the blend composition and it shows a reducing trend with the increase in HIPS content. This indicates that the presence of residual stress is a contributing factor leading to brittle fracture in PS rich blends and this tendency gradually falls with increase in HIPS content and leads to their ductile mode of failure.

CHEMICAL MODIFICATION EFFECT on THE MECHANICAL PROPERTIES of HIPS/COCONUT FIBER COMPOSITES

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