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力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。     

HIPS的官能化及HIPS/PBT共混体系的研究

以过氧化二异丙苯（DCP）为引发剂，甲基丙烯酸缩水甘油酯（GMA）为活性单体，高抗冲苯乙烯（HIPS）通过熔融接枝制得了动能化的高抗冲聚苯乙烯接枝物（HIPS－g-GMA)。用红外光谱和电子能谱对其结构进行了表征。HIPS－g-GMA的红外谱图，证明GMA已经接枝到HIPS上。电子能谱分析也提供了相似的结论。研究了单体浓度和DCP用量对产物接枝率的影响，并用化学滴定方法测定了接枝物的接枝率。用DSC、SEM、WAXD、DMA等研究了PBT／HIPS和PBT、HIPS－g-GMA的结晶、形态结构、动态力学性能及力学性能随组成的变化。SEM及DMA分析表明增容后体系的相容性得到改善，力学性能有较大提高。     

原子力-红外光谱定量分析聚1-丁烯／聚丙烯共混物的相区组成

在聚1-丁烯（PB）中混入聚丙烯（PP）能够调节前者的结晶行为，二者的共混物因此引起了人们的兴趣，其中关于两个组分的相容性目前还存在争议。本文首先建立PB／PP共混物组成的傅里叶变换红外光谱仪（FT-IR）定量分析方法，以1460和1378 cm^－1吸收峰的面积比来确定共混物中PB的质量分数，进而利用原子力-红外（AFM-IR）光谱与FT-IR光谱的一致性将其应用于AFM-IR谱的数据处理，以获得共混物中微相区的组成。研究发现PB质量分数为70%的PB／PP共混物发生了相分离，两个组分部分互溶，形成了富PB相和富PP相，分别含有78%和19%的PB。     

接枝和交联对纳米Si02改性NR／PP共混型热塑弹性体的影响

动态硫化制备纳米二氧化硅（SiO2）改性天然橡胶，聚丙烯共混型热塑性弹性体（NR/PPTPE）．研究了马来酸酐，苯乙烯，过氧化二异丙苯（MAH／St／DCP）多单体“就地”熔融接枝、交联对TPE力学性能、耐溶剂性能和耐热变形性能的影响，并用SEM分析了TPE的断面形貌．结果表明：纳米SiO2和MAH／St／DCP的最佳质量分数分别为0．03和0．0375／0．0188／0．00375时，MAH／St／DCP接枝、交联改性NR／PP／纳米SiO：TPE的力学性能、耐溶剂性能和耐热变形性能最佳．MAH／St／DCP“就地”接枝、交联通过细化交联NR分散相、改善交联NR分散的均匀性和增加两相之间的共交联，使NR与PP两相界面结合强度明显提高，NR／PPTPE的综合性能得到明显的改善．     

苯甲酰基化聚苯乙烯的合成和表征

合成并表征了具有芳香酮侧链结构的苯甲酰基聚苯乙烯（BPS）,讨论了反应时间,温度,溶剂,催化剂用量及投料比对聚苯乙烯（PS）转化为BPS的转化率和交联反应的影响,结果表明,PS在合适条件下可转化成BPS,PS转化成BPS后其UV吸收强度明显增大,BPS在紫外光照射下发生降解,BPS中的羰基可以与某些肼反应生成腙。     

插层聚合制备聚丙烯/蒙脱土纳米复合材料及其结构性能表征

将插层聚合的概念引入烯烃聚合,制备了聚丙烯／蒙脱土（PP／MMT）纳米复合材料。X射线衍射和TEM分析结果表明,蒙脱土在聚丙烯基体中达到了纳米级的分散,动态力学性能研究结果表明,在高于Tg的温度区域内PP／MMT纳米复合材料的储能模量（E′）成倍增加,加入8％的蒙脱土（MMT）,PP／MMT的E′提高近3倍。PP／MMT的玻璃化转变温度Tg有一定程度的提高,随蒙脱土含量的增加,PP／MMT的热分解温度和热变形温度（HDT）都有大幅度提高。     

St存在下MAH熔融接枝PP机理的探讨

在哈克转矩流变仪和双螺杆挤出机中,对苯乙烯（St）存在下马来酸酐（MAH）熔融接枝聚丙烯（PP）进行了研究.实验表明：St的加入不仅可显著提高MAH的接枝率,而且可减少PP的降解;当St和MAH的摩尔比为1时,MAH接枝率最大.通过反应机理分析得出：没有St时,MAH主要以单分子形式在PP降解之后接枝到PP上;而在St存在下,St与MAH以交替接枝的形式或者配合物（CTC）形式在PP降解之前接枝到PP上,形成St和MAH交替聚合的长链.后者使MAH的接枝率增加,同时增大了PP的交联,减小了PP的降解.     

聚苯乙烯分子链构象与其薄膜的玻璃化转变行为

本文利用椭偏仪研究了成膜方式对不同分子量聚苯乙烯(PS)超薄膜玻璃化转变行为的影响.发现PS超薄膜的玻璃化转变温度(Tg)随着厚度降低的幅度与其成膜方式、分子量有关.当PS膜低于一定厚度时,旋涂法制备的PS膜的Tg比相同厚度浇铸法制备的膜低,且二者Tg差值随着厚度的降低而增大.这二种膜Tg的差值和Tg发生偏离时膜的临界厚度随聚苯乙烯分子量的增加而增加.利用非辐射能量转移荧光光谱证实成膜方式主要是影响PS分子链在膜中的构象.旋涂法制备的PS膜相对于本体在近表面区域分子链的形变更大.分子量愈大,分子运动时内摩擦阻力愈大,近表面区域分子的残余应力愈大.由于强运动能力的活性层(空气/PS界面)对PS薄膜Tg的影响占主导,相同厚度下分子链愈伸展,残余应力越大,PS薄膜的Tg越低,导致成膜方式与分子量的影响也愈大.     

丙烯酸及其接枝物对纳米CaCO3/PP结晶与熔融行为的影响

制备了丙烯酸(AA)及其接枝聚丙烯(PP—g-AA)改性的纳米CaC03／PP复合材料。用DSC研究了纳米CaCO3对PP、PP-g-A和AA对纳米CaCO3／PP中PP结晶与熔融行为的影响。结果表明：随纳米CaCO3用量增加，PP结晶与熔融温度提高，PP—g—AA加入使PP结晶温度进一步提高，PP的结晶温度也随从用量增加而提高；在过氧化二异丙苯(DCP)存在下，少量AA能明显提高PP的结晶温度，但增加从用量对结晶温度的影响较小；WAXD证实纳米CaCO3／PP复合材料中存在β晶。     

阻燃高抗冲聚苯乙烯热降解研究

利用热失重-红外联用仪(TGA-IR)分析了高抗冲聚苯乙烯(HIPS)的热降解过程,结合热裂解气相色谱-质谱联用仪(Py-GC/MS)分析了HIPS的热裂解产物,利用化学方程式阐述了HIPS自由基降解反应.对十溴二苯乙烷、三氧化二锑复配阻燃体系的热降解过程进行了研究,讨论了阻燃HIPS的凝聚相阻燃、气相阻燃机理.实验表明,HIPS燃烧时主要发生β-断裂,大量烟雾主要由苯乙烯、甲苯、α-甲基苯乙烯、苯乙烷、丁二烯等组成,其中凝聚相主要是1,3,5-三苯基苯乙烯及其他部分低聚物.在不同的温度下,阻燃HIPS的热裂解产物不同,在较高的温度下,小分子化合物明显增多.     

Effects of polystyrene‐b‐poly(ethylene/propylene)‐b‐polystyrene compatibilizer on the recycled polypropylene and recycled high‐impact polystyrene blends

The recycled polypropylene/recycled high‐impact polystyrene (R‐PP/R‐HIPS) blends were melt extruded by twin‐screw extruder and produced by injection molding machine. The effects of polystyrene‐b‐poly(ethylene/propylene)‐b‐polystyrene copolymer (SEPS) used as compatibilizer on the mechanical properties, morphology, melt flow index, equilibrium torque, and glass transition temperature (T_g) of the blends were investigated. It was found that the notch impact strength and the elongation at break of the R‐PP/R‐HIPS blends with the addition of 10 wt% SEPS were 6.46 kJ/m² and 31.96%, which were significantly improved by 162.46% and 57.06%, respectively, than that of the uncompatibilized blends. Moreover, the addition of SEPS had a negligible effect on the tensile strength of the R‐PP/R‐HIPS blends. Additionally, the morphology of the blends demonstrated improved distribution and decreased size of the dispersed R‐HIPS phase with increasing the SEPS content. The increase of the melt flow index and the equilibrium torque indicated that the viscosity of the blends increased when the SEPS was incorporated into the R‐PP/R‐HIPS blends. The dynamic mechanical properties test showed that when the content of SEPS was 10 wt%, the difference of T_g decreased from 91.72°C to 81.51°C. The results obtained by differential scanning calorimetry were similar to those measured by dynamic mechanical properties, indicating an improved compatibility of the blends with the addition of SEPS.     

Synthesis and characterization of polyethylene‐g‐polystyrene as the compatibilizer for polypropylene/ Polystyrene blends

Polyethylene‐g‐polystyrene (PE‐g‐PS) was synthesized as a compatibilizer for polypropylene/polystyrene­(PP/PS) blends by the living radical polymerization of styrene with polyethylene‐co‐glycidylmethacrylate (PE‐co‐GMA). The compatibilizer effect of PE‐g‐PS on the morphology and thermal properties of PP/PS blends was investigated. The crystalline temperature of PP in PP/PS blends decreased with increasing PE‐g‐PS contents. Morphologies of PP/PE‐g‐PS/PS blends showed much better dispersion of each domain for higher PE‐g‐PS contents. The molecular weight of PS segment in PP/PE‐g‐PS/PS blend was increased by addition of styrene monomer during the post melt blending process where post living radical polymerization reaction proceeded. Copyright © 2003 John Wiley & Sons, Ltd.     

New high impact polystyrene: Use of poly(1‐hexene) and poly(1‐hexene‐co‐hexadiene) as impact modifiers

In this study, polystyrene (PS) was melt blended with different amounts of poly1‐hexene (PH) and poly(1‐hexene‐co‐hexadiene) (COPOLY) and the blends were compared with conventional PS/polybutadiene (PS/PB) one. Scanning electron microscope revealed that the dispersion of PH and COPOLY in PS matrix was more uniform with the appearance of small particles in PS matrix; however, in the case of PS/PB blends, the fracture surface showed nonhomogenous morphology with the appearance of bigger rubber particles. Based on Differential Scanning Calorimetry (DSC) and dynamic mechanical thermal analysis results, T_g of the blends decreased in comparison with it in neat PS. Impact strength of PS/PH and PS/COPOLY blends was considerably higher than that in PS/PB and significantly higher than the value for neat PS. Tensile test showed substantial improvement in stress at yield and better elongation at break for COPOLY containing blend than the samples containing PH and PB rubbers. Also, blending of PS with 10% of the rubbers was considered in the presence of dicumylperoxide as a probable grafting/cross‐linking agent to produce XPS/COPOLY10 and XPS/PB10 samples, respectively. IR results of the nonsoluble solvent extracted gel showed that COPOLY and PB were grafted to PS matrix during melt blending, which caused higher impact strength in the related samples.     

反应性单体改性PP/PS共混物结晶与熔融行为

制备了三种反应性单体和两种PP接枝物改性的PP／PS共混物,用DSC研究了改性PP／PS共混物的结晶与熔融行为。结果表明：PS的加入提高了PP的结晶温度,两种接枝物的加入进一步提高共混物中PP的结晶温度,少量反应性单体对结晶温度影响不大,但高用量时则明显提高共混物的结晶温度;外加接枝物或者反应性单体对共混物中PP的熔融温度影响不大,但是熔融峰形与结晶温度高低有关。     

Study on Dynamic Vulcanized EPDM/PP Thermoplastic Elastomer

Based upon the THE,HAAK RHEOCORD 90 and Wx-ray observation,a study was made on the structure and property of ethylene-propylene-ethlidene norborene (EPDM)/polyprolene (PP) blending systems ,and the experimental results were fully explained. (1) The effect of Mooney viscosity (ML)of EPDM、 melt flow rate(MFR) of peroxide(DCP) and mixing steps on mechanical properties of EPDM/PP blends was studied. The results showed that the mechanical and process properties of EPDM?PP thermoplastic elastomers were better using EPDM with the ML of 60 and PP with MFR of 7.5g/10min as matrix,DCP with the content of 1.2 per cent with the help of twostep curing process at the temperature of 170-175 ℃.     

Preparation of microcellular polypropylene/polystyrene blend foams with tunable cell structure

By using supercritical carbon dioxide (sc‐CO₂) as the physical foaming agent, microcellular foaming was carried out in a batch process from a wide range of immiscible polypropylene/polystyrene (PP/PS) blends with 10–70 wt% PS. The blends were prepared via melt processing in a twin‐screw extruder. The cell structure, cell size, and cell density of foamed PP/PS blends were investigated and explained by combining the blend phase morphology and morphological parameters with the foaming principle. It was demonstrated that all PP/PS blends exhibit much dramatically improved foamability than the PP, and significantly decreased cell size and obviously increased cell density than the PS. Moreover, the cell structure can be tunable via changing the blend composition. Foamed PP/PS blends with up to 30 wt% PS exhibit a closed‐cell structure. Among them, foamed PP/PS 90:10 and 80:20 blends have very small mean cell diameter (0.4 and 0.7 µm) and high cell density (8.3 × 10¹¹ and 6.4 × 10¹¹ cells/cm³). Both of blends exhibit nonuniform cell structure, in which most of small cells spread as “a string of beads.” Foamed PP/PS 70:30 blend shows the most uniform cell structure. Increase in the PS content to 50 wt% and especially 70 wt% transforms it to an irregular open‐cell structure. The cell structure of foamed PP/PS blends is strongly related to the blend phase morphology and the solubility of CO₂ in PP more than that in PS, which makes the PP serve as a CO₂ reservoir. Copyright © 2009 John Wiley & Sons, Ltd.     

PA6/HIPS/PP-g-(GMA-co-St)反应共混体系的研究

通过扫描电镜、热分析、熔体流动速率、熔融扭矩和力学性能等测试方法研究了甲基丙烯酸缩水甘油酯(GMA)和苯乙烯(St)多单体熔融接枝聚丙烯[PP-g-(GMA-co-St)]对PA6/HIPS共混物的熔融流变性能、结晶行为、相形态和力学性能的影响.结果表明,在熔融共混过程中,PP-g-(GMA-co-St)中的环氧基与PA6的端氨基原位生成的接枝共聚物有效地降低了共混物的界面张力,提高了共混物的界面粘着力,使共聚物的流动速率降低,熔融扭矩提高;PA6分子链的规整性降低,结晶完善性变差.在PP-g-(GMA-co-St)的质量分数为10%时,共混物分散相的尺寸明显减少,力学性能得到较大提高;其中冲击强度超过纯PA6,达到HIPS水平.通过反应共混,制备了力学性能均衡的PA6/HIPS/PP-g-(GMA-co-St)共混物合金.     

Studies on partial compatibility of PP and PS

<正>Blends of polystyrene(PS) and polypropylene(PP) were prepared through melt compounding.With an increase of PS content up to 30 wt%,the tensile strength of PP/PS blends increased from 37.4 MPa to 42.2 MPa,although the blends were widely regarded as immiscible.The DSC results showed that there's slight decrease in melting temperature of PP, showing insufficient evidence for partial compatibility between PP and PS.Almost no variation of distinct characterization peaks were observed in FTIR spectra of PS/PP blends compared with those of neat PP and PS,indicating there is no chemical interactions between PP and PS.Since the morphology investigation showed a droplet structure as PS content was up to 30 wt%,the improvement of tensile strength could be simply considered as due to the reinforcing effect of dispersed rigid PS particles on the PP,combining with partial compatibility between them as evaluated by change of C_p at glass transition for both PS and PP.More interestingly,DSC and DMA results showed that the blending of PS and PP could lead to a substantial decrease of the glass transition temperature(T_g) of PP,and increase of T_g of PS.The annealing experiment was carried out to understand the change of T_g in PP/PS blends.It is believed that the compressive stress generated by the contracting PP should be the dominant mechanism for the T_g elevation of PS.On the other hand,the T_g decrease of PP is likely owing to the creation of a large amount free interface of PP and the dilatation of the PP phase resulting from the corresponding tension exerted by PS during cooling.     

Photochemical aging of in situ polymerized blends of polystyrene and poly[acrylonitrile-g-(ethylene-co-propylene-co-diene)-g-styrene] (AES)

The influence of photochemical aging of in situ polymerized PS/AES blends on their mechanical properties has been studied. The PS/AES blends were subjected to photochemical aging for 168 h and 720 h. Tensile properties and Izod impact resistance of aged and non-aged samples were evaluated. The mechanical properties of the PS/AES blends are influenced by the polymerization temperature and blend composition and represent a balance between the toughness of EPDM and the stiffness of SAN in the PS matrix. Even though the impact resistance and strain at break of HIPS are higher than those of the PS/AES blends, after the aging period all PS/AES blends showed higher strain at break than HIPS. PS/AES blends present higher photochemical stability than HIPS.