THE EFFECT OF BLENDING SEQUENCE ON PHASE MORPHOLOGY OF NYLON 6/ABS/SMA BLENDS

The preparation process-dependent phase morphology of blends composed of nylon 6 and acrylonitrile-butadiene- styrene(ABS)over a composition range of 30-70 wt% using a styrene-maleic anhydride(SMA)copolymer as the compatibilizing agent with a constant content(5phr)was investigated.The results of the scanning electron microscope (SEM)observation revealed that compared with the binary blends of nylon 6 and ABS,the existence of SMA caused a composition shift of phase inversion to a higher weight fraction of ny...

Effects of Blending Routes on the Morphology and Properties of PA-6/Nano-CaCO_3/MA-POE Ternary Composites

The effect of blending routes on the morphology and properties of Polyamide-6 (PA-6)/nano-CaCO3/Maleated ethylene-octane copolymer (MA-POE) ternary composite was analyzed using static mechanical test (DMA), TEM (transmission electronic microscope) and SEM (scanning electron microscope). It was found that MA-POE, as an impact modifier, had a profound effect upon the toughness of the PA-6/nano-CaCO3 composite. In particular, by adopting two-stage blending route, the microstructure of the ternary composites turned to core-shell structure, and the impact toughness was improved greatly. At the same time, tensile strength and dynamic storage modulus (E1) were higher than those with one-stage blending route processed ternary composite. The results suggest that blending routes may improve the properties of PA-6/nano-CaCO3/MA-POE ternary composites.

SUPER POLYOLEFIN BLENDS ACHIEVED VIA DYNAMIC PACKING INJECTION MOLDING:MORPHOLOGY AND PROPERTIES

As a long-term project aimed at developing super polyolefin blends, in this paper we summarize our work on themechanical reinforcement and phase morphology of polyolefin blends achieved by dynamic packing injection molding(DPIM). The main feature of this technology is that the specimen is forced to move repeatedly in the model by two pistonsthat move reversibly with the same frequency during cooling, which results in preferential orientation of the dispersed phaseas well as the matrix. The typical morphology of samples obtained via DPIM is a shear-induced morphology with a core inthe center, an oriented zone surrounding the core and a skin layer in the cross-section areas. Shear-induced phase dissolutionat a higher shear rate but phase separation at low shear rates is evident from AFM examination of LLDPE/PP (50/50) blends.The super polyolefin blends having high modulus (1.9-2.2 GPa), high tensile strength (100-120 MPa) and high impactstrength (6 times as that of pure HDPE) have been prepared by controlling the phase separation, molecular orientation andcrystal morphology.

TIME-DEPENDENT MORPHOLOGY OF POLYETHYLENE-POLYPROPYLENE BLENDS

The effect of time-temperature treatment on morphology of polyethylene-polypropylene (PE-PP) blends wasstudied to establish a relationship between thermal history, morphology and mechanical properties. Polypropylene (PP)homopolymers were used to blend with various polyethylenes (PE), including high density polyethylene (HDPE), lowdensity polyethylene (LDPE), linear low density polyethylene (LLDPE), and very and ultra low density polyethylene(VLDPE and ULDPE). The majority of the blends were prepared at a ratio of PE:PP = 80:20, while blends of PP and LLDPEwere prepared at various compositions. Thermal treatment was carried out at temperatures between the crystallizationtemperatures of PP and PEs to allow PP to crystallize first from the blends. On cooling further, PE crystallized too. A verydiffuse PP spherulite morphology in the PE matrix was formed in some partially miscible blends when PP was less than 20%by mass. Droplet-matrix structures were developed in other blends with either PP or PE as dispersed domains in a continuousmatrix, depending on the composition ratio. The scanning electron microscopy (SEM) images displayed a fibrillar structureof PP spherulite in the LLDPE-PP (80:20) and large droplets of PP in the HDPE-PP (80:20) blend, providing larger surfacearea and better bonding in the LLDPE-PP (80:20) blends. This explains why the blends with diffuse spherulite morphologyshowed greater improvement in tensile properties than droplet-matrix morphology blends after time-temperature treatment.

EFFECT OF DRAWING ON MORPHOLOGY,STRUCTURE AND MECHANICAL PROPERTIES OF BLENDS OF A LIQUID CRYSTALLINE POLYMER AND MODIFIED POLY(PHENYLENE OXIDE)

Polymer strands with various draw ratios of a thermotropic liquid crystalline polymer (LCP) and modified poly(phenylene oxide) were prepared by drawing the melts leaving a slit die in open air. The morphology, structure and mechanical properties of the resulting strands were studied as a function of LCP content and draw ratio. It was found that the thermal and mechanical properties of the matrix phase did not change dramatically with the amount of LCP and draw ratio, but the orientation of LCP phase could be increased with draw ratio. The mechanical properties of the strands could be improved by moderately drawing the melts. Wide angle X-ray diffraction suggested that the improvement in tensile strength of the strands was due to the resultant fibrillation of LCP phase and enhanced molecular orientation. Morphological observation indicated that excessive drawing of the strands could lead to the break down of the microfibrils of LCP and thus resulted in the decrease of mechanical strength.

ESTIMATION OF BLENDING RATIO OF TWO-COMPONENT FIBER BUNDLE FROM BUNDLE LOAD-ELONGATION CURVE

In this paper, two methods were developed to assess the blending ratio of two-componentfiber bundles. They were the peak-height method and the slope method. The relationship be-tween blending ratio and testing data was analysed, and the regression curves were obtained bystepwise regression method. It was pointed out that the testing errors of both methods were lessthan two percent. The validities of both methods were verified by experiments, All calculationsof both methods were completed by computer. The blending ratio was ascertained from the test-ing data of bundle fiber strength tester which was made by the authors themselves.

Electrical Behaviour and Spherulites Morphology of HDPE/PP Polyblends with HDPE as Base Material

Polymer composites of virgin high density poly ethylene (HDPE) and virgin polypropylene (PP) are prepared. PP of weight% of 20, 30 and 50 are reinforced to HDPE in the form of pellets. They are converted into raw polymer sheets using a two roll milling machine. The prepared raw sheets have undergone compression moulding to fabricate polymer sheets to study electrical properties like dielectric strength, surface resistivity and volume resistivity at atmospheric temperature and pressure. Result shows dielectric strength and volume resistivity decreases with addition of PP to HDPE, whereas surface resistivity increases. Crystal growth rate is observed using a cross polarised microscope (PLM). The microscopy results reveal, the PP crystallizes faster than HDPE and the growth rate declines for the polyblend;showing non-uniform and hazy spherulitic structure.

聚丙烯腈对聚乙烯醇膜形貌和性能的改进

通过流延成膜的方法制备了聚乙烯醇/聚丙烯腈共混薄膜。通过扫描电镜分析了共混膜的形貌。通过差式扫描量热仪、热重分析、拉伸测试、表面接触角测试研究了共混膜的热力学性能、机械性能和化学性能。测试结果显示聚丙烯腈对聚乙烯醇膜的形貌和性能产生了显著的影响。

Some Mechanical and Thermal Properties of PC/ABS Blends

A series of blends of Acrylonitrile-Butadiene-Styrene (ABS) and Polycarbonate (PC) were prepared and some of their thermal and mechanical properties were determined. The Young’s modulus changed gradually and monotonically with the polycarbonate content. This effect was tentatively explained as the antiplasticization of the PC which is ascribed to the chain mobility, which permits the PC chains to pack more tightly, to the secondary cross-linking between the PC chains, or to the secondary attachment of bulky side-chains to the PC, thus producing steric hindrance to the rotation of the PC main chains. The experimental values found for the impact strength were intermediate between those of the neat polymers, depending upon the dispersed rubber particles of butadiene in the matrix of SAN (Styrene-Acrylonitrile), and the dispersed PC particles which generally make the ABS more brittle. A maximum value of about 88 KJ/m2 for the impact strength was observed for the blend with 90% PC. This may be attributed to the strong polymer-polymer interactions for this particular composition. The variations in the heat deflection temperature HDT and the Vicat softening point with the blend composition were very similar, and allowed us to assume that the phase inversion between the matrices of the two polymers takes place at 50% PC. The morphology of the blends revealed by SEM observation, show a co-continuous structure.

Influence of Blend Composition and Compatibilizer on Mechanical and Morphological Properties of Recycled HDPE/PET Blends

Polymer blends based on recycled high density polyethylene (rHDPE) and recycled poly(ethylene terephthalate) (rPET) with and without ethylene-glycidyl methacrylate copolymer (E-GMA) as compatibilizer were fabricated in a co-rotating twin screw extruder. The effects of rPET and compatibilizer content on the mechanical properties and morphological stability of rHDPE-rich blends were investigated. The rHDPE/rPET (75/25 wt/wt) blend compatibilized with 5 php (per 100 part of polymer) E-GMA showed an enhancement of about 7% - 26% in tensile properties and flexural strength as compared with those of the neat rHDPE. The strain at break showed a decreasing trend as the rPET content increased. The addition of E-GMA to the rHDPE/rPET blends was found to recover the blend toughness as well as improving the compatibility between HDPE and PET. In this study, the highest strain at break was obtained for the rHDPE/rPET blends at 75/25 (wt/wt) composition with E-GMA content of 5 php. FTIR and SEM analysis of the compatibilized blends confirmed the chemical interaction and improved interfacial bonding between the two phases.

FIBRE REINFORCED COMPOSITES BASED ON NOVEL BLEND MATRICES

A series of glass fibre reinforced composites based on novel blend matrices were fabricated us-ing reaction injection moulding （RIM） processing.The blends were made of sub-sequentialinterpenetrating polymer networks of acrylic-polyurea or acrylic-copoly（urea-isocyanurate）.Themechanical and thermal properties were characterized by tensile test and dynamic mechanical ana-lysis.The fracture data from single edge notch bend tests were analysed using fracture mechanicsfor the composites to give KIC and GIC.The correlation between reaction kinetics and morphologyof the blend and the composite properties were discussed.The investigations showed that the novelblends have good bonding property on glass fibre,thus good processability in RIM,and the re-suited composites have good mechanical and thermal properties.

Effect of nano powder(Al2O3-CaO)addition on the mechanical properties of the polymer blend matrix composite

This work describes the preparation and study of the properties of composite nanoparticles prepared by the sol-gel method which consists of two materials(Al2 O3-CaO),and study the effect of these nanoparticles on the mechanical behavior of a polymer blend(EP 4%+96%UPE).The powder was evaluated by X-ray diffraction analysis,scanning electron microscopy analysis(SEM),particle size analysis,and energy dispersive X-ray analysis(EDX).The mechanical behavior of the co mposite material was assessed by tensile test,bending test and hardness test.The evaluation results of the composite nanoparticles showed good distribution of the chemical composition between aluminum oxide and calcium oxide,smoothness in particles’size at calcination in high and low temperatures,formation of different shapes of nanoparticles and different(kappa and gamma)phases of the Al2 O particles.The results of mechanical behavior tests showed marked improvement in the mechanical properties of the resulted composite material,especially at 1.5%,compared with polymer blend material without nano powder addition.The tensile properties improved about(24 and 14.9)%and bending resistance about(23.5 and16.8)%and hardness by(25 and 22)%when adding particles of size(63.8 and 68.6)respectively.Therefore,this reflects the efficiency of the proposed method to manufacture the nanoco mposite powder and the possibility of using this powder as a strengthening material for the composite materials and using these composite materials in bio applications,especially in the fabrication of artificial limbs.

Thermal, Mechanical and Rheological Properties of Low Density/Linear Low Density Polyethylene Blend for Packing Application

Packaging is the subject of considerable commercial development by a variety of organizations around the world. In this study the mechanical, thermal and rheological properties were investigated for different blend ratios of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). The weight percent of the LDPEs used in the blends were 50, 60, 70, 80 and 90. The polymer blends were prepared in a twin screw extruder to produce a thin sheet (1-mm thickness) similar to the packaging grade. Tensile results showed that the 50/50 composition exhibited the highest stress at break, where the differential scanning calorimetry results indicated a co-crystalline phase in some blends. The results produced by the rheometer revealed the LLDPE effect over the complex viscosity and consequently blend easy processing. The present study conclusively demonstrates that at low weight percent of linear low density polyethylene in the blend displays better properties for packaging application.

Influences of Reactive Compatibilizer R-Styrene-Maleic Anhydride Copolymer on PA6/PP Blends

The effect of R-styrene-maleic anhydride copolymer(R-SMA) compatibilzation on Nylon 6(PA6)/polypropylene(PP) blends has been investigated experimentally through Molau test,microscopic morphology,and chemical structure.Results show that the moderate R-SMA addition can promote reaction between anhydride in R-SMA and amino in PA6,and lead to a new PA6-g-R-SMA copolymer in the blends.Such PA6-g-R-SMA copolymer in the blends can effectively reduce the interfacial tension and PP particle size,and improve the compatibility of two immiscible phases in the blends.The crystallinity of PA6 in PA6/PP blends has greatly decreased by PP blends.The blends have the best comprehensive mechanical and thermal properties when the mass ratio of PA6/PP/R-SMA is 90:10:2 to 90:10:4.The impact strength of the PA6/PP blends with the compatibilizer is increased by more than 150%.

硅烷偶联剂对咖啡渣的表面改性及其对咖啡渣/聚丙烯木塑复合材料性能的影响

为解决咖啡渣(Spent coffee grounds,SCG)与聚丙烯(Polypropylene,PP)界面相容性差的问题,研究3种不同类型的硅烷偶联剂改性SCG及其对SCG/PP木塑复合材料性能的影响。以3-氨丙基三甲氧基硅烷(3-aminopropyl trimethoxy-silane,KH540)、3-氨丙基三乙氧基硅烷(3-aminopropyl triethoxy-silane,KH550)和乙烯基三甲氧基硅烷(vinyl trimethoxy-silane,A171)这3种硅烷偶联剂作为表面改性剂,分别对SCG进行表面改性处理,并将改性SCG作为填料,通过熔融共混法制备了SCG/PP木塑复合材料;采用场发射扫描电子显微镜、傅里叶红外光谱仪和视频接触角仪对SCG的微观形貌、官能团特征和亲疏水性进行分析,并通过万能试验机、场发射扫描电子显微镜、热重分析仪、差示扫描量热仪、X射线衍射仪测试SCG/PP复合材料的力学性能、界面相容性、热稳定性、熔融结晶性能。结果表明:这3种硅烷偶联剂均成功接枝到SCG上,并有效提高了SCG的疏水性,增强了与PP之间的界面结合能力。3种硅烷偶联剂均可提高复合材料的拉伸强度,同时降低断裂伸长率;其中硅烷偶联剂A171改性制备的复合材料综合性能最好,拉伸强度比未经改性处理的SCG/PP复合材料提高48.6%,断裂伸长率仅下降4.4%。该研究可为解决SCG与PP界面相容问题及制备高性能SCG/PP复合材料提供参考。

氢环境对高钢级管线钢力学性能影响规律研究

在“双碳”目标背景下,天然气管道掺氢将成为未来大规模、长距离输送氢气的主要方式。但氢气的掺入将会对现有天然气管道运行、安全维护等方面带来新的挑战。针对纯氢环境下高钢级管道力学性能劣化规律不明确的问题,通过总结并对比现有试验过程中纯氢环境模拟方法,优选出高压动态气相充氢作为试验的纯氢环境模拟方法,并在不同纯氢环境、1.01×10^(-4)和1.01×10^(-5)mm/s这2种位移速率下,针对X80管线钢开展了多组高压慢应变速率拉伸试验,获得试验数据及试样断口形貌,分析氢对管线钢力学性能的影响。分析结果认为:在纯氢环境中X80管线钢的屈服强度、极限抗拉强度相对于空气环境中略微增加,增加程度均小于8%;在1.01×10^(-4)和1.01×10^(-5)mm/s这2种位移速率的氢环境下,X80管线钢的断后伸长率分别减小了6.04%和14.88%,表明随着位移速率的减小,管线钢氢损伤程度增大;气相缓蚀剂和环己胺对X80管线钢氢损伤均有抑制作用。研究结果对高压天然气管道掺氢或纯氢管道的设计与评价具有一定的参考价值。

通过调控氯化聚乙烯橡胶相交联密度计算氯化聚乙烯橡胶/丁腈橡胶共混胶应力-应变关系

以氯化聚乙烯橡胶(CM)和丁腈橡胶(NBR)为主要原料,采用机械共混法制备了CM/NBR共混硫化胶,通过改变CM/NBR共混硫化胶中CM相硫化体系的用量并采用平衡溶胀法、力学性能测试、理论计算等手段表征了CM/NBR共混硫化胶中CM相的交联密度及CM/NBR共混硫化胶的应力-应变关系,研究了CM相交联密度变化对CM/NBR共混硫化胶中两相定伸应力匹配程度和力学性能的影响。结果表明,由CM相交联密度增加所引起CM/NBR共混硫化胶定伸应力的变化大于CM相本身的定伸应力变化;随着定伸应力的增加,CM相交联密度变化对CM/NBR共混硫化胶定伸应力的影响增大;通过CM/NBR共混硫化胶中CM相和NBR相应力-应变关系的对比和CM/NBR共混硫化胶力学性能的变化验证了CM相交联密度的降低是两相定伸应力逐渐匹配的过程;与测试的应力-应变关系相比,采用拟合模型预测的共混硫化胶应力-应变关系的误差相对较小,表明此法具有一定的适用性。

生物可降解PBAT的合成方法与结构特性及降解机理

介绍了聚己二酸-对苯二甲酸丁二醇酯(PBAT)的合成方法、结构特性及降解机理。PBAT结合了芳香族聚酯优异的加工性和脂肪族聚酯的可降解性,具有较好延展性、耐热性和冲击性能,可完全降解。PBAT力学性能较低,目前大多采用原位聚合、熔融共混及溶剂浇铸等方法向PBAT中添加填料制备复合材料来改善其力学性能,而PBAT基复合材料工业化进程较缓,建议采用熔融共混法时应重点关注PBAT的高黏度对填料分散性的负面影响。PBAT主要通过自然环境中细菌等酶促进的分解作用和热降解等非酶作用进行降解,在降解过程中影响因素较多,尤其是PBAT基复合材料中填料的引入会导致降解机理更为复杂。在改善PBAT基复合材料力学性能的同时,保持其高效的生物降解性能将会是未来研究的重点方向之一。

不同因素对聚碳酸酯/聚对苯二甲酸乙二醇酯共混物的性能影响研究

通过挤出和注塑制备聚碳酸酯/聚对苯二甲酸乙二醇酯(PC/PET)共混物,探究成核剂对PC/PET共混物的结晶形态、热行为、形貌及力学性能的影响。此外,对相容剂添加量和PC/PET质量配比等变量也做了性能影响分析。最佳条件为:相容剂添加0.5%、PC/PET=3/7、成核剂TiO_(2)添加1%。适量粒径均匀、细小的TiO_(2)作为成核剂能很好地分散在PC/PET基体内,得到的PC/PET共混物形貌平整光滑,拉伸强度、弹性模量及冲击强度分别为40.5MPa、7654.0N/mm^(2)及14.3J/m,在DSC曲线上出现明显的冷、热结晶峰,热结晶的结晶温度均高于冷结晶,且DMA结果显示成核剂的加入使玻璃化转变温度降低,不相容PC相和PET相的Tg不断靠近。

基于隧道防火用的多孔注浆基材料研究

采用溶液共混法制备了多孔聚氨酯注浆材料,以纳米SiO2为增强相,研究了改性多孔注浆基材料的结构形貌、力学性能、阻燃性能和导热性能,研究结果表明:纳米SiO2掺杂后与聚氨酯基体发生了键合,增强了多孔注浆材料的孔壁强度,形态结构更加完整,多孔注浆材料的拉伸强度和粘接强度得到了改善,并随纳米SiO2掺杂量的增大呈现出先增大后降低的趋势,纳米SiO2掺杂量0.8%的多孔注浆材料的拉伸强度和粘接强度均达到了最大值。随纳米SiO2掺杂量的增加,多孔注浆材料的最高蓄热温度先降低后升高,降温速率先增加后降低,导热系数持续增加。阻燃测试表明:0.8%纳米SiO2掺杂的注浆材料的垂直燃烧时间最短为20.8 s,阻燃性能最优。综合各性能来看,纳米SiO2最佳掺杂量为0.8%,该掺杂比例下多孔注浆基材料最高蓄热温度为143℃,降温速率为1.75℃/min,导热系数为0.368 W/(m·K),垂直燃烧时间为20.8 s,在隧道防火应用方面具有广阔的应用前景。