含氢氧化镁的阻燃硅烷交联聚乙烯

在硅烷交联聚乙烯体系中 ,添加氢氧化镁阻燃剂制备无卤阻燃的硅烷交联聚乙烯。详细讨论了硅烷和氢氧化镁用量对材料力学性能及阻燃性能的影响。采用了拉伸性能试验、氧指数试验和锥形量热计试验对交联物的性能进行了表征。     

线形低密度聚乙烯／废胶粉热塑弹性体动态硫化性能研究

利用动态硫化法制备了线形低密度聚乙烯(LLDPE)/废胶粉(GTR)热塑弹性体。重点研究了两种交联剂:硫和过氧化二异丙苯(DCP)对共混物性能的影响。加入一定量的苯乙烯-丁二烯-苯乙烯(SBS)共聚物作为增容剂。结果表明,经过DCP动态硫化后的共混物的力学性能比简单共混的共混物有明显的提高,而加入硫磺体系对共混物力学性能影响不大甚至有所下降。通过红外光谱、热分析(DSC)和扫描电镜(SEM)对共混物的热行为和表面形态研究表明,加入DCP交联剂使LLDPE、SBS和胶粉之间发生了交联反应,从而增加了胶粉颗粒与LLDPE间的界面相容性,使其热塑性弹性体的力学性能得以提高。     

LLDPE/SMA共混膜表面接枝PEG的研究

聚乙烯综合性能优良且价格低廉,但由于较低的表面能和惰性化学结构,其着色性、生物相容性及制品表面涂饰性能差,与各种涂饰剂的粘结强度很低,限制了其用途的拓展,须进行表面改性.聚乙烯制品的表面改性方法已有不少研究报道[1~4],相对而言,采用添加表面改性剂的方法在工艺上仍最     

聚乙烯/聚乙二醇共混物中极性组分的表面富集

采用衰减全反射傅立叶变换红外光谱(FTIR-ATR)和扫描电子显微镜研究了极性组分聚乙二醇在聚乙烯／聚乙二醇共混物中的表面富集特性。研究结果认为不同组分表面自由能的差异以及聚乙烯基体的结晶异相排斥作用是导致聚乙二醇组分向共混物表面富集的主要驱动力，而极性组分相区的大小和分布则是影响其选择性迁移过程的重要因素。因此，可以通过添加合适相容剂的办法对聚乙二醇组分的表面富集程度进行有效的调控。     

碳纳米管对羟基磷灰石基复合材料力学性能的影响

将力学性能优良的碳纳米管(CNTs)与羟基磷灰石(HA)生物陶瓷相复合,发展CNTs/HA复合材料来应用于骨组织修复领域,有望解决HA生物陶瓷力学性能的不足。通过3种不同的制备方法,即通过表面活性剂将CNTs分散在HA基体中、通过酸碱中和反应将CNTs与HA共沉淀以及通过体外浸泡在CNTs上矿化生长HA等方法来获得CNTs/HA复合材料。深入研究CNTs的表面结构和分散状态对CNTs/HA复合材料力学性能的影响。结果表明,CNTs的添加改变了HA的脆性,导致复合材料抗压力学性能得到提高。但是,由于复合材料制备方法的不同,导致CNTs在HA基体中的分散状态、表面结构的完整性以及与HA的界面结合情况不同,导致其抗压力学性能不同。其中,通过表面活性剂将CNTs分散在HA基体中而获得复合材料的抗压力学性能表现最好,而CNTs与HA通过共沉淀法所获得复合材料的抗压力学性能表现最差。     

二氧化硅与液体介质的亲和性表征

利用动态核磁脉冲(Dynamic NMR)技术对高浓度的二氧化硅浆料的亲和性进行研究,并建立表征束缚层厚度与亲和性的定量模型。结果表明,在纯丁酮溶剂中,二氧化硅的含量越高,分散时间越长,填料表面束缚层厚度越大;而在树脂溶液体系中,在30%二氧化硅含量附近,填料表面束缚层厚度最大。当处理剂用量约为0.5%(w/w)时,颗粒表面与介质的吸附作用最强。使用不同处理剂制备的二氧化硅浆料,其表面吸附效应也有所不同,并且当浆料静置16 h后,其厚度层发生不同的变化,在丁酮体系中,束缚层厚度部分增加,而甲苯体系中,束缚层厚度减小。     

乙烯等离子体处理的云母表面结构及表面性质

用元素分析、色-质谱、裂解气相色谱和顺磁共振等方法研究了经乙烯等离子体处理的云母表面化学结构及处理过程。结果表明,云母颗粒表面形成了厚数十埃的等离子体聚乙烯膜,其化学结构与反应体系中无云母时得到的等离子体聚乙烯膜相同。通过扫描电镜观察到云母片表面的聚合膜具有规则的海星状花样,随处理时间的延长花样按比例长大。水与云母表面的接触角数据说明,乙烯等离子体处理使云母表面的疏水性提高到聚乙烯的水平,比氩气等离子体、硅烷偶联剂及钛酸酯偶联剂处理的效果均更为显著。     

二氧化硅与液体介质的亲和性表征

利用动态核磁脉冲(Dynamic NMR)技术对高浓度的二氧化硅浆料的亲和性进行研究,并建立表征束缚层厚度与亲和性的定量模型。结果表明,在纯丁酮溶剂中,二氧化硅的含量越高,分散时间越长,填料表面束缚层厚度越大;而在树脂溶液体系中,在30%二氧化硅含量附近,填料表面束缚层厚度最大。当处理剂用量约为0.5%(ω/ω)时,颗粒表面与介质的吸附作用最强。使用不同处理剂制备的二氧化硅浆料,其表面吸附效应也有所不同,并且当浆料静置16 h后,其厚度层发生变化,在丁酮体系中,束缚层厚度部分增加,而甲苯体系中,束缚层厚度减小。     

聚乙烯光引发交联过程中的表面光氧化和光稳定

通过测定凝胶含量并利用红外-光声光谱和光电子能谱对光交联聚乙烯表面氧化程度和氧化产物进行了研究.结果表明,聚乙烯光交联过程中随着光照时间的增加,表面光氧化加剧,氧化产物主要是氢过氧化物和含羰基的化合物.考察了预辐照和添加受阻胺型光稳定剂对聚乙烯光交联过程的影响,发现这两种方法都能有效地降低光交联聚乙烯(XLPE)的表面氧化,但有些光稳定剂会降低XLPE的交联度.     

SMA高级醇酯的合成及其对HDPE表面的改性

以苯乙烯-马来酸酐共聚物(SMA)为骨架,通过酯化反应,在SMA上接枝不同链长的高级脂肪醇侧链,制备了一系列大分子表面改性剂。将SMA及其高级醇酯化物与高密度聚乙烯(HDPE)进行共混,利用全反射红外光谱(FT-IR-ATR)及水接触角对共混体系的表面特性进行了研究。结果表明:在较低添加量范围内(w≤0.04),SMA的高级醇酯化物可以在HDPE薄膜的表面择优富集,可明显降低薄膜的水接触角,提高薄膜的表面能。     

Effect of GMA polymer compatibilizers on highly filled composites of low density polyethylene/magnesium hydroxide

Functional polymers such as polyethylene grafted glycidyl methacrylate （PE-g-GMA） and ethylene-methyl acrylate-glycidyl methacrylate terpolymer （E/MA/GMA） were used as compatibilizers in the preparation of highly filled composites of polyethylene/magnesium hydroxide（PE/MH）. Comparative studies were performed on the effect of magnesium hydroxide and stearic acid on the interface within polymer and magnesium hydroxide composites. The effect of polymeric compatibilizers on the properties of the composites was studied using tensile and impact tests, torque rheological analysis, differential scanning calorimetry and environmental scanning electron microscopy （ESEM）. The microstructure of highly filled PE/MH composites changed after the addition of functional polymers. The mechanical properties of the composite material increased after compatibilization. The compatibilization processes of PE-g-GMA and E/MA/GMA were different. The grafted polymer was more compatible with polyethylene, which led to a polar polymer phase. In contrast, the tercopolymer tended to adhere to the surface of MH particles.     

MORPHOLOGY AND PROPERTIES OF LINEAR LOW-DENSITY POLYETHYLENE HIGHLY LOADED WITH ALUMINUM HYDROXIDE

An experimental study was carried out to investigate the effects of isopropoxy tri(dioctyl pyrophosphoryl) titanatecoupling agent on the mechanical performance, rheological property and microstructures of polyethylene highly loaded withaluminum hydroxide (Al(OH)_3) composite. It was found that the addition of coupling agent results in reduced tensile strengthand increased percentage elongation of the filled systems. Silane crosslinkable polyethylene substituting for polyethylene asmatrix improves the tensile strength of the composite, while the percentage elongation of the composite still remains at adesired level. Melt viscosity of the composite will be improved by addition of titanate coupling agent. Microstructures of thecomposites were also studied by means of the scanning electron microscopy (SEM) technique. SEM micrographs reveal thatfiner dispersion of Al(OH)_3 will be obtained upon treatment of titanate and a transition from brittle to tough fracture takesplace before and after silane crosslinking structure is introduced into polyethylene highly filled with Al(OH)_3 composite.     

Tensile and flexural properties of polypropylene composites filled with highly effective flame retardant magnesium hydroxide

The reinforcing effects of highly effective flame retardant magnesium hydroxide (FMX) content on the tensile and flexural properties of filled polypropylene (PP) composites were investigated within the FMX weight fraction range from 5 to 60 wt%. It was found that the Young's modulus and flexural modulus increased approximately linearly while the tensile yield strength and tensile fracture strength decreased slightly with increasing the FMX weight fraction. When the FMX weight fraction was lower than 20%, the tensile elongation at break decreased considerably, and then decreased slightly; the flexural strength increased when the FMX weight fraction was lower than 30%, and then decreased slightly. The tensile properties increased with increasing rate of tension. Moreover, the tensile yield strength of the composites was estimated using an equation proposed in previous work, and good agreement was shown between the predicted and the measured data.     

Evaluation of magnesium sulphate attack in mortar-metakaolin system by thermal analysis

This paper reports an experimental study on the magnesium sulphate resistance of mortar specimens incorporating 0, 10 and 20% of metakaolin (MK). The evidence of the attack was evaluated through the content of calcium hydroxide (portlandite) and formation of magnesium hydroxide (brucite) by thermal analysis (thermogravimetric and derivative thermogravimetric analysis). The mechanical degradation of the mortar specimens was evaluated through splitting tensile tests after 200 days of exposition to the magnesium solution. The addition of metakaolin resulted in a reduction in the content of calcium hydroxide and in a smaller formation of brucite in comparison with reference mixture. A tensile strength loss of about 7% was observed for the metakaolin mortars submitted to the magnesium solution attack for 200 days.     

The effect of surface coating of CNTs on the mechanical properties of CF‐filled HDPE composites

Mechanical properties of carbon fiber (CF) and carbon nanotube (CNT)‐filled thermoplastic high‐density polyethylene (HDPE) composites were studied with particular interest on the effects of filler content and fiber surface treatment by coupling agent. Surface‐treated CF‐filled HDPE composites increased their tensile strength and impact strength, which is further increased with the addition of CNT. SEM showed that CNT‐coating‐treated CF‐HDPE composites show better dispersion of the filler into the matrix, which results in better interfacial adhesion between the filler and the matrix. Copyright © 2014 John Wiley & Sons, Ltd.     

Fracture morphology and mechanical properties of ethylene/vinyl acetate rubber vulcanizates reinforced by in situ prepared sodium methacrylate

Ethylene/vinyl acetate rubber (EVM) was reinforced by sodium methacrylate (NaMAA) that was in situ prepared through the neutralization of sodium hydroxide and methacrylic acid in EVM during mixing. The mechanical properties of EVM vulcanizates with different NaMAA loadings and at different crosslink densities were studied and compared with those of high abrasion furnace carbon black (HAF) filled EVM vulcanizates. The fracture surfaces of gum and filled EVM vulcanizates were observed with scanning electron microscopy. The results showed that NaMAA‐reinforced EVM vulcanizates had better mechanical properties than HAF/EVM vulcanizates. When the NaMAA loading was 50 phr, the tensile strength of the NaMAA/EVM vulcanizate was 30 MPa, the tear strength was 102 kN/m, and the elongation at break was over 400%. Fourier transform infrared analysis confirmed that NaMAA formed in the compounding process and underwent polymerization during vulcanization. Scanning probe microscopy analysis revealed that nanoscale particles dispersed in the NaMAA/EVM vulcanizates. The mechanical properties were correlated with the fracture morphology of all the vulcanizates. The tensile rupture of NaMAA‐filled EVM vulcanizates occurred through tearing from a crack in the bulk of the samples. Tear deviation occurred with the addition of NaMAA and resulted in a rough surface, leading to an improvement in the tear strength of NaMAA‐filled EVM vulcanizates. The micrographs of the tear surfaces of the vulcanizates indicated that the different fracture modes depended on the NaMAA loading and the crosslink density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1715–1724, 2004     

The Effect of Acrylic Acid on Tensile and Morphology Properties of Wollastonite Filled High Density Polyethylene/Natural Rubber Composites

Inorganic filler manufactured for incorporation into thermoplastic elastomers usually are surface treated with organic reagents in order to improve the interfacial adhesion between filler and the matrix. In the present paper, the effects of acrylic acid (AA) on tensile and morphology properties of wollastonite (WS) filled high density polyethylene (HDPE)/Natural Rubber (NR) composites were studied. The untreated and treated HDPE/NR/WS composites were melt-blending at 180 °C with rotor speed of 50 rpm for 10 minutes. The composites were tensile-tested according to ASTM D638 and the etched surfaces were observed using scanning electron microscope (SEM). Tensile strength and elongation at break of the compositesdecreased upon the addition of wollastonite, but Young's modulus improves. The results of this study showed that the treated composites are found to have better tensile properties than the untreated composites. The morphology of treated composite showed better interfacial interaction between HDPE/NR and wollastonite.     

Etude ATD-ATG du polyethylene ignifuge par l’hydroxyde de magnesium

Fire resistance of polyethylene is realized by magnesium hydroxide which is distinguished from halogenated fire-proofing agents by its lower cost and its non toxicity. Magnesium hydroxide decomposed by an endothermic reaction with liberation of water, contributing to fire proofing. The sample used (Kisuma 5A-N^*) is constituted from a powder (0.6–0.8 micrometre) its surface is treated by plastic material in order to ameliorate its compatibility. We studied the thermal decomposition by DTA and TG, of mixtures constituted by polyethylene and magnesium hydroxide. A sudden decomposition began at 385°C for pure polyethylene and decomposition took place at 429°C for the mixture polyethylene-Kisuma (50–50). Incorporation of magnesium hydroxide in polyethylene increases fire resistance.     

包覆重钙粉为填充剂的橡胶加工及性能

重钙粉作为填充剂被广泛应用于橡胶加工过程,但由于其表面具有极性,分散性较差,导致与橡胶材料界面结合较差,影响了橡胶产品的抗拉强度、断裂伸长率等力学性能。 本文采用沉淀法,在CaCl₂-H₂O-NH₃-CO₂体系中生成碳酸钙直接结晶于重钙粉颗粒表面,实现对重钙粉的表面包覆,将n(CaCl₂)：n(重钙粉)=1：100、5：100、10：100的包覆重钙粉填充到天然橡胶和再生胶中,橡胶的力学性能与填充未包覆重钙粉的橡胶相比有了一定的提升。 通过比较,在填充量较大(8.5%、15%)时,包覆重钙粉橡胶产品在硬度、定伸应力等力学性能上要好于轻钙粉橡胶产品;在填充量(5%、8.5%)时,包覆重钙粉橡胶产品的抗拉强度、断裂伸长率接近于白炭黑,硬度高于白炭黑橡胶产品。     

Properties of wood-polymer composites with a polymer matrix containing sevilens

The effect of vinylacetate unit content in sevilen used as a polymer matrix or polyethylene compatibilizer on the properties of wood-polymer composites with a thermoplastic binders and filler of plant origin is studied. It is shown that the introduction of vinylacetate units decreases the tensile strength, contact elastic modulus, Brinell hardness, and water absorption of the composites, but increases the relative tensile elongation and impact viscosity without notch.