分子量对聚丙烯拉伸微孔膜结构的影响

以重均分子量和分子量分布不同的三种聚丙烯树脂为原料,采用熔融挤出-退火-室温拉伸-热拉伸的方法制备了聚丙烯微孔膜.采用凝胶渗透色谱(GPC)、松弛时间谱、差示扫描量热(DSC)、扫描电镜(SEM)等测试手段表征了分子量对最终微孔膜结构的影响.结果表明,重均分子量为587.0 kg/mol、特征松弛时间最长的T30S粒料...     

硬弹性聚丙烯中空纤维的形成

通过应力场下聚丙烯熔体结晶制备出硬弹性聚丙烯中空纤维 .利用对样品弹性回复率及力学性能测试等手段 ,研究了硬弹性聚丙烯中空纤维的形成 .结果表明 :纺丝温度下降、熔体拉伸比增加及热处理等均有利于硬弹性聚丙烯中空纤维的形成 ,聚丙烯原料的分子量、纺丝冷却条件等对硬弹性的形成也有影响 .所制备的硬弹性中空纤维具有典型的应力 -应变行为 .     

高填充竹塑包装盒盒坯注塑成型工艺及性能研究

采用竹纤维与聚烯烃为主要原料,并辅以少量改性与加工助剂,通过同向平行双螺杆挤出造粒线,制备高填充竹塑复合材料颗粒,用于注塑成型包装盒盒坯。研究竹纤维填充量、润滑剂与填料对复合材料加工性能的影响,聚烯烃树脂与填料对成型周期的影响,以及树脂基体、模具温度对包装盒盒坯翘曲变形的影响。研究结果表明:随着竹纤维含量的增加,复合材料的熔融指数快速下降,竹纤维质量分数超过50%后下降速度减缓;润滑剂可以提高复合材料的熔融指数,且内外润滑平衡的复合润滑剂最稳定;滑石粉较碳酸钙更有利于改善复合材料的流动性。聚丙烯比聚乙烯基体复合材料的注塑冷却时间短,滑石粉在缩短冷却时间方面优于碳酸钙。竹塑包装盒盒坯的翘曲变形量随着混合树脂基体中聚丙烯含量的增加而减少,随着模具温度的变化出现波动,最佳模具温度为50℃左右。     

影响夹层挤出复合层间剥离强度的主要因素的探讨

夹层挤出复合是生产复合包装材料的常规工艺之一，影响复合层间剥离强度的因素很多，现就主要影响因素论述如下：一、树脂温度一般夹层挤出复合工艺采用的挤出树脂为高压聚乙烯或聚丙烯，由于不同型号的树脂其溶点和熔融指数不同，因此需要充分熔化所需的热量也不同且流动性不同。对树脂的加热温度偏低或熔化时间过短，都会造成挤出树脂塑化不完全，树脂呈塑料微粒状不能与其它材料产生粘连，且挤出的树脂由于温度低造成从出膜口至复合点之间氧化不够，引起复合层剥离强度下降；若加热温度过高，塑化过头，造成树脂中的填料及低分子量的物质…     

化学降解法制备PP无纺布专用料

以化学降解法研制聚丙烯(PP)无纺布专用料,对PP粉料特性、降解剂母粒、加工工艺等因素对PP无纺布专用料流动性的影响进行了系统研究。结果表明,通过有效控制PP粉料质量、降解剂母粒加入量、挤出设备及工艺等条件,可生产质量稳定、可纺性高和流动性MFR为30 g/10min~100 g/10min可控的专用料。     

熔纺UHMWPE纤维在拉伸过程中的结构与力学性能

采用高流动性的超高分子量聚乙烯(UHMWPE)树脂颗粒,以熔融纺丝法制备出了拉伸强度为1.6GPa的UHMWPE纤维。利用热分析(DSC)、广角X射线衍射(WAXD)、小角X射线散射(SAXS)、拉伸试验研究了UHMWPE纤维在拉伸过程中结构和力学性能的变化。研究显示,随着拉伸倍数的增加,UHMWPE纤维的结晶度增加,晶粒尺寸下降,纤维的缺陷度逐渐下降,取向度逐渐增大,拉伸强度逐渐增加;其结构和力学性能变化规律与凝胶法相似;有效拉伸倍率低可能是导致熔纺UHMWPE纤维的拉伸性能不如凝胶纺丝纤维的主要原因。     

原位形成FPP偶联Al(OH)3/PP复合材料的结构与性能

用熔融挤出一步法制备了原位形成官能团化聚丙烯（FPP）偶联Al(OH)3/PP复合材料，研究了原位形成FPP对Al(OH)3/PP复合材料的结晶与熔融行为，熔融指数，热降解行为，阻燃性能，力学性能和断裂形态等的影响。原位形成FPP使Al(OH)3/PP的结晶温度和熔点降低，熔融指数，拉伸和弯曲强度提高。但对热降解行为和氧指数影响不大。     

微支化型高分子量PPS树脂的合成及表征

用硫磺、对二氯苯为原料，在极性有机溶剂中，以１，２，４－三氯苯作共聚反应第三单体，共缩聚制得了微支化型高分子量聚苯硫醚（ＰＰＳ）树脂，在缩聚反应中，第三单体量一定时，一定时间内聚合物对数低切变粘度值与反应时间具有线性关系。聚合物经元素分析，红外光谱分析、Ｘ射线衍射分析、激光拉曼光谱分析以及热分析表明，微量（＜１．０％）三氯苯引入分子链对ＰＰＳ的组成和结构影响不大，产品仍为结晶性高聚物，不含双硫键。由于分子量提高，聚合物的热稳定性得到提高，根据不同需要合成的一定分子量范围的微支化型高分子量ＰＰＳ树脂不经热氧交联处理即可直接挤出造粒，用于注射成型和挤出成型。     

三嗪膨胀阻燃母粒的制备及在聚丙烯中的应用

以高熔指聚丙烯(HM-PP)粉料为基体,通过双螺杆挤出机将聚磷酸铵(APP)、三嗪成炭发泡剂(CFA)和纳米二氧化硅(Si O2)与聚丙烯进行捏合,经挤出、冷却及切粒后,制备三嗪膨胀阻燃母粒,同时研究了膨胀阻燃剂与聚丙烯基体的不同质量比对母粒加工性能的影响。将制备的阻燃母粒以一定的添加量与聚丙烯(M02)混合后直接注塑,制备阻燃聚丙烯材料,通过极限氧指数(LOI)和垂直燃烧(UL-94)测试研究了材料的阻燃性能,通过拉伸、弯曲和冲击性能的测试研究了材料的力学性能,通过扫描电镜对材料截面的测试研究了阻燃剂在材料中的分散性及相容性,同时还研究了阻燃PP材料的耐水性能。结果表明,在阻燃剂添加量为65%的时候,阻燃母粒具有很好的加工性能,加工过程中无断条现象。当母粒的添加量为33.8%(阻燃剂含量为22%)时,材料通过UL-94 V-0级,LOI值达到了34.3%,表现出很好的阻燃效果。与单独添加膨胀阻燃剂的阻燃PP材料相比,阻燃母粒与聚丙烯树脂具有更好的相容性且在树脂中分散均匀,阻燃母粒的加入提高了材料的力学性能,同时材料的耐水性能也得到了很好的提高,材料在耐水测试后依然能保持很好的阻燃性能。     

成核剂对聚丙烯力学性能的影响

聚丙烯是一种热塑性塑料，比重轻，成品表面硬度大，弹性高，耐热性、化学稳定性、绝缘性良好。产品的加工适应性很强，广泛应用于注塑、挤出扁丝、吹膜、喷丝、改性工程塑料等工业和民用塑料制品加工领域。日常应用非常广泛，不同的添加剂对其力学性能有较大的影响，本文着重分析了成核剂对聚丙烯力学性能的影响，结果表明：a成核剂的加入使聚丙烯结晶度增大刚性增加，强度总体下降趋势，β成核剂的加入使聚丙烯拉伸强度和拉伸模量下降，韧性增大，在β成核剂质量分数为0．57％时，简支梁缺口冲击强度和断裂伸长率达到最大值，皆为聚丙烯的两倍多。     

高熔体强度聚丙烯的制备与应用进展

综述了高熔体强度聚丙烯的几种制备方法,如射线辐照法、过氧化物反应挤出法、大分子单体共聚法和反应性聚烯烃中间体法等。同时还介绍了高熔体强度聚丙烯在挤出发泡、热成型、挤出涂布以及吹塑薄膜等领域的应用情况。     

Characterization of a novel natural cellulose fabric from Manicaria saccifera palm as possible reinforcement of composite materials

Identifying novel natural fibers/fabrics with proper properties as reinforcement material is a new challenge in the field of bio-composites. Hence, the aim of this paper is to study the possibility of using a natural fabric extracted from Manicaria saccifera palm as a novel reinforcement in composites. This fabric was extensively characterized by chemical composition analysis, infrared spectroscopy (FTIR) analysis, morphological studies (SEM), thermo-gravimetric analysis (TGA) and physical /mechanical properties studies. From SEM analysis it was identified globular protrusions spread uniformly over the fiber which could help the mechanical interlock with the resin. As well, Manicaria fabric showed good thermal stability, low density, low moisture content and good tensile properties. Further, their properties are comparable to most natural cellulose fabrics and some synthetic fabrics, such as fiber glass fabrics. Manciaria saccifera fabric showed to be a suitable candidate as natural reinforcement material for the development of bio- composite.     

Hybrid composites made of carbon and glass woven fabrics under quasi-static loading

Experimental studies are presented on in-plane mechanical properties for two types of hybrid composites made using 8H satin weave T300 carbon fabrics and plain weave E-glass fabrics with epoxy resin. Results are also presented for 8H satin weave T300 carbon/epoxy and plain weave E-glass/epoxy. Studies are carried out under both tensile and compressive in-plane quasi-static loading. It is observed that for hybrid composites, placing glass fabric layers in the exterior and carbon fabric layers in the interior gives higher tensile strength and ultimate tensile strain than placing carbon fabric layers in the exterior and glass fabric layers in the interior. Quantitative data is given for different mechanical properties.     

三维立体打印织物的制备及其拉伸性能

将3D打印技术引入到纺织技术应用领域,生产三维立体打印织物。利用自主设计的3D打印机,通过Solidworks三维建模、模型分层处理、生成扫描路径逐层打印堆积成型的过程试织了平纹结构的三维立体织物试样,并从经向方向测试了其拉伸力学性能。试验结果表明:三维立体打印织物与普通织物类似,试样在拉伸初始阶段属于力学高模量区,经向伸长缓慢。三维立体打印织物的拉伸破坏过程不是同时发生,首先在织物熔融凝结固着点的最弱处断裂,应力集中后结构遭到破坏,试样断裂。     

Stiff and strong polyethylene with shish kebab morphology by continuous melt extrusion

In a previous work, it was shown that highly oriented fibres with 10 GPa modulus could be obtained by continuous single-stage melt extrusion of a medium molecular weight polyethylene to which 3% ultra-high molecular weight (M _w ∼ 3 to 5 × 10⁶) material had been added by solution blending. It was demonstrated that a special interlocking shish kebab structure was responsible for the favourable mechanical properties. In the present work, we succeeded in achieving the same effect from an unblended polyethylene by choosing starting materials with an inherently suitable molecular weight distribution. Both the high and low molecular weight tails of the distribution are very influential: the high tail contributes to the formation of extended-chain fibrils (which constitute the backbones of the shish kebabs), while the low tail affects melt extrudability and strength. Melt strength is important because unusually high tensile stresses are required during wind-up. The wind-up stress was measured and found to be an order of magnitude greater than that encountered in conventional melt spinning — where no shish kebabs are formed. The implications of the above findings for polymer processing, crystal morphology and melt rheology are discussed.     

Assessment of granulation technologies for an API with poor physical properties

Granulation technologies are widely used in solid oral dosage forms to improve the physical properties during manufacture. Wet, dry, and melt granulation techniques were assessed for Compound A, a BCS class II compound. Characterization techniques were used to quantify physical property limitations inherent for Compound A including hygroscopicity, low solubility and bulk density, and poor powder flowability. High shear aqueous wet granulation induced an undesirable water mediated phase transition of the solid form. A formulation and process for dry granulation by roller compaction was developed and scaled to 10 kg batch size. Roll force, and roll gap parameters were assessed. Porosity of compacted ribbons was analyzed by mercury intrusion porosimetry, and particle size distributions of milled ribbons by sieve analysis. A roll force of 15 kN/cm produced granules with higher density and improved flow properties compared to the pre-blend. Fines content (<75 µm) decreased from approximately 90% pre-granulation to 26% post-granulation. Cohesive properties of Compound A limited drug loading (API:excipient ratio) in roller compaction to 0.6:1 or less. Hot melt granulation by extrusion assessed with four polymers. A vast improvement in drug loading of 4:1 was achieved via melt processes using low molecular weight thermo-binders (glyceryl behenate and Polyethylene glycol 4000). Granules produced by melt processing contained less fines compared to wet and dry granulation. Both roller compaction and melt extrusion are viable granulation process alternatives for scale up to overcome the physical property limitations of Compound A.     

Recycling of waste nylon 6/spandex blended fabrics by melt processing

A unique approach for reclaiming waste nylon 6/spandex blended fabrics was demonstrated by melt processing through mixing and molding. Spandex from the waste fabrics was removed by hydrolysis under controlled conditions. Morphological analysis showed that the fracture surface was homogeneous for samples of neat nylon 6 and treated fabrics, and voids were observed for samples from untreated fabrics. Thermal analysis indicated that the materials from waste fabrics exhibited both similar melting temperature (around 220 °C) and similar crystallization temperature (around 185 °C). Infrared spectroscopy showed nearly the same main absorption peaks of neat nylon 6 and samples from nylon 6/spandex fabrics. The viscosity of treated fabric samples was lower than that of untreated fabric composites at low and medium frequencies, as an effect of the spandex removal after treatment. The recycled plastics from treated fabrics exhibited good mechanical properties with a tensile strength of 46.6 MPa and a Young's modulus exceeding 2.4 GPa.     

再生PET纤维/PP复合材料的结构及力学性能

为满足环境保护和可持续发展的需要,废弃无纺布的回收再利用已经成为材料领域的又一研究热点。本文以废弃无纺布为研究对象制得再生聚对苯二甲酸乙二醇酯(PET)纤维,通过热压成型技术制备不同纤维含量的PET/聚丙烯(PP)复合材料。综合利用SEM、DSC、XRD、拉伸性能测试等手段对PET/PP复合材料的结构和性能进行了研究。结果表明:低含量的PET纤维均匀分散在PP基体中,与基体间界面结合紧密;PET纤维的异相成核作用促进了PP分子链的结晶,提高了结晶度,使晶粒细化;这些微结构的变化有利于PET/PP复合膜力学性能的提高,当PET纤维含量仅为0.1%时,PET/PP复合膜的拉伸强度提高了25.99%,断裂韧性提高了61.96%。     

Influence of fiber-like nanofillers on the rheological,mechanical, thermal and fire properties of polypropylene: An application to multifilament yarn

Polypropylene and polypropylene grafted maleic anhydride based composites with modified and non-modified carbon nanotubes and sepiolite were prepared by melt extrusion. Their thermal, rheological, and dynamic mechanical properties were evaluated. Multifilament yarns were obtained from the composites by spin-drawing process and their mechanical properties were measured. Knitted fabrics from the multifilament yarns were characterized by cone calorimetry. The best interaction was obtained for polypropylene/carbon nanotubes and polypropylene/polypropylene grafted maleic anhydride/sepiolite composites, as was confirmed by the increasing on the elastic modulus and thermal resistance. Nanofillers changed the thermal decomposition profiles compared to bare polypropylene. Knitted structures containing sepiolite decrease the maximum of heat release rate in comparison with unfilled samples.     

Commingled yarns of surface nanostructured glass and polypropylene filaments for effective composite properties

Developing commingled yarn technologies and understanding the fundamental interface nanostructures of reinforcement and thermoplastic filaments are of significant current interest. Previous research on commingled yarns was mainly focused on the air-jet texturing process, while the mechanical properties of the composites are strongly influenced by the impregnation homogeneity, the polymer sizing properties and consolidation process. Here, we report a unique melt spinning equipment for E-glass fiber which is compatibly combined with a melt spinning extruder to manufacture commingled yarns. The in-situ commingling enables to combine homogeneously both glass and polypropylene filament arrays in one processing step and without fiber damage compared to commingling by air texturing. Variation of processing conditions are investigated, i.e. sizings, diameter ratios, and arrangements of sizing/finish application related to intermingling of filament arrays. A rapid processing is achieved because of good intermingling and the low flow paths. We found that the sizing enables a good strand integrity with the polypropylene yarn. The interfacial adhesion can be improved with a sizing for glass fibers consisting of aminosilane and maleic anhydride grafted polypropylene film former, which results in both improved transverse tensile strength and compression shear strength. We also found that a very small amount of single-wall carbon nanotubes (SWNTs) in the sizing provides significantly improved interfacial adhesion strength. This is attributed to the change in fracture behavior of the nano-structured interface and morphology of the model single-fiber composites.