聚丙烯发泡塑料性能突显研究开发大有可为

正泡沫塑料中,聚丙烯PP发泡材料有很多优点:聚丙烯刚性优于聚乙烯PE,PP弯曲模量大约为1.52GPa,PE仅为207MPa,耐化学性与PE相似;聚丙烯的玻璃化温度低于室温,抗冲击性能优于PS,而且相比PS泡沫的难回收性,聚丙烯泡沫是一种环境友好的材料;聚丙烯有较高的热变形温度,可以在一些高温领域中应用。聚丙烯是一种结晶聚合物,其发泡只能在结晶熔点附近进行,超过熔点熔体粘     

高熔体强度聚丙烯发泡进展

本文介绍了聚丙烯发泡材料因其具有较高的刚性、优良的力学性能、良好热和化学稳定性及可回收性等,在多领域方面得以应用。而普通聚丙烯发泡温度窄,普遍提出以高熔体强度聚丙烯制备聚丙烯发泡材料。本文还介绍了制备高熔体强度聚丙烯四种方法及制备聚丙烯发泡材料的四种加工方法,并对聚丙烯发泡材料的应用前景进行探讨。     

发泡聚丙烯材料的研究生产现状

综述了发泡聚丙烯材料的三种制备工艺 :高熔体强度聚丙烯发泡、交联聚丙烯发泡、共混体系发泡工艺及其国内外研究发展现状 ,介绍了Trexel公司超临界流体发泡技术及研究 ,列举了发泡聚丙烯材料及制品的主要生产厂家     

聚丙烯珠粒发泡研究进展

聚丙烯(PP)珠粒发泡材料具有优异的耐热、隔音、抗冲击以及耐化学腐蚀等性能,近年来被广泛应用在包装、建筑、汽车等行业。PP在其熔点温度附近的熔体强度会急剧下降,低熔体强度导致其难以得到好的泡孔结构,所以PP珠粒发泡的技术难度大,目前只有少数国家掌握了PP珠粒发泡的技术,因此PP珠粒发泡的研究受到了国内外的广泛关注。文中从制备工艺、发泡装备、性能改进、表征方法等方面综述了近年来国内外PP珠粒发泡的研究动态,并对该领域今后的研究方向进行了展望。     

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。     

弹性体对微发泡聚丙烯复合材料发泡行为的影响

以化学发泡为主线,在聚丙烯(PP)基体中添加弹性体三元乙丙橡胶(EPDM)制备微发泡聚丙烯复合材料。利用旋转流变仪、差示扫描量热法和扫描电镜等手段,系统地研究EPDM对微发泡PP材料发泡行为的影响。结果表明,EPDM的加入提高了PP材料的熔体强度,对PP材料发泡质量有明显改善;同时使PP复合材料的降温结晶峰向高温移动,能有效抑制泡孔的变形及并泡等恶化现象。当EPDM的质量分数为20%时,泡孔形态较为理想,其泡孔直径和泡孔密度分别为14.43μm,2.49×10⁷cm^-3。与未加EPDM的微发泡PP复合材料比较,EPDM的加入能够拓宽发泡PP复合材料的发泡温度窗口,发泡温度范围为180~195℃。     

滑石粉对微孔发泡木粉/聚丙烯复合材料结晶行为及泡孔结构的影响

以滑石粉为成核剂,超临界CO_2为发泡剂,采用间歇釜式方法制备微孔发泡木粉/聚丙烯复合材料。采用DSC、XRD和SEM对微孔发泡木粉/聚丙烯复合材料的结晶行为与泡孔结构进行了测定与分析。结果表明:滑石粉的添加能够提高微孔发泡木粉/聚丙烯复合材料的结晶温度,诱导产生不完善的α晶型;能够提高聚合物基体的熔体黏度,减小泡孔尺寸,增加泡孔密度,促使泡孔尺寸分布更均匀,最终能够形成泡孔密度为1.0×10~9个/cm~3、平均泡孔半径为16.4μm、发泡倍率为18倍、表观密度约为0.055g/cm~3的微孔发泡木粉/聚丙烯复合材料。     

聚丙烯-超临界CO_2挤出发泡研究进展

聚丙烯(PP)发泡材料具有轻质、缓冲、隔热隔音等优异性能,同时挤出发泡具有连续性和稳定性的特点,是效率最高的一种加工方式。但是相较其他加工方式,超临界CO_2挤出发泡PP由于连续生产的特点,发泡条件要求很高,PP挤出发泡存在不少难点。文中对挤出发泡过程中存在的主要难点进行了分析,从PP结晶行为调控、CO_2溶解性和熔体强度对发泡性能的影响等方面叙述了近年来国内外PP挤出发泡的研究动态,并对该领域今后的研究方向进行了展望。     

聚丙烯发泡技术的进展

阐述了超临界流体技术的概念及其在聚丙烯发泡技术中的应用情况,对高熔体强度聚丙烯的性质,应用及其挤出发泡设备的最新进展作了介绍,并对交联发泡聚丙烯,聚丙烯共混发泡技术和应用等作了概述。     

改性聚丙烯吸塑薄片的生产技术

聚丙烯薄片具有卫生性能好,比重小,能在较高温度下使用,并具有较高的机械性能和化学稳定性。用它吸塑成型的容器,将是理想的食品包装材料,属国家重点发展的食品吸塑包装材料更新换代产品。但是,由于聚丙烯是结晶性聚合物,在结晶熔化前,几乎没有高弹态区域。在结晶熔化前,薄片强度很大,很难吸塑拉伸;在结晶熔化后,薄片的熔体强度又骤然下降。一吸就破。因此,用国产的单一的聚丙烯制     

Effect of Process Parameters on Porosity in Aluminum Lost Foam Process

1.IntroductionLost foam casting process is still a new technology,and is gaining confidence among manufacturers[1].It isexpected to dramatically improve the competitiveness ofthe foundry industry.Many advantages like eliminatingmachining steps,making complex casting without coresand reducing environmental loads can be offered by thisprocess,because molding binder is not added into themold of the lost foam process.Aluminum alloy castings are widely used in the auto-mobile and aerospace industri…     

TAIC助交联对聚丙烯发泡性能的影响

在过氧化二异丙苯(DCP)引发下,研究三烯丙基异氰脲酸酯(TAIC)对聚丙烯(PP)的交联改性,比较单纯DCP和DCP/TAIC交联体系对PP熔体强度及其发泡性能的影响。加入TAIC前后,分别对PP的抗熔垂能力和熔体流动速率、PP发泡材料的凝胶率和力学性能进行测定。结果表明,与单纯DCP相比,DCP/TAIC交联体系对PP熔体强度的改善效果较好,而且相应的发泡材料具有较高的拉伸强度和直角撕裂强度,同时,偏光显微镜观察结果表明,经DCP/TAIC交联后的PP发泡材料表面更为光滑、泡孔细密且均匀一致。     

THE NUCLEATION OF MICROCELLULAR FOAMS IN SEMI CRYSTALLINE THERMOPLASTICS*

The nucleation of microcellular foams in amorphous thermoplastics has been performed by supersaturation with gas at an elevated temperature. Pressure and temperature are then carefully reduced in the vicinity of the glass transition temperature of the material. The result is a foam structure with cells on the order of 10 microns. This material exhibits greatly increased impact strength, as well as thermal and electrical insulation properties as compared to conventional foams. A new process has been developed to produce microcellular foams in semi-crystalline polymers. The process operates in the vicinity of the polymer's melting point, as opposed to the glass transition point. This is due the low solubility of the gases in and the rigidity of the crystalline phase. Microcellular foams have been produced successfully in polypropylene. The effects of various additives have been investigated experimentally. The theory developed for the amorphous materials has been compared to these new experimental results and again qualitatively agrees.     

A novel technology to manufacture biodegradable polylactide bead foam products

Bead foaming technology with double crystal melting peak structure has been recognized as a promising method to produce high-performance low-density foams with complex geometries. Polylactide (PLA) bead foaming has been of the great interest of researchers due to its origin from renewal resources and biodegradability. However, due to the PLA’s low melt strength and slow crystallization kinetics, the attempts have been limited to the manufacturing methods used for expanded polystyrene (EPS). In this study, we developed microcellular PLA bead foams with double crystal melting peak structure in a large content using a lab-scale autoclave system followed by molding of the beads. PLA bead foams were produced with expansion ratios and average cell sizes ranging from 6 to 31-fold and 6 to 50 μm, respectively. The high-melting point crystals generated during gas-saturation significantly affected the expansion ratio and cell density of the PLA bead foams by enhancing the PLA’s melt strength and promoting cell nucleation around the crystals. The tensile properties of the molded EPLA bead foams showed that EPLA bead foams with double crystal melting peak can be a promising substitute not only for EPS but also for expanded polypropylene (EPP) bead foams.     

直立式医用聚丙烯输液瓶的熔融行为和结晶结构

利用DSC和W AXD研究了医用聚丙烯专用料(TPC)及其密封式直立吹塑瓶(TPCC)的熔融行为和结晶结构。结果表明经过吹塑成型过程后,TPCC的熔融温度、结晶度均较TPC有所提高,DSC熔融半峰宽明显下降,微晶尺寸明显增大,同时晶面取向因子发生显著变化,表明成型过程中晶区尺寸增大,且晶体结构更均匀规整,赋予了输液瓶良好的性能。     

Technological characterization of PE/EVA blends for foam injection molding

Foam injection molding is one of the most important processes for producing lightweight plastic parts. The main feature of this process is the use of a foam blowing agent (physical or chemical) that decomposes during heating, generating gasses that are dispersed into the melt. Predicting the microstructure of the final part requires the investigation of the foam process which is a complex problem because it is necessary to combine transport phenomena of the multi-phase flow in non-isothermal conditions with foam kinetics and gas formation. The aim of this work is to evaluate the material-processing relationship in foam injection molding. The experimental measurements of PE/EVA blends, properly formulated, coupled to two types of ADC foaming agents were carried out using differential scanning calorimetry and rotational rheometry. The injection molding and direct measurements of foamed parts were then performed, based on previous measurements, to evaluate the process performance.     

注塑工艺对透明聚丙烯制品雾度的影响

通过实验研究了不同注塑工艺对用成核剂增透改性的透明聚丙烯制品雾度的影响,结果表明合适的熔融温度、较低的模温、较慢的注射速度、较长的保压时间和较大的保压压力有利于得到透明度较好的制品。找到原料最佳的注塑条件,有利于最大限度地发挥出原料的透明度潜能,得到理想的透明聚丙烯制品。这对塑料制品企业有积极的意义。     

汉麻秆芯/玉米秸秆充填缓冲发泡材料的制备及性能研究

目的 为减少对化石燃料的广泛依赖,用生物质复合材料替代合成纤维增强复合材料,制备轻质、缓冲等高性能天然纤维复合材料,开辟环境新材料领域创新的方向.方法 通过不同种类生物质填充物及配比变化,一步成型制备一种可降解轻质发泡缓冲材料,研究缓冲材料产品缓冲性能.结果 相同填充比例条件下,玉米秸秆发泡体缓冲性能优于汉麻秆芯材料;相同填充物条件下,填充比例为30％～40％,缓冲性能良好.结论 为各行业应用提供了环境友好的替代性结构产品,扩展了复合材料应用范围,尤其研发成本低、性能好的生物质复合材料具有重要战略意义.     

聚乙烯醇发泡成型技术及其吸水性能研究进展

目的综述聚乙烯醇(PVA)发泡成型技术及其吸水性能的研究进展。方法详细介绍PVA泡沫的4种发泡方法(机械发泡、化学发泡、成孔剂发泡、物理发泡剂发泡),4种成型工艺(模压、熔融挤出、注塑、熔融沉积)以及吸水性能的研究进展,并对其在海军舰艇冷链运输中的应用进行展望。结果 PVA极性泡沫是一种新型的环保泡沫塑料,通过不同的发泡方法和成型工艺,配以不同的改性剂,可以制得不同领域需求的材料。结论 PVA泡沫具有性能优良、可生物降解、经济环保等特点,在农产品冷链运输和包装领域具有较大的发展潜力,在发泡方法和成型工艺的优化、储水储热性能等方面有较大的研究空间。     

水辅助注塑制件壁厚分析

根据水辅助注塑技术应用短射法成型中空圆管制品的聚合物熔体流动的基本特征,把水辅助注塑充模阶段聚合物熔体流动行为简化为等温条件下幂率流体的稳态流动,应用流体力学理论,对圆管水辅助注塑中影响制件壁厚的因素进行分析。结果表明,制件的壁厚主要由水与熔体界面处的压力梯度和熔体前端压力梯度的比值确定,同时制件壁厚也受熔体的流变性能影响。