聚丙烯树脂熔融浸渍连续玻璃纤维毡过程的研究

通过将聚丙烯熔体对玻纤毡的浸渍过程分成束间浸渍（熔体在纤维束之间的流动）和束内浸渍（港体在纤维束内部的流动）两个过程建立数学模型进行分析，指出熔体在纤维束内部的浸渍过程是实际浸渍过程的难点。提高熔体在纤维束内部的浸渍的主要手段是：适当延长浸渍时间、适当升高体系温度、增加纤维束内部的孔隙率、适当增加单丝直径、减少纤维束直径和减少熔体在纤维束内部的流动路径。但升高温度和提高浸渍压力对浸渍过程的影响相对较小。     

玻璃纤维增强热塑性片(板)材发展概况

分别介绍了国外3种玻璃纤维增强热塑性塑料产品即玻纤毡增强热塑性片材、短纤维增强热塑性片材和连续纤维增强热塑性片(板)材的发展概况、品牌产品、主要性能和用途,以期对我国玻璃纤维增强热塑性塑料产品的开发有所参考.     

玻纤增强PP热塑性片材的制备及力学性能研究

采用熔融浸渍法制备了玻璃纤维毡增强聚丙烯（PP）热塑性复合片材；通过在PP中加入复合改性PP改善了基体与增强纤维间的相容性；考察了相容剂、PP种类及玻纤毡种类对复合片材的影响。结果表明，相容剂的加入可使复合片材的拉伸强度提高29％、拉伸模量提高23％、弯曲强度提高42％、弯曲模量提高25％；高熔体质量流动速率PP可使片材的弯曲与冲击性能进一步改善。连续玻纤毡和长玻纤毡增强PP复合片材，前者综合力学性能良好，而后者则冲击强度较弱、弯曲性能加强。     

立体混合法制毡工艺及其对玻纤增强热塑性材料力学性能的影响

为了改进玻纤增强热塑性复合材料中基体树脂对玻璃纤维的浸渍效果,从而提升制品的力学性能,本文研究开发出一种新型的制毡工艺——立体混合法。该工艺是将基体树脂与玻璃纤维分别拉制成丝束状,展纤后,经改进的开松、混合、气流成网设备制成三维立体结构的连续针刺毡。将制作好的基毡采用层合热压法制备成板材,并对其进行力学性能测试。研究结果表明,制成立体混合毡后的玻纤增强板材浸渍工艺适应性更强,基体树脂与玻璃纤维之间的浸渍距离缩短,接触面积增加,使增强材料浸渍透彻,由该工艺制作出的热塑性板材比传统工艺制作出的板材浸渍效果好。在同等克重和玻纤含量条件下,其拉伸强度、弯曲强度、抗冲击强度有了大幅度提升。     

RTM工艺中玻纤增强材料渗透率的测量与分析

通过对树脂传递模塑成型工艺中广泛使用的纤维增强材料——玻纤连续毡渗透率的测量和分析，建立了该增强材料在模具中的纤维体积含量与渗透率之间的关系，考察了纤维增强材料的渗透率与注模时间的关系，分析对比了纤维增强材料的结构型式对注模时间和纤维浸透性的影响。结果表明；随着纤维体积含量的增大，渗透率迅速下降，对于玻纤连续毡，其渗透率ｋ与纤维体积含量ｖｆ的关系可以表示为一个多项式；在恒定的压力下，渗透率大，注模需要的时间越短，体积含量相同的玻纤连续毡和玻纤方格布比较，玻纤连续毡的渗透率约大一倍，而所需注模时间约为玻纤方格布的１／２；玻纤方格布中存在渗透率相差特别大的两大区域是造成其浸透性差的主要原因。     

关于新型玻纤增强基材及应用的讨论

玻璃纤维作为增强基材,是当今纤维增强塑料（FRP）的主导材料。FRP制品有很强的结构性,材料性质和结构与制品工艺有十分密切的关系。介绍了颇具发展潜力的5种玻纤增强基材即玻纤薄毡、增强热塑性塑料用玻纤、玻纤经编织物、玻纤预浸渍产品和玻纤预成型体的发展概况,意在和玻纤复材制品行业交流,促进上下产业链的共同发展。     

熔融浸渍工艺参数对纤维束渗透率影响的研究

在连续长纤维增强热塑性复合材料浸渍模型中,渗透率是一个十分重要的参数。准确测量熔融浸渍工艺中高黏度树脂熔体浸润纤维束的渗透率,有助于浸渍模型更好指导熔融浸渍模具设计和工艺参数优化,制备出性能优异的热塑性树脂基复合材料。本文通过自制实验装置,测定了熔融浸渍工艺中高黏度树脂浸渍单向纤维束时纤维束张力和浸渍压力变化对渗透率的影响,根据实验结果拟合出工艺参数与渗透率关系的计算公式。结果表明：纤维束张力越大渗透率越低;浸渍压力越大,纤维束渗透率越大,但增大幅度随张力增大而降低。     

GMT片材发展概况

<正>1简介GMT是玻纤毡增强热塑性塑料片材的英文缩写。它于上世纪60年代中期问世,是用玻璃纤维毡和一种热塑性塑料用干法(熔体浸渍法)或湿法(抄纸法)制成的轻质复合片材。这种中间材料可通过模压、冲压或流动模塑法成型为最终制品。GMT兼具材料和工艺性能     

超细碳纤维毡的制备及其形貌研究

采用静电纺丝法制备了聚酰胺酸（PAA）无纺布纤维毡,通过亚胺化工艺得到聚酰亚胺（PI）纤维毡,再以PI纤维毡为前驱体经高温碳化工艺制备PI基超细碳纤维毡,并对制得的PI基超细碳纤维毡进行了扫描电镜（SEM）形貌分析和元素分析。经SEM分析得知,随着碳化温度的升高碳纤维毡中纤维的直径逐渐减小,其分布略变窄,主要分布在200-300nm之间,当碳化温度达到1000℃时,PI基超细碳纤维毡中纤维的碳含量为96.16％。     

麻纤维/玻璃纤维混杂增强聚丙烯复合材料的性能研究

采用新的混杂复合工艺,将不同形式的玻璃纤维、剑麻纤维、玻璃纤维毡与黄麻纤维毡用不同的混杂方式（Ⅰ层内,Ⅱ夹芯）混杂增强聚丙烯.研究结果表明,在强度和刚性得到明显改善的同时,冲击韧性得到了大幅度的提升,而且短纤维层内混杂和连续纤维夹芯混杂呈现出不同的特点,不同的铺层设计导致力学性能有明显差异.通过对材料断面的电镜分析看出,用短玻璃纤维和麻纤维毡混杂增强聚丙烯时,冲击破坏过程以界面脱黏为主,而用玻璃纤维毡和麻纤维毡混杂增强时,破坏断面中玻璃纤维存在大量的拔出现象.利用混杂效应理论公式计算了混杂效应系数,并和实测值进行了比较.     

Impregnation of thermoplastic resin in jute fiber mat

Impregnation rate of thermoplastic resin (polypropylene) in jute fiber mat and influence of relative factors on impregnation were studied, aiming to develop the continuous melt impregnation technique and to investigate the effect of impregnation rate and temperature on processing conditions and mechanical properties of natural fiber mat-reinforced thermoplastics. Influence of pressure on porosity of fiber mat and effect of melt viscosity on impregnation rate were also investigated. The modified capillary rheometer was used as apparatus and experimental data were analyzed based on the one-dimension Darcy’s law. Results showed that at a given pressure, the impregnation rate is inversely proportional to melt viscosity and jute fiber mat has higher porosity than glass fiber mat. The architecture, compressibility, permeability and fiber diameter of jute fiber mat were compared with those of glass fiber mat and their effects on impregnation were discussed further. It could be seen that the average diameter of jute fiber is much bigger; the porosity of jute fiber mat is significantly higher and inner bundle impregnation does not exist in jute fiber mat. Therefore, it is not difficult to understand why the impregnation rate in jute fiber mat is 3.5 times higher and permeability is 14 times greater. Kozeny constants of jute and glass fiber mats calculated based on the capillary model are 2950 and 442, respectively. __________ Translated from Journal of Chemical Engineering of Chinese Universities, 2007, 21(4): 586–591 [译自: 高校化学工程学报]     

Impregnation of thermoplastic resin in jute fiber mat

Impregnation rate of thermoplastic resin (polypropylene) in jute fiber mat and influence of relative factors on impregnation were studied, aiming to develop the continuous melt impregnation technique and to investigate the effect of impregnation rate and temperature on processing conditions and mechanical properties of natural fiber mat-reinforced thermoplastics. Influence of pressure on porosity of fiber mat and effect of melt viscosity on impregnation rate were also investigated. The modified capillary rheometer was used as apparatus and experimental data were analyzed based on the one-dimension Darcy’s law. Results showed that at a given pressure, the impregnation rate is inversely proportional to melt viscosity and jute fiber mat has higher porosity than glass fiber mat. The architecture, compressibility, permeability and fiber diameter of jute fiber mat were compared with those of glass fiber mat and their effects on impregnation were discussed further. It could be seen that the average diameter of jute fiber is much bigger; the porosity of jute fiber mat is significantly higher and inner bundle impregnation does not exist in jute fiber mat. Therefore, it is not difficult to understand why the impregnation rate in jute fiber mat is 3.5 times higher and permeability is 14 times greater. Kozeny constants of jute and glass fiber mats calculated based on the capillary model are 2950 and 442, respectively.     

短切麻纤维无纺针刺毡的制备研究

为了把麻纤维用作复合村料的增强体,本文在针刺制毡设备上制备了短切苎麻、黄麻纤维无纺针刺毡,并对利用这种现有工业设备制备麻纤维毡的工艺条件进行了研究,测试了麻毡的有关性能.结果表明,适当改变工艺参数,利用现有工艺业针刺设备可以制备短切麻纤维毡.制备的短切麻纤维无纺针刺毡面密度和厚度分布均匀,满足使用要求.     

New GMT material suitable for various polymers and high glass fibre content

Abstract

As a kind of long fibre reinforced thermoplastic, a new glass mat thermoplastic (GMT)-like material is introduced. It is designed to be suitable for various polymers and high glass fibre (GF) content, which might be a promising attempt to overcome the limit of conventional GMT material (PP matrix and maximum 40 wt-% GF). The concept is based on a multi-layered hybrid structure consisting of several thin GF sub-layers and polymer films having an inherently high viscosity. They are then needle-matted all together. The capability of higher GF content was derived from the porosity changes under pressure and the cross-sectional view after impregnation. It was finally confirmed by measurement of flexural properties up to 70 wt-% of GF content in PP grade. Moreover, PA6 grade was investigated to show the other capability of multi-layered hybrid mat for various polymers.     

玻璃纤维毡增强聚丙烯在压缩模塑流动过程中的纤维分布

通过测定玻璃纤维毡增强聚丙烯经挤压流动后不同区域的纤维含量,研究了基体树脂,增强材料的结构与性质,坯料设计,模具温度及坯料的预热温度等对玻璃纤维毡增强聚丙烯在压缩模塑流动过程中纤维发布的影响。结果表明,适当提高基体的粘度及采用多层坯料叠层的坯料设计方法,有利于制品内纤维的均匀分布;针刺密度适当的连续针刺毡及由短切纤维组成的复合针刺毡与聚丙烯形成的复合材料（GMT0,在压缩模塑的流动过程中纤维分布的均匀性较好,随着针刺密度的增加,纤维分布的均匀性下降;用粘结剂粘结而成的连续原丝毡与聚丙烯复合得到的GMT材料,纤维分布的均匀性较差,经适当针刺以后,纤维分布的均匀性得到一定程度的改善,过低的模具温度及坯料预热温度,会引起材料充模流动能力下降,但模具温度及坯料预热温度过高时,流动前沿区域的树脂富集现象将加剧。     

硅灰石与连续玻璃纤维毡组合增强聚丙烯的力学性能

采用硅灰石与连续玻璃纤维毡组合增强聚丙烯,研究了硅灰石的含量,玻璃纤维毡的面密度、基体树脂的性质及界面改性等对材料力学性能的影响。结果表明：采用硅灰石与连续玻璃纤维毡组合增强,可提高复合材料的拉伸、弯曲强度及模量,但过高的硅灰石含量,会导致拉伸及弯曲强度下降,材料的力学性能随着所用玻璃纤维毡面密度的增大而显著提高,采用偶联剂对硅灰石进行处理及在基体聚丙烯中添加功能化聚丙烯,可改善界面结合、提高材料性能,随着功能化聚丙烯含量的增加,材料的拉伸、弯曲强度及模量有所提高,但含量过高时,会引起材料冲击强度的下降;组合增强材料的性能与基体树脂本身的力学性能密切相关,同时还受基体树脂熔体流动性的影响。     

基体性质对GMT-PP复合材料力学性能的影响

研究了基体树脂的性质及基体配方中炭黑、结晶成核剂、接枝极性基团的功能化聚丙烯（ＰＰ）等对玻璃纤维毡增强ＰＰ复合材料力学性能的影响。结果表明：提高基体树脂熔体的流动性,有利于复合体系的浸渍过程;复合材料的弯曲强度及模量随基体树脂强度及模量的增大而提高;采用韧性较好的ＰＰ或ＰＰ增韧体系作为基体,可获得抗冲性能较好的复合材料;随着炭黑加入,复合体系的弯曲及冲击强度有所下降;结局成核剂的加入,可改善复合体