Utilization of Pineapple Crown Fiber and Recycled Polypropylene for Production of Sustainable Composites

Nowadays,the production of consumer goods is based on the use of non-renewable raw materials,which in recent years has been performing as a problem for the environment.Considering the large number of available biofibers in nature,their use in the development of polymeric composites has inevitably emerged,it is also necessary to take into account the countless discarded plastics that still have the potential to be reused.In this work,fibers were extracted from pineapple crown residues and utilized to compose sustainable composites using recycled polypropylene from cups discarded in the trash as a matrix.However,it is known that for good performance,it is necessary to achieve a good chemical interaction between the fiber and the matrix.In order to improve this interaction,alkaline mercerization treatment was carried out on the surface of the fibers removing some components incompatible with the polymer.In this work,the effect of the mercerization treatment on the properties of the fibers was studied,as well as their interaction with the matrix.The effect of fiber concentration on the mechanical and thermal properties of composites was also evaluated.Levels of 5 and 7 wt%were used for both natural and mercerized fibers.A decrease in the number of degradation stages was observed through thermogravimetry analyses(from four in natural fiber to two in mercerized fibers),showing that the mercerization performed on the fibers was effective.An increase in the degree of crystallinity of mercerized fibers was also observed through the results of X-ray diffraction.Both techniques indicate that amorphous compounds,such as hemicellulose and lignin,were partially removed.Through the tensile test,it could be noted that all composites presented higher values of de elastic modulus than recycled polypropylene without added load;however,there were no differences in the elastic modulus between the different types of fibers and load levels.Therefore,it is interesting to use fibers as reinforcing agents in polymers;however,the treatment did not increase the mechanical properties of the composites.In parallel,other factors,such as the dispersion of the components,must be taken into account to justify this result.

Recipe Development and Mechanical Characterization of Carbon Fibre Reinforced Recycled Polypropylene 3D Printing Filament

Recycled polypropylene filaments for fused filament fabrication were investigated with and without 14 wt% short fibre carbon reinforcements. The microstructure and mechanical properties of the filaments and 3D printed specimens were characterized using scanning electron microscopy and standard tensile testing. It was observed that recycled polypropylene filaments with 14 wt% short carbon fibre reinforcement contained pores that were dispersed throughout the microstructure of the filament. A two-stage filament extrusion process was observed to improve the spatial distribution of carbon fibre reinforcement but did not reduce the pores. Recycled polypropylene filaments without reinforcement extruded at high screw speeds above 20 rpm contained a centreline cavity but no spatially distributed pores. However, this cavity is eliminated when extrusion is carried out at screw speeds below 20 rpm. For 3D printed specimens, interlayer cavities were observed larger for specimens printed from 14 wt% carbon fibre reinforced recycled polypropylene than those printed from unreinforced filaments. The values of tensile strength for the filaments were 21.82 MPa and 24.22 MPa, which reduced to 19.72 MPa and 22.70 MPa, respectively, for 3D printed samples using the filaments. Likewise, the young’s modulus of the filaments was 1208.6 MPa and 1412.7 MPa, which reduced to 961.5 MPa and 1352.3 MPa, respectively, for the 3D printed samples. The percentage elongation at failure for the recycled polypropylene filament was 9.83% but reduced to 3.84% for the samples printed with 14 wt% carbon fiber reinforced polypropylene filaments whose elongation to failure was 6.58%. The SEM observations on the fractured tensile test samples showed interlayer gaps between the printed and the adjacent raster layers. These gaps accounted for the reduction in the mechanical properties of the printed parts.

β成核剂和退火对rPP/rPE共混物性能的影响

采用熔融共混法将β成核剂(β-NA)添加到废旧聚丙烯(PP)/废旧聚乙烯(PE)(rPP/rPE)共混物中,制备了rPP/rPE/β-NA共混物,并对共混物进行退火处理,研究了β-NA的含量以及退火对rPP/rPE/β-NA共混体系力学性能的影响,研究了含量为0.05%(rPP/rPE总质量的0.05%)的β-NA以及退火对共混物的热性能、结晶性能、动态力学性能、流变性能以及微观形貌的影响。力学性能测试表明,当β-NA含量为0.05%时,rPP/rPE/β-NA和退火后rPP/rPE/β-NA的缺口冲击强度、断裂伸长率最大,较rPP/rPE的4.42 kJ/m^(2)和295.10%分别增加了31.22%,115.21%和120.14%,12.75%;差示扫描量热测试和广角X射线衍射测试表明,β-NA诱导PP出现β晶,退火后共混物中PE和β晶PP(β-PP)结晶度增加,α晶PP(α-PP)结晶度基本不变;热重测试表明,r PP/rPE/β-NA热稳定性下降,退火后热稳定性增加,这是因为β-PP热稳定性比α-PP差,而退火后晶体结构完善热稳定性增加;流变性能测试表明,rPP/rPE/β-NA和退火后的共混物的复数黏度降低,β-NA起到润滑的作用,退火后共混物在熔融状态下流动性增强;动态力学性能测试表明,退火后的共混物玻璃化转变温度降低;扫描电子显微镜测试表明,退火后的共混物冲击断面比退火前粗糙,断裂形式为韧性断裂。

A Circular Economy Use of Post-Consumer Polypropylene Packaging for Low Thermal Conductive and Fire-Retardant Building Material Applications

Wastes from polypropylene(PP)packages are accumulating every year because it is one of the most widely consumed and short lifecycle products.This paper aims to develop low thermal conductive and fire-retardant materials from post-consumer PP(pPP)packages.Ammonium polyphosphate(APP)and hollow glass microsphere(HGM)were further added to improve the fire retardancy and thermal conductivity of pPP.The influence of APP and HGM on the mechanical and thermal properties,fire retardancy and thermal conductivity of pPP were investigated and compared with that of virgin PP(vPP).HGM was constantly added at 5 wt%while the content of APP was varied from 5 to 20 wt%.Experimental results showed that the tensile and flexural strengths were reduced with increasing APP concentrations.A morphological study confirmed the poor interfacial adhesion and debonding of each component during the applied load.Formulations containing APP less than 10 wt%did not show a satisfying fire retardancy rating due to the long self-extinguishing time.Further flame dipping and cotton ignition were observed for these formulations.With 15 and 20 wt%APP,the fire rating was significantly improved from no rating to V-0.The conductive heat transfer coefficient(k)was reduced by the presence of HGM.Based on these results,the formulation with 15 and 20 wt%could be used as a low k,fire-retardant building material.

Recyclable Polypropylene-based Insulation Materials for HVDC Cables:Progress and Perspective

Polypropylene(PP)-based recyclable materials have attracted tremendous interest for HVDC cable insulation applications due to their superior electrical properties,e.g.,high thermal stability and superior recyclability.Compared with crosslinked polyethylene(XLPE),PP-based materials exhibit the advantages of not only higher working temperatures but also facile and efficient cable manufacturing with reduced costs,which are highly desirable in HVDC cable manufacturing.Considering their promising advantages,PP-based materials have received significant attention from both academia and industry in the field of HVDC cable insulation.In order to adopt PP as a cable insulation material,the mechanical flexibility of PP should be improved.However,regulations of the mechanical properties inevitably influences the electrical properties of PP.So extensive research has been conducted on the regulation of the mechanical and electrical properties of PP.This review summarizes the research progress on recyclable PP-based materials for HVDC cable insulation applications.Particular attention is placed on the electrical property regulations and material structure-property relationships.The challenges that remain to be addressed and the opportunities for future studies on PP-based recyclable HVDC cable insulation materials are also presented.

Effectiveness of Compatibilizer on Mechanical Properties of Recycled PET Blends with PE, PP, and PS

Recycled PET (R-PET) is well known to exhibit brittle behavior in the presence of notches and indicated the low heat distortion temperature. In addition, it is hard to prevent some impurities such as cap or label of the bottle that mixed into R-PET during the recycling process. In this paper, the effect of the amounts and kinds of compatibilizers on the morphological characteristics and mechanical performance of recycled poly(ethylene terephthalate) (R-PET) compounded with polyethylene (PE), polypropylene (PP), and polystyrene (PS) was investigated. From the results, with an increase in the glycidyl methacrylate modified PE (EGMA) additive contents, in the increment of the Izod impact strength of Composite-G was obtained. In addition, it was found that the miscibility of Composite-G was improved with increasing the amount of EGMA, which indicated from the result of SEM images.

聚丙烯纤维再生混凝土在建筑工程中的应用

通过添加聚丙烯纤维可以改善再生混凝土的力学性能及耐久性,使得再生混凝土的经济效益、便捷性等优势在建筑工程中广泛应用。对于解决建筑垃圾、优化环境具有重要价值,成为高性价比的建筑材料。

接枝聚丙烯电缆绝缘材料的电树枝特性及机理

开发高性能的可回收聚丙烯电缆绝缘材料已成为近年来电绝缘领域的研究热点之一。该文对纯聚丙烯(PP)及甲基丙烯酸甲酯(MMA)接枝改性聚丙烯试样的电树枝引发和生长特性进行了研究。试验结果发现,相较于纯聚丙烯试样,接枝试样的电树枝引发时间显著提高,电树枝劣化区域和生长速率明显减小。分析表明,接枝MMA单体在聚丙烯试样内部引入了大量深陷阱,并减小了球晶尺寸,有利于抑制载流子的输运行为并显著压缩了非晶区通道的空间尺度,进而改善了接枝试样的电树枝引发特性。此外,接枝试样的球晶尺寸减小使得非晶区通道更为曲折狭长,显著增加了电树枝沿着电场方向生长的阻力,进而改善了接枝试样的电树枝生长特性。随着MMA单体掺杂含量的增多,接枝试样的电树枝引发和生长特性逐渐提升。研究结果可为高性能接枝聚丙烯电缆绝缘材料的研发提供参考。

废旧家电回收塑料的改性研究

使用回收洗衣机外壳塑料为主要原料,加入回收电视机外壳塑料进行共混改性,研究回收电视机外壳塑料加入量对共混料熔体流动速率(MFR)、拉伸性能、冲击性能的影响,确定最佳配料比。结果表明:回收洗衣机外壳塑料主要成分为聚丙烯(PP)、回收电视机外壳塑料主要成分为ABS树脂,二者相容性好,加工性能优异。加入回收电视机外壳塑料,可以提高回收洗衣机外壳塑料的强度和韧性。最佳配料比为回收电视机外壳塑料加入量为25%,此时共混料的MFR为0.17 g/10 min、抗拉强度达到25.71 MPa,断裂伸长率达到27.8%,冲击强度为18.94 kJ/m^(2)。

不同纤维掺量再生混凝土骨料轻质混凝土性能研究

为了研究聚丙烯(PP)纤维增强再生混凝土骨料轻质混凝土的性能,以普通硅酸盐水泥、再生废弃混凝土粗骨料、聚丙烯纤维、泡沫为主要材料,选取PP纤维掺量为变量,对试样进行室内试验研究。结果表明:随PP纤维掺量增加,浆体流动度呈下降趋势;当采用再生粗骨料级配(即粒径为9.5~16 mm、16~19 mm、19~26.5 mm、26.5~31.5 mm、31.5~37.5 mm的5类骨料的质量比)为2∶4∶8∶3∶3和30%体积率时,建议浆体流动度大于210 mm;试件抗压强度和劈裂抗拉强度随PP纤维掺量的增加均呈先增大后减小趋势,说明PP纤维对再生混凝土骨料轻质混凝土性能提升效果有限;PP纤维的掺入会使再生混凝土骨料轻质混凝土材料早期抗压强度和劈裂抗拉强度形成速度降低;当纤维掺量由0增大为0.2%时,增加了孔隙率,降低了平均孔径。

滚筒洗衣机塑料外桶成分分析与性能检验

通过分析其热性能和力学性能,为判断滚筒洗衣机塑料外桶的成分寻找证据。红外光谱和X射线荧光光谱分析的结果表明,塑料外桶用复合材料以聚丙烯为基础原料,不含邻苯类增塑剂,几乎没有检测到重金属元素。球晶形态观察结果表明,复合材料的结晶尺寸小。热性能分析结果显示,复合材料的熔点略低于纯聚丙烯,但是最大热分解温度与纯聚丙烯和聚丙烯再生料均接近。力学性能测试结果表明,塑料外桶破碎料的拉伸强度、弯曲强度和冲击强度均与市售聚丙烯-玻纤复合材料的强度接近。所用结构分析手段和静态力学性能测试结果表明,目前滚筒洗衣机塑料外桶用复合材料中不包含再生料。

聚丙烯纤维再生混凝土主破裂前兆特征研究

为研究聚丙烯纤维再生混凝土的破裂尺度和主破裂前兆特征,设计制作了20组粗骨料替代率为25%和50%的试件,通过开展单轴压缩声发射试验,提取聚丙烯纤维再生混凝土破裂过程声发射能量和主频。以能量为媒介,探讨破裂尺度和声发射信号特征之间的对应关系。采用K-means聚类方法将大尺度破裂和小尺度破裂进行二维聚类分析,然后运用支持向量机得到大尺度破裂和小尺度破裂两类聚类的分界线。分析了聚丙烯纤维再生混凝土破裂过程声发射信号演化规律,发现存在声发射事件率减少,大尺度破裂信号增加,低能量小尺度破裂信号消失等特征。引入前兆响应系数概念,计算结果表明低能量小尺度破裂信号消失特征的前兆响应系数最大,前兆响应时间最早。

聚丙烯升级回收研究进展

聚丙烯是世界第二大塑料品种,随着产能不断增加,废弃聚丙烯塑料带来的各种问题已不容忽视,如何实现聚丙烯的高效升级回收面临艰巨挑战。从聚丙烯废弃与回收现状、废塑料回收方法分类、回收基本原理等角度综述了近年来聚丙烯升级回收的研究进展,比较了机械回收和多种化学回收方法的异同,并从C—C键解离、C—H键功能化的角度介绍了聚丙烯化学回收的主要方法,重点论述了共价适应性网络这一新兴方法在聚丙烯升级回收中的应用潜力。

废胶粉/再生聚乙烯/再生聚丙烯功能化复合改性沥青及其混合料性能研究

废胶粉(wTG)、再生聚乙烯(rPE)及再生聚丙烯(rPP)是产量较多的废旧聚合物材料,将其应用于交通建设中,不仅可以降低其对环境的污染而且在一定程度上可以改善沥青路面的使用性能。基于此,本文通过在基体配方m(rPE)∶m(rPP)=3∶2中添加不同含量wTG制备三元共混改性剂(TM),重点研究和分析了TM对改性沥青及其混合料(AC⁃13)性能影响。结果表明,随着wTG含量的增加,TM改性沥青软化点增加、针入度降低,而延度则出现最大值,并通过傅里叶变换红外光谱(FTIR)、微观形貌对改性机理进行分析评价。另外,随着wTG含量的增加,TM改性沥青混合料动稳定度存在先快速增加后增速放缓的变化趋势。对于低温抗裂性能、水稳定性性能(冻融劈裂强度比)及抗渗水性能方面,则均呈现先增加后下降的趋势。综合分析得出,在本实验条件下,建议20%的wTG含量有利于整体改善AC⁃13改性沥青混合料性能,这为今后工程应用提供重要的理论依据。

聚丙烯复合材料在车用内饰件中的应用研究进展

综述了PP复合材料在车用内饰件中的应用研究进展。使用添加铯钨纳米氧化物粉体改性的PP复合材料用于汽车内饰材料可以降低制件的表面温度。采用石墨烯-金属有机骨架吸附材料对PP改性,用于汽车内饰材料可以解决气味和挥发性有机物的难题。低挥发性有机物含量、低有害气体释放量的再生PP复合材料、再生PP组合物可用于制备汽车内饰件。

R-PP/BM/SEP复合材料的制备及其性能

以日杂聚丙烯废塑料(简称R-PP)为原料,海泡石(SEP)和勃姆石(BM)为阻燃剂,通过熔融挤出制备了R-PP/BM/SEP复合材料,对复合材料的极限氧指数(LOI)、垂直燃烧等级(UL 94)及力学性能进行测试与分析。结果表明:w(BM)为25%时,R-PP/BM复合材料的LOI提高到26.9%,厚度为3.2 mm的试样阻燃等级达UL 94 V-1级,质量损失5%时的温度(t_(5%))、质量损失速率最大时的温度(t_(max))和残炭量都相应提高;SEP与BM在R-PP中有协同阻燃效果,w(SEP)为3%,w(BM)为22%时,复合材料的LOI为31.4%,厚度为3.2,2.0 mm的试样阻燃等级分别达到UL 94 V-0,V-1级,与单独添加25%(w)BM的R-PP/BM复合材料相比,其热释放速率峰值、平均热释放速率、总热释放量和总生烟量较低,点燃时间,火灾性能指数,t_(5%),t_(max)和残炭量较高;添加SEP可以提高R-PP/BM的力学性能。

回收聚丙烯纳米复合材料的性能

采用硅烷偶联剂和硬脂酸对纳米二氧化硅(nano-SiO2)进行了复合改性,再通过双螺杆挤出机熔融共混制备了回收聚丙烯(RPP)纳米复合材料。研究表明,改性nano-SiO2有良好的疏水亲油性能和良好的分散效果。随着改性nano-SiO2质量分数的增加,RPP纳米复合材料的熔体质量流动速率先增大后减小,当改性nano-SiO2的质量分数为1%时,复合材料的熔体质量流动速率达到最大值。当改性nano-SiO2的质量分数仅为0.5%时,RPP复合材料的缺口冲击强度达到最大值22.23 kJ/m^(2),比0.5%未改性nano-SiO2/RPP的缺口冲击强度提高了134.99%。随着改性nano-SiO2质量分数的不断增加,复合材料的拉伸强度呈先增大后下降的趋势,3%改性nano-SiO2/RPP的拉伸强度达到最大值20.6 MPa。当红磷(RP)的质量分数为20%,改性nanoSiO2的质量分数为2%和3%时,RPP复合材料的阻燃级别达到UL94 V-0级。通过研究改性nano-SiO2对RPP的结构和性能的影响,为回收聚烯烃材料的高质化再生利用提供了价值参考。

气相法聚丙烯原料精制塔排放气回收改造

当前煤制烯烃化工在我国越来越盛行,其中以聚乙烯、聚丙烯为主要产品。聚丙烯生产过程中,聚合催化剂体系对共聚单体中的杂质相当敏感。这些杂质会造成催化剂中毒,影响装置的平稳生产和产品性能。因此,从界区来的原料必须经过精制才能进入反应系统。本文依据现场实际情况,针对聚丙烯原料精制系统吸附剂再生和转产共聚物牌号时的排放气无法回收问题,进行论证,改造。改造后将产生的排放气全部回收,为企业增加了经济效益。

聚丙烯装置除盐水系统运行问题分析及对策

对中国石油宁夏石化公司10万t/a聚丙烯(PP)装置除盐水单耗高的原因进行了分析,并采取了相应的改进措施。结果表明:用于挤压造粒工段和干燥系统N_(2)洗涤塔(T-502)的除盐水用量较大,且T-502溢流口洗涤水未得到有效回收利用是装置除盐水单耗高的主要原因;通过增设回收-过滤水箱对T-502溢流口洗涤水进行回收,同时定期用新鲜除盐水对T-502内自循环洗涤水进行补水置换,使装置除盐水单耗由0.45 t/t降至0.23 t/t,且减缓了因洗涤水杂质增多及呈弱酸性带来的设备腐蚀问题。

回收聚丙烯基复合材料的耐候性与阻燃性能

以回收聚丙烯(RPP)为基体,添加茶粉、纳米二氧化钛(Nano-TiO_(2))及聚磷酸铵(APP)制备了茶塑复合材料,并考察了茶粉、Nano-TiO_(2)用量对茶塑复合材料性能的影响。结果表明,适量茶粉可提高RPP的抗拉强度,茶粉质量分数10%时,抗拉强度增加了26.1%;Nano-TiO_(2)既能增加茶塑复合材料的抗拉强度,也可抑制热老化过程中抗拉强度的下降,从而增加了材料的耐候性。考察了Nano-TiO_(2)与APP对茶塑复合材料阻燃性能的协同作用,发现Nano-TiO_(2)与APP共同作用能进一步降低茶塑复合材料的水平燃烧速度。在Nano-TiO_(2)质量分数为4%时,水平燃烧速度最低,仅有23.3 mm/min,比不含Nano-TiO_(2)时降低了40.6%。当固定Nano-TiO_(2)质量分数为4%,改变APP用量时,在APP质量分数为15%时,水平燃烧速度仅为20.2 mm/min。