A morphological study of melt‐spun polypropylene filaments by atomic force microscopy

Surface morphology of melt‐spun polypropylene (PP) filaments, spun from an additive‐free PP powder and from a commercial‐grade PP with different draw ratios, were examined with atomic force microscopy (AFM). The surface morphology of as‐spun filaments was spherulitic. The gradual transformation of the surface structure from a spherulitic morphology to a fibrillar morphology during stretching was studied. In the filaments spun from the commercial‐grade PP, the transformation was initiated by deformation of spherulites with a draw ratio of 1.2 and continued with association of lamellar stacks into fibrillar chains with a draw ratio between 1.2 and 2.0. A hierarchical morphological microstructure of fibrils, microfibrils, and nanofibrils was developed with a draw ratio of 4.0. In the filaments spun from the additive‐free PP, the association of lamellar stacks into fibrillar morphology occurred considerably later, between draw ratios of 2.0 and 4.0. An oriented lamellar structure was found in these filaments, still with a draw ratio of 4.0. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1242–1249, 1999     

再生远红外丙纶生产工艺探讨

以远红外聚丙烯废料为原料 ,在普通涤纶纺丝设备上纺制再生远红外丙纶短纤维 ,并对造粒、干燥、纺丝成形、拉伸等工艺进行了探讨。远红外聚丙烯经过再造粒后 ,其熔体流动指数较原料高出 10左右 ,干燥温度一般控制 10 0～ 12 0℃ ,干燥时间 4～ 8h ,纺丝温度设定高于熔点 10 0℃左右 ,拉伸倍数 2～ 3较适宜     

Structural deformation behavior of isotactic polypropylene with different molecular characteristics during hot drawing process

Structural evolution in hot drawing process of isotactic polypropylene (iPP) films with different molecular weight distribution (MWD) and isotacticity (IT) was investigated by in situ time-resolved measurements of synchrotron-sourced wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). Any significant difference was not recognized among different molecular characteristics as for the changes in the WAXD patterns, indicating that the deformation behavior viewed at the crystal lattice scale was almost the same among these samples. On the other hand, the deformation behavior of lamellar stacking structure was found to be significantly dependent on the molecular characteristics of the sample used. For iPP sample with narrower MWD and higher IT, only the lamellar stacking structure with c-axis crystallites oriented along the drawing direction was detected at the deformation stage after necking, but the oriented fibrillar structure was observed in addition to the lamellar stacking structure for the iPP sample with broader MWD and IT distribution. The structural deformation models were presented for both the samples with different molecular characteristics, and these models were reasonably related with the difference in the stress-strain curve.     

Water absorption and dimensional stability of short kenaf fiber‐filled polypropylene composites treated with maleated polypropylene

The purpose of this research was to investigate the water absorption behavior and associated dimensional stability of kenaf‐polypropylene‐filled (PP/KF) composites. Composites with different fiber loadings, ranging from 0 to 40 wt %, were prepared with a twin‐screw extruder followed by hot press molding. The influence of the compatibilizer was also studied for PP/KF composite with 5 wt % maleated PP (MAPP). Water absorption testing was carried out at room temperature for 7 weeks. Tensile, flexural, and impact tests were also performed on control, wet, and re‐dried specimens. Increasing the fiber content resulted in higher water absorption and thickness swelling. The inferior mechanical properties of the wet composites were attributed to the effect of water, which deteriorates the interfacial properties of composites. On re‐drying, all properties were almost recovered because of the recovery of interfacial area as evident in scanning electron micrographs. Incorporation of the MAPP significantly improved the compatibility between the fiber and matrix and the mechanical properties of the composites compared with those without MAPP. It also diminished the water absorption as well as the related thickness swelling in the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A numerical study on warm deep drawing of polypropylene

Warm deep drawing of polypropylene, a semi-crystalline thermoplastic polymer, is studied using finite element analysis. In this process, a circular polypropylene blank is preheated to a temperature much below its melting temperature and deep drawn into the shape of a flat-bottom cylindrical cup using a punch-die combination, both initially at 25°C. The material model used for the analysis considers the effects of varying temperature and strain rate during the deep drawing process on the depth of draw. The effects of blank holder force, initial blank temperature, blank diameter, and die and punch corner radii on the depth of draw are determined. Thickness, temperature, and strain variations in the drawn cups, punch forces, and failure modes are also determined.     

双单体固相接枝聚丙烯技术研究

以马来酸酐和苯乙烯为单体,采用固相接枝法将单体接枝到聚丙烯上;考察了反应温度、反应时间、引发剂用量、溶胀时间、粒径、单体物质的量比对接枝率的影响;红外光谱分析产物结构.结果表明:马来酸酐和苯乙烯接枝到聚丙烯上;最佳条件下接枝率为9.6%.     

Customized blends of polypropylene for extrusion based additive manufacturing

Filament-based material extrusion (MatEx) additive manufacturing has garnered great interest due to its simplicity, customizability, and cost-effectiveness. However, MatEx of semicrystalline polymers is still largely relegated to prototyping applications. Major issues involving volumetric shrinkage and warpage of the printed parts must be addressed in order to employ them for printing functional parts. Moreover, the crystallization behavior and rheology of the polymer are dependent on the MatEx processing conditions. In the current work, the printability of blends of isotactic polypropylene with a soft, low crystallinity propylene based homopolymer is evaluated. Addition of the homopolymer resulted in an increase in the crystallization window of the blends by ~6°C that had a profound impact on the interlayer adhesion and residual stress state. The shear-dependent melt flow behavior inside the printing nozzle as well as the interlayer chain diffusion and interlayer welding on the print bed were investigated. Rheological characterizations also indicate sufficient dispersion and miscibility of the homopolymer in the neat polypropylene matrix. The incorporation of the homopolymer as an additive significantly improved the dimensional accuracy of the printed parts through better dissipation of the entrapped residual stresses during MatEx. Moreover, the degree of mechanical anisotropy of the parts was significantly lower than that obtained using many 3D printable grade polymers. The findings from this study can be leveraged in toolpath planning, process parameter optimization, and new feedstock development, highlighting current limitations as well as providing valuable insights into necessary processing modifications in order to enable MatEx of next generation semicrystalline polymers.     

Mechanical and structural properties of melt spun polypropylene/nylon 6 alloy filaments

Investigated in the present study are the physical properties, morphology, and structure of PP/N6 alloy filaments (10, 20 wt % N6) made with or without PP‐g‐MAH as compatibilizer. The alloy filaments produced at the take‐up speeds of 300 and 800 m/min were drawn with draw ratio of 3.5 and 2, respectively. Stress–strain curves of PP and alloy filaments show ductile and brittle behavior, respectively. It is suggested that the brittle behavior of alloy filaments is due to the presence of microvoids or micropores at the interface of PP and N6; these lead to stress concentration and thus to a decrease in tenacity, modulus, and elongation at break. Effects of the blending of N6 with PP on birefringence and crystalline and amorphous orientation factors of the composite filaments are studied. The amorphous orientation factor, f_am, of PP was found to increase with an increase in the amount of N6. The alloy filaments behaved like isostrain materials and most of the force in spinning and drawing was born by the PP phase. The presence of N6 fibrils helped to orient PP chain molecules in amorphous regions. However, the crystalline factor, f_c, of PP decreased with the increase in nylon fraction. This means the presence of the crystals of N6 caused a decrease in the orientation of the PP crystals. LSCM micrographs of the filament showed the presence of matrix–fibril morphology with the N6 fibrils oriented along the axis. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 532–544, 2005     

聚丙烯专用树脂的开发与生产

介绍了盘锦乙炮有限责任公司近年来研制生产的聚丙烯专用树脂，具体阐述了电容膜专用树脂F400A在降低产品的灰分，控制分子量分布，提高使用时成膜率的情况；生产涂覆级专用树脂J741时，在高熔体流动指、高乙烯含量状态下，解决了下料管线堵塞问题，并使生产过程中熔体流动指数、乙烯含量等控制平稳；研制的高抗冲共聚管材专用树脂P340A使产品的韧性提高，长期耐老化性得到改善；大口径管材专用树脂P240实现了低熔体流动指数下的平稳控制。     

Dyeing behavior of polypropylene blend fiber. III. Effect of drawing on dyeability

A modified polypropylene fiber was prepared containing 6% of a basic polymeric additive. The fiber was drawn to various ratios and its dyeability with an acid dye was tested. Structural changes due to the drawing were evaluated by application of eight different physical techniques: wide-angle X-ray diffraction, small-angle X-ray scattering, dark-field and optical microscopies, scanning electron microscopy, and density, birefringence, and tensile testing. Variations in dyeability were attributed to density variations from macrovoids in the specimen. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 719–727, 1999     

3D polymer composite filament development from post-consumer polypropylene and disposable chopstick fillers

This study focused on the development of three-dimensional (3D) polymer composite filament made of disposable chopstick (DC) and post-consumer polypropylene (PPP). The PPP/DC composite parts were printed via fused filament fabrication (FFF) process. The effect of the printing temperature and different DC fiber content on the properties of the 3D printed parts were investigated. The printing temperature of 200–220°C was suitable for these filaments because the printing temperature did not show any thermal degradation, as proven by thermogravimetric analysis. Furthermore, the thermal stability of the 3D filament increased with DC content. The chemical modification with sodium hydroxide (NaOH) was carried out on DC to remove the unwanted organic components by showing changes in peak intensity in the Fourier transform infrared analysis. Moreover, the melt flow index of the composite filaments decreased with increasing of the DC content and caused the composites' viscosity increased. The results show that the optimum printing temperature of 210°C would reduce the warping and gave better tensile properties to the 3D printed parts. Nevertheless, the tensile strength and elongation at break of the 3D printed PPP/DC parts reduced as the DC content increased because the presence of some air gap and fiber pull out on the fracture surface of 3D printed parts, which are in line with the results observed from scanning electron microscopy. However, the tensile strength and elongation at break percentage of all 3D printed PPP/DC composite parts were higher in comparison with the 3D parts printed by commercial wood plastic composite filament.     

聚丙烯高性能化改性研究

研究了橡胶和弹性体的种类与用量、加工助剂等对聚丙烯(PP)的悬臂梁缺口冲击强度、拉伸强度、硬度、加工性能以及透明性的影响。结果表明:与添加其他橡胶的PP相比,添加乙丙橡胶(EPR)1的PP合金具有较高的悬臂梁缺口冲击强度、透光率及流动性,较低拉伸强度与硬度;添加聚乙烯蜡的PP的综合性能最好。     

PP等规指数的优化控制

分析了外给电子体加入量、催化剂种类对聚丙烯(PP)等规指数的影响。结果表明:外给电子体加入量与等规指数成正比;不同类型催化剂对PP等规指数可调范围、可调敏感性的影响不同;在间歇釜式PP装置和连续双环管PP装置的运行中,工艺路线不同,等规指数的控制范围不同。在200 kt/a连续双环管PP装置上生产PP T30S时,主催化剂为CS-Ⅱ型催化剂,外给电子体用量为0.010~0.017 kg/t,PP等规指数可控制在95.0%~98.0%,从开工至今连续运行208天,打破了国内PP装置最长连续运行188天的记录。     

Study on the thermal stability of heterogeneous nucleation effect of polypropylene nucleated by different nucleating agents

The thermal stability of the heterogeneous nucleation effect of polypropylene (PP) nucleated with an organic phosphate (A) and two kinds of sorbitol derivatives (B and D) was investigated by DSC multiscanning. For pure PP, the peak temperature of crystallization (T) was little changed with an increasing number of DSC scans, indicating that nucleation of PP is thermally stable. For the PP nucleated with an organic phosphate (PPA), the temperatures at the onset of crystallization (T) and at the completion of crystallization (T); the peak temperature of crystallization (T) and melting (T); and the heat of crystallization (ΔH_c) and fusion (ΔH_m) of PP are higher than those of pure PP and were little influenced with an increasing number of DSC scans. For PP nucleated with the sorbitol derivatives (PPB and PPD), the T, T, T, and T decreased with an increasing the number of scans. These results indicated that the thermal stability of heterogeneous nucleation effect of the nucleating agent A is higher than that of nucleating agents B and D. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1643–1650, 2002     

Radiation grafting of acrylic acid on to polypropylene filaments. I: Effect of reaction conditions

Graft copolymerization of acrylic acid on to polypropylene filaments was investigated by a simultaneous irradiation technique. The effect of various solvents and solvent combinations on swelling behaviour and on percentage grafting was studied. At a constant dose, the percentage grafting was found to be higher at low dose rates and it increased linearly up to 0.25 Mrad and then saturated. It was also observed that grafting increases with increasing monomer concentration up to 2 mole/litre. Graft copolymers were characterized by infrared spectroscopy and colour formation with methylene blue.     

PP中成核剂的异相成核作用的热稳定性

用差示扫描量热计（DSC）研究了聚丙烯（PP）中不同类型成核剂的异相成核作用的热稳定性,观察到随扫描次数增加,纯PP的成核作用稳定,降温结晶温度基本不变,而有机磷酸盐类成核剂成核PP的结晶温度比纯PP的高,而且异相成核作用受DSC扫描次数的影响也很小,但山梨醇类成核剂成核PP的异相成核作用随DSC扫描次数增加,结晶温度逐步降低,表明其异相成核作用对热不稳定。     

国产三乙基铝在间歇式聚丙烯装置上的应用

介绍了国产助催化剂三乙基铝在金陵石化有限责任公司塑料厂100kt/a间歇式聚丙烯装置上的试用情况，并与进口三乙基铝的使用情况进行了对比。     

聚丙烯（PP）／黏土复合材料熔融剂的研究

以马来酸酐（MAH）等为单体接枝聚丙烯作为聚丙烯（PP）／黏土复合材料熔融剂,考察了马来酸酐用量、引发剂过氧化苯甲酰（BPO）用量、反应时间、温度等因素对产物接枝率的影响,并通过红外光谱图对PP-g-MAH进行表征。结果表明,当m（PP）：m（复配单体）：m（BPO）=10．0：2．0：0．6、反应温度控制在120℃左右、复配单体为马来酸酐／苯乙烯时,熔融剂PP-g-MAH的接枝率可获得较大值3．9％。实验同时表明,反应时间对接枝率的影响不大;苯乙烯的加入对接枝率有较大的影响,与普通单体单一马来酸酐相比,加入苯乙烯的接枝率明显提高。     

丙纶纤维自增强聚丙烯树脂的研究

以丙纶纤维为增强体,聚丙烯树脂为基体,采用热压成型的方法制备丙纶纤维/PP复合材料板材.研究了不同热压温度、不同纤度的丙纶纤维用量对复合材料力学性能的影响.结果表明:本实验最佳热压温度为195℃,在此温度下,随着纤维用量的增加,复合材料的拉伸强度呈先升后降的趋势,在用量为15%时达到最高点,纤度为240D的丙纶纤维/P...