Microporous polypropylene hollow fibers containing poly(methylsilsesquioxane) fillers

Microporous polypropylene hollow fibers were prepared by stretching polypropylene microtubes containing poly(methylsilsesquioxane) fillers with uniform particle sizes. The properties of the resultant hollow fibers are controllable by adjusting the particle size of the filler, the filler content, and the stretching degree. Also, it is elucidated that the hollow fibers have a fine texture of split PP fibrils, in which the filler particles are dispersed. © 1994 John Wiley & Sons, Inc.     

Microporous polypropylene hollow fibers with double layers

Microporous polypropylene hollow fibers with double layers were prepared by stretching double layered polypropylene microtubes containing polymethylsilsesquioxane fillers: the relatively smaller filler in the inner layer and relatively larger filler in the outer layer. The resultant hollow fibers have a finely interconnected fibrous structure parallel to fiber axis. Their N₂ gas permeabilities were measured to estimate the fibrous structure: tortuosity factor, effective porosity, and pore size. © 1995 John Wiley & Sons, Inc.     

Microporous polypropylene sheets containing CaCO3 filler

Biaxial stretching of polypropylene sheets containing CaCO₃ filler results in microporous sheets, that feel soft and dry. Their properties depend on filler content, particle size of the filler, and stretching degree etc. We have studied the dependency of some properties of the microporous polypropylene sheets on stretching degree. It is elucidated that mechanical properties are controllable by adjusting stretching degrees in machine and transverse directions. © 1993 John Wiley & Sons, Inc.     

Microporous polypropylene sheets containing CaCO3 filler: Effects of stretching ratio and removing CaCO3 filler

Microporous polypropylene sheets are prepared by biaxially stretching polypropylene sheets containing CaCO₃ filler. Here, the stretching ratio is one of the most important factors in the preparative process, and removing the CaCO₃ filler also affects the sheet properties. Their effects were studied in relation to the properties and the structure of the microporous polypropylene sheets. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1543–1553, 1998     

Preparation of microporous polypropylene sheets containing CaCO3 filler: Effect of draft ratio

Microporous polypropylene sheets were prepared as follows. First, polypropylene pellet-containing CaCO₃ filler was extruded to prepare base sheets, which were then biaxially stretched. The draft effect at the extrusion process was studied in relation to some properties of the resultant microporous polypropylene sheets. © 1996 John Wiley & Sons, Inc.     

Structure of microporous polypropylene sheets containing CaCO3 filler

The microporous polypropylene sheets were prepared by biaxially stretching polypropylene sheets containing CaCO₃ filler (particle size, 0.08–3.0 μm), when the CaCO₃ filler content was 59% by weight and the stretching ratio was 2.8 × 1.8. The microstructure of the sheets were investigated in relation to the CaCO₃ particle size by a N₂ gas permeation method. (1) Effective porosity increases with decreasing mean particle size of filler. (2) The tortuosity factor of the pore is in the range of 25–40 and becomes relatively smaller with decreasing mean particle size of filler. (3) The equivalent pore size becomes relatively smaller with decreasing mean particle size of filler.     

Microporous polypropylene fibers containing fine particles of poly(styrene‐co‐divinylbenzene) or poly(glycidylmethacrylate‐co‐divinylbenzene)

Styrene‐divinylbenzene or glycidylmethacrylate‐divinyl‐benzene were copolymerized in powdery polypropylene suspended in water and the resultant polymer composites were blended with a definite amount of polypropylene. The products consisted of polypropylene and the fine particles of the copolymer, which were uniformly dispersed in polypropylene phase. These products were melt‐spun to prepare polypropylene fibers containing the fine particles and then the fibers were stretched to make the fibers microporous. Some properties were estimated: porosity, 1.6–19.7%; average pore size, 0.004–0.009 µm; and specific surface, 9–137 m²/g. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 722–727, 1999     

Microporous polypropylene fibers containing fine particles of poly(glycidylmethacrylate-co-divinylbenzene)

Glycidylmethacrylate and divinylbenzene were copolymerized in a n-hexane solution of poly(propylene-co-1-butene). The resultant polymer composite contains fine particles of poly(glycidylmethacrylate-co-divinyl benzene). This composite was blended with polypropylene. Next, the resultant polypropylene composites were melt spun and stretched. Microporous polypropylene fibers were thus prepared and their properties were evaluated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1549–1553, 1999     

Physical modification of polyacrylonitrile precursor fiber: Its effect on mechanical properties

Polyacrylonitrile precursor fiber of a special grade for making carbon fibers was modified by stretching in the prestabilization stage to various extents. The effect of such stretching on tensile properties of the original precursor fiber, intermediate (oxidized) fiber, and resultant carbon fiber prepared through a continuous process was monitored. Improvements in tensile modulus of fibers at various stages were observed with increasing stretch ratios. However, no obvious enhancement of tensile strength of final carbon fibers was found. © 1994 John Wiley & Sons, Inc.     

Morphology and tensile properties of polypropylene‐multiwalled carbon nanotubes composite fibers

In this work, we analyzed tensile properties of polypropylene‐multiwalled carbon nonotubes composite fibers. The multiwalled carbon nanotubes (MWCNTS) were used in different contents of 0, 1, 2, 3, 4, and 5 wt %. Dispersing agents were used to disperse MWCNTs in polypropylene matrix. After the dispersing agent was removed, the mixture was melt mixed. The fibers were spun by a home‐made melt spinning equipment and stretching was done at a draw ratio of 7.5. By using 1–5 wt % of MWCNTs, the modulus of composite fibers increased by 69–84% and tensile strength increased about 39% when compared with the virgin polypropylene fibers. In addition, the MWCNTs dispersion in the matrix was monitored by scanning electron microscopy and transmission electron microscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

β成核剂与无机填料对聚丙烯力学性能的影响

无机填料可以提高聚丙烯的刚性、硬度、抗化学性、尺寸稳定性和气体阻隔性,同时减少聚合物的用量,降低产品成本。滑石粉和碳酸钙是聚丙烯复合材料中大量使用的两种填料。主要研究β成核剂和无机填料对聚丙烯成核效应的协同作用,考察经β成核剂FB-1分别与无机填料滑石粉和碳酸钙共同改性的聚丙烯力学性能。     

Mechanical Properties of Biodegradable Composites Reinforced with Short Spartium Junceum Fibers before and after Treatments

In the present study, Spartium junceum (SJ) fibers were chemically treated with different concentrations of two coupling agents, silane N [-3 Trimethoxysilyl propyl] ethylene diamine (Z-6020) and stearic acid, in order to improve the mechanical properties of polypropylene/Spartium junceum fibers (PP/SJ) composites. The chemical modification efficiency was verified by FTIR analysis, which showed the appearance of bands around 1260 and 1100 cm^?1 attributed to asymmetric stretching of Si-O-Si linkage and Si-O-Cellulose for (Z-6020) modified SJ fibers. The mechanical properties of the composites prepared from chemically treated Spartium junceum fibers are found to increase substantially compared to those with untreated fibers.     

An investigation on the mechanical and dynamic rheological properties of single and hybrid filler/polypropylene composites based on talc and calcium carbonate

Some results of experiments on the mechanical and rheological properties of mineral filled polypropylene were presented. Single filler and hybrid filler composites of talc and calcium carbonate (CaCO₃) were prepared in a co‐rotating twin‐screw extruder. The effect of filler type, filler content, and coupling agent on the mechanical and rheological properties of the polypropylene were studied. The coupling agent was maleic anhydride‐grafted polypropylene (PP‐g‐MA). It was found that the mechanical properties are affected by filler type, filler concentration, and the interaction between filler and matrix. The tensile strength of the composite is more affected by the talc while the impact strength is influenced mostly by CaCO₃ content. The elongation at break of PP/CaCO₃ composites was higher than that of PP/talc composites. The incorporation of coupling agent into PP/mineral filler composites increased the mechanical properties. Rheological properties indicated that the complex viscosity and storage modulus of talc filled samples were higher than those of calcium carbonate filled samples while the tan δ was lower. The rheological properties of hybrid‐filler filled sample were more affected by the talc than calcium carbonate. The PP‐g‐MA increased the complex viscosity and storage modulus of both single and hybrid composites. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

软木纤维增强PP复合材料的研究

采用软木纤维作为增强材料提高聚丙烯性能。为了改善软木纤维和聚丙烯母体之间的相容性,用马来酸酐接枝聚丙烯(MAPP)对软木纤维进行接枝处理,用MAPP或用三元乙丙橡胶(EPDM)对软木纤维进行改性处理。结果表明,与未经处理木纤维的复合材料相比,三种处理方法都使复合材料的热性能、加工性能和力学性能有了较大的提高。用MAPP接枝和用MAPP表面处理木纤维的方法比用EPDM表面处理木纤维的方法在提高复合材料热性能、加工流动性和拉伸强度方面更为显著。用EPDM表面处理木纤维在改善复合材料的冲击强度、断裂伸长率上更明显。此外,木纤维在复合材料中的浓度对复合材料其它性能的影响,以及MAPP接枝木纤维和MAPP处理木纤维的不同实验结果也进行了评价。     

Water uptake and mechanical characteristics of natural filler–polypropylene composites

Water uptake characteristics and some mechanical properties of polypropylene composites containing three types of natural fillers, purified α‐cellulose, wastepaper fibers, and wood flour were studied. The fiber contents were 15, 25, and 35% by weight. Two percent maleic anhydride polypropylene (MAPP) was also added to the mix, as the compatibilizer agent. Mixing process was performed in a Brabender Plasticorder until a constant torque was reached. Composites made out of these combinations were then pressed in a laboratory press and ASTM standard test specimens were cut out of the sheets. Water absorption and tensile tests were performed on these specimens. The results showed a significant difference between the various filler types regarding water uptake. Water uptake also increased by the increase in filler content. Tensile strength and elongation at break in composites declined when compared with pure polypropylene, but their modulus of elasticity increased. Among the three types of fillers, no significant discrepancies were observed in terms of improving mechanical properties in composites. Filler content increase had no drastic effect regarding strength improvement. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 941–946, 2003     

Structure–property relationships of thermally bonded polypropylene nonwovens

The effect of fiber structure and morphology on the resultant mechanical and low load deformation properties of thermally bonded nonwoven polypropylene fabrics has been studied. Commercially available staple polypropylene fibers varying in linear density and draw ratio (Herculon and Marvess staple fibers) were used in this study. The orientation of these fibers was characterized by birefrigence measurements. Differential scanning calorimetry measurements were made to determine the heat of fusion and melting point of fibers. Experiments confirm that tensile strength and stiffness of the fabrics correlate with this fiber structure. Under the same bonding conditions fabrics made from fibers with low draw ratios show higher tensile strength and stiffness than do fibers with high draw ratios. The mechanical properties of fabrics were found to be greatly affected by the thermal bonding temperature. The tenacity and flexural rigidity of fabrics made from poorly oriented fibers show higher values than those made from highly oriented fibers. The shrinkage of the fabrics was observed to increase with increasing bonding temperature in both machine and cross machine directions. The changes in fabric thickness due to the thermal bonding are considerably lower for poorly oriented fibers.     

Polypropylene composites with fine particles of poly(styrene‐divinylbenzene)

Polypropylene composites were prepared by copolymerizing styrene and divinylbenzene in molten polypropylene by using an extruder. The resultant copolymers are of very fine particles uniformly dispersed in polypropylene phase with no aggregation. The properties of the resultant polypropylene composites were studied: crystalline structure, and mechanical, dynamic viscoelastic, and thermal properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1614–1620, 2000     

Crystallization,mechanical, and fracture behavior of mullite fiber‐reinforced polypropylene nanocomposites

This study describes the reinforcement effect of surface modified mullite fibers on the crystallization, thermal stability, and mechanical properties of polypropylene (PP). The nanocomposites were developed using polypropylene‐grafted‐maleic anhydride (PP‐g‐MA) as compatibilizer with different weight ratios (0.5, 1.0, 1.5, 2.5, 5.0, and 10.0 wt %) of amine functionalized mullite fibers (AMUF) via solution blending method. Chemical grafting of AMUF with PP‐g‐MA resulted in enhanced filler dispersion in the polymer as well as effective filler‐polymer interactions. The dispersion of nanofiller in the polymer matrix was identified using scanning electron microscopy (SEM) elemental mapping and transmission electron microscopy (TEM) analysis. AMUF increased the Young's modulus of PP in the nanocomposites up to a 5 wt % filler content, however, at 10 wt % loading, a decrease in the modulus resulted due to agglomeration of AMUF. The impact strength of PP increased simultaneously with the modulus as a function of AMUF content (up to 5 wt %). The mechanical properties of PP‐AMUF nanocomposites exhibited improved thermal performance as compared to pure PP matrix, thus, confirming the overall potential of the generated composites for a variety of structural applications. The mechanical properties of 5 wt % of AMUF filled PP nanocomposite were also compared with PP nanocomposites generated with unmodified MUF and the results confirmed superior mechanical properties on incorporation of modified filler. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43725.     

Viscoelastic evaluation of effects of fiber size and composition on cellulose‐polypropylene composite of high filler content

The dispersion of filler in resin is an important factor which determines the mobility of a compound in a molder and also the mechanical properties of molded products in wood/plastic composite, especially with high wood filler content. In this report, the dispersion of components in the melt‐mixture of a compound in response to the size of cellulose filler and resin content was examined for compounds with a high content of cellulose in polypropylene by the evaluation of viscoelasticity using a cone rheometer, and the following conclusions were obtained: (1) The viscoelasticity measured by a cone rheometer was dependent on the dispersion state of the compound, and it was confirmed that the presented evaluation method of viscoelasticity affords information relevant to the dispersion state of filler in a compound; (2) On the basis of the viscoelastic evaluation of compounds with different resin contents, a model for the distribution of cellulose and resin is proposed in terms of the tangle of fibers; (3) Viscoelastic analysis showed that cellulose size has an influence on the tangle of fibers; (4) The results of viscoelasticity and mechanical properties of molded products suggested that an important factor determining the tangle of fibers is the average aspect ratio. The proposed analysis of viscoelasticity presents a simple technique for estimating the dispersion state of a compound with high filler content, which is hardly possible by conventional fluid evaluation methods. POLYM. ENG. SCI., 48:168–176, 2008. © 2007 Society of Plastics Engineers     

Characterization of PAN-based nonburning (nonflammable) fibers

In this article, a continuous stabilization process is used to make nonburning (nonflammable) fibers from polyacrylonitrile (PAN) fibers. The effect of the shrinkage behavior and the stretching process of PAN fibers during the stabilization process on the physical properties, morphology, and flammability of the resultant nonourning fibers is studied for the first time. The higher shrinkage of PAN fibers during the continuous stabilization process is found to increase the diameter, the core proportion, and flammability and decrease the Al value, density, mechanical properties, and formation of oriented molecular chains in the resultant nonburning fibers. The effect of the shrinkage behavior of PAN fibers on the fracture surface of the nonburning fibers is also discussed. The nonburning fibers show a fracture structure radiating from the fiber center to the boundary. The structures are composed of small and fine radial strip-layer–like fibrils. Nonburning fibers developed using an optimum stretch process, not only had increased preferred orientation and density, but also had improved mechanical properties. Those fibers also have sufficient nonflammability. © 1993 John Wiley & Sons, Inc.