The influence of filler treatment on the properties of TPU/PP blends: I. Thermal properties and stability

Commercially available organosilane (3‐glycidoxypropyltrimethoxysilane (GPTMS)) coupling agent was used to treat talc in order to improve the affinity relative between the filler and the polymer in composites as well as filler and polymer in the thermoplastic polyurethane/polypropylene (TPU/PP) blends (talc content was 5 wt%). The talc particles were first modified with GPTMS and then introduced into TPU, PP as well as TPU/PP blends with different weight ratios of polymers using blending method and subsequently injection molded in a hydraulic press. The aim was to report the effect of silane coupling agent on the thermal and morphological properties of talc filled composites and blends. The results showed that the thermal properties of the TPU, PP composites and TPU/PP blends were improved with the addition of silane treated talc (higher melting (T_m), crystallization (T_c) temperatures and degree of crystallinity (χ_c)). The glass transition temperature (T_g) obtained by dynamic mechanical analysis (DMA) of the TPU soft segments in TPU/PP blends increased with the addition of untreated and silane treated talc due to lower mobility of the soft segments in TPU and better miscibility of TPU and PP. TPU/PP blends with the silane treated talc show better thermal stability than the TPU/PP blends with untreated talc. POLYM. ENG. SCI., 55:1920–1930, 2015. © 2014 Society of Plastics Engineers     

Influence of talc genesis and particle surface on the crystallization kinetics of polypropylene/talc composites

Talc is a laminar silicate, considered as an excellent nucleating agent for polypropylene (PP) crystallization. However, properties of PP/talc composites depend on the morphology, size, and surface of mineral particles. In this sense, talc from several ores, having different morphology, imparts specific characteristics on these materials. Also, taking into account that PP‐talc adhesion is not necessarily good due to the apolar character of PP, talc surface has been modified in order to increase this parameter. In this work, the effects of talc genesis, geomorphologic aspects, and particle surface characteristics on crystallization of PP/talc composites are analyzed. Isothermal crystallization of PP/talc composites was studied by using differential scanning calorimetry, based on Avrami model. The final crystalline morphology of talc‐filled PP was analyzed by means optical microscopy. The results show that the blocky talc morphology favors even more the crystallization compared to the platy one, at the same particle size. Taking into account the surface treatment studied in this work, the talc surface is made hydrophobic and the particle delamination is favored. As a consequence, so‐modified talc is very effective in increasing the crystallization temperature of PP and the nuclei number that grow during the crystallization with respect to the untreated talc. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Study of dynamically cured PP/MAH‐g‐PP/talc/epoxy composites

In the present study, an epoxy resin was dynamically cured in a polypropylene (PP)/maleic anhydride–grafted PP (MAH‐g‐PP)/talc matrix to prepare dynamically cured PP/MAH‐g‐PP/talc/epoxy composites. An increase in the torque at equilibrium showed that epoxy resin in the PP/MAH‐g‐PP/talc composites had been cured by 2‐ethylene‐4‐methane‐imidazole. Scanning electron microscopy analysis showed that MAH‐g‐PP and an epoxy resin had effectively increased the interaction adhesion between PP and the talc in the PP/talc composites. Dynamic curing of the epoxy resin further increased the interaction adhesion. The dynamically cured PP/MAH‐g‐PP/talc/epoxy composites had higher crystallization peaks than did the PP/talc composites. Thermogravimetric analysis showed that the addition of MAH‐g‐PP and the epoxy resin into the PP/talc composites caused an obvious improvement in the thermal stability. The dynamically cured PP/MAH‐g‐PP/talc/epoxy composites had the best thermal stability of all the PP/talc composites. The PP/MAH‐g‐PP/talc/epoxy composites had better mechanical properties than did the PP/MAH‐g‐PP/talc composites, and the dynamically cured PP/MAH‐g‐PP/talc/epoxy composites had the best mechanical properties of all the PP/talc composites, which can be attributed to the better interaction adhesion between the PP and the talc. The suitable content of epoxy resin in the composites was about 5 wt %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

滑石粉、碳酸钙填充聚丙烯复合材料等温结晶行为的对比研究

用熔融共混法分别制备了聚丙烯（PP）/滑石粉、PP/碳酸钙(CaCO3)复合材料,用差示扫描量热法(DSC)考察了PP及其复合材料的等温结晶过程,并用Avrami方程对纯PP及PP/滑石粉、PP/CaCO3复合材料的等温结晶动力学行为进行了分析。结果表明,PP、PP/滑石粉及PP/CaCO3复合材料的Avrami指数均小于2.3,存在均相成核和异相成核双重成核机理,且其结晶速率常数和结晶速率均随着结晶温度的升高而减小;在该体系中,滑石粉对基体PP有明显的异相成核作用,使PP的结晶速率加快、结晶时间缩短;而CaCO3则没有明显的异相成核作用。     

聚丙烯／滑石粉复合材料的等温结晶动力学

用差示扫描量热法(DSC)研究聚丙烯(PP)及PP／滑石粉复合材料的等温结晶过程。用Avrami方程全面分析PP／滑石粉的等温结晶动力学，并由此获得相关的动力学参数；用Kissinger方程研究滑石粉对PP／滑石粉复合材料结晶活化能的影响。研究表明：加入滑石粉后明显提高PP／滑石粉复合材料的结晶速率和结晶度；证明滑石粉能促进PP材料的结晶，并在PP结晶过程中起到异相成核作用。PP／滑石粉复合材料的等温结晶过程属于典型的异相成核机理。     

Crosslinkable polypropylene composites made by the introduction of silane moieties

Silane‐crosslinkable polypropylene (PP) composites containing calcium carbonate (CaCO₃) as a filler have been investigated. The melt grafting of vinyl trimethoxysilane to PP with dicumyl peroxide (DCP) as a radical initiator is demonstrated. The thermal and mechanical properties of the crosslinkable products are also discussed. The results show that two reactions, that is, silane grafting and PP degradation, take place in parallel. The extents of silane grafting and PP degradation strongly depend on the reaction temperature, grafting formulation, and amount of the filler in the systems. Increasing the DCP concentration (up to 0.05 wt %) leads to an increase in the grafting degree. However, when the concentration of radicals is over a certain degree, the dominant reaction is PP chain scission. This results in a drastic decrease in the polymer viscosity. In systems containing both silane and CaCO₃, the viscosity of the polymer is higher than that of a grafted sample without CaCO₃ addition; in other words, the effect of the filler on the polymer viscosity compensates for the effect caused by PP degradation. Differential scanning calorimetry results show that the crystallization starts earlier for grafted samples. The percentage of the crystallinity of grafted PP is higher than that of the pure polymer. The incorporated silane does not have a strong effect on the mobility of the PP chains, as revealed by dynamic mechanical analysis. In comparison with ungrafted composites, the silane‐crosslinkable products show higher tensile stress and modulus. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1476–1483, 2005     

Surface‐modified talc particles by acetoxy groups grafting: Effects on mechanical properties of polypropylene/talc composites

This article deals with the effects of surface‐modified talc particles on mechanical properties of polypropylene (PP)/talc composites. These materials were prepared by injection molding of PP blended with different concentrations of nontreated and treated talc, under the same processing conditions. Differential thermal calorimetry and scanning electron microscopy were used to assess thermal properties and morphology of the final composites. The reinforcing effect of talc, either treated or nontreated surface, on PP is analyzed through the tensile properties as a function of the mineral content (0–10 wt%). Morphological structure of composites revealed that the talc treatment improved the particle dispersion and distribution within the PP matrix and enhanced the interfacial PP‐talc adhesion. The mechanical properties of these composites, especially the Young modulus, tensile strength and elongation at break, were found to be improved respect to PP‐untreated talc ones. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Effect of silane coupling agents on the properties of pine fibers/polypropylene composites

In the present work, PP‐based composites, reinforced with surface modified pine fibers, have been prepared. The surface of the fibers has been treated with several silane derivatives bearing specific functionalities. ? NH₂, ? SH, long aliphatic chain, and methacrylic group were chosen as functionalities of the silane derivatives for evaluating the compatibility with the polymer matrix. Mechanical analysis, contact angle and XPS spectra, SEM microscopy, and water uptake measurements were used as characterization techniques for evaluating the nature of composites. XPS as well as contact angle measurements demonstrated that pine fibers and silane derivatives were effectively coupled. The mechanical analysis showed an increase in Young's and flexural moduli, by 12% and 130% respectively, and nonsignificant changes in the ultimate tensile strength were noted after surface modification. Water uptake measurements revealed a low water absorption by the materials, always lower than 2 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3706–3717, 2007     

Effects of vinyltrimethoxy silane on thermal properties and dynamic mechanical properties of polypropylene–wood flour composites

The viability of vinyltrimethoxy silane was investigated as a coupling agent for the manufacture of wood–plastic composites (WPC). The effect of silane pretreatment of the wood flour on the thermal and the dynamic mechanical properties and thermal degradation properties of the composites were studied. Moreover, the effect of organosilane on the properties of composites was compared with the effect of maleated polypropylene (MAPP). DSC studies indicated that the wood flour acts as a PP-nucleating agent, increasing the PP crystallization rate. In general, pretreatment with small amounts of silane improved this behavior in all the WPCs studied. Thermal degradation studies of the WPCs indicated that the presence of wood flour delayed degradation of the PP. Silane pretreatment of the wood flour augmented this effect, though without significantly affecting cellulose degradation. Studies of dynamic mechanical properties revealed that the wood flour (at up to 30 wt %) increased storage modulus values with respect to those of pure PP; in WPCs with a higher wood flour amount, there was no additional increase in storage modulus. Pretreatment of the wood flour with silane basically had no effect on the dynamic mechanical properties of the WPC. These results show that with small amounts of vinyltrimethoxy silane similar properties to the MAPP are reached. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Orientation in composite of polypropylene and talc

X-ray diffraction and microscopical investigation of test samples prepared by injection molding from composites of isotactic polypropylene with talc revealed a preferred orientation of the talc and polypropylene matrix. Contrary to the situation in polypropylene alone, the preferred orientation in polypropylene–talc composites survived melting and a new crystallization. Crystallization rate measurements confirmed the nucleation activity of talc for polypropylene crystallization.     

The effects of epoxy resin nano particles on shrinkage behavior and thermal stability of talc-filled polypropylene

Reactive mixing of epoxy resin with polypropylene (PP) and talc were carried out on a co-rotating twin screw extruder. The prepared samples were injection molded to produce the specimens for the measurements of the shrinkage rate. The microstructure of the composites was studied by scanning electron microscope and correlated to the orientation of filler particles and shrinkage behavior. The nano size epoxy resin particles are obvious in SEM images both in the PP matrix and also adhered on the talc powders. The shrinkage measurement revealed that, using epoxy resin in the formulations, leads to a reduction of 14.3% in the shrinkage rates which is isotropic in both flow and transverse directions. The oven aging test at 100 °C showed a significant effect of epoxy resin on increasing the thermal stability of composites. The stabilization effect of epoxy resin was more pronounced at higher epoxy resin content. It is believed that the metallic impurities on the surface of talc powder deactivated by the functional groups of epoxy resin and the degradation reaction rate decreased.     

Mechanical,flow, and morphological properties of talc‐ and kaolin‐filled polypropylene hybrid composites

Polypropylene (PP) hybrid composites have been produced by compounding two types of mineral fillers, viz., talc and kaolin with PP copolymer using a twin screw extruder. The PP hybrid composite was injection‐molded into dumbbell specimen for tensile, flexural, and impact properties characterizations. MFI and SEM studies were used to characterize the flow and morphological properties of the PP hybrid composites. The result shows that most of the hybrid composites showed a significant decrease in flow, tensile, flexural, and impact properties compared with the single filler‐filled PP composites. However, a hybridization effect was seen for the PPT20K10 hybrid composites, through the synergistic coalescence of positive characteristics from 20 wt % of talc and 10 wt % of kaolin. This hybrid formulation have given an economically advantageous material with the mechanical properties (tensile, flexural, and impact) comparable to those of the talc‐filled PP composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 434–441, 2007     

滑石粉表面改性填充PP复合体系研究

采用钛酸酯、铝酸酯、硼酸酯及硅烷偶联剂,对滑石粉进行表面改性处理,通过接触角、活化率、吸油量和红外谱图等试验方法对改性效果进行了评定;检测滑石粉填充PP复合体系的力学性能,进一步说明了偶联剂种类和填料粒径对复合材料力学性能的影响。结果表明:活化改性后,填料表面的极性和官能团均发生了变化;硅烷和钛酸酯偶联剂改性滑石粉效果较好,1250目滑石粉填充体系的综合力学性能最优。     

Intercalated structure of polypropylene/in situ polymerization-modified talc composites via melt compounding

Talc was modified with methyl methacrylate (MMA) or butyl acrylate (BA) via in situ polymerization. The talc/isotactic polypropylene (PP) composites with nano-sized intercalated structure were formed by melt compounding of PP with the modified talc. The results showed that the talc layers were partially delaminated, aligned along the flow direction, and uniformly dispersed in the PP matrix. The thickness of the PMMA-modified talc layers in the PP matrix was in the range 80-240 nm, while the PBA-modified talc was even thinner. PMMA or PBA macromolecules attached on the surface of talc layers hindered the crystallization of the PP component. Moreover, the aligned pristine talc layers promoted the orientation of the PP crystals. However, the extent of PP crystal orientation decreased in the presence of PMMA or PBA-modified talc.     

Effect of silane‐grafted polypropylene on the mechanical properties and crystallization behavior of talc/polypropylene composites

Talc‐filled polypropylene (PP) composites coupled with silane‐grafted polypropylene (PP‐g‐Si) were prepared. Effect of PP‐g‐Si on the mechanical properties, crystallization, and melting behavior of PP composites was investigated. Compared with the uncoupled composites, the mechanical properties of Talc/PP composites coupled with a small amount of PP‐g‐Si were increased to some extent. Meanwhile, PP‐g‐Si can promote crystallization rate and increase crystallization temperature of PP in the composites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2974–2977, 2000     

Sulfuric acid treatment of ground tire rubber and its effect on the mechanical and thermal properties of polypropylene composites

Ground tire rubber (GTR) was modified by sulfuric acid in order to improve its compatibility with and reinforcement of a polypropylene (PP) matrix. Polymer composites PP/GTR were prepared by melt mixing at different concentrations, with a maximum of 50 wt % of GTR. Studies by Fourier transform infrared spectroscopy (FTIR), surface specific area by BET (Brunauer, Emmett, and Teller), and scanning electron microscopy were used to characterize the untreated GTR and treated GTR, while the mechanical and thermal properties of the PP/GTR composites were assessed to understand how the surface treatment of GTR affected the mechanical and thermal properties of the composite PP/GTR. FTIR revealed the presence of sulfonic groups on the surface of sulfuric acid–treated GTR, and BET analyses showed an increase of about 625% in the specific surface area as a result of the high porosity produced by the treatment. In all composites containing treated GTR, a higher Young's modulus was obtained than for composites containing untreated GTR. Particularly, an increase of about 275% in the Young's modulus was obtained in composites with treated GTR (40 wt %) against that containing untreated GTR. However, a more significant reduction of the elongation at break was observed in composites containing treated GTR than in those containing untreated GTR. Also, an increase of the crystallization temperature of PP as a function of GTR was observed by differential scanning calorimetry, but the crystallinity of the composites was reduced by the addition of both untreated and treated GTR. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44858.     

PP/滑石粉导热绝缘复合材料的制备与性能研究

采用聚丙烯(PP)为基体,不同粒径滑石粉为填料,通过双螺杆挤出机挤出制备导热绝缘的PP滑石粉复合材料。在滑石粉用量为3O%的条件下,探讨了粒径分别为3.6,6,12,30,50 μm的滑石粉对PP猾石粉复合材料的热导率、体积电阻率、力学性能和结晶性能的影响。结果表明,随着滑石粉粒径的减小,复合材料的拉伸强度和弯曲强度呈先增大后减小的变化趋势,而其热导率则呈先减小后增大的变化趋势。填充粒径为12μm的滑石粉时,复合材料的拉伸强度和弯曲强度达到最大值,分别为29.92MPa和52.58MPa,比纯PP分别提高了5.5%和12.8%。填充粒径为50μm的滑石粉时,复合材料的热导率最大,达到0.3237W/(m*K),比纯PP提高了32.7%。填充1:l的粒径为12μm和30μm滑石粉混合物时,PP复合材料的热导率为0.3184W/(m*K),高于相应的填充单一粒径滑石粉的PP复合材料。此外,所制备的PP滑石粉复合材料的体积电阻率均大于10^8Ω*cm     

原位聚合法制备聚乳酸/滑石粉复合材料

用硅烷偶联剂对超细滑石粉（Talc）改性后,采用原位聚合法制备出不同质量分数的聚乳酸/滑石粉（PLA/Talc）复合材料,并采用傅里叶变换红外光谱仪（FTIR）、扫描电子显微镜（SEM）、核磁共振波谱仪（NMR）、热失重分析仪（TG）、偏光显微镜（POM）等方法对复合材料进行表征。结果表明,Talc粒子在复合材料中均匀分散;PLA/含量3 %Talc的复合材料的拉伸强度、冲击强度分别比纯PLA增加了102.56 %和47.83 %,复合材料的热稳定性也明显提高;Talc促进了PLA结晶性能,在一定程度上提高其力学性能,复合材料降解速率比于纯PLA明显加快。     

Enhancement of mechanical properties of high modulus polypropylene grade for multilayer sewage pipes applications

Advances in technology have provided fresh generations of stiff polypropylene block copolymers for gravity sewerage applications. The aim of this study is to further enhance the stiffness of these materials through the incorporation of inorganic fillers. In this study, three talc filled PP and one glass fiber filled PP composites were characterized in order to be used as a middle layer in a three-layer sewage pipe. The obtained results showed an increase of approximately more than 100% and 250% in tensile and flexural moduli by the use of 30%–50 wt% talc-filled PP and 30 wt.% glass fiber-filled PP, respectively. This high increase in the rigidity of the material would allow manufacturing pipes with improving ring stiffness. Composites filled with 30 wt% talc or glass fiber showed good filler-matrix interaction and good filler distribution and dispersion. However, reduced filler-matrix interaction was observed in the case of the composite filled with 50 wt% talc. In addition, the use of Differential Scanning Calorimetry analysis revealed that the addition of fillers enhanced the crystallization temperature of the polypropylene matrix. Furthermore, Thermogravimetric Analysis showed that the high modulus PP grade retained its thermal stability in the various composites.     

纳米SiO2粒子对PP结晶行为的影响

通过X-射线光电子能谱（XPS）对经偶联剂处理的纳米SiO2粒子（简称烷基化SiO2纳米粒子）和聚甲基丙烯酸甲酯（PMMA）接枝包覆SiO2纳米粒子（简称SiO2-g-PMMA复合纳米粒子）的表面组成进行分析。将纳米SiO2粒子，烷基化SiO2纳米粒子，复合纳米粒子分别与基体PP复合制备复合材料，通过DSC，WAXD和TEM等测试方法详细研究了PP/SiO2复合材料的结晶行为与力学性能，结果发现：纳米SiO2粒子与烷基化SiO2纳米粒子并不改变基体PP的结晶形态，而复合纳米粒子诱发了基体PP的β晶型结晶，复合纳米粒子比较均匀地分散于PP基体中，对复合材料的力学性能有较大的改善。