Thermal properties and flame retardance of Al(OH)3/polypropylene composites modified by polypropylene grafting with acrylic acid

The effect of polypropylene grafting with acrylic acid, PP‐g‐AA (FPP), on crystallization and melting behavior, thermal degradation, and limiting oxygen index of Al(OH)₃/PP composites were investigated. The results indicated that crystallization temperature of PP shifted to high temperature with increasing content of Al(OH)₃ because of the interfacial heterogeneous nucleation of Al(OH)₃ and further increased by the addition of FPP and with increasing FPP content because of the improvement of the dispersion of Al(OH)₃ in PP matrix and the increase in the nucleating sites of Al(OH)₃. With adding Al(OH)₃ and increasing the content of Al(OH)₃, limiting oxygen index values of composites increased and further improved by adding FPP. This is attributed to the presence of an interfacial interaction between FPP and Al(OH)₃. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2679–2686, 2001     

Physical and mechanical properties of Al(OH)3/polypropylene composites modified by in situ‐functionalized polypropylene

Al(OH)₃/polypropylene (PP) composites modified by in situ‐functionalized polypropylene (FPP) were prepared by a one‐step melt‐extrusion process. The effect of in situ FPP on the crystallization and melting behavior, melt‐flow index, limiting oxygen index, thermal degradation, mechanical properties, and fracture morphology of Al(OH)₃/PP composites was studied. Formation of in situ FPP resulted in a decreased crystallization temperature and melting point of PP in the composites, an increased melt‐flow index, and improved tensile and flexural strengths of Al(OH)₃/PP composites, whereas the thermal degradation behavior and limiting oxygen index was not been influenced. The impact strength of the Al(OH)₃/PP composites modified by in situ FPP depended upon the content of the initiator, dicumyl peroxide, and the monomer, acrylic acid. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2850–2857, 2002; DOI 10.1002/app.10269     

Mechanical properties of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

Modified Mg(OH)₂/polypropylene (PP) composites were prepared by the addition of functionalized polypropylene (FPP); and acrylic acid (AA) and by the formation of in situ FPP. The effects of the addition of FPP and AA and the formation of in situ FPP on the mechanical properties of Mg(OH)₂/PP composites were investigated. Experimental results indicated that the addition of Mg(OH)₂ markedly reduced the mechanical properties of PP. The extent of reduction in notch impact strength of PP was higher than that in flexural strength and tensile strength. However, tensile modulus and flexural modulus increased with increased Mg(OH)₂ content. The addition of FPP facilitated the improvement in the flexural strength and tensile strength of Mg(OH)₂/PP composites. The higher the Mg(OH)₂ content was, the more significant the effect of FPP was. The incorporation of AA resulted in further increased mechanical properties, in particular the flexural strength, tensile strength, and notch impact strength of Mg(OH)₂/PP composites containing high levels of Mg(OH)₂. It not only improved mechanical properties but also increased the flame retardance of Mg(OH)₂/PP composites. Although the mechanical properties of composites modified by the formation of in situ FPP were lower than those of composites modified by only the addition of AA in the absence of diamylperoxide, the mechanical properties did not decline with increased Mg(OH)₂ content. Moreover, the mechanical properties increased with increasing AA content. The addition of an oxidation resistant did not influence the mechanical properties of the modified Mg(OH)₂/PP composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2139–2147, 2003     

Interfacial interaction in AI(OH)3/polypropylene composites modified by insitu‐functionalized polypropylene

To investigate the interfacial interaction of AI(OH)₃/polypropylene (PP) composites modified by in situ‐functionalized polypropylene (FPP), AI(OH)₃/polypropylene (PP) composites containing a low AI(OH)₃ content, modified by in situ‐grafted acrylic acid, were prepared by a one‐step melt‐extrusion process. The effect of in situ FPP on the crystallization and melting behavior, crystalline morphology of the composites, and interfacial interaction between the filler and PP was investigated. The crystallization and melting behavior and crystalline morphology of PP in the composites depended upon the interfacial physical [heterogeneous nucleation of AI(OH)₃; cocrystallization and compabilitization of PP with in situ FPP] and the interfacial chemical interaction between both the components in the composites. FTIR results indicated that there exists a chemical reaction between AI(OH)₃ and in situ FPP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 110–120, 2002; DOI 10.1002/app.10270     

Physical properties of PP-g-AA prepared by melt extrusion and its effects on mechanical properties of PP

Polypropylene grafting with acrylic acid, PP-g-AA (FPP), was prepared by melt extrusion. The physical properties of FPP and effect of FPP on mechanical properties of polypropylene (PP) were investigated. Experimental results showed that an increase in the grafting rate of FPP resulted in an increase in the crystallization peak temperature, melt peak temperature, and degree of crystallization of PP. Double melting peaks were observed for OPP prepared by adding dicumyl peroxide into PP and FPP with low grafting rate due to the degradation of PP. As the grafting rate was increased, the double melt peaks converted into a single melt peak. It is suggest that FPP with higher grafting rate resulted in enhanced nucleation and crystallization ability of PP. The grafting of AA onto the PP chain improved the thermal stability and mechanical properties of PP materials. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2609–2616, 2001     

Crystallization and melt behavior of Mg(OH)2/PP composites modified by functionalized polypropylene

The crystallization and melting behavior of Mg(OH)₂/PP composites modified by the addition of functionalized polypropylene (FPP) or acrylic acid (AA) and the formation of in situ FPP were investigated by DSC. The results indicated that addition of FPP increased the crystallization temperatures of PP because of the nucleation effect of FPP. The formation of in situ FPP resulted in a reduced crystallization rate, melting point, and degree of crystallization attributed to the decreased regularity of the PP chain. For Mg(OH)₂/PP composites, the addition of Mg(OH)₂ increased the crystallization temperatures of PP resulting from a heterogeneous nucleation effect of Mg(OH)₂. The addition of FPP into Mg(OH)₂/PP composites further enhanced the crystallization temperatures of PP. It is suggested that there is an activation of FPP to the heterogeneous nucleation effect on the Mg(OH)₂ surface. The addition of AA also increased the crystallization temperatures of PP in Mg(OH)₂/PP composites, although the crystallization temperature of PP was not influenced by the AA content, which is explained by the heterogeneous nucleation effect of the Mg(OH)₂ surface activated by FPP and AA. A synergistic effect on the crystallization of PP in Mg(OH)₂/PP composites further increased the crystallization temperatures of PP. However, The crystallization temperatures of Mg(OH)₂/PP composites modified by in situ FPP were lower than those of Mg(OH)₂/PP composites modified by addition of either FPP or AA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3610–3621, 2004     

原位形成FPP偶联Al(OH)3/PP中的界面相互作用研究

制备低含量Al(OH)3填充PP复合材料[Al(OH)3/PP]，研究原位形成的官能团化聚丙烯（FPP）在Al(OH)3/PP中的结晶、熔融行为，结晶形态，以及与各组分间的相互作用。研究认为，在复合材料中存在Al(OH)3与FPP间的化学作用，FPP与PP的相容与共结晶作用，Al(OH)3表面异相诱导成核作用，FPP对Al(OH)3表面异相诱导成核作用的活化作用等，从而改善了Al(OH)3/PP的物理与力学性能。     

Crystallization and melt behavior of magnesium hydroxide/polypropylene composites modified by functionalized polypropylene

The crystallization and melting behavior of Mg(OH)₂/polypropylene (PP) composites modified by the addition of functionalized polypropylene (FPP) or acrylic acid (AA) and the formation of in situ FPP were investigated by DSC. The results indicated that addition of FPP increased crystallization temperatures of PP attributed to the nucleation effect of FPP. The formation of in situ FPP resulted in a reduced crystallization rate, melting point, and degree of crystallization because of the decreased regularity of the PP chain. For the Mg(OH)₂/PP composites, addition of Mg(OH)₂ increased the crystallization temperatures of PP attributed to a heterogeneous nucleation effect of Mg(OH)₂. Addition of FPP into Mg(OH)₂/PP composites further enhanced the crystallization temperatures of PP. It is suggested that there is an activation of FPP to the heterogeneous nucleation effect of Mg(OH)₂ surface. The addition of AA also increased the crystallization temperatures of PP in Mg(OH)₂/PP composites, but crystallization temperatures of PP were not influenced by the AA content, a phenomenon explained by the heterogeneous nucleation effect of the Mg(OH)₂ surface activated by FPP and AA. A synergistic effect on crystallization of PP in Mg(OH)₂/PP composites further increased the crystallization temperatures of PP. However, the crystallization temperatures of Mg(OH)₂/PP composites modified by in situ FPP were lower than those of Mg(OH)₂/PP composites modified by the addition of FPP or AA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3899–3908, 2004     

Flammability and mechanical properties of Al(OH)3 and BaSO4 filled polypropylene

The flammability and mechanical properties of Al(OH)₃/BaSO₄/polypropylene (PP) composites were investigated. The flow, morphological, and thermal properties were also analyzed by melt flow index (MFI), Scanning electron microscopy (SEM), and Differential scanning calorimeter (DSC) studies, respectively. Total filler amount was fixed at 30 wt % to optimize physical characteristics of the composites. In addition to the flame retardant filler Al(OH)₃, BaSO₄ was used to balance the reduction in impact strength at high filler loadings. Substantial improvement in mechanical properties was achieved for 20 wt % Al(OH)₃ (i.e., 10 wt % BaSO₄) composition while maximum flammability resistance was obtained for 30 wt % Al(OH)₃ composite. SEM studies showed that the presence of aggregated Al(OH)₃ particles led to low interfacial adhesion between them and PP matrix ending up with decreased mechanical strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fracture morphology of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

The morphologies of the fracture surface under impact and flexural testing of Mg(OH)₂/Polypropylene (PP) composites and their modified composites were investigated by scanning electron microscopy. Experimental results indicated that addition of functionalized polypropylene (FPP) and acrylic acid (AA) and the formation of in situ FPP changed the fracture morphologies of Mg(OH)₂/PP composites. We believe that addition of these modifiers improved the interfacial interaction and enhanced the interface adhesion between the particle and the matrix in Mg(OH)₂/PP composites. The degree of improvement was more significant in Mg(OH)₂/PP composites modified by the formation of in situ FPP. At low Mg(OH)₂ content, 2 phr AA exhibited a marked effect, but at high Mg(OH)₂ content, 4 phr AA afforded good effect. Due to the improved interface adhesion by interface interactions the fracture mechanism transformed from interface debonded fracture into a matrix fracture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2148–2159, 2003     

官能团化聚丙烯改性Mg(OH)2阻燃PP的热稳定性

制备了官能团化聚丙烯(FPP)、反应性单体AA和在引发剂存在下从改性氢氧化镁阻燃PP材料，用TGA研究了添加FPP、AA和原位形成FPP对PP、阻燃PP的热稳定性的影响以及抗氧剂对热稳定性的影响。结果表明Mg(OH)2的加入使PP初始分解温度提高，分解速率降低，热稳定性提高。FPP的加入使高含量Mg(OH)2阻燃PP热稳定性进一步提高。DCP存在下从改性有利于提高阻燃PP热稳定性，尤其高用量Mg(OH)2阻燃PP。在抗氧剂和DCP同时存在下，高用量AA改性阻燃PP具有更高的稳定性。     

Physical and mechanical properties of nano-CaCO3/PP composites modified with acrylic acid

Abstract

Nano-CaCO₃/polypropylene (PP) composites modified by the reactive monomer acrylic acid (AA) with or without the initiator dicumyl peroxide (DCP) were prepared using a two-step method. The effects of nano-CaCO₃ and AA on the physical and mechanical properties of nano-CaCO₃/PP composites were investigated. Differential scanning calorimetry (DSC) results showed that the incorporation of nano-CaCO₃ increased the crystallisation temperature as a result of the heterogeneous nucleation effect of nano-CaCO₃ on PP, and induced the formation of β phase PP. The addition of AA further increased the crystallisation temperature of PP and the intensity of β phase PP. The mechanical tests indicated that nano-CaCO₃ could simultaneously reinforce and toughen PP, and the mechanical properties of nano-CaCO₃/PP composites were higher than those of micro-CaCO₃/PP composites. In addition, incorporation of AA further increased the mechanical properties of the composites. In the presence of DCP, a small amount of AA could increase markedly the mechanical properties of nano-CaCO₃/PP composites.     

Mechanical and thermal properties of chitosan‐filled polypropylene composites: The effect of acrylic acid

The mechanical properties, morphology, and thermal properties of chitosan‐filled polypropylene (PP) composites have been studied. The effect of the chemical modification of chitosan by acrylic acid treatment was also investigated. Results showed that the tensile strength and elongation at break decreased but that the Young's modulus of the composites increased with increasing filler loading. Chemical modification of chitosan with acrylic acid improved the tensile strength and Young's modulus of the composites but reduced the elongation at break. Thermogravimetric analysis showed that the addition of chitosan improved the thermal stability of the PP/chitosan composites as compared to that of neat PP. Chemical modification of chitosan had a positive effect on the thermal stability of the composites. This change was attributed to improvement of the interfacial adhesion between the chitosan and PP matrix due to formation of a covalent bond between chitosan and acrylic acid. Meanwhile, differential scanning calorimetric analysis showed that the addition of filler did not significantly change the melting temperature (T_m) of the PP/chitosan composites. The degree of crystallinity of the composites decreased with the addition of chitosan. At a similar chitosan loading, the chemically treated PP/chitosan composites exhibited higher crystallinity than the untreated composites and exhibited slightly increased T_m. A scanning electron microscopy study of the tensile fracture surface of chemically treated PP/chitosan composites indicated that the presence of acrylic acid increased the interfacial interaction between chitosan and the polypropylene matrix. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

A study of the flame‐retardant properties of polypropylene/Al(OH)3/Mg(OH)2 composites

Polymeric materials are used extensively, but their applications are limited because many of them are flammable. Therefore ways to make them flame retardant have received much attention. In this work, polypropylene (PP) was used as the matrix resin, aluminium hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂) as flame‐retardant additives and zinc borate (ZB) as a flame‐retardant synergist. PP/Al(OH)₃/Mg(OH)₂ and PP/Al(OH)₃/Mg(OH)₂/ZB flame‐retardant composites were prepared with a twin‐screw extruder. The flame‐retardant properties, i.e. oxygen index (OI), burning velocity and smoke density, of the composites were measured. The results showed that OI increased with an increase of the filler content and decreased with an increase of the filler particle diameter. The burning velocity decreased with an increase of the filler content, while it first increased and then decreased with an increase of the filler particle diameter. The smoke density decreased with an increase of the filler content and increased with an increase of the filler particle diameter. There was a flame‐retardant synergy between Al(OH)₃/Mg(OH)₂ and ZB in the composites, and the smoke suppression effect was marked when ZB was added. Copyright © 2009 Society of Chemical Industry     

Conifer fibers as reinforcing materials for polypropylene‐based composites

Conifer fibers were used to reinforce polypropylene (PP). To improve the compatibility between the conifer fibers and the PP matrix, the fibers were either grafted with maleated PP (MAPP), treated by adding MAPP, or mixed with ethylene/propylene/diene terpolymer (EPDM). The treatments resulted in improved processing, as well as improvements in the thermal and mechanical properties of the resultant composites compared with the composites filled with untreated conifer fibers. Moreover, MAPP grafting and MAPP treating displayed more obvious benefits than EPDM treating in terms of thermal properties, processing flowability, and tensile strength improvements. EPDM treating also produced more significant benefits than either MAPP grafting or MAPP treating in terms of impact strength and tensile elongation improvements. These improvements were attributed to surface coating of the fibers when EPDM was used. In addition, the effect of the concentration of the conifer fibers on the properties of the composites and the difference between MAPP grafting and MAPP treating were evaluated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2833–2841, 2001     

PP-g-AA对PP/云母增容作用的研究

研究了聚丙烯(PP)与云母共混时,添加第3组分PP—g—AA对PP/云母共混体系的影响。用扫描电镜观察共混体系中云母的分布状况。研究结果表明,加入第3组分增加了共混体系的相容性,使拉伸强度和抗冲击强度均明显提高。     

Effect of matrix graft modification using acrylic acid on the PP/Mg(OH)2 composites and its possible mechanism

The matrix graft modification using an acrylic acid (AAc) was employed on the polypropylene/Mg(OH)₂ flame-retardant composite. The graft modification of PP matrix was carried out via an in-situ reactive extrusion by a twin-screw extruder. The tensile strength of the composites was analyzed using an equation developed by Pukanszky from which both matrix tensile strength σ₀ and interfacial adhesion strength were found to be increased. The enhancement of σ₀ is due to the intermolecular crosslinking of PP by AAc grafting. This crosslinking causes increases of tensile strength, Young’s modulus, impact resistance, and thermal resistance, but decreases the elongation at break of the composites.     

Effect of compatibilizing agents on the mechanical property of rice husk flour as nano-potential filler in polypropylene biocomposite

In this article, rice husk flour filler/polypropylene (RH/PP) composites with different ratios of the filler were prepared without and with maleated PP, which was used as a compatibilizer. The RH filler in the RH/PP composites was treated with acid and alkali, and their mechanical properties were measured. The mechanical properties were improved with the addition of the compatibilizer. In this study, grafting of maleic anhydride (MA) onto PP with different ratios of benzoyl peroxide (BPO) and MA was prepared. Infrared analysis showed characteristic bands at 1786 and 1863 cm⁻¹ for the grafted sample (maleated PP). Also, from chemical titration, the optimum MA and BPO contents were 4 and 1 part per hundred parts (php of polymer), respectively. The results showed that the morphology of the grafted sample was a flat with coarse surface, and that of the composite clearly elucidated that the interfacial bonding between RH and PP was enhanced by the presence of the compatibilizer. Thermal stability of the grafted PP was enhanced by the grafting process. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Performance evaluation of synthesized acrylic acid grafted polypropylene within CaCO3/polypropylene composites

A polymeric coupling agent acrylic acid grafted polypropylene (AAgPP) was synthesized and its efficiency in CaCO₃/PP composite was investigated. The grafting of acrylic acid monomer (AA) onto polypropylene was performed using an internal mixer. The effect of peroxyde, acrylic acid monomer content, temperature and RPM was studied. A grafting reaction between the polypropylene and the acrylic acid was evidenced through FTIR, UV, DSC and MFI testing. The highest grafting yield was obtained at 0.85 phr peroxide and 5 phr acrylic acid. The selected mixing temperature was 200°C, the rotor speed 150 rpm and the residence time 5 min. The obtained coupling agent (AAgPP) was used with 30 wt% CaCO₃ filled polypropylene. Strong interactions with the composite were observed. The effect of increasing the coupling agent content on Izod impact and tensile properties was investigated. A maximum in the above properties is attained at 15 wt% AAgPP. The most important effect is clearly shown in the Izod test. In fact, a threefold increase has been observed for either notched and untoched specimen. The 15 wt% AAgPP is considered to be a critical concentration for the composite considered. This corresonds to maximum interactions occurring between the matrix and the filler. SEM analysis clearly shows strong interactions between the filler and the matrix in the presence of acrylic acid grafted polypropylene. This is another proof of the efficiency of the synthesized AAgPP as a potential coupling agent for CaCO₃ filled PP.     

Parameters regulating interfacial and mechanical properties of short glass fiber reinforced polypropylene

The performance of thermoplastic composites is known to depend on the intrinsic properties of the two composite components, the quality of the fiber–matrix interface, and the crystalline properties of their matrix. The objective of this work is to characterize the effect of the addition of modified polypropylene (PP) and silane coupling agent on the mechanical and interfacial properties of short fiber reinforced PP composites. Differential scanning calorimetry (DSC), single fiber composite fragmentation tests (SFC), and mechanical testing are used to understand the different parameters regulating the interfacial properties of composites. No influence of the modified PP on the level of crystallinity is observed. Some differences in the size of the spherulites are observed for acrylic acid grafted PP (PP‐g‐AA). Those samples also show lower mechanical properties in spite of good interfacial interactions. Maleic anhydride grafted PP (PP‐g‐MAh) leads to better mechanical performances than PP‐g‐AA. A high MAh content PP‐g‐MAh grade with low viscosity is the best polymeric additive used in the present work. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2047–2060, 2000