Use of silane agents and poly(propylene‐g‐maleic anhydride) copolymer as adhesion promoters in glass fiber/polypropylene composites

Two organofunctional silanes and a copolymer were used to increase the interfacial adhesion in glass fiber polypropylene (PP) reinforced composites. The performance of the coupling agents was investigated by means of mechanical property measurements, scanning electron microscopy (SEM), and dynamic mechanical analysis. The increased adhesion between the glass fibers and PP matrix observed with SEM resulted in an improvement of the mechanical and dynamic mechanical properties of the composites. Coupling achieved with the copolymer poly(propylene‐g‐maleic anhydride) (PP‐g‐MA) proved to be the most successful compared with 3‐aminopropyltrimethoxysilane and 3‐aminopropyltriethoxysilane. The combination of PP‐g‐MA with the silanes resulted in further property improvements because of the ability of the MA groups to react with the amino groups of the silanes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 701–709, 2001     

Effect of filler content and surface treatment on the tensile properties of glass‐bead‐filled polypropylene composites

The tensile properties of polypropylene (PP) filled with two A‐glass beads with the same size, PP/3000 (glass bead surface pretreated with a silane coupling agent) and PP/3000U (no surface pretreatment), have been measured by using an Instron materials testing machine at room temperature, to identify the effects of the filler surface pretreatment and its content on the tensile properties of these composites. The results show that the Young's modulus E_c of the composites increases non‐linearly with increasing volume fraction of glass beads ϕ_f, while the tensile yield strength σ_yc and tensile stress at break σ_bc of the composites decrease with an increase of ϕ_f, in the ϕ_f range 0–30%. Furthermore, the values of E_c and σ_bc of the PP/3000 system are somewhat higher than those of the PP/3000U system under the same test conditions, but this is in contrast to the tensile strain at break ε_bc and tensile fracture energy E_bc, especially at higher ϕ_f values. Good agreement is shown between the measured tensile strength and the predicted value by using an equation proposed in previous work. In addition, ε_bc and E_bc reach maximum values at ϕ_f = 25% for both systems. This indicates that there is a brittle–ductile transition for the composites in tension. © 2000 Society of Chemical Industry     

长玻璃纤维增强聚丙烯复合材料的韧性

以玻璃纤维和聚丙烯为原料,制备了长玻璃纤维增强聚丙烯(LFT-PP)复合材料,研究了基体韧性、纤维长度和界面相容剂对LFT-PP韧性的影响。结果表明LFT-PP韧性随基体韧性增加而增加;当玻璃纤维长度从2.06mm增加到4.66mm时,LFT-PP的悬臂梁缺口冲击强度从134.4J/m提高到238.0J/m,增加了约80%;添加界面改性剂降低了LFT-PP悬臂梁缺口冲击强度,从311.4J/m降为181.8J/m。     

The effect of atmospheric plasma treatment of recycled carbon fiber at different plasma powers on recycled carbon fiber and its polypropylene composites

To increase the mechanical properties of recycled carbon fiber-reinforced polypropylene (PP) composites, recycled carbon fibers (RCF) were subjected to atmospheric plasma treatment at different plasma powers (100, 200, and 300 W). The changes on surface topography and roughness of RCF were examined by atomic force microscopy. Plasma treatment of RCF increased the roughness value of RCF. The variation of surface elemental compositions and tensile strength of RCF were determined by using X-ray photoelectron spectroscopy and tensile test, respectively. Plasma-treated RCF-reinforced PP composites were fabricated using high speed thermo-kinetic mixer. Plasma treatment of RCF at 100 W increased the tensile and flexural strength values of RCF-reinforced PP composites considerably by 17 and 11%, respectively. However, plasma treatment of RCF at higher plasma powers (200 W and 300 W) decreased tensile and flexural strength values of composites because of the etching of RCF. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47131.     

Role of silanes in adhesion. Part II. Dynamic mechanical properties of silane-treated glass fiber/polyester composites

—Glass fiber/unsaturated polyester composites, prepared by impregnating glass braid with varying thickness coatings (from 200 Å up to 1600 Å thick) of polyester resin, were tested with a DuPont Dynamic Mechanical Analyzer. The effects of the polyester resin thickness and silane treatments on the dynamic mechanical properties of the composites were evaluated. The results are supported by Fourier transform infrared spectroscopy of the composite materials. It is shown that both the concentration and the organo-functional group of the silane coupling agent influence the damping, storage, and loss moduli as well as the glass transition temperature (T_g) of the matrix resin in the closest vicinity to the glass/resin bondline. In the absence of a silane inner layer, a low T_g, 'soft' boundary layer exists due to inhibition of the polyester resin cure by the glass surface. It is noted that a reactive silane, such as γ-methacryloxypropyltrimethoxysilane, promotes the formation of a 'soft' or 'rigid' (high T_g) boundary layer, depending on the concentration of the silane in the treating solution. On the other hand, a non-reactive silane, such as methyltrimethoxysilane, produces a 'rigid' interphase in the entire range of concentrations of the silane solution. An attempt was made to correlate the dynamic mechanical properties of the boundary layer with the fiber/polymer interfacial shear strength. Upon pretreatment of glass fibers with silane coupling agents, the relative magnitude of the loss modulus, E", and the nature of the boundary layer (T_g) seem to be better indicators of efficient stress transfer from the polymer to the glass fiber in the composite system than tan δ. Efficient stress transfer is characterized by a low value of E" and 'soft' boundary layers. The results suggest that the mere presence of glass/polyester chemical bonding is insufficient to ensure effective stress transfer. A strong bond results from the synergistic effect of glass/silane/polymer chemical bonding and a 'soft' boundary layer.     

Use of silanes and copolymers as adhesion promoters in glass fiber/polyethylene composites

Two organofunctional silanes and three functionalized copolymers were used as adhesion promoters in glass fiber/polyethylene‐reinforced composites. The performance of the coupling agents was investigated by mechanical property measurements, scanning electron microscopy, and dynamic mechanical analysis. Coupling achieved with the poly(ethylene‐g‐maleic anhydride) copolymer proved to be the most successful compared with the other copolymers (ethylene/vinyl alcohol, ethylene/acrylic acid) and silane agents (γ‐methacryloxypropyltrimethoxy, cationic styryl). The combined coupling performance of the silanes and copolymers examined in this study appears to be controlled by the coupling performance of the copolymer. Effective coupling was reflected in increased mechanical properties. Increased fiber/matrix adhesion is not always associated with effective coupling because structural changes occurring at the interface region can result in a deterioration of the material property. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2877–2888, 2001     

Influence of the recycled glass fibers from nonmetals of waste printed circuit boards on properties and reinforcing mechanism of polypropylene composites

The feasibility of reusing the recycled glass fibers (RGF) from nonmetals of waste printed circuit boards in polypropylene (PP) composites is studied by mechanical properties, vicat softening temperature and heat distortion temperature. The influence of RGF on reinforcing mechanism of the composites is watched under scanning electron microscopy (SEM) in situ tensile test. The results show that the mechanical and thermal properties of the RGF/PP composites can be significantly improved by adding the RGF into PP. In situ SEM observation results show that the RGF are the excellent supporting bodies and can effectively lead to mass microcracks. Crack initiation, propagation, and fiber breakage dissipate tremendous energy. Therefore, the mechanical properties are reinforced. All the above results indicate that the reuse of RGF in the PP composites represents a promising way for closing the recycling loop and realizing the high added value utilization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

PP-g-Si对PP／GF的增容作用

制备了硅烷接枝聚丙烯(PP-g-Si)，研究了PP-g-Si作为聚丙烯／玻纤(PP／GF)复合体系的界面相容剂对界面结合和力学性能的影响，并与马来酸酐接枝聚丙烯(PP-g-MAH)的增容效果进行了比较。结果表明，PP-g-Si对PP／GF体系有增容作用，不仅可以改善PP／GF复合体系的拉伸强度，而且可以改善其韧性。硅烷接枝聚丙烯可以降低PP／GF复合体系的最大扭矩。玻纤的加入可以提高聚丙烯的热变形温度，硅烷接枝聚丙烯对PP／GF复合体系的热变形温度有稍微改善。扫描电镜观察表明，玻纤与基体间具有强有力的界面结合，硅烷接枝聚丙烯的增容效果优于马来酸酐接枝聚丙烯。     

Influence of functionalized polyolefin on interfacial adhesion of glass fiber‐reinforced polypropylene

Several types of functionalized polyolefins, grafted with maleic anhydride, were synthesized and used to modify the surface of fiberglass in reinforced polypropylene composites. The influence of maleated polyolefin, matrix, and compounding conditions on the interfacial bonding strength of composite were studied by measuring interfacial shear strength. The results showed that strong interactions, e.g., chemical bonding, were formed between maleated polyolefin and fiber surface. When the modified fibers were compounded with polypropylene, firm entanglements of molecular chain were formed due to the segmental interdiffusion between maleated polyolefin and matrix polypropylene. As a result, the degree of fiber‐matrix adhesion was improved. The extent of such improvement depended on the grafting degree, chain length of maleated polyolefin, and the compatibility between maleated polyolefin and matrix resin. At the same time, the compounding temperature and the cooling procedure affected the interfacial adhesion too. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1359–1365, 2000     

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     

Structures and properties of low‐shrinkage polypropylene composites

The high shrinkage and the low impact strength severely limit the applications of the isotactic polypropylene (iPP). In this article, we studied the shrinkage, microstructure, and mechanical properties of the composites consisted of iPP, short glass fiber (GF), maleic anhydride grafted polypropylene (MPP), maleic anhydride grafted polypropylene/polyolefin elastomer (MPPPOE) or composite toughening agents (CTAs). The results show that the shrinkage of the composite with 40% GF reduces to 0.0754% (24 h) and 0.0893(48 h), respectively, under room temperature, which is far lower than the shrinkage [1.782% (24 h) and 1.821% (48 h)] of the pure iPP. For the composite of PP/GF/MPPPOE/CTAs (55/30/5/10), the tensile strength increases to 65.53 MPa (33.8 MPa for pure iPP), the tensile modulus is 1445 MPa which is 136% higher than pure iPP, and the izod impact strength reaches 22.72 kJ/m² (only 5.28 kJ/m² for pure iPP). Not only the scale stability of iPP is remarkably improved, but also the comprehensive mechanical properties are enhanced drastically. This work may generate potential opportunities for iPP in those applications demanding high scale stability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44275.     

玻璃纤维增强聚丙烯复合材料的研究进展

综述了长、短玻璃纤维增强聚丙烯（GFRPP）复合材料的研究进展，总结出纤维含量、纤维长度及分布、纤维取向及分布、纤维与基体界面结合和改性等均为影响GFRPP性能的因素。在复合材料中，长度大于临界长度的玻璃纤维对材料的强度才有作用；增强玻璃纤维与聚丙烯的界面结合也是提高增强效果的有效手段。     

汽车外饰用再生聚丙烯材料性能研究

本研究在原生聚丙烯（VPP）中加入不同比例的消费后回收聚丙烯（PCR⁃PP）,制得一系列不同再生含量（0、10 %、30 %、50 %）的再生聚丙烯（RPP）材料,进而研究再生材料添加比例对RPP材料的拉伸、弯曲、压缩、冲击等力学性能的影响规律,并以差示扫描量热（DSC）、熔体流动速率等热学性能检测方法及扫描电子显微镜显微分析手段探索RPP材料性能衰减的内在机理。结果表明,随着PCR⁃PP含量的提升,RPP材料的抗老化性能变差,结晶性能和加工性能逐步降低,造成产品各项强度性能及塑性表现出不同程度的下降趋势。当PCR⁃PP含量≤30 %时,RPP材料的各项强度及塑性保持率均维持在90 %以上,此时如果在产品中针对性地辅以补强剂,RPP材料的物理性能可以满足车规级使用要求。此研究结果为RPP材料在汽车行业的广泛应用提供了重要数据支撑。     

汽车保险杠用再生聚丙烯材料的性能研究

为验证再生聚丙烯（RPP）应用于汽车保险杠的可行性,研究了不同比例消费后回收聚丙烯（PCR⁃PP）的用量对RPP的冲击、拉伸、弯曲、压缩等力学性能的影响规律,并对RPP的热性能和拉伸断口形貌进行了分析。结果表明,在PCR⁃PP含量占比分别为0、10 %、30 %和50 %的情况下,随着PCR⁃PP添加量的增加,RPP力学性能总体呈现缓慢下降趋势,断裂伸长率从467 %下降至210 %,下降最为明显;当添加10 %PCR⁃PP时,材料的冲击、拉伸、弯曲性能变化较小,均可满足应用于保险杠材料的性能要求。     

玻璃纤维增强聚丙烯复合材料研究进展

对玻璃纤维增强聚丙烯复合材料的研究近况进行了简单介绍,对其界面改性、增韧增强、结晶行为、长切玻璃纤维增强、材料性能及成型工艺条件进行了较详细的讨论,并对该复合材料今后的研究进行了展望。     

Chemical grafting of metallocene‐catalyzed functional polypropylene copolymer on glass substrates through surface modification

This work deals with surface modification of soda‐lime glass slides which, by itself, does not have hydroxyl groups at the surface. So, a glass surface pretreatment is needed, to create hydroxyl groups onto it, before carrying out the polypropylene (PP) grafting reaction. Different acid/base pretreatments were performed to develop an adequate concentration of superficial hydroxyl groups. Subsequently, a metallocenic polymerization (propylene‐α olefin graft reaction, catalyzed by EtInd₂ZrCl₂/methylaluminoxane), was carried out to provide graft‐PP chains chemically linked to the glass surface. The surface so modified can be further functionalized and tailored for different applications, including polymer composites. The pretreatment conditions that best preserved homogeneity and caused less damage to the glass surface resulted from a step of contact with dilute HF/NH₄F buffer, a washing step with distilled water, and a final exposure to KOH. After the propylene copolymerization was performed, part of the graft copolymer formed remained chemically bonded to the glass slide surface. The presence of grafted PP at the surface was confirmed by SEM, FTIR, and EDAX characterization, even after the physically adsorbed polymer was excluded by a severe solvent extraction treatment. From these results, the copolymerization of a hydroxy α‐olefin, grafted on a MAO‐pretreated glass slide, is foreseen as a possible way to graft polymers onto inorganic solids. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Silane primers for epoxy adhesives

A rapid screening test is described for measuring the water resistance of epoxy bonds to glass and metals. Thin films of epoxy, cured on glass or metal coupons, were soaked in water until the films could be loosened with a razor blade. Penetration of water to the interface was almost immediate, magnifying the differences in times to failure between primed and unprimed surfaces. Comparative qualitative ratings are given for standard silane primers with typical epoxy formulations. Additional modifications of primers are suggested for optimizing the water resistance of the bonds. Test results show that proper formulation of silane adhesion promoters may provide very water-resistant bonds between epoxies and metals or glass.     

Effect of hybridization and compatibilization on the mechanical properties of recycled polypropylene‐hemp composites

Hemp fibers and particles, with different sizes and contents, were used to make hybrid composites based on recycled polypropylene (PP). In particular, the effect of maleated polypropylene (MAPP) addition on the morphology and mechanical properties is reported. The results show that better adhesion is obtained with MAPP addition. In general, fiber content and size had a substantial effect on the tensile, flexural, torsion, and impact properties of the resulting composites. Although, adding MAPP to the samples improved the impact strength of the composites, the values were always lower than neat PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Microscopical damage mechanisms in glass fiber reinforced polypropylene

The damage mechanisms in two structurally different glass mat reinforced polypropylene materials were studied. In situ microscopy was applied during the tensile testing of thin notched sheets. Micrographs of the damage processes in the two materials are presented. The major points of damage initiation were transversely oriented fibers and fiber bundles. In the swirled mat material, cracks grew along the fiber bundles; crack formation and growth was relatively unaffected by macroscopical stress concentration. In the short fiber material, crack growth occurred at the notch. In both materials the maximum load was determined by the fibers oriented in the longitudinal direction. The different damage mechanisms were interpreted in terms of damage zone size. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1319–1327, 1998