Processing and mechanical properties of organic filler–polypropylene composites

The addition of organic fillers into thermoplastic polymers is an interesting issue, which has had growing consideration and experimentation during the last years. It can give rise to several advantages. First, the cost of these fillers is usually very low. Also, the organic fillers are biodegradable (thus contributing to an improved environmental impact), and finally, some mechanical and thermomechanical properties can be enhanced. In this study, the effect of the addition of different organic fillers on the mechanical properties and processability of an extrusion‐grade polypropylene were investigated. The organic fillers came from natural sources (wood, kenaf, and sago) and were compared to short glass fibers, a widely used inorganic filler. The organic fillers caused enhancements in the rigidity and thermomechanical resistance of the matrix in a way that was rather similar to the one observed for the inorganic filler. A reduction in impact strength was observed for both types of fillers. The use of an adhesion promoter could improve their behavior. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1906–1913, 2005     

Evaluation of mechanical properties of epoxy–guar gum composites

Guar gum (GG) and hydroxypropyl guar gum (HPG) are widely used in a variety of applications ranging from foods, pharmaceutics to mining and explosives. However, there have been very few studies conducted investigating the use of these materials as fillers in polymer composites. GG and HPG were incorporated in an epoxy matrix and the mechanical properties of the resultant composites were determined. The tensile strength, flexural strength, and impact strength of the composites indicate that they provide reinforcement to the composites upto 5–7.5 phr after which there is a rapid decrease in the respective properties. HPG with higher propoxy content was found to provide greater reinforcement due to its increased hydrophobic nature leading to greater polymer–filler interaction. The nature of the filler required that the water absorption and related tests be carried out. The composites showed increased water absorption and also weight loss on exposure to acid and alkali environments, with HPGs showing greater variations when compared with GG, making the composites susceptible to moisture. The study shows that these fillers make an inexpensive, eco‐friendly, and renewable addition to conventional organic and inorganic fillers where the composites do not come into immediate contact with water. POLYM. ENG. SCI., 48:124–132, 2008. © 2007 Society of Plastics Engineers     

Kenaf‐filled biodegradable composites: rheological and mechanical behaviour

Biodegradable polymer composites, typically based on biodegradable polymer matrices and natural‐organic fillers, are gaining rising interest and importance over the last few years. Several natural‐organic fillers can be used but the most widespread so far is wood, in the form of fibres or flour. Alternative cellulosic fillers can ensure advantages in terms of resource utilization and properties of the final composite. In this work, Mater‐Bi^® based biodegradable composites were prepared with two kinds of wood flour, and directly compared with alternative composites containing kenaf fibres. The use of kenaf fibres allowed improved elastic modulus, tensile strength and interaction with the polymer matrix to be obtained, although the filler dispersion was worse. Rheological measurements evidenced higher viscosity and an increasingly elastic behaviour of the melt. Copyright © 2012 Society of Chemical Industry     

Degree of conversion and mechanical properties studies of UDMA based materials for producing dental posts

Nanocomposites are a relatively new material in producing fiber re‐enforced dental posts. The mechanical properties of nanocomposites, which strongly associate with the resin matrix, nanoparticles, and the interface between inorganic fillers and organic matrix, play an important role in determining the quality of dental posts. This work was to investigate the effect of degree of conversion (DC) and silanization of fillers on the mechanical properties of nanocomposties. Experimental Urethane dimethacrylate (UDMA) based dental composites containing unsilanized and silanized SiO₂ filler and various amount of triethylene glycol dimethacrylate (TEGDMA) were prepared at the first step. The DC of composites at different ratios of UDMA/TEGDMA, cure temperature and cure time was measured by Fourier transform infrared spectroscopy. The results showed that DC increases with the increase of TEGDMA content in resin matrix. Both increase of the cure temperature and cure time can cause the increase of DC. The incorporation of fillers, either silanized, or unsilanized filler, caused the decrease of DC. However, composites reinforced with silanized silica showed relatively lower DC, and DC decreased with the increase of silanized filler content. The effect of incorporation of fillers on the mechanical properties was investigated. Silanized silica can effectively improved the flexural strength and flexural modulus of material, and these properties increased with the increase of silica content. Thermomechanical analysis (DMA) provided the similar results to the static property measurements. SEM images of fracture surfaces of specimens from flexural testing revealed the surface morphology is strongly related to the quality of interface between inorganic fillers and organic matrix. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Study of the effect of the concentration,size and surface chemistry of zirconia and silica nanoparticle fillers within an epoxy resin on the bulk properties of the resulting nanocomposites

Epoxy resin nanocomposites were prepared by curing bisphenol‐F with an aliphatic amine in the presence of SiO₂ and ZrO₂ nanoparticles as inorganic fillers. Both types of particles were prepared with diameters of around 10 nm and 70 nm to study size effects in the nanocomposites. The nanoparticles showed a different constitution: while silica was amorphous and spherical in nature, zirconia was crystalline and non‐spherical. Both nanoparticles were surface‐functionalized with novel diethylene‐glycol‐based capping agents to increase the compatibility with the epoxy matrix. The organic functionalities were attached to the nanoparticle surface via phosphonic acid (zirconia) and trialkoxysilane (silica) anchor groups. The homogeneity of the distribution of surface‐modified inorganic nano‐sized fillers in the matrix up to 5.8 vol% in case of silica and 2.34 vol% in case of zirconia was determined by small‐angle X‐ray scattering and transmission electron microscopy. Mechanical properties such as hardness and storage modulus were increased with increasing filler content while thermal stability of the obtained materials was nearly unaffected after incorporation of nanoparticles. Copyright © 2011 Society of Chemical Industry     

Valorization of waste thermoset material as a filler in thermoplastic: Mechanical properties of phenolic molding compound waste‐filled PP composites

As most thermoset material, phenolic molding compound (PMC) wastes are an environmental problem. Very few recycling solutions have been proposed so far for this type of material. A mechanical recycling method to valorize these materials is proposed in this work. It relies on the use of phenolic waste as filler in thermoplastic. Such phenolic filler can increase mechanical properties (tensile, flexural) of the matrix, and be used in substitution of traditional particulate fillers such as calcium carbonate or talc. In this study, several morphological parameters influencing the final mechanical properties of a PMC‐filled polypropylene (PP) micro‐composite are studied, such as filler loading rate, particles size distribution of the filler, and interfacial adhesion between the filler and the matrix. Some structural parameters are also studied and linked with mechanical properties, such as dispersion of the filler and crystallinity of the matrix. Finally, the properties of PMC‐filled PP are compared with CaCO₃‐ and talc‐filled PP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45849.     

Biobased Polyurethane Composite Foams Reinforced with Plum Stones and Silanized Plum Stones

In the following study, ground plum stones and silanized ground plum stones were used as natural fillers for novel polyurethane (PUR) composite foams. The impact of 1, 2, and 5 wt.% of fillers on the cellular structure, foaming parameters, and mechanical, thermomechanical, and thermal properties of produced foams were assessed. The results showed that the silanization process leads to acquiring fillers with a smoother surface compared to unmodified filler. The results also showed that the morphology of the obtained materials is affected by the type and content of filler. Moreover, the modified PUR foams showed improved properties. For example, compared with the reference foam (PUR_REF), the foam with the addition of 1 wt.% of unmodified plum filler showed better mechanical properties, such as higher compressive strength (~8% improvement) and better flexural strength (~6% improvement). The addition of silanized plum filler improved the thermal stability and hydrophobic character of PUR foams. This work shows the relationship between the mechanical, thermal, and application properties of the obtained PUR composites depending on the modification of the filler used during synthesis.     

Studies on High Density Polyethylene Reinforced with Phosphate Ore Particles: Thermal,Rheological, Mechanical and Morphological Properties

Calcareous phosphate ore can be utilized as a cost-effective alternate to other inorganic fillers for polymer-based composites. In this study, composites of high-density polyethylene and phosphate rock ore particles were prepared by melt blending and injection-molding techniques. The thermomechanical, rheological, and mechanical properties of these composites were studied to investigate the effect of filler loading on their functionality. The reduction in the crystallinity of phosphate ore/high-density polyethylene composites was observed compared to that of the neat high-density polyethylene. The relative crystallinity of the neat high-density polyethylene decreases from 53 to 30% by the addition of 2.5–15 wt% of ore, respectively. Comparison of the linear dynamic viscoelasticity for the neat high-density polyethylene and the ore-filled composites shows t a monotonic increase in both storage modulus and loss modulus with the increasing frequency. The viscoelastic behavior at high frequencies remains unaffected. However, at lower frequencies, both G′ and G″ exhibit diminished frequency dependence. It was also observed that higher filler content decreased the tensile and impact strength, whereas the Young's modulus of the composites increased. The morphological analysis shows relatively weak interaction between the fillers and the matrix because of agglomeration which in turn adversely affects the mechanical properties of the composites.     

Magnetite‐functionalized graphene/poly(styrene‐butadiene‐styrene) composites: thermal and mechanical properties

Advanced polymer composites containing organic–inorganic fillers are gaining increasing attention due to their multifunctional applications. In this work, poly(styrene‐butadiene‐styrene) (SBS) composites containing magnetite‐functionalized graphene (FG) were prepared by a dissolution ? dispersion ? precipitation solution method. Evidently, through morphology studies, amounts of FG were well distributed in the SBS matrix. Improvements in neat SBS properties with respect to FG loading in terms of thermal stability, creep recovery and mechanical properties are presented. As expected, the addition of FG improved the thermal stability and mechanical properties of the composites. The yield strength and Young's modulus of the SBS increased by 66% and 146% at 5 wt% filler loading which can be attributed to the reinforcing nature of FG. Similarly, an increase in the storage and loss modulus of the composites showed a reinforcement effect of the filler even at low concentration. The results also showed the significant role of FG in improving the creep and recovery performance of the SBS copolymer. Creep deformation decreased with filler loading but increased with temperature. © 2017 Society of Chemical Industry     

Modification of silica nanoparticles and their application in UDMA dental polymeric composites

Advancements in nanocomposites are highly dependent on the compatibility between the organic matrix and inorganic fillers, and the dispersion level of fillers throughout the matrix. Silane coupling agents are widely used to change the chemical structure of particles' surface in order to improve their compatibility and dispersion properties of particles. SiO₂ nanoparticles were modified by ζ potential, turbidity, and relative viscosity. The results indicate that the stability and dispersion degree in organic solvents have been improved after the modification. In addition, the mechanical properties of composites with modified silica were also studied, which indicated that, after the predispersion of particles in organic media, the mechanical properties of materials could be improved, even at low filler content. POLYM. COMPOS., 28:198–207, 2007. © 2007 Society of Plastics Engineers     

混合基质膜在碳捕集领域的研究进展

膜分离技术因其低成本、低能耗及高效率的优势被认为是最具有前景的碳捕集技术之一。混合基质膜结合了有机材料与无机材料两方面的优势,是同时提升渗透性和选择性的有效手段。本文从气体在混合基质膜中的传递机制出发,以常见的无孔型与多孔型无机填料为基础,总结了近年来混合基质膜在二氧化碳捕集领域的研究进展,介绍了不同类型的填料在高分子基质中所起到的微结构调节作用,并着重阐述了在混合基质膜制备过程中无机填料与高分子基质之间所存在的相容性问题及其解决方法。最后,提出混合基质膜应在继续致力于填料结构设计、填料分散、构效关系等方面的同时,加强二维填料、微囊填料和促进传递机制等方面的研究。     

Influence of the filler material on the thermal stability of one‐component moisture‐curing polyurethane adhesives

Filler materials are part and parcel for the adjustment of adhesives, in particular, their rheological and mechanical properties. Furthermore, the thermal stability of adhesives can be positively influenced by the addition of an expedient filler, with inorganic types common practice in most cases. In this study, one‐component moisture‐curing polyurethane adhesives for engineered wood products based on isocyanate prepolymers with different polymer‐filled polyether polyols were investigated with regard to the filler's potential to increase the thermal stability of bonded wood joints. The property changes due to the addition of fillers were determined by means of mechanical tests on bonded wood joints and on pure adhesive films at different temperatures up to 200°C. Additional analyses by atomic force and environmental scanning electron microscopy advanced the understanding of the effects of the filler. The tested organic fillers, styrene acrylonitrile, a polyurea dispersion, and polyamide, caused increases in the cohesive strength and stiffness over the whole temperature range. However, the selected filler type was hardly important with regard to the tensile shear strength of the bonded wood joints at high temperatures, although the tensile strength and Young's modulus of the adhesive films differed over a wide range. Prepolymers with a lower initial strength and stiffness resulted in worse cohesion, in particular, at high temperatures. This disadvantage, however, could be compensated by means of the filler material. Ultimately, the addition of filler material resulted in optimized adhesive properties only in a well‐balanced combination with the prepolymer used. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal analysis of novel underfill materials with optimum processing characteristics

This work encompasses the development of low‐viscosity cyclic oligomer underfill formulations that cure without heat evolution. Boron nitride, silica‐coated aluminum nitride, and alumina ceramic powders were used as fillers in cyclic butylene terephthalate oligomer melts. The melts were heated with a suitable catalyst to induce polymerization. The effects of the filler type and composition on the thermal and mechanical properties of the poly(butylene terephthalate)/filler composites were examined with differential scanning calorimetry, temperature‐modulated differential scanning calorimetry, thermogravimetric analysis, thermomechanical analysis, and dynamic mechanical analysis. Scanning electron microscopy was employed to elucidate the morphology of these composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1300–1307, 2005     

Effect of the microscopic morphology of a filler on its dispersion in a PI matrix: Calculation and analysis

The preparation of crosslinked polyimide (PI) composites via a blending technique is reported. Different kinds of organic or inorganic silicon-based nanofillers have been used for this purpose. A comparison is made between carefully chosen pairs of fillers, the choice depending on the compatibility of the crosslinked PI with the filler, to study the effects of the crosslinked PI matrix structure and fillers with different micromorphology. The dispersion of the filler is characterized with SEM as uniformly dispersed or gelled. It is found that with different micromorphology of filler, the PI matrix can be loaded with different mass fractions of filler, and the point at which gelation occurs is not the same. In order to study this behavior, these fillers are subjected to a quadratic mean equation calculation and analysis. Compared to pure PI, all obtained crosslinked composites have a higher glass-transition temperature and a lower dielectric constant. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46875.     

Thermal,morphological, and X‐ray study of polymer‐clay nanocomposites

Synthesis and characterization of polymer nanocomposites consisting of diglycidyl ether of bisphenol‐A with inorganic as well as organically modified nanosized clay fillers, for example, vermiculites and montmorillonite, obtained from trade, are studied. Confirmations of intercalation and exfoliation characteristics of these fillers into the cured epoxy resin matrix have been investigated by wide angle X‐ray diffraction studies. Scanning electron microscopy and atomic force microscopy techniques have been adopted to assess the nature of filler dispersion, size of the agglomerates, and the polymer‐filler adhesion. While significant improvement in the mechanical properties (i.e., tensile, flexural strength, and modulus) has been observed, the thermo‐oxidative stability of the composites measured by thermogravimetric analysis showed only marginal improvement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhancement of basic properties of polysaccharide-based composites with organic and inorganic fillers: A review

The global shift towards biodegradable composite has made polysaccharides a green alternative to synthetic polymers owing to their biocompatibility, sustainability, and ecofriendly biomaterials. Despite the limitations in their applications, many studies have validated the effectiveness of using organic or inorganic fillers to ameliorate their mechanical and barrier properties. However, the understanding of how polysaccharides matrix is enhanced by fillers is still inexplicit. Hence, it is imperative to review the effects of using inorganic and organic fillers in some prominent polysaccharides in terms of mechanical and water barrier properties while taking into account the function of filler morphology, size and loading. Although it is intricate to indicate the best filler used for each of the polysaccharides matrices, this review served as a “food for thought” on the established works of enhanced-matrix filler combinations aimed at improving the mechanical and barrier properties of biodegradable films based on neutral or negatively charged polysaccharides-based composite films for potential application in food packaging, agriculture, biomedicine and constructions sector. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47251.     

Investigation of the Influence of Fillers on the Properties of Poly(vinyl acetate) Adhesives

The properties of poly(vinyl acetate) compositions prepared as potential wood adhesives were investigated. The paper presents the results of the influence of various kinds of inorganic fillers based on calcium carbonate and alumino-silicate and an organic filler, starch, on the adhesive composition properties. The comparison among rheological behavior of the adhesive dispersions concerning the specific role of fillers were made. Mechanical and relaxation properties of the adhesive films could reveal the effect of filler characteristics on the polymer matrix. The significant influences of particle size distribution and specific surface area on the poly(vinyl acetate) adhesive composition were determined, along with other filler characteristics.     

Investigation of the Influence of Fillers on the Properties of Poly(vinyl acetate) Adhesives

The properties of poly(vinyl acetate) compositions prepared as potential wood adhesives were investigated. The paper presents the results of the influence of various kinds of inorganic fillers based on calcium carbonate and alumino-silicate and an organic filler, starch, on the adhesive composition properties. The comparison among rheological behavior of the adhesive dispersions concerning the specific role of fillers were made. Mechanical and relaxation properties of the adhesive films could reveal the effect of filler characteristics on the polymer matrix. The significant influences of particle size distribution and specific surface area on the poly(vinyl acetate) adhesive composition were determined, along with other filler characteristics.     

Influence of silanized low‐dimensional carbon nanofillers on mechanical,thermomechanical, and crystallization behaviors of poly(L‐lactic acid) composites—A comparative study

Composites were investigated regarding the comparison of multi‐walled carbon nanotubes (MWCNTs) with exfoliated graphene(EG) in poly(L‐lactic acid) (PLLA) and the effect of silane‐treated carbon nanofillers on properties of PLLA composites. Solution blending method was used to prepare PLLA composites at a filler content of 0.5 wt %. Fourier transform infrared spectroscopy and X‐ray photoelectron spectra results indicated the attachment of silane molecules on the surface of these nanofillers. It was found that the addition of these nanofillers greatly enhanced the mechanical, thermomechanical, and crystallization behaviors of PLLA due to the heterogeneous nucleation effect. Moreover, the silane‐treated fillers further enhanced the breaking elongation moderately (although the materials are still brittle), modulus and thermal property of the nanocomposites, without sacrificing the tensile strength, compared with the pristine nanocomposites. On the other hand, composites reinforced with MWCNTs and EG perform almost the same mechanical property. And EG outperformed MWCNTs in thermomechanical properties of composites when being used as the reinforcement of PLLA. Conversely, composites reinforced with MWCNTs showed better crystallization properties than those reinforced with EG. Interestingly, no significant changes were observed for the crystallization properties of PLLA composites when MWCNTs and EG had been treated by silane coupling agent. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1194‐1202, 2013     

The effect of mineral surface nature on the mechanical properties of mineral-filled polypropylene composites

The adhesion between the polymer matrix and the inorganic filler particles are the goal of various and tremendous studies. This issue is still occupying a big part of the researchers thinking to find a proper solution, however, its difficulty returns to different factors playing roles in it. Among these factors are the filler surface, i.e., hydrophobicity and hydrophilicity, functional groups on the surface, as well as mineral filler particle size distribution, and particle shape. Therefore, in the current study, the difference in mechanical properties for two mineral fillers; namely, silica and talc, differs in their surface and rheology properties were investigated. Results showed that the difference in the mechanical properties of the same matrix when the inorganic filler is different either in type or loading. Talc showed the better results in terms of Young’s modulus and impact strength, where silica showed higher values in terms of yield stress. Moreover, both minerals addition resulted drop in all strain measures, yet silica showed relatively higher measures than talc, but the relative difference measures between the two minerals decrease with increasing their percentage of additions. In brief, the introduction of inorganic fillers to polypropylene (PP) increases toughness, stiffness and strength of the mineral-filled PP end-products.