Inorganic Filler Reinforcement

Recently, hydroxyapatite (HA)-PLA composites have been studied by many scientists, since HA particles can reinforce the material and decrease the degradation rate of PLA [63]. HA (Caio(P04)6(OH)2) is an inorganic part of naturally occurring bone. However, due to the lack of adhesion between PLA and HA filler, an improvement of the interfacial adhesion between the particles and the matrix has become the key challenge in preparing HA-PLA composites. Various methods have been developed to modify HA particles to improve adhesion between HA and PLA [64-67]. The modified HA particles were found to be better dispersed in the PLA matrix than unmodified HA particles, and the adhesion between HA particle and PLA matrix was improved. As a result, the modified HA-PLA composites showed better mechanical properties and thermal stability than the unmodified HA/PLA. 

With talc reinforcements, both crystallization kinetics and crystal microstructure of the polymer (PLA) are significantly altered, for example, the overall crystallinity is reached more quickly due to increase in crystallization kinetics. The degree of crystallinity obtained from DSC measurements increased from 3.6% in neat PLA to 15.4% in PLA-talc composites with a filler content of 7.0 wt% [68]. This in turn can lead to reduced cycle time in injection molding and stiffer materials than neat PLA, when molded under the same conditions. At similar loading level of talc (7.0 wt%), the tensile modulus increased by 15%, while flexural modulus increased by 22% [68]. 

Stable ) -anhydrite II (AH), a specific type of dehydrated gypsum, can be melt blended with PLA to produce composites with high tensile strength and thermal stability and can have potential applications in biodegradable rigid packaging or technical appUcations [69]. 

Hame retardant PLA composites have been prepared by adding PLA with various fillers, flame retardants, and other additives. For example, silane-treated metal hydroxides, combined with other additional fillers (talc, mica), are used to produce domestic appliances with flame retardant properties [70]. 

Carbon black (CB) has been used as a conducting inorganic filler with PLA and a partially miscible blend of PLA 

---

Types of PPS resin include both the crosslinked and linear type. A wide variety of grades is offered. Most of the grades are GF and/or inorganic filler reinforced, but also alloys with PTFE are available as a nonabrasive type, or alloys with elastomers as a high impact type. Tradenames appearing in the references are shown in Table 5.6. 

Silanes are well recognized and very efficient coupling agents extensively used in composites and adhesive formulations. They have been successfully applied in inorganic filler reinforced polymer composites for years and extensively used for glass fibre reinforced polymer composites.In this chapter, only silane treatment is discussed in short which is as follows ... 

A310MX04—glass fiber + inorganic filler reinforced/standard 70 0.30 815... 

AR10E—glass fiber + inorganic filler reinforced/measuring precision, low-temperature molding 70 0.30 810... 

The mbber compound usually requires an inert inorganic filler and small particle sise carbon particle for reinforcement. The mbber polymers vary in inherent tensile strength from very high in the case of natural mbber to almost nonexistent for some synthetic polymers, eg, SBR. The fillers most commonly used for mbber compounds include carbon black, clay, calcium carbonate, siUca, talc (qv), and several other inorganic fillers. 

The final properties depend not only on unstaturated polyester structure but also on a number of other parameters, such as the nature and proportion of unsaturated comonomer, the nature of the initiator, and the experimental conditions of the crosslinking reaction. Moreover, since polyester resins are mainly used as matrices for composite materials, the nature and amount of inorganic fillers and of reinforcing fibers are also of considerable importance. These aspects have been discussed in many reviews and book chapters and are beyond the scope of this chapter.7-9... 

Thermal stability is a crucial factor when polysaccharides are used as reinforcing agents because they suffer from inferior thermal properties compared to inorganic fillers. However, thermogravimetric analysis (TGA) of biocomposites suggested that the degradation temperatures of biocomposites are in close proximity with those of carbon black composites (Table-1). 

This term is applied to a wide variety of materials known chemically as hydrated aluminium silicates, used as inorganic fillers. China clay (kaolin) shows a slight reinforcing effect treated clays show considerably greater reinforcement. 

Silica powder, glass beads and fibres are commonly used for the reinforcement of plastics. The produced composite materials have an increased thermal and mechanical stability, compared to the pure polymeric material. In order to bind the inorganic filler to the organic matrix, silane molecules, with both an inorganic and organic side, are used. The silane may be mixed with the matrix and filler material in the composite preparation, or be coated onto the filler prior to mixing. The application... 

Reinforced polymers with inorganic fillers are known to show greater resistance to radiation than original polymers. Most of organic materials in fusion reactors must be designed to employ organic-matrix composites as it appears very doubtful that conventional polymers can withstand the severe radiation environment for a reasonably long operation time. 

Typically, titanate-treated inorganic fillers or reinforcements are hydrophobic, organophilic, and organofunctional and, therefore, exhibit enhanced dispersibility and bonding with the polymer matrix. When used in filled polymer systems, titanates claim to improve impact strength, exhibit lower viscosity, and enhance the maintenance of mechanical properties during aging. 

---