Degrading fillers

This represents the key aspect of polymer fire retardancy using hydrated fillers, and involves energy changes that occur on the decomposition of the filler, related heat capacity effects, which influence the degradation profile of the polymer and thermal barrier formation resulting from the residue remaining from degraded filler. 

This definition implies the existence of two ways in which a filler performs in a system -through its own properties (e.g., hardness, particle size, particle shape, etc.) and through interactions with the material (the extent of which can vary from strong chemical/physical interaction to almost no interaction at all). This allows us to include all existing fillers (even the degrading fillers which have too large a particle size and too small an interaction to combine with the material in an economical manner)... 

We may now judge the definition based on expectations developed in the discussion in Section 1.1. From a cost reduction analysis, it is evident that if a filler has a large particle size and no strong interaction with its surroundings it will decrease the intrinsic mechanical performance of the material. Such fillers are rightly called degrading fillers . The material density depends not only on the combined densities of the filler and the matrix but also on the interaction with and... 

Solvents are used to carry dissolved or suspended resin and evaporate from the coating after application. Additives in small amounts are used as mildew inhibitors (cuprous compounds), surface-drying additives (manganese and cobalt naphthanates), and barrier-forming additives to protect the resin from heat and UV degradation. Fillers (talc and mica) decrease the permeability of oxygen and water in the coating. 

The most common form of the calcium carbonate filler used in rubber is from the simple grinding of limestone into fine-particle-size filler, usually with an average particle size down to about 2 micrometers in diameter. This type of filler is very inexpensive but can be a degrading filler, deteriorating rubber compound properties. These types of calcium carbonate fillers are generally not used in tire technology or in rubber compounds used to make parts where dynamic properties are important. 

Inorganic phases can be added to the different polymer matrices in the form of micron-sized or nanoscale particles or fibers. The size of the filler particles is an important parameter that affects the mechanical properties of composite materials. This is due to the marked microstructural differences introduced by the micron-sized or nanoscale fillers that contribute towards different interactions between the filler particles and the polymer matrix. In general, the introduction of nanoscale fillers with a desired morphology can increase the mechanical strength and stiffness of the composites in comparison to the properties of the neat polymer. The use of nanoscale degradable fillers such as bioactive glass or... 

Most talcs and diy-groimd calcium carbonates are degrading fillers beeause of their large particles size, although the planar shape of the talc particles eontributes some improvement in reinforcement potential. The soft elays would fall into a class of diluent fillers that do not eontribute reinforeement, yet are not so large that they degrade properties. 

It is most logical to add equally degradable fillers to biodegradable thermoplastic starch. Natural fibers may be added to biopolymers at amounts of 1% or even up to 20-45%, depending on the kind of fibers used The most common fibers have proven to be flax, hemp, coconut, jute, or cotton fibers. To achieve better adhesion between the fiber and the matrix material, the fibers are often modified in acid solutions or in acetone for degreasing and to produce structural changes in the fiber surface [5-9]. 

Fillers. Addition of fillers is not common in polychloroprene latex formulations. Fillers are used to reduce cost and control rheology, solids content and modulus. However, cohesion and adhesion are reduced. Calcium carbonate, clay and silica are some of the fillers than can be added. Alumina trihydrate is often used when resistance to degradation by flame is important. 

Fillers can also be used to promote or enhance the thermal stability of the silicone adhesive. Normal silicone systems can withstand exposure to temperatures of 200 C for long hours without degradation. However, in some applications the silicone must withstand exposure to temperatures of 280 C. This can be achieved by adding thermal stabilizers to the adhesive formulations. These are mainly composed of metal oxides such as iron oxide and cerium oxide, copper organic complexes, or carbon black. The mechanisms by which the thermal stabilization occurs are discussed in terms of radical chemistry. 

Certain fillers are commonly added to protect the urethane backbone from oxidative degradation. Carbon black and titanium dioxide are commonly used in conjunction with antioxidants to protect polyether polyurethanes in exterior adhesive applications that may be exposed to oxygen and light (Fig. 12). 

Modulus Rigid minerals Ductility Ductility produces a more rigid composite. Particulate fillers severely degrade impact strength. 

These fillers are soft and do not dramatically affect mechanical properties. PTFE loadings commonly range from 5 to 20% the others are usually 5% or less. Higher loadings can cause mechanical degradation. 

Many impurities are present in commercial caprolactam which pass into the liquid wastes from PCA manufacture from which caprolactam monomer may be recovered. Also, the products of die thermal degradation of PCA, dyes, lubricants, and other PCA fillers may be contained in the regenerated CL. Identification of die contaminants by IR spectroscopy has led to the detection of lower carboxylic acids, secondary amines, ketones, and esters. Aldehydes and hydroperoxides have been identified by polarography and thin-layer chromatography. 

---