Clay Loading and Dispersion Effects on the Rheological Properties of Unsaturated Polyester Nanocomposites
The objective of this work is to characterize the influence of clay loading and dispersion effects on the rheological properties of unsaturated polyester composites. Toughened unsaturated polyester (UPE) composites were synthesized by the blending of delaminated clay with unsaturated polyester. Rheological behavior is shown to be strongly influenced by clay loading and the extent of clay dispersion in the polymer matrix. Transition from liquid-like behavior to solid-like behavior shifts to significantly higher solids loading at higher shear rates which may be due to the alignment of the particles in the direction of flow at high shear rates. SEM micrographs are used to display the extent of intercalation and dispersion of the clay within the polymer matrix.
INTRODUCTION AND BACKGROUND
1.1 Definition
Polymer/clay nanocomposites display a change in composition and structure over a nanometer length scale and have been shown to present considerable property enhancements relative to conventionally scaled composites. Layered silicates dispersed as a reinforcing phase in an engineering polymer matrix are one of the most important of such “hybrid organic-inorganic nanocomposites” [1]. Polymer-layered silicate nanocomposites containing low levels of exfoliated clays, such as montmorillonite and vermiculite have a structure consisting of platelets with at least one dimension in the nanometer range. One of the most important features of polymeric materials is the possibility of controlling their macroscopic physical properties by tailored manipulation of their structures at a nanoscopic scale. To influence the interactions that govern the mechanical properties of polymers, specific nanoscopic scale reinforcement is efficient and beneficial. For example, montmorillonite clay provides such reinforcement through the interaction of polymer chains with the charged surfaced of clay lamellae [2].
The use of organoclays as precursors to nanocomposite formation has been extended into various polymer systems including epoxies, polyurethanes, polyimides, nitrile rubber, polyesters, polypropylene, polystyrene and polysiloxanes, among others. Even a variety of inorganic materials, such as glass fibers, talc, calcium carbonate, and clay minerals, have been successfully used as additives or reinforcements to improve the various properties of polymers [3-10].
1.2 Structure
The optimal properties of nanocomposites arise as the clay nanolayers are uniformly dispersed (exfoliated) in the polymer matrix, as opposed to being aggregated or phase separated as tactoids or simply intercalated. As nanolayer exfoliation becomes achieved, there is a trend in the improvement in desired properties that is manifested as an increase in tensile properties, enhancement of barrier properties, a decrease in solvent uptake, an increase in thermal stability and flame retardance, among others [11-12].
For best performance in flame retardancy without deteriorating the mechanical properties (tensile strength), the optimum ratio of APP/MEL was found to be 3:1 with loading of 30%. Besides this the incorporation APP and/or APP and MEL into composites promoted the char formation and correspondingly improved the thermal stability [79].
Service life The effect of fillers on polymers is that they are very beneficial because they don’t get ruined for a long time. Glass fillers are the most commonly used fillers in polymers. This is because they last longer and their service life is longer.
A group of polymer chains can be organised together in a fiber. How the polymer chains are put together is important, as it improves the properties of the material. The flexibility, strength and stiffness of Kevlar fiber, is dependent on the orientation of the polymer chains. Kevlar fiber is an arrangement of molecules, orientated parallel to each other. This orderly, untangled arrangement of molecules is described as a “Crystalline Structure”. A manufacturing process known as ‘Spinning’ is needed to achieve this Crystallinity structure. Spinning is a process that involves forcing the liquefied polymer solution through a ‘die’ (small holes).
Hydrocolloid dressings have been utilized in the midst of countless health care facilities due to the increasing number of decubitus ulcers. Decubitus ulcer, also commonly known as bedsores or pressure ulcers, is an exposed wound on your skin frequently occurring on the skin concealing bony areas. It is mutual among the elderly, people who devote prolonged periods of time in bed or a wheelchair, and individuals who cannot move particular body parts without assistance (Solan, 2014). Many diverse prevention dressings have been introduced across the years to diagnose pressure ulcers; this paper pursues to examine appropriate literature to evaluate and compare the efficacy of hydrocolloid dressing in patients with decubitus ulcers.
Dental composites, also known as "white fillings", are a group of restorative materials composed of a mixture of powdered glass and plastic resin regularly used in modern dentistry to resemble the appearance of the natural tooth. Acrylic resin was first introduced to the dental profession in the mid 1950s. Since their introduction, acrylic based materials have continued to play a pivotal role in restorative and prosthetic dentistry. After the introduction of the bisphenol A glycidyl methacrylate, or BIS-GMA, by Bowen in the early 1960s the potential application of resins has emerged. This composition and formulation possessed a higher molecular weight and therefore better mechanical properties and reduced polymerization shrinkage, the newer polymer offered potential for much greater applications that included anterior and posterior composite resin restorations, indirect inlays/onlays, pit and fissure sealants and more wear resistant denture teeth.
The first time I experienced clay in depth was in my first ceramics class in college. This is where I spent hours of my time in the studio exploring. After my first soda firing, I knew that I wanted to start a career in clay. I am applying to the master’s program in ceramics to extend my knowledge of clay and to further develop my conceptual thought.
By using strong oxidizing agent, oxygenated functionalities are introduced in the graphite structure which not only expand the layer separation, but also makes the material hydrophilic. Hydrophilic mean that they can be dispersed in water. This properties has enable graphite oxide to be exfoliated in water by using sonification, ultimately producing single and few layer of graphene that has been known as graphene oxide. The properties of graphene oxide is its easy dispersability in water and other organic solvents, as well as in the different matrixes due to the presence of the oxygen functionality (Jesus de La Fuente., 2011).
Enhancing effect of prolonging the duration of polymerization on grafting (%GY) and homopolymer (%HP) is reflected on the extent of total conversion (%TC) (Fig. 3). The latter increased as the time of polymerization increased particularly during the initial stages of the polymerization reaction.
The most commonly produced PVC structure by addition polymerisation is the atactic PVC. As seen in Figure #, the chlorine atoms are branched randomly and asymmetrically along the carbon backbone. Unlike the other two structures, the random orientation prevents the polymers from packing closely together and is described to be ‘amorphous’.
The purpose of this experiment was to create a polymer by reacting a mixture of decanedioyl dichloride and dichloromethane with a mixture of water, 1,6-hexadiamine and sodium carbonate. Specifically, we created the polymer Nylon-6,10. Nylon-6,10 polymers are used in a vast majority of things we use in everyday life such as zippers, the bristles in brushes, and even car parts. This experiment was different from the industrial method of making nylon because that takes place at a much higher temperature. A polymer is a substance that has a structure made of similar or identical units bonded together. All polymerizations fall into two categories: step-growth and chain-growth (both of which we used to form our polymer). Step growth polymerization
He wanted to discover a material that would have a high melting point characteristic and also be impervious to oxidation which eventually directed him to form Poly (ether-ether-ketone)
The flow parameter that is readily accessible to most processors is the MFI. MFI is often used to determine how a polymer will process. However MFI takes no account of the shear, shear rate or shear history and as such is not a good measure of the processing window of a polymer. It is a single-point viscosity measurement at a relatively low shear rate and temperature. Earlier, it was often said that MFI give a ‘dot’ when actually what is needed is a ‘plot’ for the polymer processors. However, this is not true now because of a unique approach developed for estimating the rheogram merely from the knowledge of the
Rheological behavior helps to elucidate the fundamental flow behavior of composite melts, and can directly or indirectly reflect the processing performance, internal structure, and physical and mechanical performance of WPCs. For the economical consideration, researchers are attempted to incorporate high amount of wood flour. So, a clear insight of the rheological behavior is necessary in such high wood content to facilities the processing. In addition, additives are frequently used to modify processing or end properties of WPC formulations and proper rheological tests may prove useful in characterizing the efficiency of these additives [13].
Naturally occurring polymers will be proteins like silk. It will definitely depend on the type of polyamide being made because they will take many different forms such as, Nylons can help to make the inner structure of tires but can also take the shape of solids and used for machine parts and Kevlar is used in bulletproof vests. When describing the properties of polyamides it will need to be done based on the type of polyamide so I will be describing the chemical and physical properties of Nylon 6 a polyamide fiber. Nylon 6 has a density of 1.14 g/c.c, a melting point of 215℃, it also has a very good elasticity, its natural color is going to be white but it can be dyed, and has the ability to protect heat up to 150℃. The main chemical property of Nylon 6 is it is an organic solvent which means it becomes soluble in any dense acid or phenol. You have almost definitely used polyamides there are polyamides in tents, toothbrush bristles, rope, they don't have to be fibers they are sometimes used for gears, lots of times polyamides are used in packaging. Polyamides are used because they are so strong
The Company manufactures varieties of superior grade China Clay for diversified applications such as pigments, extender, filler and as raw material in different industries. Superior Coating Grade Kaolin is produced under the trademarks ‘Supercoat’, ‘Higloss’, ‘Hibrite’ and ‘BCK’ in the form of lumps, powder, and pre-dispersed Spray Dried Powder, Filler and Coating Grade Clay under trade mark ‘KCG’ as lumps, powder, and pre-dispersed Spray Dried Powder. Calcined Clay, used as a substitute for Titanium Dioxide in Paints, Paper, Detergents, and other grades, is also manufactured by EICL to cater to niche markets.