Blending Ability

The excipients were blended with paracetamol in a glass jar using a Turbula mixer (Quadro Engineering, Waterloo, Ontario, Canada). The blends of paracetamol with PVP, PVP-SD and PVP-Leu were denoted as PVP/Para, PVP-SD/Para and PVP-Leu/ Para, respectively. 

F igure 1.10 Content uniformity data of various API excipient blends. Adapted and modified form Mangal et al, 2015 [82] 

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The large difference in the A315, however, is more in its blending ability compared to the R100, so that the blend... 

Use of single-screw extmders for the addition of small amounts of additive to thermoplastic elastomers, where the amount of blending is limited, and can be enhanced by the use of mixing sections along the screw, is a distinct possibility. The effects of flood and starved feed on blending ability in two different designs of singlescrew have been studied (126). 

Uniformity of Mixture The proper type of mixer shoiJd be chosen to assure the desired degree of batch homogeneity. This cannot be compromised for other conveniences. Information is given under Types of Solids-Mixing Machines about the special abilities of various lands of machines to blend different types of materials. 

Because of the in-chain ring the Tg is as high as -i-35°C and the polymer is therefore not rubbery at usual ambient temperatures. If, however, the polymer is blended with an aromatic oil or certain ester plasticisers a rubbery material is obtained. Because of the ability of the polymer to take up large quantities of oil the Tg of a polymer-oil blend can be as low as -60°C. Such polymer-oil blends can also incorporate very large amounts of filler. 

Spandex fibres, because of their higher modulus, tensile strength and resistance to oxidation, as well as their ability to be produced at finer deniers, have made severe inroads into the natural rubber latex thread market. They have also enabled lighter weight garments to be produced. Staple fibre blends with non-elastic fibres have also been introduced. 

The early 1980s saw considerable interest in a new form of silicone materials, namely the liquid silicone mbbers. These may be considered as a development from the addition-cured RTV silicone rubbers but with a better pot life and improved physical properties, including heat stability similar to that of conventional peroxide-cured elastomers. The ability to process such liquid raw materials leads to a number of economic benefits such as lower production costs, increased ouput and reduced capital investment compared with more conventional rubbers. Liquid silicone rubbers are low-viscosity materials which range from a flow consistency to a paste consistency. They are usually supplied as a two-pack system which requires simple blending before use. The materials cure rapidly above 110°C and when injection moulded at high temperatures (200-250°C) cure times as low as a few seconds are possible for small parts. Because of the rapid mould filling, scorch is rarely a problem and, furthermore, post-curing is usually unnecessary. 

Metals are erystalline in strueture and the individual erystals eontain positive metal ions. The outer valeney eleetrons appear to be so loosely held that they are largely interspersed amongst the positive ions forming an eleetron eloud whieh holds the positive ions together. The mobility of this eleetron eloud aeeounts for the eleetrieal eonduetivity. The erystal strueture also explains the hardness and meehanieal strength of metals whereas the elastieity is explained by the ability of the atoms and ions to slide easily over eaeh other. Metals ean be blended with other metals to produee alloys with speeifie properties and applieations. Examples inelude ... 

Compatibility. Clear definition of compatibility is rather difficult. Compatibility has been defined as the ability of two or more materials to exist in close and permanent association for an indefinite period without phase separation and without adverse effect of one on the other [28]. On the other hand, compatibility is easily recognized in solvent-borne adhesives as a homogeneous blend of materials without phase separation. Normally, compatibility is understood as a clear transparent mixture of a resin with a given polymer. But, compatibility is a more complex thermodynamic phenomenon which can be evaluated from specific... 

Some of these model-dependent quantities were formulated as measures of a particular phenomenon, such as electron-pair donor ability but many of them have been proposed as empirical measures of solvent polarity, with the goal, or hope, that they may embody a useful blend of solvent properties that quantitatively accounts for the solvent effect on reactivity. This section describes many, although not all, of these empirical measures. Reichardt has reviewed this subject. 

A prospective location may appear to be right in all other respects but fails because of the manpower resource. This refers to not only the economic aspects such as the availability of labor and skills but also to the qualitative ones of being able to understand the local culture and customs, appreciation of people s attitudes and values. It also refers to the confidence in the ability to blend these with the culture and aspirations of the company to form a cohesive production unit that will work. A successful processing concept in one cultural environment may not be a success in another. 

P.V.D.F. Polyvinylidene fluoride (p.v.d.f. or p.v.f.2) dispersions are applied by the coil-coating process. They are blends of p.v.d.f. resin and acrylic. The combination produces a system which has excellent weather-ability and which can be bonded via an adhesive primer to a galvanised steel or aluminium substrate. 

Tannin chemistry is complex and tannin blends (composed of singletree species tannins mixed together) offer a number of useful water treatment functions. Apart from oxygen-scavenging abilities, they act as passivating agents, film-formers, sequestrants, and polymeric sludge dispersants (for more details, see Section 10.3). 

Consequently, when selecting and blending the various raw materials used in all-polymer/all-organic formulations, the questions of thermal and hydrolytic stability and ability to transport or otherwise control colloidal iron oxides (in addition to possible adverse effects such as copper corrosion) become increasingly important at higher boiler temperatures and pressures. 

The ability of the E-plastomers to participate in the peroxide-mediated chain-extension processes can be augmented in blends with EPDM, where the mixture is homogeneously cross-linked with free radicals [5]. The use of these blends of EPDM and E-plastomers leads to improved processing and physical properties of the combination, compared to the EPDM alone, though the resulting vulcanizates are somewhat harder than the EPDM vulcanizates alone due to the presence of the semicrystalline plastomers in the vulcanized mixture. 

The exceptional ability of PCL to form blends with many other polymers has stimulated a large amount of research. The subject has been reviewed a number of times (7,8). To date, the potential of such blends for drug delivery has been largely unexploited. The permeability of blends of PCL with cellulose propionate, cellulose... 

Resilin and elastin, unlike other structural proteins, fulfill both definitions of an elastic material. Colloquially speaking, resilin and elastin are stretchy or flexible. They also fulfill the strict definition of an elastic material, i.e., the ability to deform in proportion to the magnitude of an applied stress without a loss of energy, and the recovery of the material to its original state when that stress is removed. Resilin and elastin are alone in the category of structural proteins (e.g., collagen, silk, etc.) in that they have the correct blend of physical properties that allow the proteins to fulfill both definitions of elasticity. Both proteins have high extensibility and combine that property with remarkable resilience [208]. 

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