Polymer Dictionary

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	Heterogeneous Something relating to two ore more phases, i.e. not mixed so as to be homogeneous.
	Homogeneous Something relating to only one phase, i.e. so well mixed that the mixture have the same composition throughout.
	Vicat softening temperature Vicat softening temperature shows heat softening characteristics of thermoplastics. Flat specimen are placed in a temperature regulated heating bath, a needle type, loaded penetrator is set on the specimen surface and bath temperature is raised at a constant rate. The temperature of the bath at which the penetration of the needle has reached a predefined level is the Vicat softening temperature of the material.
	Acid scavengers Neutralise acidic residues to protect processing equipment from corrosion.
	Metal deactivators Some metal ions may contribute to accelerated degradation. For polyolefins in contact with metals, such as cable insulation of copper wires, metal deactivators are added to passivate the degradation reactions.
	Shore Hardness Resistance of a (polymer) surface to deformation. The different hardness measures applied for characterising polymers are: (a) Shore hardness (two scales, A for softer and D for harder materials) (b) Ball indentation hardness (also useable on profiled surfaces because of bigger measuring device). (c) Vickers hardness (normally used for steel)
	Heterophasic copolymers Heterophasic copolymers (HECO) also contain ethylene (and possibly higher a-olefins) as comonomer. The production is however carried out in a two-stage process, resulting in a multiphase structure with a homopolymer matrix and inclusions consisting of amorphous EP-copolymer (rubber) and crystalline PE. Variations of molar mass and composition of the elastomeric phase in relation to the matrix allow a wide variation of properties (stiffness, toughness and transparency).
	BorAPC Borealis tailor-made Advanced Process Control (APC) for polyolefin polymerisation processes. APC is process control utilising detailed knowledge, compared with traditional process control where the method is standard and not specifically adapted to the process. The basis for APC is knowledge of a process expressed as mathematical models. Model predictive control (MPC) ensures that control actions also compensate for the future behaviour of the process, leading to optimal grade changes. BorAPC includes non-linear MPC, making it well-suited for polymerisation processes and ahead of what "normal" control vendors offer.
	Comonomer sensitivity A property of the catalyst which indicates how eagerly the catalyst reacts with a comonomer, defining the relation between the relation of partial concentrations (pressures) of different monomers in the polymerisation process and the relative content in the produced polymer.. Comonomer sensitivity is determined in a test polymerisation in standard conditions.
	VLDPE Very low density polyethylene Based on the same technology as HDPE, but the density is reduced through the incorporation of longer a-olefins as comonomers. With this, another way of adapting the products to the final applications turns up. Single-site catalysts allow an expansion of the application range, mainly by allowing higher comonomer contents and a more even distribution of these.
	ULDPE Ultra low density polyethylene Based on the same technology as HDPE, but the density is reduced through the incorporation of longer a-olefins as comonomers. With this, another way of adapting the products to the final applications turns up. Single-site catalysts allow an expansion of the application range, mainly by allowing higher comonomer contents and a more even distribution of these.
	Slip agent type of additive, which provides surface lubrication to the polymer during and after conversion; especially important for films. Usual slip agents are amides of fatty acids.
	LLDPE Linear low density polyethylene Based on the same technology as HDPE, but the density is reduced through the incorporation of longer a-olefins as comonomers. With this, another way of adapting the products to the final applications turns up. Single-site catalysts allow an expansion of the application range, mainly by allowing higher comonomer contents and a more even distribution of these.
	Flexural test Like tensile test, flexural test is also used to characterize strength and stiffness of the material. Flexural properties are obtained by placing a specimen horizontally on two supports. A load is applied at a specified rate in the center, normal to specimen longitudinal axis. Measured force - deformation data is used to calculate flexural modulus and flexural strength. Flexural tests can be used if material is too brittle to withstand compressive forces of fixing in tensile grips.
	Friction When handling and storing plastic packages it is important that friction between packages and pallets, shelves etc. or between packages itself is suitable. Coefficient of starting and sliding friction (static and dynamic friction) of film is measured by using a moving sled, force transducer and a static horizontal testing table. Friction can be measured either film against film or film versus metal or other material. It is determined by the material structure and the additivation, especially the addition of slip agents and antiblocking agents.