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| thermosetting plastic thermoplastic elastoplastic |
ABS – Acrylnitrile Butadiene Styrene
ABS (1,04-1,05 g/cm³) is a relative light, amorphous technical
thermoplastic. It is relative hard and stiff and has good impact
resistance, better than allied impact resistant Polystyrene
(SB). ABS features high resistance to changing temperatures and
low water absorption (low hygroscopic). It is low weathering
resistant. ABS will be often selected for glossy cases,
multi-component-moulding parts, chrome-plated parts and for
laser-labelled parts. Natural colour is beige up to yellow-brown
and with special types transparent colour is possible. ABS will
be processed at 240-260 °C and inflames at 400 °C with glaring
and sooting flame with sweetish smell.
Additives - Compounds - Colourings - Fillers - Reinforcements
Additives are substances, which are added to a
pure plastic for enlarging and optimising its properties and to
optimise its costs to use relationship. As a rule each
plastic on the market offered for processors contains already
several additives. Aside there are additives, which processors
can add by themselves or versed compounding plants can
incorporate into their compounds. Additives are dived by
function into following groups in essence:
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• fire proofing
agents |
for reducing burning rate or for reaching
self-extinguishing - e.g. verification by classification
and registration by Underwriter Laboratories (UL)
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• lubricants and processing agents |
divided in inner (e.g. for reducing of friction and
friction temperature whilst processing - zinc stearate
and for setting viscosity) and outer (mould release
agents, agents for reducing coefficient of friction -
oils, Silicon, PTFE, MoS2, Graphite) |
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• electrical conducting agents |
for enlarging electric conductivity (metal fibres,
conductive soot, carbon fibres, and so on) |
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• impact
resistance modifier |
for optimising fracture resistance, for avoiding crack
roots and for hindering of crack spreading |
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• sugar coating and clearing agents |
for covering colour casts of natural coloured plastics
caused by necessary, not colour-neutral additives or for
covering thermal pre-damage whilst production |
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• stabiliser |
against heat, light (e.g. HALS against UV-distortion)
and against further distortion attacks with degradation
or chemical modification of the macromolecules
(anti-oxidants and more) |
Compounds are process-ready material recipes as granules
or powder. Ingredients are one or more plastics and depending on
tasks additives, colours, fillers and reinforcements. As a rule
compounds for thermoplastics and elastoplastic thermoplastics
will be produced on fitted compounding extruders with following
granulators or pelletizers. This is a very material-gentle
production which leads to very homogenous compounds. High-filled
high-viscose compounds e.g. for production of ceramic or metal
powder preforms, in which plastics are only binder, will be
produced in kneader mixers.
Colourings
of plastics take place with organic or inorganic colours or
effect pigments, which are mixed into plastics whilst processing
or compounding with as a rule 0,5-5% in form of colour powder,
liquid colour (with liquid carrier), paste colour (with paste
carrier) or colour master batch (pressed colour granule or colour
granules with low, neutral effective plastic carrier).
On high requirements for colour adaptions of item list parts of
different materials (plastic, metals, wood) as a rule
compounders or colouring manufacturers have to take on
responsibility. Calling for compounders or colouring
manufacturers involves mostly a significant price increase for
the item list parts. The technical adpation of colourings of
different item list parts will be as a rule avoided by choosing
different colours.
Fillers are as a rule budget-priced cost-reducing
substances, which don't match with their part or only in
controlled way (wood flour and more).
Reinforcements give loaded plastic parts or half-finished
products a better stiffness, higher mechanical strength and
higher heat resistance. To be used are embedded reinforcements
in the form from fibres, textures, bowls and graining consisting
of glass, carbon, plastic and minerals (light materials near the
weight of plastic), which partly equipped with coupling agents
and directional embedding enable further enlargement of
strength. Also are self-reinforcements possible by stretching of
fibres like those of Nylon and Polyethylene.
amorphous and partially crystalline
Thermoplastics are divided in amorphous and partially
crystalline types, whereas amorphous structures in a rule are
clear-transparent and partially crystalline structures are
translucent up to a shielding colour.
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| amorphous |
partially
crystalline |
Blend(s)
As a rule blends are special mixtures of two thermoplastics.
Possible is that only by chemical adapting, because
thermoplastics are incompatible among each other (distortion,
decomposition, delaminating) or they are only adhered among each
other by coating of one thermoplastic on another in the
injection mould. Well known blends are PA+ABS, PC+ABS, PC+PET,
PC+PBT.
Macromolecules - monomers - polymers - copolymers - low- and
ultra high molecular
Macromolecules contain a great number
of atoms, which are chemical bond by primary valences and will
be differentiated by Staudinger in linear molecules and ball
molecules or in case of plastics depending on their degree of
polymerization (Hemicolloids - degree of polymerization 10 up to
100, Mesocolloids - degree of polymerization 100 up to 500 und
Eucolloids - degree of polymerization > 500).
Monomers are single molecules of plastics and possess at
least one functional group (reaction- or bonding group as
condition for the bonding in polymers).
Polymers or plastics are differentiated in heteropolymers
(bonding of equal monomers) and copolymers (bonding of
monomers with differing monomers, groups or atoms) and are
produced by polymerization, polyaddition or polycondensation
(type is plastic-specific) and contain, depending on
degree of polymerization,
an equivalent number of in primary valences bond monomers.
Plastics are differentiated classified by their primary chains
into molecular closely or widely spread and by their molecular
weight between
low- and ultra high molecular.
PC – Polycarbonate
PC (1,2 g/cm³) is a middle-weight, amorphous technical
thermoplastic. It is very hard and has an excellent fracture
toughness. PC features high heat deflection temperature, low
temperature dependence and low water absorption (low
hygroscopic). PC will be mostly selected for indoor parts as
high transparent cases and covers, for high fracture-tough
components, so as for optical parts (CD’s, DVD’s, lamp
components, lenses). Natural colour is highly clear-transparent.
PC will be processed at 320-350 °C and burns in the flame and
goes out outside.
POM – Polyoxymethylene (also Acetal resin, Paraformaldehyde,
Polyformaldehyde or Polyacetate)
POM (1,42 g/cm³) is a relative heavy, partially crystalline
technical thermoplastic with structure
-(CH2-O-)n
for homopolymers. POM features in the range of not
reinforced thermoplastics with very high strength and stiffness
(also at long-term stress and at low temperatures) beside high
dimensionally stability and excellent fatigue strength.
Wear resistance is nearly as well as at PA.
POM will preferred selected for technical applications like
snap-in joints, slide bearings (also with Silicon- or PTFE-additives),
rolls and gear tooth components.
Natural colour is whitely-opaque.
POM will be processed at 180-190 °C, inflame itself at 375 °C
and burns at 323 °C with a light bluely flame with penetrative
Formaldehyde smell.
PTFE – Polytetrafluoroethylene (Trade marks: Teflon - Dupont,
Hostaflon, Dyneon, GoreTex)
PTFE (2,16 g/cm³) is a very heavy,
partially crystalline technical thermoplastic with a Shore D
hardness of
55-60. Its structure is CnF2n
and it belongs to the class of polyhalogenolefines. Indeed PTFE
is a thermoplastic material, but with near melting and
disintegration temperature. Due to this PTFE can be as a rule
only processed by sintering or pressure sintering and degrees of
freedom for design are limited to simple designs. It was
detected in 1938 by Roy Plunkett and was applied for a patent
in1941 by Dupont. PTFE bends to creep under pressure and has to
be stabilized by addition of glass fibers or other strength
increasing additives. PTFE is very less reactive.
Self aggressive acids like aqua regia cannot attack PTFE. PTFE has
one of the lowest coefficients of friction of solid materials. PTFE
slips on PTFE like wet ice on wet ice. Also sticking friction is
equal to sliding friction so that the transition from standstill
to movement acts without the stick-slip-effect. One impressive
practise example for that was the movement of the new 12,500
tons heavy Oberkassel Bridge in Düsseldorf/Germany for 47,5m on
PTFE slide bearings on April 7th and 8th 1976. It exist nearly
no material with adhere to PTFE, due to the extremely low
surface tension. PTFE is supremely resistant to all acids and
lyes, alcoholes, ketones, oils, etc. and is not resistant to
sodium. Furthermore PTFE is resistant to frost down to −200 °C;
only glueable after pretreatment; physiological harmless; not
combustible. Its natural colour is due to standard types
covering white. The working temperature reaches up to 260 °C. PTFE
melts at 327 °C and disintegrates above into high aggressive
hydrogen fluoride acid and high toxic pyrolysis products.
Since a few years PTFE is being used for the
range of furniture glides. There a unique composit of rubber and
PTFE can be named, which delivers an excellent silencer and an
optimal floor protection so as minimal values for sticking and
sliding friction while moving furnitures. This type as a rule is
a 2-3 mm flat and one side spherical rubber circular blank (square
and rectangular, too) on which is applied a more 1/10 mm strong
foil of PTFE under high pressure and temperature. These
universal slide inserts can bei equipped with a nail for wooden
chair legs or other wooden furnitures, can bei glued on or can
be inserted in furniture glides. Please look at our WebShop
range under the category "Glides (furniture, framework)" for
article series
UG/RE,
UG/RU,
UGN/RU,
GLUG,
GGUG2000 and
KKSGUG. PTFE slide
inserts are useful for easy moving of furnitures on the most
floors. PTFE slide inserts makes moving of furnitures on textile
floors much easier. For seating furnitures on smooth floors PTFE
is not suitable, because seating furnitures move unintended.
PU (PUR) – Polyurethane
PU is a very multi-purpose plastic material. Depending on recipe
and production process PU is available as thermoplastic (thermoplastic
elastomer), elastomer or thermoset. PU products we see in all
ranges of our everydays life (matresses, soles of shoes, tires
of wheels and castors, insulating materials, noise insulation
elements, resin laquer, glues, insulating foams and a lot more).
SB – Styrene Butadiene
(also impact-resistant Polystyrene, PS-HI or HIPS)
SB (1,04-1,05 g/cm³) is a relative light, amorphous
thermoplastic. It is relative hard and stiff and has good impact
resistance, better than Polystyrene (PS).
It is not weathering resistant.
SB will be mostly selected (also foamed --> SFM) for
budget-priced indoor cases and case components. Natural colour
is strong shielding whitely-opaque. SB will be processed at
180-280 °C, is easy inflaming, burns with glaring and strong
sooting flame with sweetish smell and light smelling to burned
rubber.
Tacticity
the array of side chains at main chains of
macromolecules decides essential the properties of plastics (amorphous
or partially crystalline and with that clear-transparency or
translucent up to shielding natural colour, the chemical
resistance, the mechanical properties and so on). Following
three types will be differed: atactic, isotactic and
syndiotactic
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| atactic - side chains
in unbalanced array at main chain |
isotactic - side
chains in regular one-sided array at main chain |
syndiotactic - side
chains in regular alternating array at main chain |
TPE – thermoplastic elastomers (collective term, also
elastoplastics)
Is a collective term for thermoplastics with properties like
real elastomers (with cross linked molecule chains: synthetic
rubber). These are classified depending on their allied
thermoplastics in:
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TPA (TPE-A) |
= thermoplastic Copolyamides |
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TPE (TPE-E) |
= thermoplastic Copolyesters |
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TPO (TPE-O) |
= thermoplastic Olefins (-->
Polyethylene, Polypropylene) |
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TPS (TPE-S) |
= thermoplastic Styrene derivates
(--> Polystyrene, Styrenebutadien, ABS, ASA, etc) |
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TPU (TPE-U) |
= thermoplastic Urethanes (-->
Polyurethane)
Resistance (without obligation) |
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TPV (TPE-V) |
= thermoplastic vulcanisates (e.g.
cross-linked EPDM) |
These are different to plastomers (with weight 0,9 g/cm³ very
light thermoplastics with very short molecule chains - e.g.
Polyolefinplastomers [POP's]).
Thermoplastics
(collective term)
are hard or even brittle at room temperature. By warming in
certain temperature ranges they soften and plasticise, because
the not fixed unmashed molecule chains begin to move against
each other. With more warming molecule chains begin to "flow"
and the thermoplastic melts. Thermoplastics begin gradually to
decompose above the melting temperature. In the presence of
Oxygen or open fire the thermoplastic burns with open flame or
by charing.
Thermoplastics are in quantity the largest group under he
sythetic polymers (= plastics). As examples are mentioned the
four most important: Polyethylene, Polypropylene, Polystyrene
and Polyvinylchloride. This four mass plastics take two third of
the whole plastic production. They ambient us daily in form of
wrapping, device housings and in a large range of articles of
daily use.
Thermosetting plastics (collective term)
Under collective term thermosetting plastics (before processing
one- or multicomponent resins or powders) are collected hard,
not again thermal plasticisable
plastics with
with 3-dimensional
close-mashed cross-linked molecule chains, which are primarily
the following:
Epoxy resin (EP)
Urea-Formaldehyde resin (UF)
Melamine-Formaldehyde resin (MF)
Acrylic resin (MMA)
Phenol-Formaldehyde resin (PF)
Polyester resin (unsaturated Polyester = UP)
Cross-linked thermoplastics (by radiation and/or
addition of cross-linking agents - for example cross-linked PE [VPE
or PE-X] for water tubes and for films for enhancement of
mechanical properties, chemical resistance and continuous
operating temperature)
Diverse thermosetting plastic formulations will be standardised
encountered under the term cured resin (e.g. “form stuff” FS31).
Elastomers (collective term, also synthetic rubber and
elastoplastics)
Under collective term elastomers are soft-elastic,
not again thermal plasticisable
plastics with
3-dimensional wide-mashed cross-linked molecule chains collected,
which are primarily the following:
Acrylic
Ester
rubber (ACM, ANM, AR)
Brominated Butyl rubber (BIIR)
Butyl rubber (GR-I,
IIR)
Chlorinated
Butyl
rubber (CIIR)
Chlorosulphonated
Polyethylene (CSM)
Epichlorhydrin
rubber (CO, CHR, ECO, ETER)
Ethylene-Propylene-Terpolymers (EPDM)
Ethylene-VAC-Copolymers (EVA, E/VA)
Fluorine rubber (FPM,
CFM, MFQ)
Nitrile rubber (GR-N,
NBR)
Polybutadiene (BR)
Polychloroprene,
Chloroprene rubber (CR)
Polyisoprene,
natural rubber (NK, NR)
Polysulphide rubber
(SR)
Silicone rubber
(SI)
Styrene-Butadiene
rubber (GR-S, SBR)
Urethane rubber
(AU, EU)
Rubber in liquid form is characterized with a "L" in the front
of material short cut (e.g. LBR). Mixtures of defined rubbers in
defined mixture relations under addition of homogenizers or
compatibilizers are limited and partly with extensive complexity
possible and are offered mostly by raw material producers of the
chemical industry or chemical specialists.
Felt
(industrial processed felt)
Industrial Processed Felt
is demanded beginning with the middle of
eighties of 20th century for facing of plastic
furniture glides due to preserve sensitive
floors/ground areas and due to silencer of moved
seating furnitures. In opposit to some plastic
glide facings scratching or abrasive piling on
sensitive floors (parquet, polished/smooth lime
stone floors, etc.) will be prevented and
instead of it a higher abrasive loss of felt
will be accepted. For this task strongly
depending on floor cleaning (dry suction
cleaning - avoiding contact with water and other
fluids; felt moistens and will be strongly
abraded) felt can only be a compromise
between preserving/silencer and wearing.
Industrial processed felt is practically
available in all dimensions, forms, cuts and in various specifications, like coloured,
self-adhesive, siliconized, flame-retardent, dry
cleanable, limited water resistant,
short time water-repellent, antistatic, etc. One essential
feature is its specific range of density, which
mostly enfolds 0,2-0,7 g/cm³. Qualities are
processible hard as wood or soft as wadding.
With increasing density raw material charge and
requirements to converting plants increase.
Entanglement
Wool and other animal hairs felted by friction,
warmness, humidity and lye, as upforming scales
of fibre surfaces jam with each other
unresolvable. Who unawares has washed a wool
sock with a washing machine knows the effect:
the sock is shrinked several sizes and got very
solid. What is an mishap in the household will
be processed by industrial felting by
machine-made bulging, knocking and pressing.
This kind of felting with jammed upforming
scales is a specific feature of animal hairs/wool.
In contrast other fibres will be mechanical
felted/entangled by nails with barbed hooks (look
at Manufacturing Technologies).
Felt - Definitions and Features
Felt is a layered, textile, non-woven, pressed
fleece fabric made of wool and/or fibres, which
is principle a fibre composit. It will be
processed from single fibres, which lay tangled
one upon another and partially interleaved
entangled without spinning, weaving or meshing.
Cleaned, combed, maybe coloured and to fleece processed raw wool and/or fibres
will be pressed/stabilized into a solid fabric
(textile flat material or mats with defined
features according to DIN 61205) by mechanical
treatment (felting and milling), mostly with
thermical and chemical support. Substantially
felt is a two-dimensional pressed fabric in
multi-layer array with low three-dimensional
weave. On condition of shear stress felt tends
to delaminate in layers.
Felt - Variants
Variants of felt will be differentiated between
origin of raw material or manufaturing process.
The term wool felt describes for example the
origin of fibres (substantially sheep's wool but
other suitable animal hairs, too), in opposit to
synthetic felt (synthetic fibres of Nylon,
polyester, polypropylene, polyacrylamide, Normex,
Kevlar, glass, etc.) or felt made of plant fibre
(cotton wool, rayon staple fibre, kapok, ramie
[bast fibre], jute fibre, etc.). Real felts are
made of fibre blanket, pseudo felts are made of
woven flats, which are felted in a shaping
machine. Felt can consist of one raw material,
but also of mixtures of different raw materials.
The terms needle felt, pressed and squeezed felt,
woven felt, press felt or cloth felt refer to
the manufacturing process.
Manufacturing Technologies
Wet felting (according to DIN 61210 pooled under
the term of pressed and squeezed felts) of
unbound fleece with warm water (steam) and soap
(alkaline felting support) is the traditional,
craftman's processing of wool or animal hairs.
In combination with warm water and soap the top
level scale layer (cuticula) forms up, the
scales of hairs.
Simultaneous pressing and squeezing of fibres
cause a penetration of each other.
The formed up scales wedge so strong in each
other that they are unresolvable. The workpiece
shrinks strongly and forms a solid material
(textile flat). The final form can be worked out
in one piece.
Pressing and squeezing felt is very expensive in
time and substantially will be processed in
little scale in handcraft, hobby or education.
Pressed and squeezed felt has normed features
according to DIN 61200 and DIN 61206 Part 2. The
strength of pressed and squeezed felt is given
by its densitiy. Due to animal fibres, partially
in mixture with rayon staple fibres pressed and
squeezed felt is a biodegradable natural product.
In the dry felting process wool is formed with
specific needles.
This method is the ancestor of needle-punching
with a needle girder. In the process of needle
felting fibre blanket will be repeatedly
penetrated by needles with a barbed hook (360 up
to 720 penetrations each square centimeter),
arrayed vice versa like a harpoon, so that the
fibres will be pushed into the felt and the
needle goes out without resistance, with the
effect, that fibre clusters will be drawn to the
rear side of fibre blanket and interlock to a
solid flat.
Needle fleece materials are not only made of
wool, but practical of all other fibres (for
example sythetic fibres, look at Felt - Variants).
Besides jamming will be processed with pulsed
water jets or with binders.
In this case fibres without scale structure are
suitable (for example sythetic fibres, look at
Felt - Variants). Mostly needle felts are
stiffened with the support of chemicals.
Product Ranges
Wool felt and other non-woven materials are used
in stamp pads, for machine damping, for noise
insulation, for polishing glass, granite and
some metals. Oil-moisted felt pads are used for
lubrication of machines. Due to its long-term
flexibility felt is suitable for damper in
pianos and other musical instruments. Made of
wool felt are also hats, shoes and other
articles of clothing. Furthermore felt is used
for screens, filter and sealing purposes.
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