Concise Handbook of General Engineering Plastics

Time：2022-06-13 08:50:24 / Popularity： / Source：

Materials with medium comprehensive mechanical properties-general engineering plastics refer to those engineering plastics used in engineering to make various product shells and shells for non-load bearing purposes. It is mainly plastic and plexiglass with styrene as main monomer. It is mainly formed by modification of PS. After synthesis of PS in engineering, it is found that PS has two major characteristics, one is transparent; the other is fragile, surface is easily scratched. In order to solve its shortcomings and retain its transparency, it has been modified in two ways. On the one hand, it produced a transparent AS MBS; on the other hand, it produced an opaque HIPS ABS AAS ACS

PS

Abbreviation PS
Commonly known as hard rubber, ordinary hard rubber
Scientific name Polystyrene
English name general purpose polystyrene
Monomer Styrene---a colorless liquid synthesized from petroleum
Natural color: polystyrene is a transparent glass-like material with a specific gravity of 1.05, which is basically same as water. It is hard and brittle. When it is hit, it makes a metallic "jingle" sound with a clear and crisp sound, commonly known as "sound glue". Non-toxic and tasteless. Products made of pure PS will break immediately after they fall on ground and emit a crisp sound. Because PS has good fluidity, high decomposition temperature, and stable melting specific gravity, it has become an index parameter for injection molding machines to determine plasticization efficiency. PS is used to calibrate capacity of injection molding machines in injection molding machines all over the world.

Combustion characteristics

It is flammable and can continue to burn after leaving fire. Upper end of flame is golden yellow. When it burns, it will soften and bubble, without liquid dripping, emit thick smoke and black pillars. At the same time, it emits "sweet aroma" of styrene monomer.

Advantage

Polystyrene is resistant to acids, alkalis and low-energy alcohols. It is softened by erosion of many hydrocarbons, ketones, and higher fats, it is soluble in aromatic hydrocarbons.
It has excellent electrical insulation and is a good high-frequency insulating material with excellent arc properties.
Polystyrene is a material with extremely high transparency and high surface gloss. Easy to print.
Polystyrene can be colored freely, is odorless, tasteless, non-toxic, and does not cause fungus growth.

Disadvantage

Poor mechanical properties, hard and brittle, easy to be corroded by solvents and stress cracking; low surface hardness, easy to scratch; poor heat resistance, low heat distortion temperature.

Use

Used in production of transparent lenses, crystal-like tableware and other transparent products;
Used for injection molding low-grade daily necessities and toy shells, lampshades;
Used for extrusion blow molding containers, hollow products, bottles　

Injection performance

General PS has a melting point of 173℃ and a decomposition temperature of 330℃; adjustable range of injection temperature is relatively large. During injection molding, general use temperature is 180℃--240℃; because it is an olefin plastic, it does not absorb water and does not need to be dried during production. However, for product quality, it can be dried at 60°C for 1 hour to discharge floating water; Melt viscosity of styrene is small and flow length ratio is large. Generally, it can be filled with products without large gates and runners; but PS is hard and brittle. When designing products, avoid sharp corners and pay attention to draft angle, otherwise, product will crack. Product is prone to static electricity, and surface is easy to absorb dust. Shrinkage rate is 5‰; overflow value is 0.03mm
Physical properties Mechanical properties Injection temperature see Table 1

HIPS

Referred to as HIPS
Commonly known as non-breaking rubber, high-impact hard rubber
Scientific name High impact polystyrene
English name high impact polystyrene
Monomer block copolymer formed by graft copolymerization of styrene and rubber
Natural color High-impact polystyrene is a sub-white opaque material with a matte surface, flexible and not brittle; non-toxic and tasteless.

Combustion characteristics

It is flammable and can continue to burn after leaving fire. Upper end of flame is golden yellow. When it burns, it will soften and foam, without liquid dripping, emit thick smoke and black pillars with fly ash.

Advantage

Since polystyrene is hard and brittle, fragile, and not resistant to impact, a rubber modification method is used to solve above problems. The biggest advantage of HIPS is its high impact strength, which is more than 4 times higher than ABS. Excellent electrical insulation, HIPS is easy to color and easy to print. Surface hardness of HIPS is relatively high.　

Disadvantage

Although impact strength of HIPS is very high, its elongation is less than ABS. Therefore, screw holes designed on the shell are easier to be broken by self-tapping screws. Due to addition of rubber components, surface gloss becomes dim and surface is dull; HIPS has poor thermal stability and low heat resistance.　　

Use

Used to produce housings for household appliances;
Used in production of daily necessities and toy shells;
Used for extrusion blow molding containers, hollow products, bottles.　

Injection performance

Generally, melting point of HIPS is about 170℃, decomposition temperature is 260℃; adjustable range of injection temperature is relatively large. When injection molding, general use temperature is 180℃--240℃; because of rubber component, it absorbs a small amount of water, it needs to be dried during production. It can be dried at 80-90℃ for 1-2hr; HIPS has poor thermal stability due to presence of rubber components. Therefore, do not stop HIPS in barrel during injection. Melt viscosity of HIPS is higher than that of PS, but gate and runner are general, and can also be filled with products; products are easy to be electrostatically charged and surface is easy to attract dust. Shrinkage rate is 5‰; overflow value is 0.05mm.
Physical properties Mechanical properties Injection temperature see Table 1　

ABS

Abbreviated as ABS
Commonly known as super glue
Scientific name Styrene-acrylonitrile-butadiene ternary block copolymer
English name acrylonirile butadiene styrene
Natural color Natural color of ABS is a kind of light yellow opaque particles with high gloss on the surface, with a specific gravity of 1.05, which is slightly heavier than water. It has characteristics of toughness, rigidity and rigidity.

Combustion characteristics:

It burns slowly and can continue to burn after leaving fire. Flame is yellow and emits a lot of black smoke and smoke. When burning, plastic softens and scorches, without melting and dripping.

Performance

Production of ABS is mainly due to further research on poor surface gloss of HIPS and poor mechanical properties in addition to impact strength. People are trying to find materials with better overall performance.
ABS is a terpolymer, which has good comprehensive properties; acrylonitrile makes it have good chemical resistance and surface hardness; butadiene makes it have good toughness and impact resistance; styrene makes it have good rigidity and Fluidity, makes it easy to print and dye.
Mechanical properties of ABS: tensile strength, medium. Impact strength is very good, and does not decrease rapidly at low temperatures.

Advantage:

Because it is a terpolymer, three components are different, and its performance is quite different. Generally speaking, ABS has good gloss, hardness, toughness, rigidity, and moderate mechanical properties. It is a good shell material. It is easy to print, and surface treatment such as electroplating. Its low-temperature impact performance is also relatively good, and its size is stable.　

Disadvantages　
ABS can withstand erosion of water, inorganic acid, alkali and salt. But it is not resistant to organic solvents.
ABS is susceptible to stress cracking under influence of solvents.
ABS has poor weather resistance and is susceptible to sunlight, discoloration and brittleness.

Use

Because it has good comprehensive mechanical properties, good gloss on the surface, can be electroplated and metalized, is easy to print, it is especially suitable for housing of household appliances and various products. Do some non-load-bearing structural parts.

Injection performance:

Melting point of general ABS is about 170℃, and decomposition temperature is 260℃; adjustable range of injection temperature is relatively large. During injection molding, general use temperature is 180℃--240℃; because of presence of rubber components, it absorbs a small amount of water. During production, it needs to be dried. It can be dried at 80-90℃ for 1-2hr; at the same time, due to existence of rubber components and poor thermal stability, it is relatively easy to decompose. When injection molding, raw materials should not stay in barrel for too long; melt viscosity is higher than PS, but gate and runner are general, product can be filled; product is prone to static electricity, surface is easy to absorb dust. Shrinkage rate is 5‰; overflow value is 0.05mm
Physical properties Mechanical properties Injection temperature see Table 1

AAS

Abbreviated as AAS
Scientific name Styrene-acrylonitrile-acrylate ternary block copolymer
English name acrylonirile butadiene styrene
Natural color Natural color of ABS is an opaque yellowish particle with a specific gravity of 1.07, which is slightly heavier than water. It has characteristics of toughness, rigidity and rigidity.
Combustion characteristics: similar to ABS

Advantage

Production of AAS is mainly researched on AAS in order to solve weather intolerance of ABS. Weather resistance is more than 10 times higher than that of ABS. At the same time, processing performance is also better than that of ABS.
AAS is a terpolymer, it has a good comprehensive performance; performance is similar to ABS.

Use

Because of its good weather resistance and aging resistance, it can replace ABS for outer shell and structural parts of outdoor and light situations.

Injection performance:

Generally, melting point of AAS is about 170℃, and the decomposition temperature is 300℃; adjustable range of injection temperature is relatively large. During injection molding, general use temperature is 180℃--240℃; it absorbs a small amount of water and needs to be dried during production. It can be dried at 80-90℃ for 2-3 hours; it has good thermal stability and is not easy to decompose; Melt viscosity is higher than that of PS, but gate and runner are general, and can be filled with products; shrinkage rate is 5‰; overflow value is 0.05mm
Physical properties Mechanical properties Injection temperature see Table 1

ACS

Referred to as ACS
Scientific name: styrene-acrylonitrile-chlorinated polyethylene ternary block copolymer
Natural color Natural color of ACS is an opaque yellowish particle. It has characteristics of toughness, rigidity and rigidity.
Combustion characteristics: hard to burn.

Advantage

Mechanical properties of ACS are slightly higher than that of ABS. The most notable points are:
ACS is resistant to outdoor environment, weather resistance is 10 times higher than that of ABS, and also better than AAS.
Thermal stability of ACS is better than that of ABS, and it is not easy to change color during processing.
ACS can perform simple cold forming without adding antistatic agent, but also antistatic.
ACS does not add flame retardant to flame retardant.
Disadvantages: Not resistant to organic solvents.

Use

Because of its good weather resistance and aging resistance, it can replace ABS for outer shell, structural parts of outdoor and light situations.　
Injection performance: Due to addition of chlorinated polyethylene, processing temperature cannot exceed 200℃.
Physical properties Mechanical properties Injection temperature see Table 1

AS

Abbreviated as AS SAN
Commonly known as transparent viscose
Scientific name Styrene-acrylonitrile copolymer
English name styrene acrylonirile copolymer
True color
Natural color of AS is a transparent particle with a specific gravity of 1.07, which is slightly heavier than water. Surface has a high gloss, product has characteristics of toughness, rigidity and rigidity.

Combustion characteristics:

Slow burning, it can continue to burn after leaving fire. Flame is golden yellow. It softens and emits a lot of thick black smoke when it burns. At the same time, it emits smell of acrylic fiber.

Advantage

Because PS is hard and brittle, it is transparent and fragile. In order to solve above problems and ensure its transparency, AS was created. AS has high transparency, good mechanical properties, chemical resistance, grease resistance, and good printing performance. It is raw material of excellent transparent products.

Disadvantages:

The biggest disadvantage of AS is that notch is very sensitive, there will be cracks if there is a notch, it is not resistant to fatigue and impact.

Use

Production of lenses, household appliances, tableware, daily necessities, instrument dials, transparent covers, etc.　
Injection performance: similar to PS
Physical properties Mechanical properties Injection temperature see Table 1　

MBS

Abbreviation MBS
Commonly known as transparent ABS
Scientific name Styrene-acrylonitrile-methacrylate copolymer
True color
Natural color of MBS is a transparent particle with a specific gravity of 1.10, which is slightly heavier than water. Surface has a high gloss, product has characteristics of toughness, rigidity and rigidity.

Combustion characteristics:

Slow burning, can continue to burn after leaving fire, flame is golden yellow, softens when burning and a large amount of thick black smoke emerges.

Advantage

Because PS is hard and brittle, it is transparent and fragile. ABS has excellent mechanical properties, but is opaque; AS is transparent, but is sensitive to notches, is not resistant to fatigue and impact; in order to obtain materials with excellent mechanical properties and transparency, MBS is produced. MBS has high transparency, good mechanical properties, chemical resistance, grease resistance, and good printing performance. It is raw material of excellent transparent products.　　

Disadvantages:

The biggest disadvantage of AS is that it is not resistant to weather.
Use to produce lenses, household appliances, tableware, daily necessities, instrument dials, transparent covers, etc.
Injection performance: similar to ABS
Physical properties Mechanical properties Injection temperature see Table 1　

PMMA

Abbreviated as PMMA
Commonly known as plexiglass acrylic
Scientific name Polymethylmethacrylate
English name polymethacrylate　　
True color
PMMA is a colorless transparent particle with a specific gravity of 1.19, which is heavier than water. Surface has a high gloss, product has characteristics of toughness and rigidity.

Combustion characteristics:

It is non-flammable and can continue to burn after leaving fire. Lower end of flame is blue, upper end is yellow, top is white, softening and blistering when burning, at the same time it releases smell of flowers and fruits when they rot.　

Advantage

The biggest advantage of PMMA is: its optical performance. It is transparent. Unlike other transparent materials, it can transmit light that other transparent materials cannot. Light can also be conducted inside it and used as an optical fiber. It can withstand outdoor aging and explode without affecting its transparency, while other transparent plastics do not.
It has unique electrical properties, and its power factor decreases with increasing frequency. It has good mechanical properties, resistance to dilute inorganic acids and alkalis, oils and greases, and good printing performance. .　　

Disadvantages:

The biggest disadvantage of PMMA is that it has low surface hardness and is not resistant to scratches.
Use to produce optical lenses, household appliances, tableware, daily necessities, instrument dials, transparent covers, optical fibers, etc.

Injection performance:

PMMA is an amorphous polymer with no obvious melting point. It is generally softened at 160℃, can flow around 180℃, and has a decomposition temperature of 270℃; adjustable range of injection temperature is relatively large. When injection molding, general use temperature is 180℃-240℃; it absorbs a small amount of water, and it needs to be dried during production. It can be dried at 100℃ for 2-3hr; shrinkage rate is 5‰; overflow value is 0.05mm
Physical properties Mechanical properties Injection temperature see Table 1

Table 1 General engineering plastics-physical and mechanical data
~~	~~~	~~~	PS	HIPS	ABS	AAS	ACS	AS	MBS	PMMA
1	Proportion	g/cm3	1.05	1.07	1.05	1.07	1.12	~~~	1.1	1.18
2	Water absorption	%	0.05-0.4	0.4	0.45	0.5	0.5	0.66	0.6	0.4
3	Transmittance	%	88-92	opaque	33	~~~	~~~	85-88	85-88	92-93
4	Surface hardness		M65-90	M10	R85-105	R102-108		M80-90	R100	M75
5	Shrinkage rate (range)	‰	2-6	2-6	5-7	4-8	6-8	7-9	6-8	2-6
6	Shrinkage rate (moulding)	‰	~~~	~~~	5	~~~	~~~	~~~	~~~	~~~
7	Continuous heat resistance	℃	76-104	~~~	60-98	70-104	~~~	60-96	~~~	82-93
8	Heat distortion temperature	(18.6kg/cm2)℃	82-110	79	93-103	101-107	85-83	87-104	76-85	96-100
9	Heat distortion temperature	(4.6kg/cm2)℃	90-116	~~~	99	107-115	~~~	~~~	82-93	113
10	Tensile strength	kg/cm2	460-840	350	310-530	420-560	320-420	630-840	400-410	490-700
11	Tensile strength modulus	103kg/cm2	28-42	22	16	23-26	~~~	28-39	20-22	30
12	Elongation(%)	%	1.4-2	13	5-70	20-60	20	1.5-1.7	5--20	3
13	Bending yield strength	kg/cm2	700-1200	~~~	420-770	700-840	~~~	1000-1340	700	1120-1340
14	Flexural modulus of elasticity	103kg/cm2	~~~	~~~	14-27	23-26	~~~	39	21	18-27
15	Compressive strength	kg/cm2	810-1120	~~~	320-650	670-1500	~~~	980-1200	490	770-1050
16	Compression modulus of elasticity	103kg/cm2	~~~	~~~	10--21	10.5-17.6	~~~	37	13-20	16.8-26
17	Cantilever gap	Lbs. feet/inch	0.35-0.65	1.21	5--12	6--8	~~~	0.35-0.5	5	0.3
18	Melting point	℃	173	170	170	170	150	170	170	170
19	Decomposition temperature	℃	330	260	260	300	200	290	260	260
20	Baking temperature	℃	65-70	70-90	70-85	70-85	60-70	70-85	70-85	75-95
21	Baking time	h	1	2--3	2--3	2--3	2--3	1--2	2--3	2--3
22	Injection temperature	℃	180-260	180-220	180-240	180-260	160-190	180-260	180-260	180-240
23	Mold temperature	℃	30-60	30-60	30-60	30-60	30-60	30-60	30-60	30-60
24	Can it be electroplated?	~~~	~~~	~~~	Can be electroplated	~~~	~~~	~~~	~~~	~~~