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GPPS/ HIPS
Overview
starex PS resin is divided into GPPS (General Purpose Polystyrene)and HIPS (High Impact Polystyrene). starex GPPS is a thermoplastic resin with high molecular weight of 200,000- 300,000. Such high molecular weights enhance the impact strength and its transparency is comparable to PMMA. Furthermore, its excellent processability and mechanical properties make it widely used. Transparency, residual monomer content, and molecular weight are important factors to determine material properties and should be considered when selecting a grade. HIPS is made by dissolving the rubber in a styrene monomer and then polymerizing the styrene in the usual way. Material properties of HIPS strongly depend on the content and particle size of rubber, bonding strength between rubber and matrix, and homogeneity. Generally, the rubber content of impact polystyrene is around 3% and the size of rubber particles is 1-5%. HIPS retains higher rubber content from 5 to 15% to increase impact strength, thus making it useful for products requiring such properties. In addition, due to high heat resistance and fluidity, products can be made by various processing methods such as injection molding, extrusion, vacuum forming and blow molding.
Features
starex GPPS has excellent mechanical properties, transparency, heat resistance, moldability, and coloration. In addition, the electrical insulation characteristics of starex GPPS are extremely good, and the effect of frequency on dielectric constant is negligible. It is a non-toxic resin that generates only a small amount of gas during the molding process. Due to its superb scratch resistance and fluidity, GPPS exhibits outstanding processability not only for injection molding but also for OPS (oriented polystyrene) and PSP (polystyrene paper). starex HIPS has superior mechanical properties, processability, moldability, not to mention high impact strength. Heat resistance has been improved especially for final products. The surface peeling often found on other molded products has not been observed on products using starex HIPS.
Properties
1) Mechanical
Due to the rubber component, the stress of HIPS at the breaking point is smaller than that of GPPS. However, HIPS has superior elongation and impact strength, which strengthens as the rubber content increases. In HIPS, rubber exists in discrete droplets within the polystyrene matrix. In such a form, rubber can reduce crack propagation and fracture in various ways.
2) Thermal
Thermal properties are import ant factors selecting the proper grade for both the user of the end products and for the processor. When subjected to high temperature for a long time, problems such as property deterioration of molded products and discoloration occur from thermal degradation. The starex HIPS, which possesses superb thermal stability, undergoes little color and property change with temperature variation. From the user's point of view, the very low thermal conductivity is one of the principal features of starex GPPS and HIPS.
3) Chemical Resistance
PS resin is resistant to various kinds of chemicals, such as water, alkalis, weak inorganic acids, and most kinds of salts even though it is not generally as good as PE. In benzene, toluene, chlorinated hydrocarbon, hydrogen, esters and ketones, the resin either dissolves or swells. It subordinates to concentrated sulfuric acid, nitric acid, chlorine water, boric water, and strong oxidizers such as bleaching agents. Refer to table 1 for further details.
| Chemicals
|
Results
|
Chemicals
|
Results
|
Chemicals
|
Results
|
Chemicals
|
Results
|
Sulfuric
acid
(conc.) |
Y |
Benzene
|
N |
Hydrochlor-
ic acid 10% |
Y |
Gasoline
|
N |
Sulfuric
acid
10% |
Y |
Toluene
|
N |
Hydrochlor-
ic acid (conc.) |
S |
Machine
oil |
Y |
Nitric
acid
10% |
Y |
Phenol
|
S |
Sodium
hydroxide 40% |
Y |
Silicone
oil |
Y |
Nitric
acid
20% |
Y |
Ether
|
N |
Ammonia
10% |
Y |
Distilled
water |
Y |
Acetic
acid
5% |
Y |
Ethyl
acetate |
N |
Xylene
|
N |
Ethanal
95% |
S |
| Glycerin
|
Y |
Hydroper-
oxide 3% |
Y |
Heptane
|
N |
Ethanal
50% |
Y |
Carbon
tetrachloride |
N |
Chloroform
|
N |
Dichloroe-
thane |
N |
Acetone
|
N |
Formaldeh-
yde |
Y |
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Note
Y : Absolutely no variation in appearance and strength
S : Slight variation in appearance and strength
N : Significant variation in appearance and strength
4) Transparency
Transparency, an important property of GPPS, is dependent on the injection temperature, water absorption rate, compounding method, and additives. For excellent transparency, careful processing control is advised. Cheil Industries Inc. provides various grades of GPPS which meet the user's specific requirements.
Type & Applications
|
Class |
Grades |
Characteristics
|
Typical Application
|
|
HIPS |
HF-1680 |
High flow,
High impact strength |
OA equipment,
home appliances, ashers, refrigerator parts, toys, leisure products,
radio st housing, packing containers, etc. |
|
HF-1690 |
Excellent
flow |
Thin-walled
products, toys, commodities |
|
HR-1360 |
Heat resistance,
High impact strength |
TV set housing,
home appliances, washers, refrigerator parts, toys, leisure products,
radio set housing, packing containers, etc. |
|
HR-1360H |
High impact
strength |
Large bottles,
packing containers |
|
SH-1170 |
Cold-proof
for extrusion |
Refrigerator
inner/door liners, disposable cups, trays, tables watches, washers,
commodities, etc. |
|
BM-1670 |
High flow,
Good moldability |
Yogurt containers,
large bottles |
|
HG-1760S |
High gloss,
High impact resistance |
Refrigerator
parts, products requiring high gloss |
|
GPPS |
HF-2660 |
Good melt
flow |
Toys, commodities,
cosmetic containers, cookware, furniture, medical equipment, light
aprons, etc. |
|
HF-2660S |
|
HR-2390 |
Ultra-high
heat resistance |
Lighting
equipment, cassette tapes, fan blades, medical equipment, school stationery,
optical parts, vegetable storage bins for refrigerators, dust covers,
etc. |
|
HR-2390S |
|
HF-2680 |
High melt
flow characteristics |
Disposable
cups, packing containers, lighting equipment, home appliances, commodities,
etc. |
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| © 2010 SAMSUNG CHEMICAL (USA), INC. |
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