Plastic Material Selection

In the rapidly evolving industrial landscape of today, plastic materials have become an indispensable component due to their superior performance and broad range of applications. They are not only ubiquitous in everyday life but also play a crucial role in numerous fields such as high-tech industries, medical equipment, automotive manufacturing, aerospace, and beyond. With the continuous advancement of material science, the variety and performance of plastic materials are ever-increasing, presenting engineers and designers with more choices and challenges. How to select the most suitable plastic material from the myriad of options for a specific application has become a complex yet critical issue.This article aims to provide a comprehensive guide to help readers understand the basic properties of plastic materials, processing techniques, performance requirements, and how they impact the performance and cost of the final product. We will discuss the chemical and physical characteristics of various plastic materials, analyze their performance under different environmental and application conditions, and offer practical selection advice. By delving into the process of selecting plastic materials, we hope to assist readers in making informed decisions during the product design and development phase, ensuring the reliability, durability, and economic efficiency of the products.Following this preface, we will embark on a journey into the world of plastic materials, exploring their secrets and learning how to apply this knowledge to practical product design. Whether you are an experienced engineer or a newcomer to the field of material science, we hope that this article will provide you with valuable information and inspiration. Let us begin this journey together to uncover the mysteries of plastic material selection.

Plastic Material Selection

To date,over ten thousand types of resins have been reported,with thousands of these being industrially produced.The selection of plastic materials involves choosing an appropriate variety from the vast array of resin types.At first glance,the multitude of plastic varieties available can be overwhelming.However,not all resin types have been widely applied.The selection of plastic materials we refer to is not arbitrary but is filtered within the commonly used resin types.

Principles for Plastic Material Selection:

I.Adaptability of Plastic Materials

• Comparative performance of various materials;

• Conditions not suitable for plastic selection;

• Conditions suitable for plastic selection.

II.Performance of Plastic Products

Usage Conditions of Plastic Products:

a.Mechanical stress on plastic products;

b.Electrical properties of plastic products;

c.Dimensional precision requirements of plastic products;

d.Permeability requirements of plastic products;

e.Transparency requirements of plastic products;

f.Appearance requirements of plastic products.

Usage Environment of Plastic Products:

a.Ambient temperature;

b.Ambient humidity;

c.Contact media;

d.Light,oxygen,and radiation in the environment.

III.Processing Performance of Plastics

• Processability of plastics;

• Processing costs of plastics;

• Waste generated during plastic processing.

IV.Cost of Plastic Products

• Price of plastic raw materials;

• Service life of plastic products;

• Maintenance costs of plastic products.

In the actual selection process,some resins have very similar properties,making it difficult to choose.Which one to choose is more appropriate requires multifaceted consideration and repeated weighing before a decision can be made.Therefore,the selection of plastic materials is a very complex task,and there are no obvious rules to follow.One thing to note is that the performance data of plastic materials cited from various books and publications are measured under specific conditions,which may differ significantly from actual working conditions.

Material Selection Steps:

When faced with the design drawings of a product to be developed,material selection should follow these steps:

• First,determine whether the product can be manufactured using plastic materials;

• Second,if it is determined that plastic materials can be used for manufacturing,then which plastic material to choose becomes the next factor to consider.

Selection of Plastic Materials Based on Product Precision:

Precision Grade Available Plastic Material Varieties

1 None

2 None

3 PS, ABS, PMMA, PC, PSF, PPO, PF, AF, EP, UP, F4, UHMW, PE 30%GF reinforced plastics (30%GF reinforced plastics have the highest precision)

4 PA types, chlorinated polyether, HPVC, etc.

5 POM, PP, HDPE, etc.

6 SPVC, LDPE, LLDPE, etc.

Indicators for Measuring the Heat Resistance of Plastic Products:

The commonly used indicators are heat deflection temperature,Martin heat resistance temperature,and Vicat softening point,with heat deflection temperature being the most commonly used.

Heat Resistance Performance of Common Plastics(Unmodified):

Material Heat Deflection Temperature Vicat Softening Point Martin Heat Resistance Temperature

HDPE 80℃ 120℃ -

LDPE 50℃ 95℃ -

EVA - 64℃ -

PP 102℃ 110℃ -

PS 85℃ 105℃ -

PMMA 100℃ 120℃ -

PTFE 260℃ 110℃ -

ABS 86℃ 160℃ 75℃

PSF 185℃ 180℃ 150℃

POM 98℃ 141℃ 55℃

PC 134℃ 153℃ 112℃

PA6 58℃ 180℃ 48℃

PA66 60℃ 217℃ 50℃

PA1010 55℃ 159℃ 44℃

PET 70℃ - 80℃

PBT 66℃ 177℃ 49℃

PPS 240℃ - 102℃

PPO 172℃ - 110℃

PI 360℃ 300℃ -

LCP 315℃ - -

Principles for Selecting Heat-Resistant Plastics:

• Consider the level of heat resistance:

a.Meet the heat resistance requirements without choosing too high,as it may increase costs;

b.Preferably use modified general plastics.Heat-resistant plastics mostly belong to special plastics,which are expensive;general plastics are relatively cheaper;

c.Preferably use general plastics with a large margin of heat resistance modification.

• Consider heat resistance environmental factors:

a.Instantaneous and long-term heat resistance;

b.Dry and wet heat resistance;

c.Resistance to medium corrosion;

d.Oxygen and oxygen-free heat resistance;

e.Loaded and unloaded heat resistance.

Heat Resistance Modification of Plastics:

Filled Heat Resistance Modification:

Most inorganic mineral fillers,except for organic materials,can significantly improve the heat resistance temperature of plastics.Common heat-resistant fillers include:calcium carbonate,talc,silica,mica,calcined clay,alumina,and asbestos.The smaller the particle size of the filler,the better the modification effect.

• Nano fillers:

• PA6 filled with 5%nano montmorillonite,the heat deflection temperature can be raised from 70°C to 150°C;

• PA6 filled with 10%nano meerschaum,the heat deflection temperature can be raised from 70°C to 160°C;

• PA6 filled with 5%synthetic mica,the heat deflection temperature can be raised from 70°C to 145°C.

• Conventional fillers:

• PBT filled with 30%talc,the heat deflection temperature can be raised from 55°C to 150°C;

• PBT filled with 30%mica,the heat deflection temperature can be raised from 55°C to 162°C.

Reinforced Heat Resistance Modification:

Enhancing the heat resistance of plastics through reinforcement modification is even more effective than filling.Common heat-resistant fibers mainly include:asbestos fiber,glass fiber,carbon fiber,whiskers,and poly.

• Crystalline resin reinforced with 30%glass fiber for heat resistance modification:

• PBT's heat deflection temperature is raised from 66°C to 210°C;

• PET's heat deflection temperature is raised from 98°C to 238°C;

• PP's heat deflection temperature is raised from 102°C to 149°C;

• HDPE's heat deflection temperature is raised from 49°C to 127°C;

• PA6's heat deflection temperature is raised from 70°C to 215°C;

• PA66's heat deflection temperature is raised from 71°C to 255°C;

• POM's heat deflection temperature is raised from 110°C to 163°C;

• PEEK's heat deflection temperature is raised from 230°C to 310°C.

• Amorphous resin reinforced with 30%glass fiber for heat resistance modification:

• PS's heat deflection temperature is raised from 93°C to 104°C;

• PC's heat deflection temperature is raised from 132°C to 143°C;

• AS's heat deflection temperature is raised from 90°C to 105°C;

• ABS's heat deflection temperature is raised from 83°C to 110°C;

• PSF's heat deflection temperature is raised from 174°C to 182°C;

• MPPO's heat deflection temperature is raised from 130°C to 155°C.

Plastic Blending Heat Resistance Modification

Blending plastics to enhance heat resistance involves incorporating high heat-resistant resins into low heat-resistant resins,thereby increasing their heat resistance.Although the improvement in heat resistance is not as significant as that achieved by adding heat-resistant modifiers,the advantage is that it does not significantly affect the original properties of the material while enhancing heat resistance.

• ABS/PC:The heat deflection temperature can be increased from 93°C to 125°C;

• ABS/PSF(20%):The heat deflection temperature can reach 115°C;

• HDPE/PC(20%):The Vicat softening point can be increased from 124°C to 146°C;

• PP/CaCo3/EP:The heat deflection temperature can be increased from 102°C to 150°C.

Plastic Crosslinking Heat Resistance Modification

Crosslinking plastics to improve heat resistance is commonly used in heat-resistant pipes and cables.

• HDPE:After silane crosslinking treatment,its heat deflection temperature can be increased from the original 70°C to 90-110°C;

• PVC:After crosslinking,its heat deflection temperature can be increased from the original 65°C to 105°C.

Specific Selection of Transparent Plastics

I.Daily Use Transparent Materials:

• Transparent film:Packaging uses PE,PP,PS,PVC,and PET,etc.,agricultural uses PE,PVC,and PET,etc.;

• Transparent sheets and panels:Use PP,PVC,PET,PMMA,and PC,etc.;

• Transparent tubes:Use PVC,PA,etc.;

• Transparent bottles:Use PVC,PET,PP,PS,and PC,etc.

II.Lighting Equipment Materials:

Mainly used as lamp shades,commonly used PS,modified PS,AS,PMMA,and PC.

III.Optical Instrument Materials:

• Hard lens bodies:Mainly use CR-39 and J.D;

• Contact lenses:Commonly use HEMA.

IV.Glass-like Materials:

• Automotive glass:Commonly use PMMA and PC;

• Architectural glass:Commonly use PVF and PET.

V.Solar Energy Materials:

Commonly used PMMA,PC,GF-UP,FEP,PVF,and SI,etc.

VI.Optical Fiber Materials:

Core layer uses PMMA or PC,and the cladding layer is a fluoro-olefin polymer,fluorinated methyl methacrylate type.

VII.CD Materials:

Commonly used PC and PMMA.

VIII.Transparent Encapsulation Materials:

Surface-hardened PMMA,FEP,EVA,EMA,PVB,etc.

Specific Material Selection for Different Purposes of Housings

• TV Housings:

• Small size:Modified PP;

• Medium size:Modified PP,HIPS,ABS,and PVC/ABS alloys;

• Large size:ABS.

• Refrigerator Door Liners and Inner Liners:

• Commonly use HIPS boards,ABS boards,and HIPS/ABS composite boards;

• Currently,ABS is the main material,only Haier refrigerators use modified HIPS.

• Washing Machines:

• Inner buckets and covers mainly use PP,a small amount uses PVC/ABS alloys.

• Air Conditioners:

• Use reinforced ABS,AS,PP.

• Electric Fans:

• Use ABS,AS,GPPS.

• Vacuum Cleaners:

• Use ABS,HIPS,modified PP.

• Iron:

• Non-heat resistant:Modified PP;

• Heat resistant:ABS,PC,PA,PBT,etc.

• Microwave Ovens and Rice Cookers:

• Non-heat resistant:Modified PP and ABS;

• Heat resistant:PES,PEEK,PPS,LCP,etc.

• Radios,Tape Recorders,Video Recorders:

• Use ABS,HIPS,etc.

• Telephones:

• Use ABS,HIPS,modified PP,PVC/ABS,etc.