材料导论英语

a Polymerization (聚合作用) is the process by which small molecules (分子) consisting of one unit or a few units are chemically joined to create these giant molecules. Those small molecule units are called ______

A) polymers B) monomers (单体) C) oligomers D)elastomers

b Choose the type of polymer material you might select for the following applications: an automobile bumper (保险杠), a mineral water bottle, and an insulating (绝热的) cable.

A) For automobile bumper, the best choice of polymer is Natural Rubber.

B) For mineral water bottle, the best choice of polymer is Low-Density（密度） Polyethylene (聚乙烯)

C) For insulating cable, the best choice of polymer is polystyrene (聚苯乙烯).

D) For mineral water bottle, the best choice of polymer is Polyethylene Terephthalate.

c) In general, for a given type of thermoplastic (热塑性塑胶) the tensile (可延展的) strength, creep resistance impact toughness, wear resistance, and melting temperature all increase with______

A) degree of polymerization B)density of branching C)tacticity D) crystallinity

d) ABS, composed of acrylonitrile, butadiene, and styrene (苯乙烯), is one of the most common polymer materials. Styrene and acrylonitrile form a liner copolymer (异量分子聚合物) (SNA) that serves as a matrix. Styrene and butadiene also form a liner copolymer, BS rubber, which acts as the ______ material.

A) fire retardant B) filler C) cross-linking D)plasticizer

e) Epoxies （环氧树脂）are thermosetting polymers formed from molecules containing a tight C-O-C ring. During polymerization, the C-O-C rings are opened and the bonds are rearranged to join the molecules. If epoxy is used as an adhesive (粘剂) for a variety of applications, which kind of adhesives does it belong to?

A) Chemically Reactive Adhesives

B) Evaporation or Diffusion Adhesives

C) Hot-Melt Adhesives D) Pressure-Sensitive Adhesives

f) What area the major advantages associated with plastic compared to ceramics, glasses, and metallic materials?

A) lightweight and corrosion(铁锈，腐蚀)-resistant

B) high strength and high-temperature resistant

C) high-temperature resistant and insulating

D) high stiffness and corrosion-resistant

g) Which one is not a thermoset polymer?

A) Polyethylene B) Natural Rubber C) Epoxy D) Phenolic

h) Depending on the degree of cross-linking, the polyurethanes behave as thermosetting polymers, thermoplastics (热塑性塑胶), or elastomers. These polymers find application as fibers, coatings, and foams for furniture, mattress, and insulation. Why polyurethanes are versatile?

A) for their polar repeat unit B) for their linear structure

C) for their multi-functional monomer D) for their tactictity structure

h) Liquid Crystalline(透明的) Polymers are polymers which behave as ______

A) liquid B) thermoplastic C) thernoset D)

oriented(取向) rods

l) The glass temperature (Tg) is typically about ______ times the absolute melting temperature (Tm).

A) 0.2 to 0.3 B) 0.5 to 0.7 C) 0.8 to 1.0 D) 1.0 to 2.0

i) Most thermoplastic exhibit a non-Newtonian and visicoelastic behavior. The stress and train are not linearly related for most parts of the stress-strain curve. The viscoelastic behavior means when an external (外部的) force is applied to a thermoplastic _______ deformation occurs.

A) only elastic B) both elastic and plastic (塑性)

C) only plastic D) neither elastic nor plastic

l) Compare the tensile strength of LDPE, HDPE, PVE, PP, and arrange them in sequence(顺序) from high strength to low tensile strength.

A) LOPE>HDPE>PVE>PP B) LDPE>HDPE>PP>PVC

C) PVC>PP>HDPE>LDPE D) PVC>HDPE>PP>LDPE

m) Degree of polymerization is usually used to characterize ________

A) cross-linking network B) thermosetting polymer

C) polymer degradation D) thermoplastic polymer

14) Silicones(硅) are important elastomer based on chains composed of silicon and oxygen atoms. The silicone rubbers provide high-temperature resistance, permitting use of the elastomer at temperature as high as _____℃. Low molecular weight silicones form liquids and are known as silicon oils.

A) 100 B) 150 C) 200 D) 300

15) There are a lot of thermoplastic processing methods, typical forming process includes: extrusion, blow molding, injection molding, thermoforming, calendaring and spinning. If we want to produce sping water bottles, which processing way is best choice?

A) extrusion B) blow molding C) injection molding D) thermoforming

16) The recycling of thermoplastics is relatively easy and practiced widely. Many of the everyday plastic products you encounter (bags, soda bottles, yogurt containers, etc.) have numbers stamped on them. For PRT products, the number is 1. For HDPE and LDPE, the numbers are_______, respectively. Other plastics are marked number 7,

A) 3 and 4 B) 4 and 5 C) 2 and 4 D) 2 and 3

17) The temperature above which a polymer burns, chars, or decompose. Which team is appropriately used in describing the remperature.

A) Tg B) Td C) Tm D) HDT

18) Which forming process is not a best choice for thermosetting polymers.

A) Compression molding B)transfer molding

C) reaction injection D) spinning

19) Elastomers are thermoplastics or lightly cross-linked thermosets that exhibit greater than _______ elastic deformation.

A) 0.2% B ) 2% C) 20% D)200%

20) Thermoplastic elastomers combine feature of both thermoplastics and elastomers. At high temperature, these polymers behave as ________ and are plastically into shapes, at how temperature, they behave as _________

A) thermoplastics; elastomers B) thermoplastics; thermosetting polymers

C) elastomers; thermoplastic D) elastomers; thermosetting polymers



21 Define (a) a thermoplastic, (b

) thermosetting plastics, (c) elastomers, and (d) thermoplastic elastomers.

22) Explain what the following terms mean in polymer materials: decompositions temperate (Td), heat distortion temperature (HDT), glass temperature (Tg), and melting temperature (Tm).

23) Typical forming processes for thermoplastic are schematicly shown blew, give each forming process a name and explain what kind of plastic products can be made by corresponding forming process.

挤出 吹塑 延展 喷涂…………

24) The molecular weight of polymethyl methacrylate (PMMA) is 250,000g/mol. If all of the polymer chains are the same length.

a) calculate the degree of polymerization, and

b) the number of chains in 1g of the polymers.

25) Explain why low-density polyethylene is good to make grocery bags, however, ultra-high molecular weight polyethylene must be used where strength and very high wear resistance is needed.

26) How do the glass temperature of polyethylene, polypropylene, and polymethyl methacrylate compare? Explain their difference, based on the structure of the monomer?

27) Give a materials example in your everyday life, explain the relationship of their structure and properties.

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