Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 15: Problem 11

For thermoplastic polymers, cite five factors that favor brittle fracture.

Short Answer

Expert verified
Answer: The five factors that contribute to brittle fracture in thermoplastic polymers are: 1. Low temperature 2. High strain rate 3. Presence of flaws or defects 4. Molecular structure and morphology 5. Aging and degradation

Step by step solution

01

1. Low temperature

At low temperatures, thermoplastic polymers become less ductile and more brittle. This is due to reduced molecular mobility, which results in lower energy absorption and increased brittleness. When these materials experience a load or impact at low temperatures, there is a higher likelihood of brittle fracture.
02

2. High strain rate

When thermoplastic polymers are subjected to high strain rates, their ability to deform undergoes a drastic change. The increased rate at which the material is being deformed reduces its ability to dissipate energy, leading to brittle fracture. Under high strain rates, the material behaves more like a glassy material, with reduced ductility and increased brittleness.
03

3. The presence of flaws or defects

The presence of flaws or defects within the material structure can serve as stress concentrators and promote brittle fracture. These flaws can include notches, cracks, or voids. When stress is applied to the material, these flaws concentrate the stress and can cause the material to fracture in a brittle manner, even at lower stress levels than would typically be expected.
04

4. Molecular structure and morphology

The molecular structure and morphology of a thermoplastic polymer can also contribute to brittle fracture. Polymers with highly interconnected or crosslinked structures exhibit reduced mobility of the polymer chains and are more prone to brittle behavior. Moreover, the presence of crystalline phases or the orientation of the polymer chains may also affect ductility, resulting in brittle failure under certain conditions.
05

5. Aging and degradation

Over time, thermoplastic polymers can experience aging and degradation due to various factors such as exposure to heat, chemicals, or radiation. These processes can alter the material properties and structure, leading to embrittlement and a higher risk of brittle fracture. This aging and degradation of the material can reduce molecular mobility and chain flexibility, further promoting brittle behavior.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Fifteen kilograms of polychloroprene is vulcanized with \(5.2 \mathrm{~kg}\) of sulfur. What fraction of the possible crosslink sites is bonded to sulfur crosslinks, assuming that, on the average, \(5.5\) sulfur atoms participate in each crosslink?

For the vulcanization of polyisoprene, com\(+\) pute the weight percent of sulfur that must be added to ensure that \(10 \%\) of possible sites will be crosslinked; assume that, on the average, \(3.5\) sulfur atoms are associated with each crosslink.

(a) Contrast the manner in which stress relaxation and viscoelastic creep tests are conducted. (b) For each of these tests, cite the experimental parameter of interest and how it is determined.

Make two schematic plots of the logarithm of relaxation modulus versus temperature for an amorphous polymer (curve \(C\) in Figure \(15.8\) ). (a) On one of these plots, demonstrate how the behavior changes with increasing molecular weight. (b) On the other plot, indicate the change in behavior with increasing crosslinking.

Why must fiber materials that are melt-spun and then drawn be thermoplastic? Cite two reasons.
See all solutions

Recommended explanations on Physics Textbooks

Nuclear Physics

Read Explanation

Physics of Motion

Read Explanation

Work Energy and Power

Read Explanation

Electromagnetism

Read Explanation

Kinematics Physics

Read Explanation

Torque and Rotational Motion

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free