Michael Sepe Independent Consultant

Materials Know How 19 Mar 2024

Fundamentals of Polyethylene – Part 3: Field Failures

Polyethylene parts can fail when an inappropriate density is selected. Let’s look at some examples and examine what happened and why.

polyolefins 12 Mar 2024

The Fundamentals of Polyethylene – Part 2: Density and Molecular Weight

PE properties can be adjusted either by changing the molecular weight or by altering the density. While this increases the possible combinations of properties, it also requires that the specification for the material be precise.

Materials Know How 5 Mar 2024

The Fundamentals of Polyethylene – Part 1: The Basics

You would think we’d know all there is to know about a material that was commercialized 80 years ago. Not so for polyethylene. Let’s start by brushing up on the basics.

Engineering Resins 1 Aug 2019

PART 2: The Importance of Mold Temperature When Processing Polycarbonate

Don’t be afraid to increase mold temperature to improve part quality when making PC parts. Take a look at a few examples here.

Materials Know How 1 Jul 2019

Part 1: The Importance of Mold Temperature When Processing Polycarbonate

An often overlooked factor in optimizing the ductility of PC is the rate at which the polymer is cooled in the mold.

Materials Know How 1 May 2019

Part 5: Heat Deflection Temperature vs. Dynamic Mechanical Analysis

In the final part of this five-installment series, we bring DMA to a practical level using the results for glass-filled nylon.

Testing 1 Apr 2019

Part 4: Heat Deflection Temperature vs. Dynamic Mechanical Analysis

The presentation of DMA data can sometimes frustrate users and discourage its adoption. Those unfamiliar with DMA should insist on receiving data relevant to the manner in which the part they are developing will be used.

Materials 11 Mar 2019

Heat Deflection Temperature vs. Dynamic Mechanical Analysis (Part 3)

DMA provides a rich and detailed picture of polymer performance, and it can be challenging to understand all the things that we can and should know about our materials. But the fact that it may be hard does not mean that it should not be attempted.

Testing 1 Feb 2019

PART 2 Heat Deflection Temperature vs. Dynamic Mechanical Analysis

Here’s a real-world example of a part failure demonstrating why DMA curves have more value than single-point data generated by HDT.

Testing 1 Jan 2019

Part 1: Heat Deflection Temperature vs. Dynamic Mechanical Analysis

Does the industry need a better way of reporting the temperature-dependent behavior of plastics? With DMA, it already has one. But it’s been glacially slow to catch on.

Materials Know How 30 Nov 2018

Part 11: A Processor's Most Important Job

It’s the processors job to ensure molded parts contain enough stabilizer to perform to the expectations of the end use.

business 30 Oct 2018

A Processor’s Most Important Job, Part 10: Fiber-Length Retention

Glass and carbon fibers are often used to increase material strength and modulus. To maintain these properties, the aspect ratio of these fibers must be maintained.