Ashton Petersen

Project 1: Analytic Narrative (Revised)

When I began my Spring 2025 research internship at Pacific Northwest National Laboratory, I assumed that writing started when the engineering work ended. As a mechanical engineering student, I was accustomed to treating calculations, equipment, experiments, and data as the “real” work. A report seemed like the final step: a clean summary written after the problem had already been solved. By the end of the internship, however, I understood writing very differently. Drafting my research report forced me to decide what our experiments meant, which details mattered, how strongly the evidence supported our conclusions, and what another researcher would need in order to continue the project. I came to see that technical writing does not merely describe research. It is one of the main ways research becomes coherent, reproducible, and useful.

That realization developed while I wrote Fabrication of Self-reinforced PPS Composites via a Novel Injection Over-molding Method, the report that documented my internship project. The project focused on polyphenylene sulfide, or PPS, a high-performance engineering thermoplastic valued for its thermal stability, chemical resistance, rigidity, and tensile strength. Many polymer composites strengthen a plastic matrix with a different material, such as glass or carbon fiber. Our project instead placed PPS fabric inside a PPS resin matrix, creating a “self-reinforced” composite in which the reinforcement and matrix were chemically similar. This approach could simplify the material system, improve recyclability, reduce thermal-expansion mismatch, and provide a lightweight alternative for automotive and other engineering applications. We attempted to fabricate the composite through injection over-molding, a process in which melted matrix material is injected around a reinforcement already positioned inside a mold.

Explaining that background was one of the first substantial changes I needed to make as a writer. My early draft moved too quickly into equipment and trial numbers, as though every reader already knew what PPS was and why embedding PPS fabric in PPS resin was unusual. Peer feedback confirmed that a non-engineering reader could easily become lost in the terminology. Revising the introduction taught me that technical accuracy is not the same as technical density. Before readers could understand the processing problems, they needed the larger idea: conventional PPS composites had been studied extensively, while self-reinforced PPS composites remained less explored because the fibers and matrix have nearly the same melting temperature. That similarity made the material promising, but it also made fabrication difficult. Once I explained that tension, the experiments had a clear purpose instead of appearing as an isolated series of molding trials.

The report was the culmination of my PNNL internship, so its immediate audience included my mentors, other laboratory researchers, and interns in the Department of Energy program. Yet I gradually realized that the real audience was broader: any researcher who might evaluate the work, repeat the process, or decide what to test next. The six-page report format and its required sections gave me an explicit structure, but the community also had implicit expectations. By observing senior researchers, reading previous reports and articles, and responding to questions from my mentors, I learned to ask whether another person could understand what we did, whether the processing conditions were specific enough, and whether each claim was supported by evidence. These expectations were not arbitrary rules. They existed because research writing must allow other people to inspect and reuse the work rather than simply trust the author.

My biggest drafting problem was deciding what belonged in the report. In the laboratory, every temperature, pressure, heating time, injection speed, and visual observation felt important. My notebook preserved those details chronologically, and my first attempts at the report sounded much the same: first we tried one setting, then a part failed, then we changed another setting. The result was complete in one sense, but it was not clear. I had confused a laboratory record with a research narrative. Through revision, I learned to select details according to the reasoning they revealed. A temperature belonged in the report when it explained why the PPS did not flow, why the fabric deformed, or why a later trial succeeded. A failed part mattered when it justified the next procedural change. Writing became an act of finding relationships among the details, not merely preserving all of them.

That lesson became clearest while I described the trial-and-error process. We began with high-density polyethylene, or HDPE, as a substitute matrix so that we could establish basic manual injection-molding parameters without wasting PPS. The melted HDPE entered the mold, but inconsistent injection speed and pressure allowed it to cool too early, producing incomplete parts. After preparing each setup, opening the mold to find another unusable sample was discouraging. Still, the failures gave us information. We preheated the mold to reduce the temperature difference between the hot material and the cooler tooling, and by Trial 8 we produced a bonded HDPE/PPS sample that was good enough to justify moving forward.

Switching from HDPE to PPS created a more difficult set of problems. Because ready-made PPS pellets were unavailable, we initially cut PPS fabric into pieces and attempted to use it as both the matrix feedstock and the reinforcement. We increased the matrix temperature from 289 °C to as high as 312 °C because the material cooled and hardened quickly after ejection. At the same time, raising the mold temperature too far caused the reinforcement fabric to deform; prolonged exposure above 250 °C made it unusable. Eventually, a matrix temperature of 312 °C and a mold temperature of 210 °C produced a fully bonded self-reinforced composite. Later automatic-molding trials introduced another challenge: the low-density cut fibers did not feed or compress consistently. Extruding the PPS into a continuous strip and granulating it into small pellets finally created a matrix material that injected more completely.

Writing this sequence changed how I understood both failure and credibility. At first, I worried that unsuccessful trials would make the project look weak. In a personal story, I might have focused mainly on the frustration of repeated setbacks. In the technical report, however, I needed to transform that frustration into useful reasoning: what happened, why it likely happened, what variable changed next, and what the result of that change suggested. A failed trial was not empty space between successful ones. It was evidence that established a processing limit or eliminated an approach. Scientific writing does not earn trust by pretending that research follows a straight line. It earns trust by making the decision-making process visible and by being honest about what remains uncertain.

The final organization helped me make that reasoning visible. The abstract condensed the material system, fabrication method, testing, and central findings. The introduction established the research gap through previous literature. The project-progress section showed how the procedure developed across manual and automatic molding. The future-work section identified unresolved problems, including voids in the matrix, movement of the fabric inside the mold, the need for larger fiber-volume fractions, and the possible use of commercial PPS pellets. The impact section connected the preliminary work to lightweight and durable materials for transportation and other applications. The conclusion then stated what the limited evidence could support. Each section answered a different question for the reader, and together they turned a collection of experiments into an argument.

Some of the most important conventions were less visible. I used first-person plural because the experiments were completed by a research team, not by me alone. I also had to replace broad judgments with measured claims. The tensile-testing results were complicated: many self-reinforced specimens performed poorly because voids and fabric dislocation weakened them, while two specimens from a single-sided mold exceeded the pure-PPS benchmarks. It would have been misleading to write that self-reinforcement always made PPS stronger. Instead, the report stated that successful specimens with about a 9% fiber volume fraction showed a 15.66% increase in ultimate tensile strength and a 33% increase in elastic modulus compared with pure PPS specimens. The numbers did more than sound precise. They defined exactly which samples supported the claim and prevented a promising result from becoming an exaggerated conclusion.

The figures also became part of the argument rather than decoration. One multi-panel process figure combined photographs of the extrusion step, the resulting PPS pellets, the fabric-containing mold, and the automatic Mini-Jector. A second figure showed the composite plate being water-jet cut into dogbone-shaped specimens and then tested in tension. The final results figure combined stress-strain curves, a table of tensile strengths and fiber-volume fractions, and a photograph of a fractured specimen. Together, these visuals connected the manufacturing process to the measured mechanical response. The accompanying research poster later compressed the same logic into a visual sequence, which made me notice how captions, labels, arrows, and layout guide a technical audience. Whether in a report or a poster, the visual evidence had to help readers see how the process produced the data and how the data supported the conclusion.

This project also changed my sense of myself as a writer and as an engineer. My mechanical engineering background helped me understand tensile strength, elastic modulus, fabrication, and mechanical testing, but the project required me to think more like a materials researcher. I had to connect melting behavior, thermal gradients, fiber-matrix bonding, polymer processing, void formation, and chemical similarity. Writing the report made those connections clearer because I could not simply say that a setting worked; I had to explain why it mattered to the material. It also showed me that communicating the broader value of a project requires restraint. Self-reinforced PPS composites may offer lighter, durable, and more recyclable material options, but our tests were preliminary and many specimens failed. Presenting both the potential and the limitations was more responsible – and ultimately more persuasive – than presenting the project as a finished success.

I entered the internship believing that writing came after engineering. I left understanding that writing is part of engineering because it shapes how evidence is selected, interpreted, questioned, and shared. Revising this narrative has reinforced that lesson. I now see several habits that I will carry into future research: define unfamiliar concepts before relying on them, establish why the problem matters, organize experiments around decisions rather than chronology, quantify claims, explain failures without hiding them, and use visuals as evidence. A meaningful research project is not only one that produces a promising material or a successful test. It is one that another person can evaluate, repeat, challenge, and build upon. Technical writing is what makes that possible.

References

Petersen, A., Boushab, D., Qiao, Y., Ni, Y., Ramos, J., & Simmons, K. L. (2025). Fabrication of self-reinforced PPS composites via a novel injection over-molding method [Research report]. Pacific Northwest National Laboratory.