Mechanical, Thermal and Morphological Characterization of Polycarbonate/Oxidized Carbon Nanofiber Composites Produced with a Lean 2-Step Manufacturing Process

Abstract

In this study we report the advantages of a 2-step method that incorporates an additional process pre-conditioning step for rapid and precise blending of the constituents prior to the commonly used melt compounding method for preparing polycarbonate/oxidized carbon nanofiber composites. This additional step (equivalent to a manufacturing cell) involves the formation of a highly concentrated solid nano-nectar of polycarbonate/carbon nanofiber composite using a solution mixing process followed by melt mixing with pure polycarbonate. This combined method yields excellent dispersion and improved mechanical and thermal properties as compared to the 1-step melt mixing method. The test results indicated that inclusion of carbon nanofibers into composites via the 2-step method resulted in dramatically reduced ( 48% lower) coefficient of thermal expansion compared to that of pure polycarbonate and 30% lower than that from the 1-step processing, at the same loading of 1.0 wt%. Improvements were also found in dynamic mechanical analysis and flexural mechanical properties. The 2-step approach is more precise and leads to better dispersion, higher quality, consistency, and improved performance in critical application areas. It is also consistent with Lean Manufacturing principles in which manufacturing cells are linked together using less of the key resources and creates a smoother production flow. Therefore, this 2-step process can be more attractive for industry.

Structurally Induced Dielectric Constant Promotion and Loss Suppression for Poly(vinylidene fluoride) Nanocomposites

“…Therefore, the interaction between CNFs and the PVDF matrix was enhanced. Even with the functionalized CNFs, we also found that the interaction could be poor when entanglements/agglomerates existed due to an ineffective processing method 22. In this study and our other reported work, it was found that improving the dispersion could also improve the interaction between the nanofillers and the polymer matrix materials.…”

Analysis tools for fibrous nanofiller polymer composites: Macro‐ and nanoscale dispersion assessments correlated with mechanical and electrical composite properties

“…In addition to the observance of the loss modulus curves, examining the area under the loss modulus curves can expose the different damping behavior exhibited by the nanocomposites . The area values demonstrate the material's ability to convert mechanical energy into heat through molecular motion .…”

A quantitative analysis tool for quality assessment of nanocomposite masterbatches

“…14,15,[24][25][26][27][28][29][30][31] Additionally, it has been demonstrated that this method may bring very high accuracy for the analysis of systems with high amounts of large agglomeration which is commonly found in masterbatches. 5,22 Therefore, this new approach is likely to be highly effective for use with two-step processes and practical for various sample preparation procedures for optical microscopy making it broadly applicable for industry assessment.…”

“…A popular process aimed to improve the industry friendliness of nanocomposite manufacturing involves dividing the manufacturing process into two steps: step one creates a well dispersed nanocomposite commonly named a masterbatch and the second step distributes and/or dilutes the masterbatch with the neat polymer to achieve the final nanocomposite at a desired loading. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] There are several benefits to industry with this two-step process: (1) the dispersion of the nanofiller can be handled separately from the distribution meaning current polymer production equipment can be used for the second step, (2) the manufacturing is practical for high volume industry processes, and (3) safety is increased for the second step because nanofillers do not need to be directly handled in their nano-form. Masterbatches are already commercially available for several polymer and nanofiller combinations, but there are no published methods or standards for assessing masterbatch quality.…”

“…To date, if a study is demonstrating the effectiveness of a two-step masterbatch process, the studies generally assume that the masterbatch has good dispersion and no assessment is performed on the masterbatch. [1][2][3][4][5] Through characterization of the final composites, it is normally shown that the two-step process yields improved dispersion over a one-step process where the polymer and nanofiller are directly added together during composite processing. 5 In this way it is demonstrated that starting with a well dispersed masterbatch improved the quality of the final composite versus a traditional one-step method.…”