Effect of hotpress tool temperature on physical, thermal, and mechanical properties of polyphenylene sulfide composite

• Main Author: Sharif, Emy Aqillah
• Format: Thesis
• Language: English; English
• Published: 2025
• Subjects: T Technology; TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utem.edu.my/id/eprint/29375/

This study investigates the influence of hot press tooling temperature on cooling rates and examines how these rates impact the physical, thermal and mechanical properties of carbon fiber-reinforced polyphenylene sulfide (CF/PPS) composites. CF/PPS composites are increasingly used in aerospace applications due to their high-to-weight ratio, chemical resistance and recyclability. The research focuses on understanding how different tool temperatures of 150°C, 170°C, 180°C, and 195°C during the hot press forming process affect key properties of the composite material. Test panels were fabricated using six plies of 5- harness CF/PPS pre-consolidated laminates with a [(0,90)/(±45)/(0,90)]s stacking sequence. Physical characterization involved determining the surface energy through the sessile drop method and void content (Vc) via acid digestion by following the EN2564 standard. Mechanical properties including flexural and tensile strengths were evaluated using universal testing machine (UTM) by following the EN2562 and EN2561 standards respectively. The degree of crystallinity (DoC) was analysed through differential scanning calorimetry (DSC) to assess thermal properties. The results indicate that increasing tool temperature improves the DoC and enhances mechanical properties up to an optimal temperature of 180°C. At this tool temperature, the composite exhibited the highest flexural and tensile strengths as well as minimal void content. However, further increasing the tool temperature to 195°C led to slight degradation in material properties, likely due to excessive resin flow and potential thermal degradation. To strenghen the findings, morphological analysis was conducted by using Scanning Electron Microscopy (SEM). Fractured tensile samples of CF/PPS after hot press forming process were investigated to observe the interfacial bonding between carbon fibres and polyphenylene sulfide. Lastly, a strong correlation was determined in order to analyse the relationship between cooling rate, crystallinity and mechanical performance by using SPSS software. The correlation revealed strong relationships, notably a significant negative correlation between cooling rate and flexural strength, indicating that faster cooling tends to reduce the material's flexural performance. Furthermore, a very strong inverse relationship was observed between void content and degree of crystallinity, alongside strong positive intercorrelations among surface energy, degree of crystallinity, tensile strength, and flexural strength. These findings provide beneficial input for optimizing the hot press forming process to achieve superior CF/PPS composites for aerospace applications.