**2. Manufacture of the final product with LATP/LAFP technology**

The steps for the production of a quality final product in this process are given in **Figure 1**; in each subchapter, all the steps are elaborated in more detail.

#### **2.1 Selection of raw material UD thermoplastic prepreg**

A very important process parameter is the material used in LATP/LAFP processes. The production process for obtaining composites from thermoplastic materials mainly depends on the viscosity of the resin and therefore, impregnation is very

*Unidirectional Carbon Fiber Reinforced Thermoplastic Tape in Automated Tape Placement… DOI: http://dx.doi.org/10.5772/intechopen.101110*

**Figure 1.**

*Procedure for making a quality product with LATP technology.*

important in the processing of thermoplastic materials, that is, the characteristics of the raw material. The characteristics of the thermoplastic prepreg determined by the content of pores, volume fraction of fibers, degree of wetting of the fibers, uniformity, surface roughness, etc. determine the potential of the process. In order to make a suitable and good quality product from thermoplastic prepreg, the first thing that needs to be done is to look for suitable raw material. Thermoplastic tapes, for the purposes of this LATP/LAFP process, consist of unidirectionally aligned carbon fiber tows in widths of up to 12 inches/305 mm, prepregged with a thermoplastic resin. The resins most commonly used in aerospace and other high-performance applications are the following high-performance thermoplastics—polyether ketone ketone (PEKK), polyether ether ketone (PEEK), polyaryl ether ketone (PAEK), polyphenylene sulfide (PPS), and polyetherimide (PEI). Some manufacturers offer tapes prepregged with commodity thermoplastic resins, such as polyamide (PA6), polyether sulfone (*PES* or PESU), polypropylene (PP), and others, but these are generally considered unsuitable for large aerostructures.

Thermoset tapes are available in widths of up to 60 inches/1524 mm and can go thousands of meters without a defect, while thermoplastic tapes typically top out at 12 inches/305 mm and show as many as 30 defects in just 210 m ft. It is because the thermoplastic UD prepregs rely on a powder-based application process that is more difficult to control and can create resin-rich and dry areas. Such nonuniformity can lead to problematic interplay porosity.

Some materials used in this technology from different manufacturers are given in the **Table 1** and **Figure 2**.

The key point is that high-quality tapes, with low void content, are an enabler of fast, automated processing of high-quality composites. Tapes with high levels of voids will require longer consolidation cycles to produce high-quality parts. Today there are several manufacturers of thermoplastic UD tapes, such as Suprem,


#### **Table 1.**

*UD tape thermoplastic prepreg from different suppliers for LATP/LAFP.*

Barrday, Tejlin (Toho Tenax), Toray advanced composite (Tan Cate), Solvay, Celstrane, etc. They all offer different thermoplastic tapes as mentioned above with different matrices and of course with different carbon fibers (**Figure 2**). So, before

*Unidirectional Carbon Fiber Reinforced Thermoplastic Tape in Automated Tape Placement… DOI: http://dx.doi.org/10.5772/intechopen.101110*

**Figure 2.**

*Materials for LATP/LAFP technology suppliers for UD thermoplastic prepreg.*

we start making the part, we need to know what type of fiber we need and which matrix (depending on which characteristics the final product we want to get). After determining the type of fibers and the matrix, the next step is to procure materials from several manufacturers. After that, the second phase of quality control of the raw material begins.
