## 4 Synthesis and Characterizations of Ball Milled Variants
### Synthesis of Polymer Nanocomposites  
Ball milling in polymers helps in the chemical transformation of many block polymers under mechanical agitation even without the presence of solvents. The most common method of mechanical alloying is via the wet milling process, where the polymer is dispersed/dissolved in the solvent [97]. [PERSON] et al. [98] reported the production of nanocomposites using poly(vinylidene fluoride) (PVDF) by high energy ball milling and subsequent hot pressing. The pulverization was carried out under cryogenic conditions for an hour with intermittent breaks. This allowed homogenous dispersion of barium titanate  
Figure 11: Hysteresis loop of SmCo\({}_{5}\)/\(\alpha\)-Fe magnetic nanocomposites [96]. (License obtained to use this Figure from Elsevier Publications, Journal of Magnetism and Magnetic Materials).  
Figure 10: XRD patterns of (**a**) La-doped SmCo\({}_{5}\)/\(\alpha\)-Fe (**b**) Ce-doped SmCo\({}_{5}\)/\(\alpha\)-Fe at different annealing temperatures [96]. (License obtained to use this Figure from Elsevier Publications, Journal of Magnetism and Magnetic Materials).  
and MWCNTs into the polymer matrix, which enhanced the permittivity and decreased the dielectric loss of PVDF without compromising the piezoelectric characteristics. [PERSON] et al. synthesized Ca\({}^{2+}\)-Zr\({}^{4+}\) doped BaTiO\({}_{3}\) and checked the effects of high energy mechanical milling on the hysteresis and dielectric behavior of these ferroelectric materials [99]. The authors observed interesting results on PE hysteresis loops and dielectric parameters via high energy mechanical milling for various duration with respect to particle sizes of the treated specimens.  
[PERSON] et al. [100] developed a one-pot in situ method for the synthesis of polymer/graphene composite with the support of wet ball milling and hot pressing. The solution of ultrasonicated maleic anhydride grafted poly (ethylene-co-vinyl acetate) and graphene was subjected to ball milling for 30 h at a speed of 300 rpm. The decomposition temperature of the polymer nanocomposite was found to be much higher.  
Physical and chemical modifications enhance the physicochemical properties of starch by controlling its microstructure [101]. [PERSON] et al. [102] developed starch nanocrystal by mechanical alloying pretreatment to prevent it from damage during the hydrolysis process. The pre-treated starch nanocrystal was then hydrolyzed using sulfuric acid. The hydrolysis took less time and produced a higher yield as a function of time duration of milling, as shown in Figure 12.  
In a work by [PERSON] et al. [103], the hexagonal boron nitride and the polydopamine solution were mixed ball milled at 400 rpm for 24 h; further cellulose nanocrystal was added obtaining higher thermal conductivity as shown in Figure 13. [PERSON] et al. [104] examined the interfacial interaction and mechanical properties of PBT/nano-Sb\({}_{2}\)O\({}_{3}\) composites. Poly(butylene terephthalate) (PBT) and the additives were first dispersed by a high-speed rotating (HSR) mixer before being introduced into the planetary ball mill and milled at 300 rpm for 6 h. Homogenous dispersion of nanofiller in the polymer was obtained by high energy ball milling (HEBM) as compared to the high-speed rotating mixer as evident from Figure 14. Moreover, it exhibits good interfacial interactions which improved the mechanical strength of the nanocomposite. In the successive studies by [PERSON] et al. [105], preparation of PBT/nano-Sb\({}_{2}\)O\({}_{3}\) composites by high-energy ball milling (at 400 rpm for 6 h) and subsequent melt blending process could observe an improvement in the flammability and mechanical properties.  
Figure 12: The yield % of hydrolyzed starches as a function of ball milling times (0, 30 and 45 min) during the 1–5 days of hydrolysis’s period [102]. (RightsLink License obtained to use this Figure from CCC, Copyright Clearance Center, Carbohydrate Polymers).