Shear thickening fluid (STF) impregnated 3D E-glass fabric is evaluated for its cushioning, yarn pull-out, and flexibility using chemically modified polyethylene glycol (PEG 400). By extending the chain length of PEG with hexamethylene diisocyanate, citric acid, and adipic acid, H-STF, C-STF, and A-STF were produced, respectively. FTIR confirmed chemical modification. PEG chemical modification boosted H-bonding between STF and particles, increasing critical viscosity compared to pure STF (P-STF). A drop-weight testing machine examined the impact time duration and maximum force of two, five, and seven-layer samples. The graph widens (increases time) as the number of layers increases and peak force decreases. The A-STF/fabric composite's impact time was 2.07, 1.59, 1.39, and 1.12 times that of neat fabric, P-STF/fabric, H-STF/fabric, and C-STF/fabric, respectively. The A-STF/fabric composite's peak force was 2.30, 1.78, 1.37, and 1.15 times that of neat fabric, P-STF/fabric, H-STF/fabric, and C-STF/fabric, respectively. P-STF/fabric, A-STF/fabric, C-STF/fabric, and H-STF/fabric required 3.55, 3.10, 2.52, and 2.14 times the yarn pull-out force of neat fabric. As a result of the PEG modifications, composites performed significantly better in energy absorption and cushion performance when compared to conventional STF impregnated fabric.