 Solution

Taking the stated melting point as the reference for a crystallizable A, introducing acetate-bearing units disrupts regular sequences and crystal packing. The expected result is a lower melting point for B, often with broader or less complete crystallization. The ideal copolymer melting-point depression estimate iswhen unlike units are excluded from the crystal. The larger vinyl ester in the drawing is vinyl pentanoate: its acyl substituent has a four-carbon alkyl chain. At comparable incorporation it should generally disrupt regular packing more and favour a still lower melting range or suppressed crystallinity, although the exact trend depends on composition and side-group interactions. The formula concerns melting of crystallites, not the glass transition; a universal numerical melting point cannot be inferred for an unspecified real PVC copolymer.