SQL & PL/SQL :: Variable Value Not Displaying Inside Loop

I have below peice of SQL,Im trying to form the P_attribute1 value by using the Loop index(i) but the P_attribute1 value which i assigned in declaration not displaying in the output.

DECLARE P_attribute1 VARCHAR2(100) := '110000027';
P_attribute VARCHAR2(100);
l_cnt NUMBER := 10;
v_buffer VARCHAR2(500);
v_buffer1 VARCHAR2(500);
BEGIN
FOR i IN 1 .. l_cnt
LOOP
v_buffer := v_buffer || '' || 'P_attribute' || i || '' || '!';
END LOOP;
dbms_output.put_line('v_buffer :' || v_buffer);
END;
v_buffer :P_attribute1!P_attribute2!P_attribute3!P_attribute4!P_attribute5!P_attribute6!P_attribute7!P_attribute8!P_attribute9!P_attribute10!