$A$	Corresponding proportion coefficient
$B$	Corresponding proportion coefficient
$C$	Corresponding proportion coefficient
$D$	Corresponding proportion coefficient
$E$	Corresponding proportion coefficient
$m_c$	Material total mass of the foaming start without PBA, g
$m_d$	The PBA dissolution mass, g
$m_e$	The PBA efficiency mass, g
$m_l$	The PBA mass loss, g
$m_{PBA}$	The PBA mass in the material total mass, g
$Q_d$	The heat absorbing by PBA dissolution mass, J
$Q_e$	The heat absorbing by PBA efficiency mass, J
$Q_l$	The heat absorbing by PBA mass loss, J
$Q_m$	The heat absorbed per unit mass of PBA, J·g−1
$Q_{PBA}$	The total heat absorbing by PBA during the foaming process, J
$R$	Gas constant, J·mol−1·K−1
$r_{PBA}$	The ratio of each PBA’s three states to the total mass of PBAs used, %
$r_{dPBA}$	The dissolution rate of PBA relative to the total moles of PBA used, %
$r_{dT}$	The dissolution rate of PBA relative to the total mass of materials used, wt%
$r_{ePBA}$	The efficiency rate of PBA relative to the total moles of PBA used, %
$r_{eT}$	The efficiency rate of PBA relative to the total mass of materials used, wt%
$r_{lPBA}$	The loss rate of PBA relative to the total moles of PBA used, %
$r_{lT}$	The loss rate of PBA relative to the total mass of materials used, wt%
$r_T$	The ratio of the three states of each PBA relative to the total amount of material used, wt%
$T_0$	The initial foaming temperature, K
$T_1$	The temperature of PBA at the surface escape, K
$T_r$	Contrast temperature
$T_{r1}$	Contrast temperature in the state of “1”
$T_{r2}$	Contrast temperature in the state of “2”
$T_F$	Temperature inside foam when it stops expanding, K
$w$	The initial mass content of PBA in PU materials, wt%
$Z$	Compressibility factor
$\omega$	Eccentricity factor
$\gamma$	The latent heat of vaporization of PBA at the temperature $T_0$, J·g−1
$(\mathsf{\Delta }{h}_v{)}_1$	Enthalpy changes in the state of “1”, J·g−1
$(\mathsf{\Delta }{h}_v{)}_2$	Enthalpy changes in the state of “2”, J·g−1
$C_{g0}$	Specific heat capacity of PBA gas at the temperature of $T_0$, J·g−1·K−1
$C_{g1}$	Specific heat capacity of PBA gas at the temperature of $T_1$, J·g−1·K−1
$C_{gF}$	Specific heat capacity of PBA gas at the temperature of $T_F$, J·g−1·K−1
$C_{L0}$	Liquid specific heat capacity of PBA at the temperature of $T_0$, J·g−1·K−1
$C_{LF}$	Liquid specific heat capacity of PBA at the temperature of $T_F$, J·g−1·K−1
$C_p$	Specific heat capacity at constant pressure for PBA in the liquid state, J·g−1·K−1
$C_{p0}$	Liquid specific heat capacity of PBA at temperature $T_0$, J·g−1·K−1
$C_p^{\prime }$	Specific heat capacity at constant pressure for PBA in its ideal gas state, J·g−1·K−1
$C_{p0}^{\prime }$	Ideal gas specific heat capacity of PBA at temperature $T_0$, J·g−1·K−1
$C_{pF}$	Liquid specific heat capacity of PBA at temperature $T_F$, J·g−1·K−1
$C_{pF}^{\prime }$	Ideal gas specific heat capacity of PBA at temperature $T_F$, J·g−1·K−1