50 Years of the K-BKZ Constitutive Relation for Polymers

Table 1

Relaxation spectra and material constants for two polymer melts obeying the K-BKZ model: LDPE at 160°C [45] and HDPE at 190°C [46].

LDPE				HDPE
𝛼=7.336,𝜃=0				𝛼=10.15,𝜃=0
k	𝜆𝑘 (s)	𝑎𝑘 (Pa)	𝛽𝑘	k	𝜆𝑘 (s)	𝑎𝑘 (Pa)	𝛽𝑘
1	1.28 × 10^−4	4.50 × 10^5	1	1	0.537 × 10^−8	0.236 × 10^9	0.6
2	2.51 × 10^−3	98,795	1	2	0.782 × 10^−5	0.576 × 10^7	0.6
3	2.06 × 10^−2	48,899	0.18	3	0.263 × 10^−2	99,508	0.6
4	1.62 × 10^−1	22,089	0.45	4	0.10591	92,960	0.6
5	1.224	8,842	0.049	5	0.168 × 10^−1	0.104 × 10^6	0.6
6	6.733	3,397	0.026	6	0.70421	46,958	0.6
7	43	948.5	0.024	7	4.2105	12,169	0.6
8	248	287	0.014	8	30.494	1,438.6	0.6