??????????? (????) ??????? ??? ??????
1.2g / cm 3 dens ??????? ???? ??????????? (PC) ??? 1950 ????? ?? ????? ?? ?????? ?? ?? ??? ?????? ???????? ?????????? ???????. ??? ??????? ????????? ??????????????? ???????? ??????????? ????? ?????? ??.
????? ??? ?????????? ????????
(1) ?????? ?????? ????????
30 ~ 130 of ? ??????? ??????, ?????????? ????????? ??? ?????, ???????? ??????? ????? ?? ???, PC ????????? ???? ?????? ????? ??, ?????? ??? ?????? ????????? ?????????? ????? ???? ??????? ?????? ?? ???? ?? ????? ????.
(2) ??? ?????????? ??????
????? ??? ????? ??? ?????? ???????????? ?? ??? ?????????????????? ??, ??? ???????? ??????? ????? 60N / mm ??? ??, ?? ?? ??? ??????? ?????? ?????????? ?????????? ??, ??????? ?? ?????? ??????? ???? ????????, ??? ??????? ???? ??????? ?? ????????? ???? ?????? ?????? ????? ???? ??? ??????????? ???????? ?????.
(3) ???????? ??????? ????????? ???? ???????
????? ??? ??? ?????? ????? ???????? ???? ???? ??? ?????? ?????????? ????? ???? ?????? ?? ???? ?????? ???????? ??? ?? ?????; ? ???? ??? ?????? ??????????? ??? ????? ???, ????? ????? ??? ????????? ??? ??? ??? ????????? ?????? ??. ????, ??????? ???????? ???? ?????? ?.
(4) ??????? ??????????
???? ?????, ?????? ????, ????????? ?? ????????? ???? ??? ?? ???? ????? ?????. ??? ?????, ??????????? ????? ??? ??????? ????????, ???? ????, ??? ????????????? ?? ??? ???????????? ??. ?????? ?? ????? ????????? ???????? ????? ?????? ????? ???? ?????? ?? ?????. ??????????, ??????? ?????????? ?? ????????? ??????????, ???? ???? ?????????? ?? ????? ?????.